sysctl(9): Fix a few mandoc related issues

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

/*      $NetBSD: arch.c,v 1.177 2020/11/14 21:29:44 rillig Exp $        */

/*
 * Copyright (c) 1988, 1989, 1990, 1993
 *      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) 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.
 */

/* Manipulate libraries, archives and their members.
 *
 * The first time an archive is referenced, all of its members' headers are
 * read and cached and the archive closed again.  All cached archives are kept
 * on a list which is searched each time an archive member is referenced.
 *
 * The interface to this module is:
 *
 *      Arch_Init       Initialize this module.
 *
 *      Arch_End        Clean up this module.
 *
 *      Arch_ParseArchive
 *                      Parse an archive specification such as
 *                      "archive.a(member1 member2)".
 *
 *      Arch_Touch      Alter the modification time of the archive
 *                      member described by the given node to be
 *                      the time when make was started.
 *
 *      Arch_TouchLib   Update the modification time of the library
 *                      described by the given node. This is special
 *                      because it also updates the modification time
 *                      of the library's table of contents.
 *
 *      Arch_UpdateMTime
 *                      Find the modification time of a member of
 *                      an archive *in the archive* and place it in the
 *                      member's GNode.
 *
 *      Arch_UpdateMemberMTime
 *                      Find the modification time of a member of
 *                      an archive. Called when the member doesn't
 *                      already exist. Looks in the archive for the
 *                      modification time. Returns the modification
 *                      time.
 *
 *      Arch_FindLib    Search for a library along a path. The
 *                      library name in the GNode should be in
 *                      -l<name> format.
 *
 *      Arch_LibOODate  Decide if a library node is out-of-date.
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/param.h>
#ifdef HAVE_AR_H
#include <ar.h>
#else
struct ar_hdr {
        char ar_name[16];               /* name */
        char ar_date[12];               /* modification time */
        char ar_uid[6];                 /* user id */
        char ar_gid[6];                 /* group id */
        char ar_mode[8];                /* octal file permissions */
        char ar_size[10];               /* size in bytes */
#ifndef ARFMAG
#define ARFMAG  "`\n"
#endif
        char ar_fmag[2];                /* consistency check */
};
#endif
#if defined(HAVE_RANLIB_H) && !(defined(__ELF__) || defined(NO_RANLIB))
#include <ranlib.h>
#endif
#ifdef HAVE_UTIME_H
#include <utime.h>
#endif

#include "make.h"
#include "dir.h"

/*      "@(#)arch.c     8.2 (Berkeley) 1/2/94"  */
MAKE_RCSID("$NetBSD: arch.c,v 1.177 2020/11/14 21:29:44 rillig Exp $");

typedef struct List ArchList;
typedef struct ListNode ArchListNode;

static ArchList *archives;      /* The archives we've already examined */

typedef struct Arch {
    char *name;                 /* Name of archive */
    HashTable members;          /* All the members of the archive described
                                 * by <name, struct ar_hdr *> key/value pairs */
    char *fnametab;             /* Extended name table strings */
    size_t fnamesize;           /* Size of the string table */
} Arch;

static FILE *ArchFindMember(const char *, const char *,
                            struct ar_hdr *, const char *);
#if defined(__svr4__) || defined(__SVR4) || defined(__ELF__)
#define SVR4ARCHIVES
static int ArchSVR4Entry(Arch *, char *, size_t, FILE *);
#endif


#if defined(_AIX)
# define AR_NAME _ar_name.ar_name
# define AR_FMAG _ar_name.ar_fmag
# define SARMAG  SAIAMAG
# define ARMAG   AIAMAG
# define ARFMAG  AIAFMAG
#endif
#ifndef  AR_NAME
# define AR_NAME ar_name
#endif
#ifndef  AR_DATE
# define AR_DATE ar_date
#endif
#ifndef  AR_SIZE
# define AR_SIZE ar_size
#endif
#ifndef  AR_FMAG
# define AR_FMAG ar_fmag
#endif
#ifndef ARMAG
# define ARMAG  "!<arch>\n"
#endif
#ifndef SARMAG
# define SARMAG 8
#endif


#ifdef CLEANUP
static void
ArchFree(void *ap)
{
    Arch *a = ap;
    HashIter hi;

    /* Free memory from hash entries */
    HashIter_Init(&hi, &a->members);
    while (HashIter_Next(&hi) != NULL)
        free(hi.entry->value);

    free(a->name);
    free(a->fnametab);
    HashTable_Done(&a->members);
    free(a);
}
#endif


/*
 * Parse an archive specification such as "archive.a(member1 member2.${EXT})",
 * adding nodes for the expanded members to nodeLst.  Nodes are created as
 * necessary.
 *
 * Input:
 *      pp              The start of the specification.
 *      nodeLst         The list on which to place the nodes.
 *      ctxt            The context in which to expand variables.
 *
 * Output:
 *      return          TRUE if it was a valid specification.
 *      *pp             Points to the first non-space after the archive spec.
 *      *nodeLst        Nodes for the members have been added.
 */
Boolean
Arch_ParseArchive(char **pp, GNodeList *nodeLst, GNode *ctxt)
{
    char *cp;                   /* Pointer into line */
    GNode *gn;                  /* New node */
    char *libName;              /* Library-part of specification */
    char *libName_freeIt = NULL;
    char *memName;              /* Member-part of specification */
    char saveChar;              /* Ending delimiter of member-name */
    Boolean expandLibName;      /* Whether the parsed libName contains
                                 * variable expressions that need to be
                                 * expanded */

    libName = *pp;
    expandLibName = FALSE;

    for (cp = libName; *cp != '(' && *cp != '\0';) {
        if (*cp == '$') {
            /*
             * Variable spec, so call the Var module to parse the puppy
             * so we can safely advance beyond it...
             */
            const char *nested_p = cp;
            void *result_freeIt;
            const char *result;
            Boolean isError;

            /* XXX: is expanded twice: once here and once below */
            (void)Var_Parse(&nested_p, ctxt, VARE_WANTRES | VARE_UNDEFERR,
                            &result, &result_freeIt);
            /* TODO: handle errors */
            isError = result == var_Error;
            free(result_freeIt);
            if (isError)
                return FALSE;

            expandLibName = TRUE;
            cp += nested_p - cp;
        } else
            cp++;
    }

    *cp++ = '\0';
    if (expandLibName) {
        (void)Var_Subst(libName, ctxt, VARE_WANTRES | VARE_UNDEFERR, &libName);
        /* TODO: handle errors */
        libName_freeIt = libName;
    }


    for (;;) {
        /*
         * First skip to the start of the member's name, mark that
         * place and skip to the end of it (either white-space or
         * a close paren).
         */
        Boolean doSubst = FALSE; /* TRUE if need to substitute in memName */

        pp_skip_whitespace(&cp);

        memName = cp;
        while (*cp != '\0' && *cp != ')' && !ch_isspace(*cp)) {
            if (*cp == '$') {
                /*
                 * Variable spec, so call the Var module to parse the puppy
                 * so we can safely advance beyond it...
                 */
                void *freeIt;
                const char *result;
                Boolean isError;
                const char *nested_p = cp;

                (void)Var_Parse(&nested_p, ctxt, VARE_WANTRES | VARE_UNDEFERR,
                                &result, &freeIt);
                /* TODO: handle errors */
                isError = result == var_Error;
                free(freeIt);

                if (isError)
                    return FALSE;

                doSubst = TRUE;
                cp += nested_p - cp;
            } else {
                cp++;
            }
        }

        /*
         * If the specification ends without a closing parenthesis,
         * chances are there's something wrong (like a missing backslash),
         * so it's better to return failure than allow such things to happen
         */
        if (*cp == '\0') {
            Parse_Error(PARSE_FATAL, "No closing parenthesis in archive specification");
            return FALSE;
        }

        /*
         * If we didn't move anywhere, we must be done
         */
        if (cp == memName) {
            break;
        }

        saveChar = *cp;
        *cp = '\0';

        /*
         * XXX: This should be taken care of intelligently by
         * SuffExpandChildren, both for the archive and the member portions.
         */
        /*
         * If member contains variables, try and substitute for them.
         * This will slow down archive specs with dynamic sources, of course,
         * since we'll be (non-)substituting them three times, but them's
         * the breaks -- we need to do this since SuffExpandChildren calls
         * us, otherwise we could assume the thing would be taken care of
         * later.
         */
        if (doSubst) {
            char *buf;
            char *sacrifice;
            char *oldMemName = memName;

            (void)Var_Subst(memName, ctxt, VARE_WANTRES | VARE_UNDEFERR,
                            &memName);
            /* TODO: handle errors */

            /*
             * Now form an archive spec and recurse to deal with nested
             * variables and multi-word variable values.... The results
             * are just placed at the end of the nodeLst we're returning.
             */
            buf = sacrifice = str_concat4(libName, "(", memName, ")");

            if (strchr(memName, '$') != NULL &&
                strcmp(memName, oldMemName) == 0) {
                /*
                 * Must contain dynamic sources, so we can't deal with it now.
                 * Just create an ARCHV node for the thing and let
                 * SuffExpandChildren handle it...
                 */
                gn = Targ_GetNode(buf);
                gn->type |= OP_ARCHV;
                Lst_Append(nodeLst, gn);

            } else if (!Arch_ParseArchive(&sacrifice, nodeLst, ctxt)) {
                /* Error in nested call. */
                free(buf);
                return FALSE;
            }
            free(buf);

        } else if (Dir_HasWildcards(memName)) {
            StringList *members = Lst_New();
            Dir_Expand(memName, dirSearchPath, members);

            while (!Lst_IsEmpty(members)) {
                char *member = Lst_Dequeue(members);
                char *fullname = str_concat4(libName, "(", member, ")");
                free(member);

                gn = Targ_GetNode(fullname);
                free(fullname);

                gn->type |= OP_ARCHV;
                Lst_Append(nodeLst, gn);
            }
            Lst_Free(members);

        } else {
            char *fullname = str_concat4(libName, "(", memName, ")");
            gn = Targ_GetNode(fullname);
            free(fullname);

            /*
             * We've found the node, but have to make sure the rest of the
             * world knows it's an archive member, without having to
             * constantly check for parentheses, so we type the thing with
             * the OP_ARCHV bit before we place it on the end of the
             * provided list.
             */
            gn->type |= OP_ARCHV;
            Lst_Append(nodeLst, gn);
        }
        if (doSubst) {
            free(memName);
        }

        *cp = saveChar;
    }

    free(libName_freeIt);

    cp++;                       /* skip the ')' */
    /* We promised that pp would be set up at the next non-space. */
    pp_skip_whitespace(&cp);
    *pp = cp;
    return TRUE;
}

/* Locate a member of an archive, given the path of the archive and the path
 * of the desired member.
 *
 * Input:
 *      archive         Path to the archive
 *      member          Name of member; only its basename is used.
 *      addToCache      TRUE if archive should be cached if not already so.
 *
 * Results:
 *      The ar_hdr for the member, or NULL.
 *
 * See ArchFindMember for an almost identical copy of this code.
 */
static struct ar_hdr *
ArchStatMember(const char *archive, const char *member, Boolean addToCache)
{
#define AR_MAX_NAME_LEN (sizeof arh.AR_NAME - 1)
    FILE *arch;                 /* Stream to archive */
    size_t size;                /* Size of archive member */
    char magic[SARMAG];
    ArchListNode *ln;
    Arch *ar;                   /* Archive descriptor */
    struct ar_hdr arh;          /* archive-member header for reading archive */
    char memName[MAXPATHLEN + 1];
                                /* Current member name while hashing. */

    /*
     * Because of space constraints and similar things, files are archived
     * using their basename, not the entire path.
     */
    const char *lastSlash = strrchr(member, '/');
    if (lastSlash != NULL)
        member = lastSlash + 1;

    for (ln = archives->first; ln != NULL; ln = ln->next) {
        const Arch *a = ln->datum;
        if (strcmp(a->name, archive) == 0)
            break;
    }

    if (ln != NULL) {
        struct ar_hdr *hdr;

        ar = ln->datum;
        hdr = HashTable_FindValue(&ar->members, member);
        if (hdr != NULL)
            return hdr;

        {
            /* Try truncated name */
            char copy[AR_MAX_NAME_LEN + 1];
            size_t len = strlen(member);

            if (len > AR_MAX_NAME_LEN) {
                len = AR_MAX_NAME_LEN;
                snprintf(copy, sizeof copy, "%s", member);
                hdr = HashTable_FindValue(&ar->members, copy);
            }
            return hdr;
        }
    }

    if (!addToCache) {
        /*
         * Caller doesn't want the thing cached, just use ArchFindMember
         * to read the header for the member out and close down the stream
         * again. Since the archive is not to be cached, we assume there's
         * no need to allocate extra room for the header we're returning,
         * so just declare it static.
         */
        static struct ar_hdr sarh;

        arch = ArchFindMember(archive, member, &sarh, "r");
        if (arch == NULL)
            return NULL;

        fclose(arch);
        return &sarh;
    }

    /*
     * We don't have this archive on the list yet, so we want to find out
     * everything that's in it and cache it so we can get at it quickly.
     */
    arch = fopen(archive, "r");
    if (arch == NULL)
        return NULL;

    /*
     * We use the ARMAG string to make sure this is an archive we
     * can handle...
     */
    if (fread(magic, SARMAG, 1, arch) != 1 ||
        strncmp(magic, ARMAG, SARMAG) != 0) {
        (void)fclose(arch);
        return NULL;
    }

    ar = bmake_malloc(sizeof *ar);
    ar->name = bmake_strdup(archive);
    ar->fnametab = NULL;
    ar->fnamesize = 0;
    HashTable_Init(&ar->members);
    memName[AR_MAX_NAME_LEN] = '\0';

    while (fread(&arh, sizeof arh, 1, arch) == 1) {
        char *nameend;

        /* If the header is bogus, there's no way we can recover. */
        if (strncmp(arh.AR_FMAG, ARFMAG, sizeof arh.AR_FMAG) != 0)
            goto badarch;

        /*
         * We need to advance the stream's pointer to the start of the
         * next header. Files are padded with newlines to an even-byte
         * boundary, so we need to extract the size of the file from the
         * 'size' field of the header and round it up during the seek.
         */
        arh.AR_SIZE[sizeof arh.AR_SIZE - 1] = '\0';
        size = (size_t)strtol(arh.AR_SIZE, NULL, 10);

        memcpy(memName, arh.AR_NAME, sizeof arh.AR_NAME);
        nameend = memName + AR_MAX_NAME_LEN;
        while (nameend > memName && *nameend == ' ')
            nameend--;
        nameend[1] = '\0';

#ifdef SVR4ARCHIVES
        /*
         * svr4 names are slash terminated. Also svr4 extended AR format.
         */
        if (memName[0] == '/') {
            /*
             * svr4 magic mode; handle it
             */
            switch (ArchSVR4Entry(ar, memName, size, arch)) {
            case -1:    /* Invalid data */
                goto badarch;
            case 0:             /* List of files entry */
                continue;
            default:    /* Got the entry */
                break;
            }
        } else {
            if (nameend[0] == '/')
                nameend[0] = '\0';
        }
#endif

#ifdef AR_EFMT1
        /*
         * BSD 4.4 extended AR format: #1/<namelen>, with name as the
         * first <namelen> bytes of the file
         */
        if (strncmp(memName, AR_EFMT1, sizeof AR_EFMT1 - 1) == 0 &&
            ch_isdigit(memName[sizeof AR_EFMT1 - 1])) {

            int elen = atoi(memName + sizeof AR_EFMT1 - 1);

            if ((unsigned int)elen > MAXPATHLEN)
                goto badarch;
            if (fread(memName, (size_t)elen, 1, arch) != 1)
                goto badarch;
            memName[elen] = '\0';
            if (fseek(arch, -elen, SEEK_CUR) != 0)
                goto badarch;
            if (DEBUG(ARCH) || DEBUG(MAKE))
                debug_printf("ArchStatMember: Extended format entry for %s\n",
                             memName);
        }
#endif

        {
            struct ar_hdr *cached_hdr = bmake_malloc(sizeof *cached_hdr);
            memcpy(cached_hdr, &arh, sizeof arh);
            HashTable_Set(&ar->members, memName, cached_hdr);
        }

        if (fseek(arch, ((long)size + 1) & ~1, SEEK_CUR) != 0)
            goto badarch;
    }

    fclose(arch);

    Lst_Append(archives, ar);

    /*
     * Now that the archive has been read and cached, we can look into
     * the addToCache table to find the desired member's header.
     */
    return HashTable_FindValue(&ar->members, member);

badarch:
    fclose(arch);
    HashTable_Done(&ar->members);
    free(ar->fnametab);
    free(ar);
    return NULL;
}

#ifdef SVR4ARCHIVES
/*-
 *-----------------------------------------------------------------------
 * ArchSVR4Entry --
 *      Parse an SVR4 style entry that begins with a slash.
 *      If it is "//", then load the table of filenames
 *      If it is "/<offset>", then try to substitute the long file name
 *      from offset of a table previously read.
 *      If a table is read, the file pointer is moved to the next archive
 *      member.
 *
 * Results:
 *      -1: Bad data in archive
 *       0: A table was loaded from the file
 *       1: Name was successfully substituted from table
 *       2: Name was not successfully substituted from table
 *-----------------------------------------------------------------------
 */
static int
ArchSVR4Entry(Arch *ar, char *inout_name, size_t size, FILE *arch)
{
#define ARLONGNAMES1 "//"
#define ARLONGNAMES2 "/ARFILENAMES"
    size_t entry;
    char *ptr, *eptr;

    if (strncmp(inout_name, ARLONGNAMES1, sizeof ARLONGNAMES1 - 1) == 0 ||
        strncmp(inout_name, ARLONGNAMES2, sizeof ARLONGNAMES2 - 1) == 0) {

        if (ar->fnametab != NULL) {
            DEBUG0(ARCH, "Attempted to redefine an SVR4 name table\n");
            return -1;
        }

        /*
         * This is a table of archive names, so we build one for
         * ourselves
         */
        ar->fnametab = bmake_malloc(size);
        ar->fnamesize = size;

        if (fread(ar->fnametab, size, 1, arch) != 1) {
            DEBUG0(ARCH, "Reading an SVR4 name table failed\n");
            return -1;
        }
        eptr = ar->fnametab + size;
        for (entry = 0, ptr = ar->fnametab; ptr < eptr; ptr++)
            if (*ptr == '/') {
                entry++;
                *ptr = '\0';
            }
        DEBUG1(ARCH, "Found svr4 archive name table with %lu entries\n",
               (unsigned long)entry);
        return 0;
    }

    if (inout_name[1] == ' ' || inout_name[1] == '\0')
        return 2;

    entry = (size_t)strtol(&inout_name[1], &eptr, 0);
    if ((*eptr != ' ' && *eptr != '\0') || eptr == &inout_name[1]) {
        DEBUG1(ARCH, "Could not parse SVR4 name %s\n", inout_name);
        return 2;
    }
    if (entry >= ar->fnamesize) {
        DEBUG2(ARCH, "SVR4 entry offset %s is greater than %lu\n",
               inout_name, (unsigned long)ar->fnamesize);
        return 2;
    }

    DEBUG2(ARCH, "Replaced %s with %s\n", inout_name, &ar->fnametab[entry]);

    snprintf(inout_name, MAXPATHLEN + 1, "%s", &ar->fnametab[entry]);
    return 1;
}
#endif


static Boolean
ArchiveMember_HasName(const struct ar_hdr *hdr,
                      const char *name, size_t namelen)
{
    const size_t ar_name_len = sizeof hdr->AR_NAME;
    const char *ar_name = hdr->AR_NAME;

    if (strncmp(ar_name, name, namelen) != 0)
        return FALSE;

    if (namelen >= ar_name_len)
        return namelen == ar_name_len;

    /* hdr->AR_NAME is space-padded to the right. */
    if (ar_name[namelen] == ' ')
        return TRUE;

    /* In archives created by GNU binutils 2.27, the member names end with
     * a slash. */
    if (ar_name[namelen] == '/' &&
        (namelen == ar_name_len || ar_name[namelen + 1] == ' '))
        return TRUE;

    return FALSE;
}

/* Locate a member of an archive, given the path of the archive and the path
 * of the desired member.
 *
 * Input:
 *      archive         Path to the archive
 *      member          Name of member. If it is a path, only the last
 *                      component is used.
 *      out_arh         Archive header to be filled in
 *      mode            "r" for read-only access, "r+" for read-write access
 *
 * Output:
 *      return          The archive file, positioned at the start of the
 *                      member's struct ar_hdr, or NULL if the member doesn't
 *                      exist.
 *      *out_arh        The current struct ar_hdr for member.
 *
 * See ArchStatMember for an almost identical copy of this code.
 */
static FILE *
ArchFindMember(const char *archive, const char *member, struct ar_hdr *out_arh,
               const char *mode)
{
    FILE *arch;                 /* Stream to archive */
    int size;                   /* Size of archive member */
    char magic[SARMAG];
    size_t len, tlen;
    const char *lastSlash;

    arch = fopen(archive, mode);
    if (arch == NULL)
        return NULL;

    /*
     * We use the ARMAG string to make sure this is an archive we
     * can handle...
     */
    if (fread(magic, SARMAG, 1, arch) != 1 ||
        strncmp(magic, ARMAG, SARMAG) != 0) {
        fclose(arch);
        return NULL;
    }

    /*
     * Because of space constraints and similar things, files are archived
     * using their basename, not the entire path.
     */
    lastSlash = strrchr(member, '/');
    if (lastSlash != NULL)
        member = lastSlash + 1;

    len = tlen = strlen(member);
    if (len > sizeof out_arh->AR_NAME) {
        tlen = sizeof out_arh->AR_NAME;
    }

    while (fread(out_arh, sizeof *out_arh, 1, arch) == 1) {

        if (strncmp(out_arh->AR_FMAG, ARFMAG, sizeof out_arh->AR_FMAG) != 0) {
            /*
             * The header is bogus, so the archive is bad
             * and there's no way we can recover...
             */
            fclose(arch);
            return NULL;
        }

        DEBUG5(ARCH, "Reading archive %s member %.*s mtime %.*s\n",
               archive,
               (int)sizeof out_arh->AR_NAME, out_arh->AR_NAME,
               (int)sizeof out_arh->ar_date, out_arh->ar_date);

        if (ArchiveMember_HasName(out_arh, member, len)) {
            /*
             * To make life easier for callers that want to update the
             * archive, we reposition the file at the start
             * of the header we just read before we return the stream.
             * In a more general situation, it might be better to leave
             * the file at the actual member, rather than its header, but
             * not here.
             */
            if (fseek(arch, -(long)sizeof *out_arh, SEEK_CUR) != 0) {
                fclose(arch);
                return NULL;
            }
            return arch;
        }

#ifdef AR_EFMT1
        /*
         * BSD 4.4 extended AR format: #1/<namelen>, with name as the
         * first <namelen> bytes of the file
         */
        if (strncmp(out_arh->AR_NAME, AR_EFMT1, sizeof AR_EFMT1 - 1) == 0 &&
            ch_isdigit(out_arh->AR_NAME[sizeof AR_EFMT1 - 1]))
        {
            int elen = atoi(&out_arh->AR_NAME[sizeof AR_EFMT1 - 1]);
            char ename[MAXPATHLEN + 1];

            if ((unsigned int)elen > MAXPATHLEN) {
                fclose(arch);
                return NULL;
            }
            if (fread(ename, (size_t)elen, 1, arch) != 1) {
                fclose(arch);
                return NULL;
            }
            ename[elen] = '\0';
            if (DEBUG(ARCH) || DEBUG(MAKE))
                debug_printf("ArchFindMember: Extended format entry for %s\n",
                             ename);
            if (strncmp(ename, member, len) == 0) {
                /* Found as extended name */
                if (fseek(arch, -(long)sizeof(struct ar_hdr) - elen,
                          SEEK_CUR) != 0) {
                    fclose(arch);
                    return NULL;
                }
                return arch;
            }
            if (fseek(arch, -elen, SEEK_CUR) != 0) {
                fclose(arch);
                return NULL;
            }
        }
#endif

        /*
         * This isn't the member we're after, so we need to advance the
         * stream's pointer to the start of the next header. Files are
         * padded with newlines to an even-byte boundary, so we need to
         * extract the size of the file from the 'size' field of the
         * header and round it up during the seek.
         */
        out_arh->AR_SIZE[sizeof out_arh->AR_SIZE - 1] = '\0';
        size = (int)strtol(out_arh->AR_SIZE, NULL, 10);
        if (fseek(arch, (size + 1) & ~1, SEEK_CUR) != 0) {
            fclose(arch);
            return NULL;
        }
    }

    fclose(arch);
    return NULL;
}

/* Touch a member of an archive, on disk.
 * The GNode's modification time is left as-is.
 *
 * The st_mtime of the entire archive is also changed.
 * For a library, it may be required to run ranlib after this.
 *
 * Input:
 *      gn              Node of member to touch
 *
 * Results:
 *      The 'time' field of the member's header is updated.
 */
void
Arch_Touch(GNode *gn)
{
    FILE *f;
    struct ar_hdr arh;

    f = ArchFindMember(GNode_VarArchive(gn), GNode_VarMember(gn), &arh, "r+");
    if (f == NULL)
        return;

    snprintf(arh.ar_date, sizeof arh.ar_date, "%-ld", (unsigned long)now);
    (void)fwrite(&arh, sizeof arh, 1, f);
    fclose(f);                  /* TODO: handle errors */
}

/* Given a node which represents a library, touch the thing, making sure that
 * the table of contents is also touched.
 *
 * Both the modification time of the library and of the RANLIBMAG member are
 * set to 'now'. */
void
Arch_TouchLib(GNode *gn MAKE_ATTR_UNUSED)
{
#ifdef RANLIBMAG
    FILE *f;
    struct ar_hdr arh;          /* Header describing table of contents */
    struct utimbuf times;

    f = ArchFindMember(gn->path, RANLIBMAG, &arh, "r+");
    if (f == NULL)
        return;

    snprintf(arh.ar_date, sizeof arh.ar_date, "%-ld", (unsigned long)now);
    (void)fwrite(&arh, sizeof arh, 1, f);
    fclose(f);                  /* TODO: handle errors */

    times.actime = times.modtime = now;
    utime(gn->path, &times);    /* TODO: handle errors */
#endif
}

/* Update the mtime of the GNode with the mtime from the archive member on
 * disk (or in the cache). */
void
Arch_UpdateMTime(GNode *gn)
{
    struct ar_hdr *arh;

    arh = ArchStatMember(GNode_VarArchive(gn), GNode_VarMember(gn), TRUE);
    if (arh != NULL)
        gn->mtime = (time_t)strtol(arh->ar_date, NULL, 10);
    else
        gn->mtime = 0;
}

/* Given a non-existent archive member's node, update gn->mtime from its
 * archived form, if it exists. */
void
Arch_UpdateMemberMTime(GNode *gn)
{
    GNodeListNode *ln;

    for (ln = gn->parents->first; ln != NULL; ln = ln->next) {
        GNode *pgn = ln->datum;

        if (pgn->type & OP_ARCHV) {
            /*
             * If the parent is an archive specification and is being made
             * and its member's name matches the name of the node we were
             * given, record the modification time of the parent in the
             * child. We keep searching its parents in case some other
             * parent requires this child to exist...
             */
            const char *nameStart = strchr(pgn->name, '(') + 1;
            const char *nameEnd = strchr(nameStart, ')');
            size_t nameLen = (size_t)(nameEnd - nameStart);

            if ((pgn->flags & REMAKE) &&
                strncmp(nameStart, gn->name, nameLen) == 0) {
                Arch_UpdateMTime(pgn);
                gn->mtime = pgn->mtime;
            }
        } else if (pgn->flags & REMAKE) {
            /*
             * Something which isn't a library depends on the existence of
             * this target, so it needs to exist.
             */
            gn->mtime = 0;
            break;
        }
    }
}

/* Search for a library along the given search path.
 *
 * The node's 'path' field is set to the found path (including the
 * actual file name, not -l...). If the system can handle the -L
 * flag when linking (or we cannot find the library), we assume that
 * the user has placed the .LIBS variable in the final linking
 * command (or the linker will know where to find it) and set the
 * TARGET variable for this node to be the node's name. Otherwise,
 * we set the TARGET variable to be the full path of the library,
 * as returned by Dir_FindFile.
 *
 * Input:
 *      gn              Node of library to find
 */
void
Arch_FindLib(GNode *gn, SearchPath *path)
{
    char *libName = str_concat3("lib", gn->name + 2, ".a");
    gn->path = Dir_FindFile(libName, path);
    free(libName);

#ifdef LIBRARIES
    Var_Set(TARGET, gn->name, gn);
#else
    Var_Set(TARGET, gn->path == NULL ? gn->name : gn->path, gn);
#endif
}

/* Decide if a node with the OP_LIB attribute is out-of-date. Called from
 * GNode_IsOODate to make its life easier.
 * The library is cached if it hasn't been already.
 *
 * There are several ways for a library to be out-of-date that are
 * not available to ordinary files. In addition, there are ways
 * that are open to regular files that are not available to
 * libraries.
 *
 * A library that is only used as a source is never
 * considered out-of-date by itself. This does not preclude the
 * library's modification time from making its parent be out-of-date.
 * A library will be considered out-of-date for any of these reasons,
 * given that it is a target on a dependency line somewhere:
 *
 *      Its modification time is less than that of one of its sources
 *      (gn->mtime < gn->youngestChild->mtime).
 *
 *      Its modification time is greater than the time at which the make
 *      began (i.e. it's been modified in the course of the make, probably
 *      by archiving).
 *
 *      The modification time of one of its sources is greater than the one
 *      of its RANLIBMAG member (i.e. its table of contents is out-of-date).
 *      We don't compare the archive time vs. TOC time because they can be
 *      too close. In my opinion we should not bother with the TOC at all
 *      since this is used by 'ar' rules that affect the data contents of the
 *      archive, not by ranlib rules, which affect the TOC.
 */
Boolean
Arch_LibOODate(GNode *gn)
{
    Boolean oodate;

    if (gn->type & OP_PHONY) {
        oodate = TRUE;
    } else if (!GNode_IsTarget(gn) && Lst_IsEmpty(gn->children)) {
        oodate = FALSE;
    } else if ((!Lst_IsEmpty(gn->children) && gn->youngestChild == NULL) ||
               (gn->mtime > now) ||
               (gn->youngestChild != NULL &&
                gn->mtime < gn->youngestChild->mtime)) {
        oodate = TRUE;
    } else {
#ifdef RANLIBMAG
        struct ar_hdr *arh;     /* Header for __.SYMDEF */
        int modTimeTOC;         /* The table-of-contents's mod time */

        arh = ArchStatMember(gn->path, RANLIBMAG, FALSE);

        if (arh != NULL) {
            modTimeTOC = (int)strtol(arh->ar_date, NULL, 10);

            if (DEBUG(ARCH) || DEBUG(MAKE))
                debug_printf("%s modified %s...",
                             RANLIBMAG, Targ_FmtTime(modTimeTOC));
            oodate = gn->youngestChild == NULL ||
                     gn->youngestChild->mtime > modTimeTOC;
        } else {
            /* A library without a table of contents is out-of-date. */
            if (DEBUG(ARCH) || DEBUG(MAKE))
                debug_printf("no toc...");
            oodate = TRUE;
        }
#else
        oodate = FALSE;
#endif
    }
    return oodate;
}

/* Initialize the archives module. */
void
Arch_Init(void)
{
    archives = Lst_New();
}

/* Clean up the archives module. */
void
Arch_End(void)
{
#ifdef CLEANUP
    Lst_Destroy(archives, ArchFree);
#endif
}

Boolean
Arch_IsLib(GNode *gn)
{
    static const char armag[] = "!<arch>\n";
    char buf[sizeof armag - 1];
    int fd;

    if ((fd = open(gn->path, O_RDONLY)) == -1)
        return FALSE;

    if (read(fd, buf, sizeof buf) != sizeof buf) {
        (void)close(fd);
        return FALSE;
    }

    (void)close(fd);

    return memcmp(buf, armag, sizeof buf) == 0;
}