Merge bmake-20210206

[FreeBSD/FreeBSD.git] / contrib / bmake / job.c

/*      $NetBSD: job.c,v 1.420 2021/02/05 22:15:44 sjg Exp $    */

/*
 * Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Adam de Boor.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Copyright (c) 1988, 1989 by Adam de Boor
 * Copyright (c) 1989 by Berkeley Softworks
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Adam de Boor.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * job.c --
 *      handle the creation etc. of our child processes.
 *
 * Interface:
 *      Job_Init        Called to initialize this module. In addition,
 *                      the .BEGIN target is made including all of its
 *                      dependencies before this function returns.
 *                      Hence, the makefiles must have been parsed
 *                      before this function is called.
 *
 *      Job_End         Clean up any memory used.
 *
 *      Job_Make        Start the creation of the given target.
 *
 *      Job_CatchChildren
 *                      Check for and handle the termination of any
 *                      children. This must be called reasonably
 *                      frequently to keep the whole make going at
 *                      a decent clip, since job table entries aren't
 *                      removed until their process is caught this way.
 *
 *      Job_CatchOutput
 *                      Print any output our children have produced.
 *                      Should also be called fairly frequently to
 *                      keep the user informed of what's going on.
 *                      If no output is waiting, it will block for
 *                      a time given by the SEL_* constants, below,
 *                      or until output is ready.
 *
 *      Job_ParseShell  Given a special dependency line with target '.SHELL',
 *                      define the shell that is used for the creation
 *                      commands in jobs mode.
 *
 *      Job_Finish      Perform any final processing which needs doing.
 *                      This includes the execution of any commands
 *                      which have been/were attached to the .END
 *                      target. It should only be called when the
 *                      job table is empty.
 *
 *      Job_AbortAll    Abort all currently running jobs. Do not handle
 *                      output or do anything for the jobs, just kill them.
 *                      Should only be called in an emergency.
 *
 *      Job_CheckCommands
 *                      Verify that the commands for a target are
 *                      ok. Provide them if necessary and possible.
 *
 *      Job_Touch       Update a target without really updating it.
 *
 *      Job_Wait        Wait for all currently-running jobs to finish.
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <sys/time.h>
#include "wait.h"

#include <errno.h>
#if !defined(USE_SELECT) && defined(HAVE_POLL_H)
#include <poll.h>
#else
#ifndef USE_SELECT                      /* no poll.h */
# define USE_SELECT
#endif
#if defined(HAVE_SYS_SELECT_H)
# include <sys/select.h>
#endif
#endif
#include <signal.h>
#include <utime.h>
#if defined(HAVE_SYS_SOCKET_H)
# include <sys/socket.h>
#endif

#include "make.h"
#include "dir.h"
#include "job.h"
#include "pathnames.h"
#include "trace.h"

/*      "@(#)job.c      8.2 (Berkeley) 3/19/94" */
MAKE_RCSID("$NetBSD: job.c,v 1.420 2021/02/05 22:15:44 sjg Exp $");

/*
 * A shell defines how the commands are run.  All commands for a target are
 * written into a single file, which is then given to the shell to execute
 * the commands from it.  The commands are written to the file using a few
 * templates for echo control and error control.
 *
 * The name of the shell is the basename for the predefined shells, such as
 * "sh", "csh", "bash".  For custom shells, it is the full pathname, and its
 * basename is used to select the type of shell; the longest match wins.
 * So /usr/pkg/bin/bash has type sh, /usr/local/bin/tcsh has type csh.
 *
 * The echoing of command lines is controlled using hasEchoCtl, echoOff,
 * echoOn, noPrint and noPrintLen.  When echoOff is executed by the shell, it
 * still outputs something, but this something is not interesting, therefore
 * it is filtered out using noPrint and noPrintLen.
 *
 * The error checking for individual commands is controlled using hasErrCtl,
 * errOn, errOff and runChkTmpl.
 *
 * In case a shell doesn't have error control, echoTmpl is a printf template
 * for echoing the command, should echoing be on; runIgnTmpl is another
 * printf template for executing the command while ignoring the return
 * status. Finally runChkTmpl is a printf template for running the command and
 * causing the shell to exit on error. If any of these strings are empty when
 * hasErrCtl is FALSE, the command will be executed anyway as is, and if it
 * causes an error, so be it. Any templates set up to echo the command will
 * escape any '$ ` \ "' characters in the command string to avoid unwanted
 * shell code injection, the escaped command is safe to use in double quotes.
 *
 * The command-line flags "echo" and "exit" also control the behavior.  The
 * "echo" flag causes the shell to start echoing commands right away.  The
 * "exit" flag causes the shell to exit when an error is detected in one of
 * the commands.
 */
typedef struct Shell {

        /*
         * The name of the shell. For Bourne and C shells, this is used only
         * to find the shell description when used as the single source of a
         * .SHELL target. For user-defined shells, this is the full path of
         * the shell.
         */
        const char *name;

        Boolean hasEchoCtl;     /* whether both echoOff and echoOn are there */
        const char *echoOff;    /* command to turn echoing off */
        const char *echoOn;     /* command to turn echoing back on */
        const char *noPrint;    /* text to skip when printing output from the
                                 * shell. This is usually the same as echoOff */
        size_t noPrintLen;      /* length of noPrint command */

        Boolean hasErrCtl;      /* whether error checking can be controlled
                                 * for individual commands */
        const char *errOn;      /* command to turn on error checking */
        const char *errOff;     /* command to turn off error checking */

        const char *echoTmpl;   /* template to echo a command */
        const char *runIgnTmpl; /* template to run a command
                                 * without error checking */
        const char *runChkTmpl; /* template to run a command
                                 * with error checking */

        /* string literal that results in a newline character when it appears
         * outside of any 'quote' or "quote" characters */
        const char *newline;
        char commentChar;       /* character used by shell for comment lines */

        const char *echoFlag;   /* shell flag to echo commands */
        const char *errFlag;    /* shell flag to exit on error */
} Shell;

typedef struct CommandFlags {
        /* Whether to echo the command before or instead of running it. */
        Boolean echo;

        /* Run the command even in -n or -N mode. */
        Boolean always;

        /*
         * true if we turned error checking off before printing the command
         * and need to turn it back on
         */
        Boolean ignerr;
} CommandFlags;

/*
 * Write shell commands to a file.
 *
 * TODO: keep track of whether commands are echoed.
 * TODO: keep track of whether error checking is active.
 */
typedef struct ShellWriter {
        FILE *f;

        /* we've sent 'set -x' */
        Boolean xtraced;

} ShellWriter;

/*
 * FreeBSD: traditionally .MAKE is not required to
 * pass jobs queue to sub-makes.
 * Use .MAKE.ALWAYS_PASS_JOB_QUEUE=no to disable.
 */
#define MAKE_ALWAYS_PASS_JOB_QUEUE ".MAKE.ALWAYS_PASS_JOB_QUEUE"
static int Always_pass_job_queue = TRUE;
/*
 * FreeBSD: aborting entire parallel make isn't always
 * desired. When doing tinderbox for example, failure of
 * one architecture should not stop all.
 * We still want to bail on interrupt though.
 */
#define MAKE_JOB_ERROR_TOKEN "MAKE_JOB_ERROR_TOKEN"
static int Job_error_token = TRUE;

/*
 * error handling variables
 */
static int job_errors = 0;      /* number of errors reported */
typedef enum AbortReason {      /* why is the make aborting? */
        ABORT_NONE,
        ABORT_ERROR,            /* Because of an error */
        ABORT_INTERRUPT,        /* Because it was interrupted */
        ABORT_WAIT              /* Waiting for jobs to finish */
        /* XXX: "WAIT" is not a _reason_ for aborting, it's rather a status. */
} AbortReason;
static AbortReason aborting = ABORT_NONE;
#define JOB_TOKENS "+EI+"       /* Token to requeue for each abort state */

/*
 * this tracks the number of tokens currently "out" to build jobs.
 */
int jobTokensRunning = 0;

typedef enum JobStartResult {
        JOB_RUNNING,            /* Job is running */
        JOB_ERROR,              /* Error in starting the job */
        JOB_FINISHED            /* The job is already finished */
} JobStartResult;

/*
 * Descriptions for various shells.
 *
 * The build environment may set DEFSHELL_INDEX to one of
 * DEFSHELL_INDEX_SH, DEFSHELL_INDEX_KSH, or DEFSHELL_INDEX_CSH, to
 * select one of the predefined shells as the default shell.
 *
 * Alternatively, the build environment may set DEFSHELL_CUSTOM to the
 * name or the full path of a sh-compatible shell, which will be used as
 * the default shell.
 *
 * ".SHELL" lines in Makefiles can choose the default shell from the
 * set defined here, or add additional shells.
 */

#ifdef DEFSHELL_CUSTOM
#define DEFSHELL_INDEX_CUSTOM 0
#define DEFSHELL_INDEX_SH     1
#define DEFSHELL_INDEX_KSH    2
#define DEFSHELL_INDEX_CSH    3
#else /* !DEFSHELL_CUSTOM */
#define DEFSHELL_INDEX_SH     0
#define DEFSHELL_INDEX_KSH    1
#define DEFSHELL_INDEX_CSH    2
#endif /* !DEFSHELL_CUSTOM */

#ifndef DEFSHELL_INDEX
#define DEFSHELL_INDEX 0        /* DEFSHELL_INDEX_CUSTOM or DEFSHELL_INDEX_SH */
#endif /* !DEFSHELL_INDEX */

static Shell shells[] = {
#ifdef DEFSHELL_CUSTOM
    /*
     * An sh-compatible shell with a non-standard name.
     *
     * Keep this in sync with the "sh" description below, but avoid
     * non-portable features that might not be supplied by all
     * sh-compatible shells.
     */
    {
        DEFSHELL_CUSTOM,        /* .name */
        FALSE,                  /* .hasEchoCtl */
        "",                     /* .echoOff */
        "",                     /* .echoOn */
        "",                     /* .noPrint */
        0,                      /* .noPrintLen */
        FALSE,                  /* .hasErrCtl */
        "",                     /* .errOn */
        "",                     /* .errOff */
        "echo \"%s\"\n",        /* .echoTmpl */
        "%s\n",                 /* .runIgnTmpl */
        "{ %s \n} || exit $?\n", /* .runChkTmpl */
        "'\n'",                 /* .newline */
        '#',                    /* .commentChar */
        "",                     /* .echoFlag */
        "",                     /* .errFlag */
    },
#endif /* DEFSHELL_CUSTOM */
    /*
     * SH description. Echo control is also possible and, under
     * sun UNIX anyway, one can even control error checking.
     */
    {
        "sh",                   /* .name */
        FALSE,                  /* .hasEchoCtl */
        "",                     /* .echoOff */
        "",                     /* .echoOn */
        "",                     /* .noPrint */
        0,                      /* .noPrintLen */
        FALSE,                  /* .hasErrCtl */
        "",                     /* .errOn */
        "",                     /* .errOff */
        "echo \"%s\"\n",        /* .echoTmpl */
        "%s\n",                 /* .runIgnTmpl */
        "{ %s \n} || exit $?\n", /* .runChkTmpl */
        "'\n'",                 /* .newline */
        '#',                    /* .commentChar*/
#if defined(MAKE_NATIVE) && defined(__NetBSD__)
        /* XXX: -q is not really echoFlag, it's more like noEchoInSysFlag. */
        "q",                    /* .echoFlag */
#else
        "",                     /* .echoFlag */
#endif
        "",                     /* .errFlag */
    },
    /*
     * KSH description.
     */
    {
        "ksh",                  /* .name */
        TRUE,                   /* .hasEchoCtl */
        "set +v",               /* .echoOff */
        "set -v",               /* .echoOn */
        "set +v",               /* .noPrint */
        6,                      /* .noPrintLen */
        FALSE,                  /* .hasErrCtl */
        "",                     /* .errOn */
        "",                     /* .errOff */
        "echo \"%s\"\n",        /* .echoTmpl */
        "%s\n",                 /* .runIgnTmpl */
        "{ %s \n} || exit $?\n", /* .runChkTmpl */
        "'\n'",                 /* .newline */
        '#',                    /* .commentChar */
        "v",                    /* .echoFlag */
        "",                     /* .errFlag */
    },
    /*
     * CSH description. The csh can do echo control by playing
     * with the setting of the 'echo' shell variable. Sadly,
     * however, it is unable to do error control nicely.
     */
    {
        "csh",                  /* .name */
        TRUE,                   /* .hasEchoCtl */
        "unset verbose",        /* .echoOff */
        "set verbose",          /* .echoOn */
        "unset verbose",        /* .noPrint */
        13,                     /* .noPrintLen */
        FALSE,                  /* .hasErrCtl */
        "",                     /* .errOn */
        "",                     /* .errOff */
        "echo \"%s\"\n",        /* .echoTmpl */
        "csh -c \"%s || exit 0\"\n", /* .runIgnTmpl */
        "",                     /* .runChkTmpl */
        "'\\\n'",               /* .newline */
        '#',                    /* .commentChar */
        "v",                    /* .echoFlag */
        "e",                    /* .errFlag */
    }
};

/*
 * This is the shell to which we pass all commands in the Makefile.
 * It is set by the Job_ParseShell function.
 */
static Shell *shell = &shells[DEFSHELL_INDEX];
const char *shellPath = NULL;   /* full pathname of executable image */
const char *shellName = NULL;   /* last component of shellPath */
char *shellErrFlag = NULL;
static char *shell_freeIt = NULL; /* Allocated memory for custom .SHELL */


static Job *job_table;          /* The structures that describe them */
static Job *job_table_end;      /* job_table + maxJobs */
static unsigned int wantToken;  /* we want a token */
static Boolean lurking_children = FALSE;
static Boolean make_suspended = FALSE; /* Whether we've seen a SIGTSTP (etc) */

/*
 * Set of descriptors of pipes connected to
 * the output channels of children
 */
static struct pollfd *fds = NULL;
static Job **jobByFdIndex = NULL;
static nfds_t fdsLen = 0;
static void watchfd(Job *);
static void clearfd(Job *);
static Boolean readyfd(Job *);

static char *targPrefix = NULL; /* To identify a job change in the output. */
static Job tokenWaitJob;        /* token wait pseudo-job */

static Job childExitJob;        /* child exit pseudo-job */
#define CHILD_EXIT "."
#define DO_JOB_RESUME "R"

enum {
        npseudojobs = 2         /* number of pseudo-jobs */
};

static sigset_t caught_signals; /* Set of signals we handle */
static volatile sig_atomic_t caught_sigchld;

static void JobDoOutput(Job *, Boolean);
static void JobInterrupt(Boolean, int) MAKE_ATTR_DEAD;
static void JobRestartJobs(void);
static void JobSigReset(void);

static void
SwitchOutputTo(GNode *gn)
{
        /* The node for which output was most recently produced. */
        static GNode *lastNode = NULL;

        if (gn == lastNode)
                return;
        lastNode = gn;

        if (opts.maxJobs != 1 && targPrefix != NULL && targPrefix[0] != '\0')
                (void)fprintf(stdout, "%s %s ---\n", targPrefix, gn->name);
}

static unsigned
nfds_per_job(void)
{
#if defined(USE_FILEMON) && !defined(USE_FILEMON_DEV)
        if (useMeta)
                return 2;
#endif
        return 1;
}

void
Job_FlagsToString(const Job *job, char *buf, size_t bufsize)
{
        snprintf(buf, bufsize, "%c%c%c",
            job->ignerr ? 'i' : '-',
            !job->echo ? 's' : '-',
            job->special ? 'S' : '-');
}

static void
job_table_dump(const char *where)
{
        Job *job;
        char flags[4];

        debug_printf("job table @ %s\n", where);
        for (job = job_table; job < job_table_end; job++) {
                Job_FlagsToString(job, flags, sizeof flags);
                debug_printf("job %d, status %d, flags %s, pid %d\n",
                    (int)(job - job_table), job->status, flags, job->pid);
        }
}

/*
 * Delete the target of a failed, interrupted, or otherwise
 * unsuccessful job unless inhibited by .PRECIOUS.
 */
static void
JobDeleteTarget(GNode *gn)
{
        const char *file;

        if (gn->type & OP_JOIN)
                return;
        if (gn->type & OP_PHONY)
                return;
        if (Targ_Precious(gn))
                return;
        if (opts.noExecute)
                return;

        file = GNode_Path(gn);
        if (eunlink(file) != -1)
                Error("*** %s removed", file);
}

/*
 * JobSigLock/JobSigUnlock
 *
 * Signal lock routines to get exclusive access. Currently used to
 * protect `jobs' and `stoppedJobs' list manipulations.
 */
static void
JobSigLock(sigset_t *omaskp)
{
        if (sigprocmask(SIG_BLOCK, &caught_signals, omaskp) != 0) {
                Punt("JobSigLock: sigprocmask: %s", strerror(errno));
                sigemptyset(omaskp);
        }
}

static void
JobSigUnlock(sigset_t *omaskp)
{
        (void)sigprocmask(SIG_SETMASK, omaskp, NULL);
}

static void
JobCreatePipe(Job *job, int minfd)
{
        int i, fd, flags;
        int pipe_fds[2];

        if (pipe(pipe_fds) == -1)
                Punt("Cannot create pipe: %s", strerror(errno));

        for (i = 0; i < 2; i++) {
                /* Avoid using low numbered fds */
                fd = fcntl(pipe_fds[i], F_DUPFD, minfd);
                if (fd != -1) {
                        close(pipe_fds[i]);
                        pipe_fds[i] = fd;
                }
        }

        job->inPipe = pipe_fds[0];
        job->outPipe = pipe_fds[1];

        /* Set close-on-exec flag for both */
        if (fcntl(job->inPipe, F_SETFD, FD_CLOEXEC) == -1)
                Punt("Cannot set close-on-exec: %s", strerror(errno));
        if (fcntl(job->outPipe, F_SETFD, FD_CLOEXEC) == -1)
                Punt("Cannot set close-on-exec: %s", strerror(errno));

        /*
         * We mark the input side of the pipe non-blocking; we poll(2) the
         * pipe when we're waiting for a job token, but we might lose the
         * race for the token when a new one becomes available, so the read
         * from the pipe should not block.
         */
        flags = fcntl(job->inPipe, F_GETFL, 0);
        if (flags == -1)
                Punt("Cannot get flags: %s", strerror(errno));
        flags |= O_NONBLOCK;
        if (fcntl(job->inPipe, F_SETFL, flags) == -1)
                Punt("Cannot set flags: %s", strerror(errno));
}

/* Pass the signal to each running job. */
static void
JobCondPassSig(int signo)
{
        Job *job;

        DEBUG1(JOB, "JobCondPassSig(%d) called.\n", signo);

        for (job = job_table; job < job_table_end; job++) {
                if (job->status != JOB_ST_RUNNING)
                        continue;
                DEBUG2(JOB, "JobCondPassSig passing signal %d to child %d.\n",
                    signo, job->pid);
                KILLPG(job->pid, signo);
        }
}

/*
 * SIGCHLD handler.
 *
 * Sends a token on the child exit pipe to wake us up from select()/poll().
 */
/*ARGSUSED*/
static void
JobChildSig(int signo MAKE_ATTR_UNUSED)
{
        caught_sigchld = 1;
        while (write(childExitJob.outPipe, CHILD_EXIT, 1) == -1 &&
               errno == EAGAIN)
                continue;
}


/* Resume all stopped jobs. */
/*ARGSUSED*/
static void
JobContinueSig(int signo MAKE_ATTR_UNUSED)
{
        /*
         * Defer sending SIGCONT to our stopped children until we return
         * from the signal handler.
         */
        while (write(childExitJob.outPipe, DO_JOB_RESUME, 1) == -1 &&
               errno == EAGAIN)
                continue;
}

/*
 * Pass a signal on to all jobs, then resend to ourselves.
 * We die by the same signal.
 */
MAKE_ATTR_DEAD static void
JobPassSig_int(int signo)
{
        /* Run .INTERRUPT target then exit */
        JobInterrupt(TRUE, signo);
}

/*
 * Pass a signal on to all jobs, then resend to ourselves.
 * We die by the same signal.
 */
MAKE_ATTR_DEAD static void
JobPassSig_term(int signo)
{
        /* Dont run .INTERRUPT target then exit */
        JobInterrupt(FALSE, signo);
}

static void
JobPassSig_suspend(int signo)
{
        sigset_t nmask, omask;
        struct sigaction act;

        /* Suppress job started/continued messages */
        make_suspended = TRUE;

        /* Pass the signal onto every job */
        JobCondPassSig(signo);

        /*
         * Send ourselves the signal now we've given the message to everyone
         * else. Note we block everything else possible while we're getting
         * the signal. This ensures that all our jobs get continued when we
         * wake up before we take any other signal.
         */
        sigfillset(&nmask);
        sigdelset(&nmask, signo);
        (void)sigprocmask(SIG_SETMASK, &nmask, &omask);

        act.sa_handler = SIG_DFL;
        sigemptyset(&act.sa_mask);
        act.sa_flags = 0;
        (void)sigaction(signo, &act, NULL);

        DEBUG1(JOB, "JobPassSig passing signal %d to self.\n", signo);

        (void)kill(getpid(), signo);

        /*
         * We've been continued.
         *
         * A whole host of signals continue to happen!
         * SIGCHLD for any processes that actually suspended themselves.
         * SIGCHLD for any processes that exited while we were alseep.
         * The SIGCONT that actually caused us to wakeup.
         *
         * Since we defer passing the SIGCONT on to our children until
         * the main processing loop, we can be sure that all the SIGCHLD
         * events will have happened by then - and that the waitpid() will
         * collect the child 'suspended' events.
         * For correct sequencing we just need to ensure we process the
         * waitpid() before passing on the SIGCONT.
         *
         * In any case nothing else is needed here.
         */

        /* Restore handler and signal mask */
        act.sa_handler = JobPassSig_suspend;
        (void)sigaction(signo, &act, NULL);
        (void)sigprocmask(SIG_SETMASK, &omask, NULL);
}

static Job *
JobFindPid(int pid, JobStatus status, Boolean isJobs)
{
        Job *job;

        for (job = job_table; job < job_table_end; job++) {
                if (job->status == status && job->pid == pid)
                        return job;
        }
        if (DEBUG(JOB) && isJobs)
                job_table_dump("no pid");
        return NULL;
}

/* Parse leading '@', '-' and '+', which control the exact execution mode. */
static void
ParseCommandFlags(char **pp, CommandFlags *out_cmdFlags)
{
        char *p = *pp;
        out_cmdFlags->echo = TRUE;
        out_cmdFlags->ignerr = FALSE;
        out_cmdFlags->always = FALSE;

        for (;;) {
                if (*p == '@')
                        out_cmdFlags->echo = DEBUG(LOUD);
                else if (*p == '-')
                        out_cmdFlags->ignerr = TRUE;
                else if (*p == '+')
                        out_cmdFlags->always = TRUE;
                else
                        break;
                p++;
        }

        pp_skip_whitespace(&p);

        *pp = p;
}

/* Escape a string for a double-quoted string literal in sh, csh and ksh. */
static char *
EscapeShellDblQuot(const char *cmd)
{
        size_t i, j;

        /* Worst that could happen is every char needs escaping. */
        char *esc = bmake_malloc(strlen(cmd) * 2 + 1);
        for (i = 0, j = 0; cmd[i] != '\0'; i++, j++) {
                if (cmd[i] == '$' || cmd[i] == '`' || cmd[i] == '\\' ||
                    cmd[i] == '"')
                        esc[j++] = '\\';
                esc[j] = cmd[i];
        }
        esc[j] = '\0';

        return esc;
}

static void
ShellWriter_PrintFmt(ShellWriter *wr, const char *fmt, const char *arg)
{
        DEBUG1(JOB, fmt, arg);

        (void)fprintf(wr->f, fmt, arg);
        /* XXX: Is flushing needed in any case, or only if f == stdout? */
        (void)fflush(wr->f);
}

static void
ShellWriter_Println(ShellWriter *wr, const char *line)
{
        ShellWriter_PrintFmt(wr, "%s\n", line);
}

static void
ShellWriter_EchoOff(ShellWriter *wr)
{
        if (shell->hasEchoCtl)
                ShellWriter_Println(wr, shell->echoOff);
}

static void
ShellWriter_EchoCmd(ShellWriter *wr, const char *escCmd)
{
        ShellWriter_PrintFmt(wr, shell->echoTmpl, escCmd);
}

static void
ShellWriter_EchoOn(ShellWriter *wr)
{
        if (shell->hasEchoCtl)
                ShellWriter_Println(wr, shell->echoOn);
}

static void
ShellWriter_TraceOn(ShellWriter *wr)
{
        if (!wr->xtraced) {
                ShellWriter_Println(wr, "set -x");
                wr->xtraced = TRUE;
        }
}

static void
ShellWriter_ErrOff(ShellWriter *wr, Boolean echo)
{
        if (echo)
                ShellWriter_EchoOff(wr);
        ShellWriter_Println(wr, shell->errOff);
        if (echo)
                ShellWriter_EchoOn(wr);
}

static void
ShellWriter_ErrOn(ShellWriter *wr, Boolean echo)
{
        if (echo)
                ShellWriter_EchoOff(wr);
        ShellWriter_Println(wr, shell->errOn);
        if (echo)
                ShellWriter_EchoOn(wr);
}

/*
 * The shell has no built-in error control, so emulate error control by
 * enclosing each shell command in a template like "{ %s \n } || exit $?"
 * (configurable per shell).
 */
static void
JobPrintSpecialsEchoCtl(Job *job, ShellWriter *wr, CommandFlags *inout_cmdFlags,
                        const char *escCmd, const char **inout_cmdTemplate)
{
        /* XXX: Why is the job modified at this point? */
        job->ignerr = TRUE;

        if (job->echo && inout_cmdFlags->echo) {
                ShellWriter_EchoOff(wr);
                ShellWriter_EchoCmd(wr, escCmd);

                /*
                 * Leave echoing off so the user doesn't see the commands
                 * for toggling the error checking.
                 */
                inout_cmdFlags->echo = FALSE;
        } else {
                if (inout_cmdFlags->echo)
                        ShellWriter_EchoCmd(wr, escCmd);
        }
        *inout_cmdTemplate = shell->runIgnTmpl;

        /*
         * The template runIgnTmpl already takes care of ignoring errors,
         * so pretend error checking is still on.
         * XXX: What effects does this have, and why is it necessary?
         */
        inout_cmdFlags->ignerr = FALSE;
}

static void
JobPrintSpecials(Job *job, ShellWriter *wr, const char *escCmd, Boolean run,
                 CommandFlags *inout_cmdFlags, const char **inout_cmdTemplate)
{
        if (!run) {
                /*
                 * If there is no command to run, there is no need to switch
                 * error checking off and on again for nothing.
                 */
                inout_cmdFlags->ignerr = FALSE;
        } else if (shell->hasErrCtl)
                ShellWriter_ErrOff(wr, job->echo && inout_cmdFlags->echo);
        else if (shell->runIgnTmpl != NULL && shell->runIgnTmpl[0] != '\0') {
                JobPrintSpecialsEchoCtl(job, wr, inout_cmdFlags, escCmd,
                    inout_cmdTemplate);
        } else
                inout_cmdFlags->ignerr = FALSE;
}

/*
 * Put out another command for the given job.
 *
 * If the command starts with '@' and neither the -s nor the -n flag was
 * given to make, we stick a shell-specific echoOff command in the script.
 *
 * If the command starts with '-' and the shell has no error control (none
 * of the predefined shells has that), we ignore errors for the entire job.
 * XXX: Why ignore errors for the entire job?
 * XXX: Even ignore errors for the commands before this command?
 *
 * If the command is just "...", all further commands of this job are skipped
 * for now.  They are attached to the .END node and will be run by Job_Finish
 * after all other targets have been made.
 */
static void
JobPrintCommand(Job *job, ShellWriter *wr, StringListNode *ln, const char *ucmd)
{
        Boolean run;

        CommandFlags cmdFlags;
        /* Template for printing a command to the shell file */
        const char *cmdTemplate;
        char *xcmd;             /* The expanded command */
        char *xcmdStart;
        char *escCmd;           /* xcmd escaped to be used in double quotes */

        run = GNode_ShouldExecute(job->node);

        Var_Subst(ucmd, job->node, VARE_WANTRES, &xcmd);
        /* TODO: handle errors */
        xcmdStart = xcmd;

        cmdTemplate = "%s\n";

        ParseCommandFlags(&xcmd, &cmdFlags);

        /* The '+' command flag overrides the -n or -N options. */
        if (cmdFlags.always && !run) {
                /*
                 * We're not actually executing anything...
                 * but this one needs to be - use compat mode just for it.
                 */
                Compat_RunCommand(ucmd, job->node, ln);
                free(xcmdStart);
                return;
        }

        /*
         * If the shell doesn't have error control, the alternate echoing
         * will be done (to avoid showing additional error checking code)
         * and this needs some characters escaped.
         */
        escCmd = shell->hasErrCtl ? NULL : EscapeShellDblQuot(xcmd);

        if (!cmdFlags.echo) {
                if (job->echo && run && shell->hasEchoCtl) {
                        ShellWriter_EchoOff(wr);
                } else {
                        if (shell->hasErrCtl)
                                cmdFlags.echo = TRUE;
                }
        }

        if (cmdFlags.ignerr) {
                JobPrintSpecials(job, wr, escCmd, run, &cmdFlags, &cmdTemplate);
        } else {

                /*
                 * If errors are being checked and the shell doesn't have
                 * error control but does supply an runChkTmpl template, then
                 * set up commands to run through it.
                 */

                if (!shell->hasErrCtl && shell->runChkTmpl != NULL &&
                    shell->runChkTmpl[0] != '\0') {
                        if (job->echo && cmdFlags.echo) {
                                ShellWriter_EchoOff(wr);
                                ShellWriter_EchoCmd(wr, escCmd);
                                cmdFlags.echo = FALSE;
                        }
                        /*
                         * If it's a comment line or blank, avoid the possible
                         * syntax error generated by "{\n} || exit $?".
                         */
                        cmdTemplate = escCmd[0] == shell->commentChar ||
                                      escCmd[0] == '\0'
                            ? shell->runIgnTmpl
                            : shell->runChkTmpl;
                        cmdFlags.ignerr = FALSE;
                }
        }

        if (DEBUG(SHELL) && strcmp(shellName, "sh") == 0)
                ShellWriter_TraceOn(wr);

        ShellWriter_PrintFmt(wr, cmdTemplate, xcmd);
        free(xcmdStart);
        free(escCmd);

        if (cmdFlags.ignerr)
                ShellWriter_ErrOn(wr, cmdFlags.echo && job->echo);

        if (!cmdFlags.echo)
                ShellWriter_EchoOn(wr);
}

/*
 * Print all commands to the shell file that is later executed.
 *
 * The special command "..." stops printing and saves the remaining commands
 * to be executed later, when the target '.END' is made.
 *
 * Return whether at least one command was written to the shell file.
 */
static Boolean
JobPrintCommands(Job *job)
{
        StringListNode *ln;
        Boolean seen = FALSE;
        ShellWriter wr = { job->cmdFILE, FALSE };

        for (ln = job->node->commands.first; ln != NULL; ln = ln->next) {
                const char *cmd = ln->datum;

                if (strcmp(cmd, "...") == 0) {
                        job->node->type |= OP_SAVE_CMDS;
                        job->tailCmds = ln->next;
                        break;
                }

                JobPrintCommand(job, &wr, ln, ln->datum);
                seen = TRUE;
        }

        return seen;
}

/*
 * Save the delayed commands (those after '...'), to be executed later in
 * the '.END' node, when everything else is done.
 */
static void
JobSaveCommands(Job *job)
{
        StringListNode *ln;

        for (ln = job->tailCmds; ln != NULL; ln = ln->next) {
                const char *cmd = ln->datum;
                char *expanded_cmd;
                /*
                 * XXX: This Var_Subst is only intended to expand the dynamic
                 * variables such as .TARGET, .IMPSRC.  It is not intended to
                 * expand the other variables as well; see deptgt-end.mk.
                 */
                (void)Var_Subst(cmd, job->node, VARE_WANTRES, &expanded_cmd);
                /* TODO: handle errors */
                Lst_Append(&Targ_GetEndNode()->commands, expanded_cmd);
        }
}


/* Called to close both input and output pipes when a job is finished. */
static void
JobClosePipes(Job *job)
{
        clearfd(job);
        (void)close(job->outPipe);
        job->outPipe = -1;

        JobDoOutput(job, TRUE);
        (void)close(job->inPipe);
        job->inPipe = -1;
}

static void
JobFinishDoneExitedError(Job *job, WAIT_T *inout_status)
{
        SwitchOutputTo(job->node);
#ifdef USE_META
        if (useMeta) {
                meta_job_error(job, job->node,
                    job->ignerr, WEXITSTATUS(*inout_status));
        }
#endif
        if (!shouldDieQuietly(job->node, -1)) {
                (void)printf("*** [%s] Error code %d%s\n",
                    job->node->name, WEXITSTATUS(*inout_status),
                    job->ignerr ? " (ignored)" : "");
        }

        if (job->ignerr)
                WAIT_STATUS(*inout_status) = 0;
        else {
                if (deleteOnError)
                        JobDeleteTarget(job->node);
                PrintOnError(job->node, NULL);
        }
}

static void
JobFinishDoneExited(Job *job, WAIT_T *inout_status)
{
        DEBUG2(JOB, "Process %d [%s] exited.\n", job->pid, job->node->name);

        if (WEXITSTATUS(*inout_status) != 0)
                JobFinishDoneExitedError(job, inout_status);
        else if (DEBUG(JOB)) {
                SwitchOutputTo(job->node);
                (void)printf("*** [%s] Completed successfully\n",
                    job->node->name);
        }
}

static void
JobFinishDoneSignaled(Job *job, WAIT_T status)
{
        SwitchOutputTo(job->node);
        (void)printf("*** [%s] Signal %d\n", job->node->name, WTERMSIG(status));
        if (deleteOnError)
                JobDeleteTarget(job->node);
}

static void
JobFinishDone(Job *job, WAIT_T *inout_status)
{
        if (WIFEXITED(*inout_status))
                JobFinishDoneExited(job, inout_status);
        else
                JobFinishDoneSignaled(job, *inout_status);

        (void)fflush(stdout);
}

/*
 * Do final processing for the given job including updating parent nodes and
 * starting new jobs as available/necessary.
 *
 * Deferred commands for the job are placed on the .END node.
 *
 * If there was a serious error (job_errors != 0; not an ignored one), no more
 * jobs will be started.
 *
 * Input:
 *      job             job to finish
 *      status          sub-why job went away
 */
static void
JobFinish (Job *job, WAIT_T status)
{
        Boolean done, return_job_token;

        DEBUG3(JOB, "JobFinish: %d [%s], status %d\n",
            job->pid, job->node->name, status);

        if ((WIFEXITED(status) &&
             ((WEXITSTATUS(status) != 0 && !job->ignerr))) ||
            WIFSIGNALED(status)) {
                /* Finished because of an error. */

                JobClosePipes(job);
                if (job->cmdFILE != NULL && job->cmdFILE != stdout) {
                        (void)fclose(job->cmdFILE);
                        job->cmdFILE = NULL;
                }
                done = TRUE;

        } else if (WIFEXITED(status)) {
                /*
                 * Deal with ignored errors in -B mode. We need to print a
                 * message telling of the ignored error as well as to run
                 * the next command.
                 */
                done = WEXITSTATUS(status) != 0;

                JobClosePipes(job);

        } else {
                /* No need to close things down or anything. */
                done = FALSE;
        }

        if (done)
                JobFinishDone(job, &status);

#ifdef USE_META
        if (useMeta) {
                int meta_status = meta_job_finish(job);
                if (meta_status != 0 && status == 0)
                        status = meta_status;
        }
#endif

        return_job_token = FALSE;

        Trace_Log(JOBEND, job);
        if (!job->special) {
                if (WAIT_STATUS(status) != 0 ||
                    (aborting == ABORT_ERROR) || aborting == ABORT_INTERRUPT)
                        return_job_token = TRUE;
        }

        if (aborting != ABORT_ERROR && aborting != ABORT_INTERRUPT &&
            (WAIT_STATUS(status) == 0)) {
                /*
                 * As long as we aren't aborting and the job didn't return a
                 * non-zero status that we shouldn't ignore, we call
                 * Make_Update to update the parents.
                 */
                JobSaveCommands(job);
                job->node->made = MADE;
                if (!job->special)
                        return_job_token = TRUE;
                Make_Update(job->node);
                job->status = JOB_ST_FREE;
        } else if (status != 0) {
                job_errors++;
                job->status = JOB_ST_FREE;
        }

        if (job_errors > 0 && !opts.keepgoing && aborting != ABORT_INTERRUPT) {
                /* Prevent more jobs from getting started. */
                aborting = ABORT_ERROR;
        }

        if (return_job_token)
                Job_TokenReturn();

        if (aborting == ABORT_ERROR && jobTokensRunning == 0)
                Finish(job_errors);
}

static void
TouchRegular(GNode *gn)
{
        const char *file = GNode_Path(gn);
        struct utimbuf times = { now, now };
        int fd;
        char c;

        if (utime(file, &times) >= 0)
                return;

        fd = open(file, O_RDWR | O_CREAT, 0666);
        if (fd < 0) {
                (void)fprintf(stderr, "*** couldn't touch %s: %s\n",
                    file, strerror(errno));
                (void)fflush(stderr);
                return;         /* XXX: What about propagating the error? */
        }

        /* Last resort: update the file's time stamps in the traditional way.
         * XXX: This doesn't work for empty files, which are sometimes used
         * as marker files. */
        if (read(fd, &c, 1) == 1) {
                (void)lseek(fd, 0, SEEK_SET);
                while (write(fd, &c, 1) == -1 && errno == EAGAIN)
                        continue;
        }
        (void)close(fd);        /* XXX: What about propagating the error? */
}

/*
 * Touch the given target. Called by JobStart when the -t flag was given.
 *
 * The modification date of the file is changed.
 * If the file did not exist, it is created.
 */
void
Job_Touch(GNode *gn, Boolean echo)
{
        if (gn->type &
            (OP_JOIN | OP_USE | OP_USEBEFORE | OP_EXEC | OP_OPTIONAL |
             OP_SPECIAL | OP_PHONY)) {
                /*
                 * These are "virtual" targets and should not really be
                 * created.
                 */
                return;
        }

        if (echo || !GNode_ShouldExecute(gn)) {
                (void)fprintf(stdout, "touch %s\n", gn->name);
                (void)fflush(stdout);
        }

        if (!GNode_ShouldExecute(gn))
                return;

        if (gn->type & OP_ARCHV)
                Arch_Touch(gn);
        else if (gn->type & OP_LIB)
                Arch_TouchLib(gn);
        else
                TouchRegular(gn);
}

/*
 * Make sure the given node has all the commands it needs.
 *
 * The node will have commands from the .DEFAULT rule added to it if it
 * needs them.
 *
 * Input:
 *      gn              The target whose commands need verifying
 *      abortProc       Function to abort with message
 *
 * Results:
 *      TRUE if the commands list is/was ok.
 */
Boolean
Job_CheckCommands(GNode *gn, void (*abortProc)(const char *, ...))
{
        if (GNode_IsTarget(gn))
                return TRUE;
        if (!Lst_IsEmpty(&gn->commands))
                return TRUE;
        if ((gn->type & OP_LIB) && !Lst_IsEmpty(&gn->children))
                return TRUE;

        /*
         * No commands. Look for .DEFAULT rule from which we might infer
         * commands.
         */
        if (defaultNode != NULL && !Lst_IsEmpty(&defaultNode->commands) &&
            !(gn->type & OP_SPECIAL)) {
                /*
                 * The traditional Make only looks for a .DEFAULT if the node
                 * was never the target of an operator, so that's what we do
                 * too.
                 *
                 * The .DEFAULT node acts like a transformation rule, in that
                 * gn also inherits any attributes or sources attached to
                 * .DEFAULT itself.
                 */
                Make_HandleUse(defaultNode, gn);
                Var_Set(gn, IMPSRC, GNode_VarTarget(gn));
                return TRUE;
        }

        Dir_UpdateMTime(gn, FALSE);
        if (gn->mtime != 0 || (gn->type & OP_SPECIAL))
                return TRUE;

        /*
         * The node wasn't the target of an operator.  We have no .DEFAULT
         * rule to go on and the target doesn't already exist. There's
         * nothing more we can do for this branch. If the -k flag wasn't
         * given, we stop in our tracks, otherwise we just don't update
         * this node's parents so they never get examined.
         */

        if (gn->flags & FROM_DEPEND) {
                if (!Job_RunTarget(".STALE", gn->fname))
                        fprintf(stdout,
                            "%s: %s, %d: ignoring stale %s for %s\n",
                            progname, gn->fname, gn->lineno, makeDependfile,
                            gn->name);
                return TRUE;
        }

        if (gn->type & OP_OPTIONAL) {
                (void)fprintf(stdout, "%s: don't know how to make %s (%s)\n",
                    progname, gn->name, "ignored");
                (void)fflush(stdout);
                return TRUE;
        }

        if (opts.keepgoing) {
                (void)fprintf(stdout, "%s: don't know how to make %s (%s)\n",
                    progname, gn->name, "continuing");
                (void)fflush(stdout);
                return FALSE;
        }

        abortProc("%s: don't know how to make %s. Stop", progname, gn->name);
        return FALSE;
}

/*
 * Execute the shell for the given job.
 *
 * See Job_CatchOutput for handling the output of the shell.
 */
static void
JobExec(Job *job, char **argv)
{
        int cpid;               /* ID of new child */
        sigset_t mask;

        if (DEBUG(JOB)) {
                int i;

                debug_printf("Running %s\n", job->node->name);
                debug_printf("\tCommand: ");
                for (i = 0; argv[i] != NULL; i++) {
                        debug_printf("%s ", argv[i]);
                }
                debug_printf("\n");
        }

        /*
         * Some jobs produce no output and it's disconcerting to have
         * no feedback of their running (since they produce no output, the
         * banner with their name in it never appears). This is an attempt to
         * provide that feedback, even if nothing follows it.
         */
        if (job->echo)
                SwitchOutputTo(job->node);

        /* No interruptions until this job is on the `jobs' list */
        JobSigLock(&mask);

        /* Pre-emptively mark job running, pid still zero though */
        job->status = JOB_ST_RUNNING;

        Var_ReexportVars();

        cpid = vfork();
        if (cpid == -1)
                Punt("Cannot vfork: %s", strerror(errno));

        if (cpid == 0) {
                /* Child */
                sigset_t tmask;

#ifdef USE_META
                if (useMeta) {
                        meta_job_child(job);
                }
#endif
                /*
                 * Reset all signal handlers; this is necessary because we
                 * also need to unblock signals before we exec(2).
                 */
                JobSigReset();

                /* Now unblock signals */
                sigemptyset(&tmask);
                JobSigUnlock(&tmask);

                /*
                 * Must duplicate the input stream down to the child's input
                 * and reset it to the beginning (again). Since the stream
                 * was marked close-on-exec, we must clear that bit in the
                 * new input.
                 */
                if (dup2(fileno(job->cmdFILE), 0) == -1)
                        execDie("dup2", "job->cmdFILE");
                if (fcntl(0, F_SETFD, 0) == -1)
                        execDie("fcntl clear close-on-exec", "stdin");
                if (lseek(0, 0, SEEK_SET) == -1)
                        execDie("lseek to 0", "stdin");

                if (Always_pass_job_queue ||
                    (job->node->type & (OP_MAKE | OP_SUBMAKE))) {
                        /*
                         * Pass job token pipe to submakes.
                         */
                        if (fcntl(tokenWaitJob.inPipe, F_SETFD, 0) == -1)
                                execDie("clear close-on-exec",
                                    "tokenWaitJob.inPipe");
                        if (fcntl(tokenWaitJob.outPipe, F_SETFD, 0) == -1)
                                execDie("clear close-on-exec",
                                    "tokenWaitJob.outPipe");
                }

                /*
                 * Set up the child's output to be routed through the pipe
                 * we've created for it.
                 */
                if (dup2(job->outPipe, 1) == -1)
                        execDie("dup2", "job->outPipe");

                /*
                 * The output channels are marked close on exec. This bit
                 * was duplicated by the dup2(on some systems), so we have
                 * to clear it before routing the shell's error output to
                 * the same place as its standard output.
                 */
                if (fcntl(1, F_SETFD, 0) == -1)
                        execDie("clear close-on-exec", "stdout");
                if (dup2(1, 2) == -1)
                        execDie("dup2", "1, 2");

                /*
                 * We want to switch the child into a different process
                 * family so we can kill it and all its descendants in
                 * one fell swoop, by killing its process family, but not
                 * commit suicide.
                 */
#if defined(HAVE_SETPGID)
                (void)setpgid(0, getpid());
#else
# if defined(HAVE_SETSID)
                /* XXX: dsl - I'm sure this should be setpgrp()... */
                (void)setsid();
# else
                (void)setpgrp(0, getpid());
# endif
#endif

                (void)execv(shellPath, argv);
                execDie("exec", shellPath);
        }

        /* Parent, continuing after the child exec */
        job->pid = cpid;

        Trace_Log(JOBSTART, job);

#ifdef USE_META
        if (useMeta) {
                meta_job_parent(job, cpid);
        }
#endif

        /*
         * Set the current position in the buffer to the beginning
         * and mark another stream to watch in the outputs mask
         */
        job->curPos = 0;

        watchfd(job);

        if (job->cmdFILE != NULL && job->cmdFILE != stdout) {
                (void)fclose(job->cmdFILE);
                job->cmdFILE = NULL;
        }

        /* Now that the job is actually running, add it to the table. */
        if (DEBUG(JOB)) {
                debug_printf("JobExec(%s): pid %d added to jobs table\n",
                    job->node->name, job->pid);
                job_table_dump("job started");
        }
        JobSigUnlock(&mask);
}

/* Create the argv needed to execute the shell for a given job. */
static void
JobMakeArgv(Job *job, char **argv)
{
        int argc;
        static char args[10];   /* For merged arguments */

        argv[0] = UNCONST(shellName);
        argc = 1;

        if ((shell->errFlag != NULL && shell->errFlag[0] != '-') ||
            (shell->echoFlag != NULL && shell->echoFlag[0] != '-')) {
                /*
                 * At least one of the flags doesn't have a minus before it,
                 * so merge them together. Have to do this because the Bourne
                 * shell thinks its second argument is a file to source.
                 * Grrrr. Note the ten-character limitation on the combined
                 * arguments.
                 *
                 * TODO: Research until when the above comments were
                 * practically relevant.
                 */
                (void)snprintf(args, sizeof args, "-%s%s",
                    (job->ignerr ? "" :
                        (shell->errFlag != NULL ? shell->errFlag : "")),
                    (!job->echo ? "" :
                        (shell->echoFlag != NULL ? shell->echoFlag : "")));

                if (args[1] != '\0') {
                        argv[argc] = args;
                        argc++;
                }
        } else {
                if (!job->ignerr && shell->errFlag != NULL) {
                        argv[argc] = UNCONST(shell->errFlag);
                        argc++;
                }
                if (job->echo && shell->echoFlag != NULL) {
                        argv[argc] = UNCONST(shell->echoFlag);
                        argc++;
                }
        }
        argv[argc] = NULL;
}

static void
JobWriteShellCommands(Job *job, GNode *gn, Boolean cmdsOK, Boolean *out_run)
{
        /*
         * tfile is the name of a file into which all shell commands
         * are put. It is removed before the child shell is executed,
         * unless DEBUG(SCRIPT) is set.
         */
        char tfile[MAXPATHLEN];
        int tfd;                /* File descriptor to the temp file */

        /*
         * We're serious here, but if the commands were bogus, we're
         * also dead...
         */
        if (!cmdsOK) {
                PrintOnError(gn, NULL); /* provide some clue */
                DieHorribly();
        }

        tfd = Job_TempFile(TMPPAT, tfile, sizeof tfile);

        job->cmdFILE = fdopen(tfd, "w+");
        if (job->cmdFILE == NULL)
                Punt("Could not fdopen %s", tfile);

        (void)fcntl(fileno(job->cmdFILE), F_SETFD, FD_CLOEXEC);

#ifdef USE_META
        if (useMeta) {
                meta_job_start(job, gn);
                if (gn->type & OP_SILENT) /* might have changed */
                        job->echo = FALSE;
        }
#endif

        *out_run = JobPrintCommands(job);
}

/*
 * Start a target-creation process going for the target described by the
 * graph node gn.
 *
 * Input:
 *      gn              target to create
 *      flags           flags for the job to override normal ones.
 *      previous        The previous Job structure for this node, if any.
 *
 * Results:
 *      JOB_ERROR if there was an error in the commands, JOB_FINISHED
 *      if there isn't actually anything left to do for the job and
 *      JOB_RUNNING if the job has been started.
 *
 * Side Effects:
 *      A new Job node is created and added to the list of running
 *      jobs. PMake is forked and a child shell created.
 *
 * NB: The return value is ignored by everyone.
 */
static JobStartResult
JobStart(GNode *gn, Boolean special)
{
        Job *job;               /* new job descriptor */
        char *argv[10];         /* Argument vector to shell */
        Boolean cmdsOK;         /* true if the nodes commands were all right */
        Boolean run;

        for (job = job_table; job < job_table_end; job++) {
                if (job->status == JOB_ST_FREE)
                        break;
        }
        if (job >= job_table_end)
                Punt("JobStart no job slots vacant");

        memset(job, 0, sizeof *job);
        job->node = gn;
        job->tailCmds = NULL;
        job->status = JOB_ST_SET_UP;

        job->special = special || gn->type & OP_SPECIAL;
        job->ignerr = opts.ignoreErrors || gn->type & OP_IGNORE;
        job->echo = !(opts.beSilent || gn->type & OP_SILENT);

        /*
         * Check the commands now so any attributes from .DEFAULT have a
         * chance to migrate to the node.
         */
        cmdsOK = Job_CheckCommands(gn, Error);

        job->inPollfd = NULL;

        if (Lst_IsEmpty(&gn->commands)) {
                job->cmdFILE = stdout;
                run = FALSE;
        } else if (((gn->type & OP_MAKE) && !opts.noRecursiveExecute) ||
            (!opts.noExecute && !opts.touchFlag)) {
                /*
                 * The above condition looks very similar to
                 * GNode_ShouldExecute but is subtly different.  It prevents
                 * that .MAKE targets are touched since these are usually
                 * virtual targets.
                 */

                JobWriteShellCommands(job, gn, cmdsOK, &run);
                (void)fflush(job->cmdFILE);
        } else if (!GNode_ShouldExecute(gn)) {
                /*
                 * Just print all the commands to stdout in one fell swoop.
                 * This still sets up job->tailCmds correctly.
                 */
                SwitchOutputTo(gn);
                job->cmdFILE = stdout;
                if (cmdsOK)
                        JobPrintCommands(job);
                run = FALSE;
                (void)fflush(job->cmdFILE);
        } else {
                Job_Touch(gn, job->echo);
                run = FALSE;
        }

        /* If we're not supposed to execute a shell, don't. */
        if (!run) {
                if (!job->special)
                        Job_TokenReturn();
                /* Unlink and close the command file if we opened one */
                if (job->cmdFILE != NULL && job->cmdFILE != stdout) {
                        (void)fclose(job->cmdFILE);
                        job->cmdFILE = NULL;
                }

                /*
                 * We only want to work our way up the graph if we aren't
                 * here because the commands for the job were no good.
                 */
                if (cmdsOK && aborting == ABORT_NONE) {
                        JobSaveCommands(job);
                        job->node->made = MADE;
                        Make_Update(job->node);
                }
                job->status = JOB_ST_FREE;
                return cmdsOK ? JOB_FINISHED : JOB_ERROR;
        }

        /*
         * Set up the control arguments to the shell. This is based on the
         * flags set earlier for this job.
         */
        JobMakeArgv(job, argv);

        /* Create the pipe by which we'll get the shell's output. */
        JobCreatePipe(job, 3);

        JobExec(job, argv);
        return JOB_RUNNING;
}

/*
 * Print the output of the shell command, skipping the noPrint text of the
 * shell, if any.  The default shell does not have noPrint though, which means
 * that in all practical cases, handling the output is left to the caller.
 */
static char *
JobOutput(char *cp, char *endp) /* XXX: should all be const */
{
        char *ecp;              /* XXX: should be const */

        if (shell->noPrint == NULL || shell->noPrint[0] == '\0')
                return cp;

        /*
         * XXX: What happens if shell->noPrint occurs on the boundary of
         * the buffer?  To work correctly in all cases, this should rather
         * be a proper stream filter instead of doing string matching on
         * selected chunks of the output.
         */
        while ((ecp = strstr(cp, shell->noPrint)) != NULL) {
                if (ecp != cp) {
                        *ecp = '\0';    /* XXX: avoid writing to the buffer */
                        /*
                         * The only way there wouldn't be a newline after
                         * this line is if it were the last in the buffer.
                         * however, since the noPrint output comes after it,
                         * there must be a newline, so we don't print one.
                         */
                        /* XXX: What about null bytes in the output? */
                        (void)fprintf(stdout, "%s", cp);
                        (void)fflush(stdout);
                }
                cp = ecp + shell->noPrintLen;
                if (cp == endp)
                        break;
                cp++;           /* skip over the (XXX: assumed) newline */
                pp_skip_whitespace(&cp);
        }
        return cp;
}

/*
 * This function is called whenever there is something to read on the pipe.
 * We collect more output from the given job and store it in the job's
 * outBuf. If this makes up a line, we print it tagged by the job's
 * identifier, as necessary.
 *
 * In the output of the shell, the 'noPrint' lines are removed. If the
 * command is not alone on the line (the character after it is not \0 or
 * \n), we do print whatever follows it.
 *
 * Input:
 *      job             the job whose output needs printing
 *      finish          TRUE if this is the last time we'll be called
 *                      for this job
 */
static void
JobDoOutput(Job *job, Boolean finish)
{
        Boolean gotNL;          /* true if got a newline */
        Boolean fbuf;           /* true if our buffer filled up */
        size_t nr;              /* number of bytes read */
        size_t i;               /* auxiliary index into outBuf */
        size_t max;             /* limit for i (end of current data) */
        ssize_t nRead;          /* (Temporary) number of bytes read */

        /* Read as many bytes as will fit in the buffer. */
again:
        gotNL = FALSE;
        fbuf = FALSE;

        nRead = read(job->inPipe, &job->outBuf[job->curPos],
            JOB_BUFSIZE - job->curPos);
        if (nRead < 0) {
                if (errno == EAGAIN)
                        return;
                if (DEBUG(JOB)) {
                        perror("JobDoOutput(piperead)");
                }
                nr = 0;
        } else {
                nr = (size_t)nRead;
        }

        /*
         * If we hit the end-of-file (the job is dead), we must flush its
         * remaining output, so pretend we read a newline if there's any
         * output remaining in the buffer.
         * Also clear the 'finish' flag so we stop looping.
         */
        if (nr == 0 && job->curPos != 0) {
                job->outBuf[job->curPos] = '\n';
                nr = 1;
                finish = FALSE;
        } else if (nr == 0) {
                finish = FALSE;
        }

        /*
         * Look for the last newline in the bytes we just got. If there is
         * one, break out of the loop with 'i' as its index and gotNL set
         * TRUE.
         */
        max = job->curPos + nr;
        for (i = job->curPos + nr - 1;
             i >= job->curPos && i != (size_t)-1; i--) {
                if (job->outBuf[i] == '\n') {
                        gotNL = TRUE;
                        break;
                } else if (job->outBuf[i] == '\0') {
                        /*
                         * Why?
                         */
                        job->outBuf[i] = ' ';
                }
        }

        if (!gotNL) {
                job->curPos += nr;
                if (job->curPos == JOB_BUFSIZE) {
                        /*
                         * If we've run out of buffer space, we have no choice
                         * but to print the stuff. sigh.
                         */
                        fbuf = TRUE;
                        i = job->curPos;
                }
        }
        if (gotNL || fbuf) {
                /*
                 * Need to send the output to the screen. Null terminate it
                 * first, overwriting the newline character if there was one.
                 * So long as the line isn't one we should filter (according
                 * to the shell description), we print the line, preceded
                 * by a target banner if this target isn't the same as the
                 * one for which we last printed something.
                 * The rest of the data in the buffer are then shifted down
                 * to the start of the buffer and curPos is set accordingly.
                 */
                job->outBuf[i] = '\0';
                if (i >= job->curPos) {
                        char *cp;

                        cp = JobOutput(job->outBuf, &job->outBuf[i]);

                        /*
                         * There's still more in that thar buffer. This time,
                         * though, we know there's no newline at the end, so
                         * we add one of our own free will.
                         */
                        if (*cp != '\0') {
                                if (!opts.beSilent)
                                        SwitchOutputTo(job->node);
#ifdef USE_META
                                if (useMeta) {
                                        meta_job_output(job, cp,
                                            gotNL ? "\n" : "");
                                }
#endif
                                (void)fprintf(stdout, "%s%s", cp,
                                    gotNL ? "\n" : "");
                                (void)fflush(stdout);
                        }
                }
                /*
                 * max is the last offset still in the buffer. Move any
                 * remaining characters to the start of the buffer and
                 * update the end marker curPos.
                 */
                if (i < max) {
                        (void)memmove(job->outBuf, &job->outBuf[i + 1],
                            max - (i + 1));
                        job->curPos = max - (i + 1);
                } else {
                        assert(i == max);
                        job->curPos = 0;
                }
        }
        if (finish) {
                /*
                 * If the finish flag is true, we must loop until we hit
                 * end-of-file on the pipe. This is guaranteed to happen
                 * eventually since the other end of the pipe is now closed
                 * (we closed it explicitly and the child has exited). When
                 * we do get an EOF, finish will be set FALSE and we'll fall
                 * through and out.
                 */
                goto again;
        }
}

static void
JobRun(GNode *targ)
{
#if 0
        /*
         * Unfortunately it is too complicated to run .BEGIN, .END, and
         * .INTERRUPT job in the parallel job module.  As of 2020-09-25,
         * unit-tests/deptgt-end-jobs.mk hangs in an endless loop.
         *
         * Running these jobs in compat mode also guarantees that these
         * jobs do not overlap with other unrelated jobs.
         */
        GNodeList lst = LST_INIT;
        Lst_Append(&lst, targ);
        (void)Make_Run(&lst);
        Lst_Done(&lst);
        JobStart(targ, TRUE);
        while (jobTokensRunning != 0) {
                Job_CatchOutput();
        }
#else
        Compat_Make(targ, targ);
        /* XXX: Replace with GNode_IsError(gn) */
        if (targ->made == ERROR) {
                PrintOnError(targ, "\n\nStop.");
                exit(1);
        }
#endif
}

/*
 * Handle the exit of a child. Called from Make_Make.
 *
 * The job descriptor is removed from the list of children.
 *
 * Notes:
 *      We do waits, blocking or not, according to the wisdom of our
 *      caller, until there are no more children to report. For each
 *      job, call JobFinish to finish things off.
 */
void
Job_CatchChildren(void)
{
        int pid;                /* pid of dead child */
        WAIT_T status;          /* Exit/termination status */

        /* Don't even bother if we know there's no one around. */
        if (jobTokensRunning == 0)
                return;

        /* Have we received SIGCHLD since last call? */
        if (caught_sigchld == 0)
                return;
        caught_sigchld = 0;

        while ((pid = waitpid((pid_t)-1, &status, WNOHANG | WUNTRACED)) > 0) {
                DEBUG2(JOB, "Process %d exited/stopped status %x.\n",
                    pid, WAIT_STATUS(status));
                JobReapChild(pid, status, TRUE);
        }
}

/*
 * It is possible that wait[pid]() was called from elsewhere,
 * this lets us reap jobs regardless.
 */
void
JobReapChild(pid_t pid, WAIT_T status, Boolean isJobs)
{
        Job *job;               /* job descriptor for dead child */

        /* Don't even bother if we know there's no one around. */
        if (jobTokensRunning == 0)
                return;

        job = JobFindPid(pid, JOB_ST_RUNNING, isJobs);
        if (job == NULL) {
                if (isJobs) {
                        if (!lurking_children)
                                Error("Child (%d) status %x not in table?",
                                    pid, status);
                }
                return;         /* not ours */
        }
        if (WIFSTOPPED(status)) {
                DEBUG2(JOB, "Process %d (%s) stopped.\n",
                    job->pid, job->node->name);
                if (!make_suspended) {
                        switch (WSTOPSIG(status)) {
                        case SIGTSTP:
                                (void)printf("*** [%s] Suspended\n",
                                    job->node->name);
                                break;
                        case SIGSTOP:
                                (void)printf("*** [%s] Stopped\n",
                                    job->node->name);
                                break;
                        default:
                                (void)printf("*** [%s] Stopped -- signal %d\n",
                                    job->node->name, WSTOPSIG(status));
                        }
                        job->suspended = TRUE;
                }
                (void)fflush(stdout);
                return;
        }

        job->status = JOB_ST_FINISHED;
        job->exit_status = WAIT_STATUS(status);

        JobFinish(job, status);
}

/*
 * Catch the output from our children, if we're using pipes do so. Otherwise
 * just block time until we get a signal(most likely a SIGCHLD) since there's
 * no point in just spinning when there's nothing to do and the reaping of a
 * child can wait for a while.
 */
void
Job_CatchOutput(void)
{
        int nready;
        Job *job;
        unsigned int i;

        (void)fflush(stdout);

        /* The first fd in the list is the job token pipe */
        do {
                nready = poll(fds + 1 - wantToken, fdsLen - 1 + wantToken,
                    POLL_MSEC);
        } while (nready < 0 && errno == EINTR);

        if (nready < 0)
                Punt("poll: %s", strerror(errno));

        if (nready > 0 && readyfd(&childExitJob)) {
                char token = 0;
                ssize_t count;
                count = read(childExitJob.inPipe, &token, 1);
                if (count == 1) {
                        if (token == DO_JOB_RESUME[0])
                                /*
                                 * Complete relay requested from our SIGCONT
                                 * handler
                                 */
                                JobRestartJobs();
                } else if (count == 0)
                        Punt("unexpected eof on token pipe");
                else
                        Punt("token pipe read: %s", strerror(errno));
                nready--;
        }

        Job_CatchChildren();
        if (nready == 0)
                return;

        for (i = npseudojobs * nfds_per_job(); i < fdsLen; i++) {
                if (fds[i].revents == 0)
                        continue;
                job = jobByFdIndex[i];
                if (job->status == JOB_ST_RUNNING)
                        JobDoOutput(job, FALSE);
#if defined(USE_FILEMON) && !defined(USE_FILEMON_DEV)
                /*
                 * With meta mode, we may have activity on the job's filemon
                 * descriptor too, which at the moment is any pollfd other
                 * than job->inPollfd.
                 */
                if (useMeta && job->inPollfd != &fds[i]) {
                        if (meta_job_event(job) <= 0) {
                                fds[i].events = 0; /* never mind */
                        }
                }
#endif
                if (--nready == 0)
                        return;
        }
}

/*
 * Start the creation of a target. Basically a front-end for JobStart used by
 * the Make module.
 */
void
Job_Make(GNode *gn)
{
        (void)JobStart(gn, FALSE);
}

static void
InitShellNameAndPath(void)
{
        shellName = shell->name;

#ifdef DEFSHELL_CUSTOM
        if (shellName[0] == '/') {
                shellPath = shellName;
                shellName = str_basename(shellPath);
                return;
        }
#endif

        shellPath = str_concat3(_PATH_DEFSHELLDIR, "/", shellName);
}

void
Shell_Init(void)
{
        if (shellPath == NULL)
                InitShellNameAndPath();

        Var_SetWithFlags(SCOPE_CMDLINE, ".SHELL", shellPath, VAR_SET_READONLY);
        if (shell->errFlag == NULL)
                shell->errFlag = "";
        if (shell->echoFlag == NULL)
                shell->echoFlag = "";
        if (shell->hasErrCtl && shell->errFlag[0] != '\0') {
                if (shellErrFlag != NULL &&
                    strcmp(shell->errFlag, &shellErrFlag[1]) != 0) {
                        free(shellErrFlag);
                        shellErrFlag = NULL;
                }
                if (shellErrFlag == NULL) {
                        size_t n = strlen(shell->errFlag) + 2;

                        shellErrFlag = bmake_malloc(n);
                        if (shellErrFlag != NULL)
                                snprintf(shellErrFlag, n, "-%s",
                                    shell->errFlag);
                }
        } else if (shellErrFlag != NULL) {
                free(shellErrFlag);
                shellErrFlag = NULL;
        }
}

/*
 * Return the string literal that is used in the current command shell
 * to produce a newline character.
 */
const char *
Shell_GetNewline(void)
{
        return shell->newline;
}

void
Job_SetPrefix(void)
{
        if (targPrefix != NULL) {
                free(targPrefix);
        } else if (!Var_Exists(SCOPE_GLOBAL, MAKE_JOB_PREFIX)) {
                Global_Set(MAKE_JOB_PREFIX, "---");
        }

        (void)Var_Subst("${" MAKE_JOB_PREFIX "}",
            SCOPE_GLOBAL, VARE_WANTRES, &targPrefix);
        /* TODO: handle errors */
}

static void
AddSig(int sig, SignalProc handler)
{
        if (bmake_signal(sig, SIG_IGN) != SIG_IGN) {
                sigaddset(&caught_signals, sig);
                (void)bmake_signal(sig, handler);
        }
}

/* Initialize the process module. */
void
Job_Init(void)
{
        Job_SetPrefix();
        /* Allocate space for all the job info */
        job_table = bmake_malloc((size_t)opts.maxJobs * sizeof *job_table);
        memset(job_table, 0, (size_t)opts.maxJobs * sizeof *job_table);
        job_table_end = job_table + opts.maxJobs;
        wantToken = 0;
        caught_sigchld = 0;

        aborting = ABORT_NONE;
        job_errors = 0;

        Always_pass_job_queue = GetBooleanVar(MAKE_ALWAYS_PASS_JOB_QUEUE,
            Always_pass_job_queue);

        Job_error_token = GetBooleanVar(MAKE_JOB_ERROR_TOKEN, Job_error_token);

        /*
         * There is a non-zero chance that we already have children.
         * eg after 'make -f- <<EOF'
         * Since their termination causes a 'Child (pid) not in table'
         * message, Collect the status of any that are already dead, and
         * suppress the error message if there are any undead ones.
         */
        for (;;) {
                int rval;
                WAIT_T status;

                rval = waitpid((pid_t)-1, &status, WNOHANG);
                if (rval > 0)
                        continue;
                if (rval == 0)
                        lurking_children = TRUE;
                break;
        }

        Shell_Init();

        JobCreatePipe(&childExitJob, 3);

        {
                /* Preallocate enough for the maximum number of jobs. */
                size_t nfds = (npseudojobs + (size_t)opts.maxJobs) *
                              nfds_per_job();
                fds = bmake_malloc(sizeof *fds * nfds);
                jobByFdIndex = bmake_malloc(sizeof *jobByFdIndex * nfds);
        }

        /* These are permanent entries and take slots 0 and 1 */
        watchfd(&tokenWaitJob);
        watchfd(&childExitJob);

        sigemptyset(&caught_signals);
        /*
         * Install a SIGCHLD handler.
         */
        (void)bmake_signal(SIGCHLD, JobChildSig);
        sigaddset(&caught_signals, SIGCHLD);

        /*
         * Catch the four signals that POSIX specifies if they aren't ignored.
         * JobPassSig will take care of calling JobInterrupt if appropriate.
         */
        AddSig(SIGINT, JobPassSig_int);
        AddSig(SIGHUP, JobPassSig_term);
        AddSig(SIGTERM, JobPassSig_term);
        AddSig(SIGQUIT, JobPassSig_term);

        /*
         * There are additional signals that need to be caught and passed if
         * either the export system wants to be told directly of signals or if
         * we're giving each job its own process group (since then it won't get
         * signals from the terminal driver as we own the terminal)
         */
        AddSig(SIGTSTP, JobPassSig_suspend);
        AddSig(SIGTTOU, JobPassSig_suspend);
        AddSig(SIGTTIN, JobPassSig_suspend);
        AddSig(SIGWINCH, JobCondPassSig);
        AddSig(SIGCONT, JobContinueSig);

        (void)Job_RunTarget(".BEGIN", NULL);
        /* Create the .END node now, even though no code in the unit tests
         * depends on it.  See also Targ_GetEndNode in Compat_Run. */
        (void)Targ_GetEndNode();
}

static void
DelSig(int sig)
{
        if (sigismember(&caught_signals, sig) != 0)
                (void)bmake_signal(sig, SIG_DFL);
}

static void
JobSigReset(void)
{
        DelSig(SIGINT);
        DelSig(SIGHUP);
        DelSig(SIGQUIT);
        DelSig(SIGTERM);
        DelSig(SIGTSTP);
        DelSig(SIGTTOU);
        DelSig(SIGTTIN);
        DelSig(SIGWINCH);
        DelSig(SIGCONT);
        (void)bmake_signal(SIGCHLD, SIG_DFL);
}

/* Find a shell in 'shells' given its name, or return NULL. */
static Shell *
FindShellByName(const char *name)
{
        Shell *sh = shells;
        const Shell *shellsEnd = sh + sizeof shells / sizeof shells[0];

        for (sh = shells; sh < shellsEnd; sh++) {
                if (strcmp(name, sh->name) == 0)
                        return sh;
        }
        return NULL;
}

/*
 * Parse a shell specification and set up 'shell', shellPath and
 * shellName appropriately.
 *
 * Input:
 *      line            The shell spec
 *
 * Results:
 *      FALSE if the specification was incorrect.
 *
 * Side Effects:
 *      'shell' points to a Shell structure (either predefined or
 *      created from the shell spec), shellPath is the full path of the
 *      shell described by 'shell', while shellName is just the
 *      final component of shellPath.
 *
 * Notes:
 *      A shell specification consists of a .SHELL target, with dependency
 *      operator, followed by a series of blank-separated words. Double
 *      quotes can be used to use blanks in words. A backslash escapes
 *      anything (most notably a double-quote and a space) and
 *      provides the functionality it does in C. Each word consists of
 *      keyword and value separated by an equal sign. There should be no
 *      unnecessary spaces in the word. The keywords are as follows:
 *          name        Name of shell.
 *          path        Location of shell.
 *          quiet       Command to turn off echoing.
 *          echo        Command to turn echoing on
 *          filter      Result of turning off echoing that shouldn't be
 *                      printed.
 *          echoFlag    Flag to turn echoing on at the start
 *          errFlag     Flag to turn error checking on at the start
 *          hasErrCtl   True if shell has error checking control
 *          newline     String literal to represent a newline char
 *          check       Command to turn on error checking if hasErrCtl
 *                      is TRUE or template of command to echo a command
 *                      for which error checking is off if hasErrCtl is
 *                      FALSE.
 *          ignore      Command to turn off error checking if hasErrCtl
 *                      is TRUE or template of command to execute a
 *                      command so as to ignore any errors it returns if
 *                      hasErrCtl is FALSE.
 */
Boolean
Job_ParseShell(char *line)
{
        Words wordsList;
        char **words;
        char **argv;
        size_t argc;
        char *path;
        Shell newShell;
        Boolean fullSpec = FALSE;
        Shell *sh;

        /* XXX: don't use line as an iterator variable */
        pp_skip_whitespace(&line);

        free(shell_freeIt);

        memset(&newShell, 0, sizeof newShell);

        /*
         * Parse the specification by keyword
         */
        wordsList = Str_Words(line, TRUE);
        words = wordsList.words;
        argc = wordsList.len;
        path = wordsList.freeIt;
        if (words == NULL) {
                Error("Unterminated quoted string [%s]", line);
                return FALSE;
        }
        shell_freeIt = path;

        for (path = NULL, argv = words; argc != 0; argc--, argv++) {
                char *arg = *argv;
                if (strncmp(arg, "path=", 5) == 0) {
                        path = arg + 5;
                } else if (strncmp(arg, "name=", 5) == 0) {
                        newShell.name = arg + 5;
                } else {
                        if (strncmp(arg, "quiet=", 6) == 0) {
                                newShell.echoOff = arg + 6;
                        } else if (strncmp(arg, "echo=", 5) == 0) {
                                newShell.echoOn = arg + 5;
                        } else if (strncmp(arg, "filter=", 7) == 0) {
                                newShell.noPrint = arg + 7;
                                newShell.noPrintLen = strlen(newShell.noPrint);
                        } else if (strncmp(arg, "echoFlag=", 9) == 0) {
                                newShell.echoFlag = arg + 9;
                        } else if (strncmp(arg, "errFlag=", 8) == 0) {
                                newShell.errFlag = arg + 8;
                        } else if (strncmp(arg, "hasErrCtl=", 10) == 0) {
                                char c = arg[10];
                                newShell.hasErrCtl = c == 'Y' || c == 'y' ||
                                                     c == 'T' || c == 't';
                        } else if (strncmp(arg, "newline=", 8) == 0) {
                                newShell.newline = arg + 8;
                        } else if (strncmp(arg, "check=", 6) == 0) {
                                /* Before 2020-12-10, these two variables
                                 * had been a single variable. */
                                newShell.errOn = arg + 6;
                                newShell.echoTmpl = arg + 6;
                        } else if (strncmp(arg, "ignore=", 7) == 0) {
                                /* Before 2020-12-10, these two variables
                                 * had been a single variable. */
                                newShell.errOff = arg + 7;
                                newShell.runIgnTmpl = arg + 7;
                        } else if (strncmp(arg, "errout=", 7) == 0) {
                                newShell.runChkTmpl = arg + 7;
                        } else if (strncmp(arg, "comment=", 8) == 0) {
                                newShell.commentChar = arg[8];
                        } else {
                                Parse_Error(PARSE_FATAL,
                                    "Unknown keyword \"%s\"", arg);
                                free(words);
                                return FALSE;
                        }
                        fullSpec = TRUE;
                }
        }

        if (path == NULL) {
                /*
                 * If no path was given, the user wants one of the
                 * pre-defined shells, yes? So we find the one s/he wants
                 * with the help of FindShellByName and set things up the
                 * right way. shellPath will be set up by Shell_Init.
                 */
                if (newShell.name == NULL) {
                        Parse_Error(PARSE_FATAL,
                            "Neither path nor name specified");
                        free(words);
                        return FALSE;
                } else {
                        if ((sh = FindShellByName(newShell.name)) == NULL) {
                                Parse_Error(PARSE_WARNING,
                                    "%s: No matching shell", newShell.name);
                                free(words);
                                return FALSE;
                        }
                        shell = sh;
                        shellName = newShell.name;
                        if (shellPath != NULL) {
                                /*
                                 * Shell_Init has already been called!
                                 * Do it again.
                                 */
                                free(UNCONST(shellPath));
                                shellPath = NULL;
                                Shell_Init();
                        }
                }
        } else {
                /*
                 * The user provided a path. If s/he gave nothing else
                 * (fullSpec is FALSE), try and find a matching shell in the
                 * ones we know of. Else we just take the specification at
                 * its word and copy it to a new location. In either case,
                 * we need to record the path the user gave for the shell.
                 */
                shellPath = path;
                path = strrchr(path, '/');
                if (path == NULL) {
                        path = UNCONST(shellPath);
                } else {
                        path++;
                }
                if (newShell.name != NULL) {
                        shellName = newShell.name;
                } else {
                        shellName = path;
                }
                if (!fullSpec) {
                        if ((sh = FindShellByName(shellName)) == NULL) {
                                Parse_Error(PARSE_WARNING,
                                    "%s: No matching shell", shellName);
                                free(words);
                                return FALSE;
                        }
                        shell = sh;
                } else {
                        shell = bmake_malloc(sizeof *shell);
                        *shell = newShell;
                }
                /* this will take care of shellErrFlag */
                Shell_Init();
        }

        if (shell->echoOn != NULL && shell->echoOff != NULL)
                shell->hasEchoCtl = TRUE;

        if (!shell->hasErrCtl) {
                if (shell->echoTmpl == NULL)
                        shell->echoTmpl = "";
                if (shell->runIgnTmpl == NULL)
                        shell->runIgnTmpl = "%s\n";
        }

        /*
         * Do not free up the words themselves, since they might be in use
         * by the shell specification.
         */
        free(words);
        return TRUE;
}

/*
 * Handle the receipt of an interrupt.
 *
 * All children are killed. Another job will be started if the .INTERRUPT
 * target is defined.
 *
 * Input:
 *      runINTERRUPT    Non-zero if commands for the .INTERRUPT target
 *                      should be executed
 *      signo           signal received
 */
static void
JobInterrupt(Boolean runINTERRUPT, int signo)
{
        Job *job;               /* job descriptor in that element */
        GNode *interrupt;       /* the node describing the .INTERRUPT target */
        sigset_t mask;
        GNode *gn;

        aborting = ABORT_INTERRUPT;

        JobSigLock(&mask);

        for (job = job_table; job < job_table_end; job++) {
                if (job->status != JOB_ST_RUNNING)
                        continue;

                gn = job->node;

                JobDeleteTarget(gn);
                if (job->pid != 0) {
                        DEBUG2(JOB,
                            "JobInterrupt passing signal %d to child %d.\n",
                            signo, job->pid);
                        KILLPG(job->pid, signo);
                }
        }

        JobSigUnlock(&mask);

        if (runINTERRUPT && !opts.touchFlag) {
                interrupt = Targ_FindNode(".INTERRUPT");
                if (interrupt != NULL) {
                        opts.ignoreErrors = FALSE;
                        JobRun(interrupt);
                }
        }
        Trace_Log(MAKEINTR, NULL);
        exit(signo);            /* XXX: why signo? */
}

/*
 * Do the final processing, i.e. run the commands attached to the .END target.
 *
 * Return the number of errors reported.
 */
int
Job_Finish(void)
{
        GNode *endNode = Targ_GetEndNode();
        if (!Lst_IsEmpty(&endNode->commands) ||
            !Lst_IsEmpty(&endNode->children)) {
                if (job_errors != 0) {
                        Error("Errors reported so .END ignored");
                } else {
                        JobRun(endNode);
                }
        }
        return job_errors;
}

/* Clean up any memory used by the jobs module. */
void
Job_End(void)
{
#ifdef CLEANUP
        free(shell_freeIt);
#endif
}

/*
 * Waits for all running jobs to finish and returns.
 * Sets 'aborting' to ABORT_WAIT to prevent other jobs from starting.
 */
void
Job_Wait(void)
{
        aborting = ABORT_WAIT;
        while (jobTokensRunning != 0) {
                Job_CatchOutput();
        }
        aborting = ABORT_NONE;
}

/*
 * Abort all currently running jobs without handling output or anything.
 * This function is to be called only in the event of a major error.
 * Most definitely NOT to be called from JobInterrupt.
 *
 * All children are killed, not just the firstborn.
 */
void
Job_AbortAll(void)
{
        Job *job;               /* the job descriptor in that element */
        WAIT_T foo;

        aborting = ABORT_ERROR;

        if (jobTokensRunning != 0) {
                for (job = job_table; job < job_table_end; job++) {
                        if (job->status != JOB_ST_RUNNING)
                                continue;
                        /*
                         * kill the child process with increasingly drastic
                         * signals to make darn sure it's dead.
                         */
                        KILLPG(job->pid, SIGINT);
                        KILLPG(job->pid, SIGKILL);
                }
        }

        /*
         * Catch as many children as want to report in at first, then give up
         */
        while (waitpid((pid_t)-1, &foo, WNOHANG) > 0)
                continue;
}

/*
 * Tries to restart stopped jobs if there are slots available.
 * Called in process context in response to a SIGCONT.
 */
static void
JobRestartJobs(void)
{
        Job *job;

        for (job = job_table; job < job_table_end; job++) {
                if (job->status == JOB_ST_RUNNING &&
                    (make_suspended || job->suspended)) {
                        DEBUG1(JOB, "Restarting stopped job pid %d.\n",
                            job->pid);
                        if (job->suspended) {
                                (void)printf("*** [%s] Continued\n",
                                    job->node->name);
                                (void)fflush(stdout);
                        }
                        job->suspended = FALSE;
                        if (KILLPG(job->pid, SIGCONT) != 0 && DEBUG(JOB)) {
                                debug_printf("Failed to send SIGCONT to %d\n",
                                    job->pid);
                        }
                }
                if (job->status == JOB_ST_FINISHED) {
                        /*
                         * Job exit deferred after calling waitpid() in a
                         * signal handler
                         */
                        JobFinish(job, job->exit_status);
                }
        }
        make_suspended = FALSE;
}

static void
watchfd(Job *job)
{
        if (job->inPollfd != NULL)
                Punt("Watching watched job");

        fds[fdsLen].fd = job->inPipe;
        fds[fdsLen].events = POLLIN;
        jobByFdIndex[fdsLen] = job;
        job->inPollfd = &fds[fdsLen];
        fdsLen++;
#if defined(USE_FILEMON) && !defined(USE_FILEMON_DEV)
        if (useMeta) {
                fds[fdsLen].fd = meta_job_fd(job);
                fds[fdsLen].events = fds[fdsLen].fd == -1 ? 0 : POLLIN;
                jobByFdIndex[fdsLen] = job;
                fdsLen++;
        }
#endif
}

static void
clearfd(Job *job)
{
        size_t i;
        if (job->inPollfd == NULL)
                Punt("Unwatching unwatched job");
        i = (size_t)(job->inPollfd - fds);
        fdsLen--;
#if defined(USE_FILEMON) && !defined(USE_FILEMON_DEV)
        if (useMeta) {
                /*
                 * Sanity check: there should be two fds per job, so the job's
                 * pollfd number should be even.
                 */
                assert(nfds_per_job() == 2);
                if (i % 2 != 0)
                        Punt("odd-numbered fd with meta");
                fdsLen--;
        }
#endif
        /*
         * Move last job in table into hole made by dead job.
         */
        if (fdsLen != i) {
                fds[i] = fds[fdsLen];
                jobByFdIndex[i] = jobByFdIndex[fdsLen];
                jobByFdIndex[i]->inPollfd = &fds[i];
#if defined(USE_FILEMON) && !defined(USE_FILEMON_DEV)
                if (useMeta) {
                        fds[i + 1] = fds[fdsLen + 1];
                        jobByFdIndex[i + 1] = jobByFdIndex[fdsLen + 1];
                }
#endif
        }
        job->inPollfd = NULL;
}

static Boolean
readyfd(Job *job)
{
        if (job->inPollfd == NULL)
                Punt("Polling unwatched job");
        return (job->inPollfd->revents & POLLIN) != 0;
}

/*
 * Put a token (back) into the job pipe.
 * This allows a make process to start a build job.
 */
static void
JobTokenAdd(void)
{
        char tok = JOB_TOKENS[aborting], tok1;

        if (!Job_error_token && aborting == ABORT_ERROR) {
                if (jobTokensRunning == 0)
                        return;
                tok = '+';              /* no error token */
        }

        /* If we are depositing an error token flush everything else */
        while (tok != '+' && read(tokenWaitJob.inPipe, &tok1, 1) == 1)
                continue;

        DEBUG3(JOB, "(%d) aborting %d, deposit token %c\n",
            getpid(), aborting, tok);
        while (write(tokenWaitJob.outPipe, &tok, 1) == -1 && errno == EAGAIN)
                continue;
}

/* Get a temp file */
int
Job_TempFile(const char *pattern, char *tfile, size_t tfile_sz)
{
        int fd;
        sigset_t mask;

        JobSigLock(&mask);
        fd = mkTempFile(pattern, tfile, tfile_sz);
        if (tfile != NULL && !DEBUG(SCRIPT))
            unlink(tfile);
        JobSigUnlock(&mask);

        return fd;
}

/* Prep the job token pipe in the root make process. */
void
Job_ServerStart(int max_tokens, int jp_0, int jp_1)
{
        int i;
        char jobarg[64];

        if (jp_0 >= 0 && jp_1 >= 0) {
                /* Pipe passed in from parent */
                tokenWaitJob.inPipe = jp_0;
                tokenWaitJob.outPipe = jp_1;
                (void)fcntl(jp_0, F_SETFD, FD_CLOEXEC);
                (void)fcntl(jp_1, F_SETFD, FD_CLOEXEC);
                return;
        }

        JobCreatePipe(&tokenWaitJob, 15);

        snprintf(jobarg, sizeof jobarg, "%d,%d",
            tokenWaitJob.inPipe, tokenWaitJob.outPipe);

        Global_Append(MAKEFLAGS, "-J");
        Global_Append(MAKEFLAGS, jobarg);

        /*
         * Preload the job pipe with one token per job, save the one
         * "extra" token for the primary job.
         *
         * XXX should clip maxJobs against PIPE_BUF -- if max_tokens is
         * larger than the write buffer size of the pipe, we will
         * deadlock here.
         */
        for (i = 1; i < max_tokens; i++)
                JobTokenAdd();
}

/* Return a withdrawn token to the pool. */
void
Job_TokenReturn(void)
{
        jobTokensRunning--;
        if (jobTokensRunning < 0)
                Punt("token botch");
        if (jobTokensRunning != 0 || JOB_TOKENS[aborting] != '+')
                JobTokenAdd();
}

/*
 * Attempt to withdraw a token from the pool.
 *
 * If pool is empty, set wantToken so that we wake up when a token is
 * released.
 *
 * Returns TRUE if a token was withdrawn, and FALSE if the pool is currently
 * empty.
 */
Boolean
Job_TokenWithdraw(void)
{
        char tok, tok1;
        ssize_t count;

        wantToken = 0;
        DEBUG3(JOB, "Job_TokenWithdraw(%d): aborting %d, running %d\n",
            getpid(), aborting, jobTokensRunning);

        if (aborting != ABORT_NONE || (jobTokensRunning >= opts.maxJobs))
                return FALSE;

        count = read(tokenWaitJob.inPipe, &tok, 1);
        if (count == 0)
                Fatal("eof on job pipe!");
        if (count < 0 && jobTokensRunning != 0) {
                if (errno != EAGAIN) {
                        Fatal("job pipe read: %s", strerror(errno));
                }
                DEBUG1(JOB, "(%d) blocked for token\n", getpid());
                wantToken = 1;
                return FALSE;
        }

        if (count == 1 && tok != '+') {
                /* make being aborted - remove any other job tokens */
                DEBUG2(JOB, "(%d) aborted by token %c\n", getpid(), tok);
                while (read(tokenWaitJob.inPipe, &tok1, 1) == 1)
                        continue;
                /* And put the stopper back */
                while (write(tokenWaitJob.outPipe, &tok, 1) == -1 &&
                       errno == EAGAIN)
                        continue;
                if (shouldDieQuietly(NULL, 1))
                        exit(6);        /* we aborted */
                Fatal("A failure has been detected "
                      "in another branch of the parallel make");
        }

        if (count == 1 && jobTokensRunning == 0)
                /* We didn't want the token really */
                while (write(tokenWaitJob.outPipe, &tok, 1) == -1 &&
                       errno == EAGAIN)
                        continue;

        jobTokensRunning++;
        DEBUG1(JOB, "(%d) withdrew token\n", getpid());
        return TRUE;
}

/*
 * Run the named target if found. If a filename is specified, then set that
 * to the sources.
 *
 * Exits if the target fails.
 */
Boolean
Job_RunTarget(const char *target, const char *fname)
{
        GNode *gn = Targ_FindNode(target);
        if (gn == NULL)
                return FALSE;

        if (fname != NULL)
                Var_Set(gn, ALLSRC, fname);

        JobRun(gn);
        /* XXX: Replace with GNode_IsError(gn) */
        if (gn->made == ERROR) {
                PrintOnError(gn, "\n\nStop.");
                exit(1);
        }
        return TRUE;
}

#ifdef USE_SELECT
int
emul_poll(struct pollfd *fd, int nfd, int timeout)
{
        fd_set rfds, wfds;
        int i, maxfd, nselect, npoll;
        struct timeval tv, *tvp;
        long usecs;

        FD_ZERO(&rfds);
        FD_ZERO(&wfds);

        maxfd = -1;
        for (i = 0; i < nfd; i++) {
                fd[i].revents = 0;

                if (fd[i].events & POLLIN)
                        FD_SET(fd[i].fd, &rfds);

                if (fd[i].events & POLLOUT)
                        FD_SET(fd[i].fd, &wfds);

                if (fd[i].fd > maxfd)
                        maxfd = fd[i].fd;
        }

        if (maxfd >= FD_SETSIZE) {
                Punt("Ran out of fd_set slots; "
                     "recompile with a larger FD_SETSIZE.");
        }

        if (timeout < 0) {
                tvp = NULL;
        } else {
                usecs = timeout * 1000;
                tv.tv_sec = usecs / 1000000;
                tv.tv_usec = usecs % 1000000;
                tvp = &tv;
        }

        nselect = select(maxfd + 1, &rfds, &wfds, NULL, tvp);

        if (nselect <= 0)
                return nselect;

        npoll = 0;
        for (i = 0; i < nfd; i++) {
                if (FD_ISSET(fd[i].fd, &rfds))
                        fd[i].revents |= POLLIN;

                if (FD_ISSET(fd[i].fd, &wfds))
                        fd[i].revents |= POLLOUT;

                if (fd[i].revents)
                        npoll++;
        }

        return npoll;
}
#endif /* USE_SELECT */