Update to bmake-20201101

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

/*      $NetBSD: dir.c,v 1.193 2020/10/31 17:39:20 rillig 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.
 */

/* Directory searching using wildcards and/or normal names.
 * Used both for source wildcarding in the makefile and for finding
 * implicit sources.
 *
 * The interface for this module is:
 *      Dir_Init        Initialize the module.
 *
 *      Dir_InitCur     Set the cur CachedDir.
 *
 *      Dir_InitDot     Set the dot CachedDir.
 *
 *      Dir_End         Clean up the module.
 *
 *      Dir_SetPATH     Set ${.PATH} to reflect state of dirSearchPath.
 *
 *      Dir_HasWildcards
 *                      Returns TRUE if the name given it needs to
 *                      be wildcard-expanded.
 *
 *      Dir_Expand      Given a pattern and a path, return a Lst of names
 *                      which match the pattern on the search path.
 *
 *      Dir_FindFile    Searches for a file on a given search path.
 *                      If it exists, the entire path is returned.
 *                      Otherwise NULL is returned.
 *
 *      Dir_FindHereOrAbove
 *                      Search for a path in the current directory and
 *                      then all the directories above it in turn until
 *                      the path is found or we reach the root ("/").
 *
 *      Dir_MTime       Return the modification time of a node. The file
 *                      is searched for along the default search path.
 *                      The path and mtime fields of the node are filled in.
 *
 *      Dir_AddDir      Add a directory to a search path.
 *
 *      Dir_MakeFlags   Given a search path and a command flag, create
 *                      a string with each of the directories in the path
 *                      preceded by the command flag and all of them
 *                      separated by a space.
 *
 *      Dir_Destroy     Destroy an element of a search path. Frees up all
 *                      things that can be freed for the element as long
 *                      as the element is no longer referenced by any other
 *                      search path.
 *
 *      Dir_ClearPath   Resets a search path to the empty list.
 *
 * For debugging:
 *      Dir_PrintDirectories
 *                      Print stats about the directory cache.
 */

#include <sys/types.h>
#include <sys/stat.h>

#include <dirent.h>
#include <errno.h>

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

/*      "@(#)dir.c      8.2 (Berkeley) 1/2/94"  */
MAKE_RCSID("$NetBSD: dir.c,v 1.193 2020/10/31 17:39:20 rillig Exp $");

#define DIR_DEBUG0(text) DEBUG0(DIR, text)
#define DIR_DEBUG1(fmt, arg1) DEBUG1(DIR, fmt, arg1)
#define DIR_DEBUG2(fmt, arg1, arg2) DEBUG2(DIR, fmt, arg1, arg2)

/* A search path is a list of CachedDir structures. A CachedDir has in it the
 * name of the directory and the names of all the files in the directory.
 * This is used to cut down on the number of system calls necessary to find
 * implicit dependents and their like. Since these searches are made before
 * any actions are taken, we need not worry about the directory changing due
 * to creation commands. If this hampers the style of some makefiles, they
 * must be changed.
 *
 * All previously-read directories are kept in openDirs, which is checked
 * first before a directory is opened.
 *
 * The need for the caching of whole directories is brought about by the
 * multi-level transformation code in suff.c, which tends to search for far
 * more files than regular make does. In the initial implementation, the
 * amount of time spent performing "stat" calls was truly astronomical.
 * The problem with caching at the start is, of course, that pmake doesn't
 * then detect changes to these directories during the course of the make.
 * Three possibilities suggest themselves:
 *
 * 1)   just use stat to test for a file's existence. As mentioned above,
 *      this is very inefficient due to the number of checks engendered by
 *      the multi-level transformation code.
 *
 * 2)   use readdir() and company to search the directories, keeping them
 *      open between checks. I have tried this and while it didn't slow down
 *      the process too much, it could severely affect the amount of
 *      parallelism available as each directory open would take another file
 *      descriptor out of play for handling I/O for another job. Given that
 *      it is only recently that UNIX OS's have taken to allowing more than
 *      20 or 32 file descriptors for a process, this doesn't seem acceptable
 *      to me.
 *
 * 3)   record the mtime of the directory in the CachedDir structure and
 *      verify the directory hasn't changed since the contents were cached.
 *      This will catch the creation or deletion of files, but not the
 *      updating of files. However, since it is the creation and deletion
 *      that is the problem, this could be a good thing to do. Unfortunately,
 *      if the directory (say ".") were fairly large and changed fairly
 *      frequently, the constant reloading could seriously degrade
 *      performance. It might be good in such cases to keep track of the
 *      number of reloadings and if the number goes over a (small) limit,
 *      resort to using stat in its place.
 *
 * An additional thing to consider is that pmake is used primarily to create
 * C programs and until recently pcc-based compilers refused to allow you to
 * specify where the resulting object file should be placed. This forced all
 * objects to be created in the current directory. This isn't meant as a full
 * excuse, just an explanation of some of the reasons for the caching used
 * here.
 *
 * One more note: the location of a target's file is only performed on the
 * downward traversal of the graph and then only for terminal nodes in the
 * graph. This could be construed as wrong in some cases, but prevents
 * inadvertent modification of files when the "installed" directory for a
 * file is provided in the search path.
 *
 * Another data structure maintained by this module is an mtime cache used
 * when the searching of cached directories fails to find a file. In the past,
 * Dir_FindFile would simply perform an access() call in such a case to
 * determine if the file could be found using just the name given. When this
 * hit, however, all that was gained was the knowledge that the file existed.
 * Given that an access() is essentially a stat() without the copyout() call,
 * and that the same filesystem overhead would have to be incurred in
 * Dir_MTime, it made sense to replace the access() with a stat() and record
 * the mtime in a cache for when Dir_MTime was actually called.
 */

typedef List CachedDirList;
typedef ListNode CachedDirListNode;

typedef ListNode SearchPathNode;

SearchPath *dirSearchPath;              /* main search path */

/* A list of cached directories, with fast lookup by directory name. */
typedef struct OpenDirs {
    CachedDirList *list;
    HashTable /* of CachedDirListNode */ table;
} OpenDirs;

static void
OpenDirs_Init(OpenDirs *odirs)
{
    odirs->list = Lst_New();
    HashTable_Init(&odirs->table);
}

#ifdef CLEANUP
static void
OpenDirs_Done(OpenDirs *odirs)
{
    CachedDirListNode *ln = odirs->list->first;
    while (ln != NULL) {
        CachedDirListNode *next = ln->next;
        CachedDir *dir = ln->datum;
        Dir_Destroy(dir);       /* removes the dir from odirs->list */
        ln = next;
    }
    Lst_Free(odirs->list);
    HashTable_Done(&odirs->table);
}
#endif

static CachedDir *
OpenDirs_Find(OpenDirs *odirs, const char *name)
{
    CachedDirListNode *ln = HashTable_FindValue(&odirs->table, name);
    return ln != NULL ? ln->datum : NULL;
}

static void
OpenDirs_Add(OpenDirs *odirs, CachedDir *cdir)
{
    HashEntry *he = HashTable_FindEntry(&odirs->table, cdir->name);
    if (he != NULL)
        return;
    he = HashTable_CreateEntry(&odirs->table, cdir->name, NULL);
    Lst_Append(odirs->list, cdir);
    HashEntry_Set(he, odirs->list->last);
}

static void
OpenDirs_Remove(OpenDirs *odirs, const char *name)
{
    HashEntry *he = HashTable_FindEntry(&odirs->table, name);
    CachedDirListNode *ln;
    if (he == NULL)
        return;
    ln = HashEntry_Get(he);
    HashTable_DeleteEntry(&odirs->table, he);
    Lst_Remove(odirs->list, ln);
}

static OpenDirs openDirs;       /* the list of all open directories */

/*
 * Variables for gathering statistics on the efficiency of the cashing
 * mechanism.
 */
static int hits;                /* Found in directory cache */
static int misses;              /* Sad, but not evil misses */
static int nearmisses;          /* Found under search path */
static int bigmisses;           /* Sought by itself */

static CachedDir *dot;          /* contents of current directory */
static CachedDir *cur;          /* contents of current directory, if not dot */
static CachedDir *dotLast;      /* a fake path entry indicating we need to
                                 * look for . last */

/* Results of doing a last-resort stat in Dir_FindFile -- if we have to go to
 * the system to find the file, we might as well have its mtime on record.
 *
 * XXX: If this is done way early, there's a chance other rules will have
 * already updated the file, in which case we'll update it again. Generally,
 * there won't be two rules to update a single file, so this should be ok,
 * but... */
static HashTable mtimes;

static HashTable lmtimes;       /* same as mtimes but for lstat */

/*
 * We use stat(2) a lot, cache the results.
 * mtime and mode are all we care about.
 */
struct cache_st {
    time_t lmtime;              /* lstat */
    time_t mtime;               /* stat */
    mode_t mode;
};

/* minimize changes below */
typedef enum CachedStatsFlags {
    CST_LSTAT = 0x01,           /* call lstat(2) instead of stat(2) */
    CST_UPDATE = 0x02           /* ignore existing cached entry */
} CachedStatsFlags;

/* Returns 0 and the result of stat(2) or lstat(2) in *mst, or -1 on error. */
static int
cached_stats(HashTable *htp, const char *pathname, struct make_stat *mst,
             CachedStatsFlags flags)
{
    HashEntry *entry;
    struct stat sys_st;
    struct cache_st *cst;
    int rc;

    if (!pathname || !pathname[0])
        return -1;

    entry = HashTable_FindEntry(htp, pathname);

    if (entry && !(flags & CST_UPDATE)) {
        cst = HashEntry_Get(entry);

        mst->mst_mode = cst->mode;
        mst->mst_mtime = (flags & CST_LSTAT) ? cst->lmtime : cst->mtime;
        if (mst->mst_mtime) {
            DIR_DEBUG2("Using cached time %s for %s\n",
                       Targ_FmtTime(mst->mst_mtime), pathname);
            return 0;
        }
    }

    rc = (flags & CST_LSTAT)
         ? lstat(pathname, &sys_st)
         : stat(pathname, &sys_st);
    if (rc == -1)
        return -1;

    if (sys_st.st_mtime == 0)
        sys_st.st_mtime = 1;    /* avoid confusion with missing file */

    mst->mst_mode = sys_st.st_mode;
    mst->mst_mtime = sys_st.st_mtime;

    if (entry == NULL)
        entry = HashTable_CreateEntry(htp, pathname, NULL);
    if (HashEntry_Get(entry) == NULL) {
        HashEntry_Set(entry, bmake_malloc(sizeof(*cst)));
        memset(HashEntry_Get(entry), 0, sizeof(*cst));
    }
    cst = HashEntry_Get(entry);
    if (flags & CST_LSTAT) {
        cst->lmtime = sys_st.st_mtime;
    } else {
        cst->mtime = sys_st.st_mtime;
    }
    cst->mode = sys_st.st_mode;
    DIR_DEBUG2("   Caching %s for %s\n",
               Targ_FmtTime(sys_st.st_mtime), pathname);

    return 0;
}

int
cached_stat(const char *pathname, struct make_stat *st)
{
    return cached_stats(&mtimes, pathname, st, 0);
}

int
cached_lstat(const char *pathname, struct make_stat *st)
{
    return cached_stats(&lmtimes, pathname, st, CST_LSTAT);
}

/* Initialize the directories module. */
void
Dir_Init(void)
{
    dirSearchPath = Lst_New();
    OpenDirs_Init(&openDirs);
    HashTable_Init(&mtimes);
    HashTable_Init(&lmtimes);
}

void
Dir_InitDir(const char *cdname)
{
    Dir_InitCur(cdname);

    dotLast = bmake_malloc(sizeof(CachedDir));
    dotLast->refCount = 1;
    dotLast->hits = 0;
    dotLast->name = bmake_strdup(".DOTLAST");
    HashTable_Init(&dotLast->files);
}

/*
 * Called by Dir_InitDir and whenever .CURDIR is assigned to.
 */
void
Dir_InitCur(const char *cdname)
{
    CachedDir *dir;

    if (cdname != NULL) {
        /*
         * Our build directory is not the same as our source directory.
         * Keep this one around too.
         */
        if ((dir = Dir_AddDir(NULL, cdname))) {
            dir->refCount++;
            if (cur && cur != dir) {
                /*
                 * We've been here before, clean up.
                 */
                cur->refCount--;
                Dir_Destroy(cur);
            }
            cur = dir;
        }
    }
}

/* (Re)initialize "dot" (current/object directory) path hash.
 * Some directories may be opened. */
void
Dir_InitDot(void)
{
    if (dot != NULL) {
        /* Remove old entry from openDirs, but do not destroy. */
        OpenDirs_Remove(&openDirs, dot->name);
    }

    dot = Dir_AddDir(NULL, ".");

    if (dot == NULL) {
        Error("Cannot open `.' (%s)", strerror(errno));
        exit(1);
    }

    /*
     * We always need to have dot around, so we increment its reference count
     * to make sure it's not destroyed.
     */
    dot->refCount++;
    Dir_SetPATH();              /* initialize */
}

/* Clean up the directories module. */
void
Dir_End(void)
{
#ifdef CLEANUP
    if (cur) {
        cur->refCount--;
        Dir_Destroy(cur);
    }
    dot->refCount--;
    dotLast->refCount--;
    Dir_Destroy(dotLast);
    Dir_Destroy(dot);
    Dir_ClearPath(dirSearchPath);
    Lst_Free(dirSearchPath);
    OpenDirs_Done(&openDirs);
    HashTable_Done(&mtimes);
#endif
}

/*
 * We want ${.PATH} to indicate the order in which we will actually
 * search, so we rebuild it after any .PATH: target.
 * This is the simplest way to deal with the effect of .DOTLAST.
 */
void
Dir_SetPATH(void)
{
    CachedDirListNode *ln;
    Boolean hasLastDot = FALSE; /* true if we should search dot last */

    Var_Delete(".PATH", VAR_GLOBAL);

    if ((ln = dirSearchPath->first) != NULL) {
        CachedDir *dir = ln->datum;
        if (dir == dotLast) {
            hasLastDot = TRUE;
            Var_Append(".PATH", dotLast->name, VAR_GLOBAL);
        }
    }

    if (!hasLastDot) {
        if (dot)
            Var_Append(".PATH", dot->name, VAR_GLOBAL);
        if (cur)
            Var_Append(".PATH", cur->name, VAR_GLOBAL);
    }

    for (ln = dirSearchPath->first; ln != NULL; ln = ln->next) {
        CachedDir *dir = ln->datum;
        if (dir == dotLast)
            continue;
        if (dir == dot && hasLastDot)
            continue;
        Var_Append(".PATH", dir->name, VAR_GLOBAL);
    }

    if (hasLastDot) {
        if (dot)
            Var_Append(".PATH", dot->name, VAR_GLOBAL);
        if (cur)
            Var_Append(".PATH", cur->name, VAR_GLOBAL);
    }
}

/* See if the given name has any wildcard characters in it and all braces and
 * brackets are properly balanced.
 *
 * XXX: This code is not 100% correct ([^]] fails etc.). I really don't think
 * that make(1) should be expanding patterns, because then you have to set a
 * mechanism for escaping the expansion!
 *
 * Return TRUE if the word should be expanded, FALSE otherwise.
 */
Boolean
Dir_HasWildcards(const char *name)
{
    const char *p;
    Boolean wild = FALSE;
    int braces = 0, brackets = 0;

    for (p = name; *p != '\0'; p++) {
        switch (*p) {
        case '{':
            braces++;
            wild = TRUE;
            break;
        case '}':
            braces--;
            break;
        case '[':
            brackets++;
            wild = TRUE;
            break;
        case ']':
            brackets--;
            break;
        case '?':
        case '*':
            wild = TRUE;
            break;
        default:
            break;
        }
    }
    return wild && brackets == 0 && braces == 0;
}

/* See if any files match the pattern and add their names to the 'expansions'
 * list if they do.
 *
 * This is incomplete -- wildcards are only expanded in the final path
 * component, but not in directories like src/lib*c/file*.c, but it
 * will do for now (now being 1993 until at least 2020). To expand these,
 * use the ':sh' variable modifier such as in ${:!echo src/lib*c/file*.c!}.
 *
 * Input:
 *      pattern         Pattern to look for
 *      dir             Directory to search
 *      expansion       Place to store the results
 */
static void
DirMatchFiles(const char *pattern, CachedDir *dir, StringList *expansions)
{
    const char *dirName = dir->name;
    Boolean isDot = dirName[0] == '.' && dirName[1] == '\0';
    HashIter hi;

    HashIter_Init(&hi, &dir->files);
    while (HashIter_Next(&hi) != NULL) {
        const char *base = hi.entry->key;

        if (!Str_Match(base, pattern))
            continue;

        /*
         * Follow the UNIX convention that dot files are only found if the
         * pattern begins with a dot. The pattern '.*' does not match '.' or
         * '..' since these are not included in the directory cache.
         *
         * This means that the pattern '[a-z.]*' does not find '.file', which
         * is consistent with bash, NetBSD sh and csh.
         */
        if (base[0] == '.' && pattern[0] != '.')
            continue;

        {
            char *fullName = isDot
                             ? bmake_strdup(base)
                             : str_concat3(dirName, "/", base);
            Lst_Append(expansions, fullName);
        }
    }
}

/* Find the next closing brace in the string, taking nested braces into
 * account. */
static const char *
closing_brace(const char *p)
{
    int nest = 0;
    while (*p != '\0') {
        if (*p == '}' && nest == 0)
            break;
        if (*p == '{')
            nest++;
        if (*p == '}')
            nest--;
        p++;
    }
    return p;
}

/* Find the next closing brace or comma in the string, taking nested braces
 * into account. */
static const char *
separator_comma(const char *p)
{
    int nest = 0;
    while (*p != '\0') {
        if ((*p == '}' || *p == ',') && nest == 0)
            break;
        if (*p == '{')
            nest++;
        if (*p == '}')
            nest--;
        p++;
    }
    return p;
}

static Boolean
contains_wildcard(const char *p)
{
    for (; *p != '\0'; p++) {
        switch (*p) {
        case '*':
        case '?':
        case '{':
        case '[':
            return TRUE;
        }
    }
    return FALSE;
}

static char *
concat3(const char *a, size_t a_len, const char *b, size_t b_len,
        const char *c, size_t c_len)
{
    size_t s_len = a_len + b_len + c_len;
    char *s = bmake_malloc(s_len + 1);
    memcpy(s, a, a_len);
    memcpy(s + a_len, b, b_len);
    memcpy(s + a_len + b_len, c, c_len);
    s[s_len] = '\0';
    return s;
}

/* Expand curly braces like the C shell. Brace expansion by itself is purely
 * textual, the expansions are not looked up in the file system. But if an
 * expanded word contains wildcard characters, it is expanded further,
 * matching only the actually existing files.
 *
 * Example: "{a{b,c}}" expands to "ab" and "ac".
 * Example: "{a}" expands to "a".
 * Example: "{a,*.c}" expands to "a" and all "*.c" files that exist.
 *
 * Input:
 *      word            Entire word to expand
 *      brace           First curly brace in it
 *      path            Search path to use
 *      expansions      Place to store the expansions
 */
static void
DirExpandCurly(const char *word, const char *brace, SearchPath *path,
               StringList *expansions)
{
    const char *prefix, *middle, *piece, *middle_end, *suffix;
    size_t prefix_len, suffix_len;

    /* Split the word into prefix '{' middle '}' suffix. */

    middle = brace + 1;
    middle_end = closing_brace(middle);
    if (*middle_end == '\0') {
        Error("Unterminated {} clause \"%s\"", middle);
        return;
    }

    prefix = word;
    prefix_len = (size_t)(brace - prefix);
    suffix = middle_end + 1;
    suffix_len = strlen(suffix);

    /* Split the middle into pieces, separated by commas. */

    piece = middle;
    while (piece < middle_end + 1) {
        const char *piece_end = separator_comma(piece);
        size_t piece_len = (size_t)(piece_end - piece);

        char *file = concat3(prefix, prefix_len, piece, piece_len,
                             suffix, suffix_len);

        if (contains_wildcard(file)) {
            Dir_Expand(file, path, expansions);
            free(file);
        } else {
            Lst_Append(expansions, file);
        }

        piece = piece_end + 1;  /* skip over the comma or closing brace */
    }
}


/* Expand the word in each of the directories from the path. */
static void
DirExpandPath(const char *word, SearchPath *path, StringList *expansions)
{
    SearchPathNode *ln;
    for (ln = path->first; ln != NULL; ln = ln->next) {
        CachedDir *dir = ln->datum;
        DirMatchFiles(word, dir, expansions);
    }
}

static void
PrintExpansions(StringList *expansions)
{
    const char *sep = "";
    StringListNode *ln;
    for (ln = expansions->first; ln != NULL; ln = ln->next) {
        const char *word = ln->datum;
        debug_printf("%s%s", sep, word);
        sep = " ";
    }
    debug_printf("\n");
}

/* Expand the given word into a list of words by globbing it, looking in the
 * directories on the given search path.
 *
 * Input:
 *      word            the word to expand
 *      path            the directories in which to find the files
 *      expansions      the list on which to place the results
 */
void
Dir_Expand(const char *word, SearchPath *path, StringList *expansions)
{
    const char *cp;

    assert(path != NULL);
    assert(expansions != NULL);

    DIR_DEBUG1("Expanding \"%s\"... ", word);

    cp = strchr(word, '{');
    if (cp) {
        DirExpandCurly(word, cp, path, expansions);
    } else {
        cp = strchr(word, '/');
        if (cp) {
            /*
             * The thing has a directory component -- find the first wildcard
             * in the string.
             */
            for (cp = word; *cp; cp++) {
                if (*cp == '?' || *cp == '[' || *cp == '*') {
                    break;
                }
            }

            if (*cp != '\0') {
                /*
                 * Back up to the start of the component
                 */
                while (cp > word && *cp != '/') {
                    cp--;
                }
                if (cp != word) {
                    char *prefix = bmake_strsedup(word, cp + 1);
                    /*
                     * If the glob isn't in the first component, try and find
                     * all the components up to the one with a wildcard.
                     */
                    char *dirpath = Dir_FindFile(prefix, path);
                    free(prefix);
                    /*
                     * dirpath is null if can't find the leading component
                     * XXX: Dir_FindFile won't find internal components.
                     * i.e. if the path contains ../Etc/Object and we're
                     * looking for Etc, it won't be found. Ah well.
                     * Probably not important.
                     */
                    if (dirpath != NULL) {
                        char *dp = &dirpath[strlen(dirpath) - 1];
                        if (*dp == '/')
                            *dp = '\0';
                        path = Lst_New();
                        (void)Dir_AddDir(path, dirpath);
                        DirExpandPath(cp + 1, path, expansions);
                        Lst_Free(path);
                    }
                } else {
                    /*
                     * Start the search from the local directory
                     */
                    DirExpandPath(word, path, expansions);
                }
            } else {
                /*
                 * Return the file -- this should never happen.
                 */
                DirExpandPath(word, path, expansions);
            }
        } else {
            /*
             * First the files in dot
             */
            DirMatchFiles(word, dot, expansions);

            /*
             * Then the files in every other directory on the path.
             */
            DirExpandPath(word, path, expansions);
        }
    }
    if (DEBUG(DIR))
        PrintExpansions(expansions);
}

/* Find if the file with the given name exists in the given path.
 * Return the freshly allocated path to the file, or NULL. */
static char *
DirLookup(CachedDir *dir, const char *base)
{
    char *file;                 /* the current filename to check */

    DIR_DEBUG1("   %s ...\n", dir->name);

    if (HashTable_FindEntry(&dir->files, base) == NULL)
        return NULL;

    file = str_concat3(dir->name, "/", base);
    DIR_DEBUG1("   returning %s\n", file);
    dir->hits++;
    hits++;
    return file;
}


/* Find if the file with the given name exists in the given directory.
 * Return the freshly allocated path to the file, or NULL. */
static char *
DirLookupSubdir(CachedDir *dir, const char *name)
{
    struct make_stat mst;
    char *file = dir == dot ? bmake_strdup(name)
                            : str_concat3(dir->name, "/", name);

    DIR_DEBUG1("checking %s ...\n", file);

    if (cached_stat(file, &mst) == 0) {
        nearmisses++;
        return file;
    }
    free(file);
    return NULL;
}

/* Find if the file with the given name exists in the given path.
 * Return the freshly allocated path to the file, the empty string, or NULL.
 * Returning the empty string means that the search should be terminated.
 */
static char *
DirLookupAbs(CachedDir *dir, const char *name, const char *cp)
{
    const char *dnp;            /* pointer into dir->name */
    const char *np;             /* pointer into name */

    DIR_DEBUG1("   %s ...\n", dir->name);

    /*
     * If the file has a leading path component and that component
     * exactly matches the entire name of the current search
     * directory, we can attempt another cache lookup. And if we don't
     * have a hit, we can safely assume the file does not exist at all.
     */
    for (dnp = dir->name, np = name; *dnp != '\0' && *dnp == *np; dnp++, np++)
        continue;
    if (*dnp != '\0' || np != cp - 1)
        return NULL;

    if (HashTable_FindEntry(&dir->files, cp) == NULL) {
        DIR_DEBUG0("   must be here but isn't -- returning\n");
        return bmake_strdup("");        /* to terminate the search */
    }

    dir->hits++;
    hits++;
    DIR_DEBUG1("   returning %s\n", name);
    return bmake_strdup(name);
}

/* Find the file given on "." or curdir.
 * Return the freshly allocated path to the file, or NULL. */
static char *
DirFindDot(const char *name, const char *base)
{

    if (HashTable_FindEntry(&dot->files, base) != NULL) {
        DIR_DEBUG0("   in '.'\n");
        hits++;
        dot->hits++;
        return bmake_strdup(name);
    }

    if (cur != NULL && HashTable_FindEntry(&cur->files, base) != NULL) {
        DIR_DEBUG1("   in ${.CURDIR} = %s\n", cur->name);
        hits++;
        cur->hits++;
        return str_concat3(cur->name, "/", base);
    }

    return NULL;
}

/* Find the file with the given name along the given search path.
 *
 * If the file is found in a directory that is not on the path
 * already (either 'name' is absolute or it is a relative path
 * [ dir1/.../dirn/file ] which exists below one of the directories
 * already on the search path), its directory is added to the end
 * of the path, on the assumption that there will be more files in
 * that directory later on. Sometimes this is true. Sometimes not.
 *
 * Input:
 *      name            the file to find
 *      path            the directories to search, or NULL
 *
 * Results:
 *      The freshly allocated path to the file, or NULL.
 */
char *
Dir_FindFile(const char *name, SearchPath *path)
{
    SearchPathNode *ln;
    char *file;                 /* the current filename to check */
    const char *base;           /* Terminal name of file */
    Boolean hasLastDot = FALSE; /* true if we should search dot last */
    Boolean hasSlash;           /* true if 'name' contains a / */
    struct make_stat mst;       /* Buffer for stat, if necessary */
    const char *trailing_dot = ".";

    /*
     * Find the final component of the name and note whether it has a
     * slash in it (the name, I mean)
     */
    base = strrchr(name, '/');
    if (base) {
        hasSlash = TRUE;
        base++;
    } else {
        hasSlash = FALSE;
        base = name;
    }

    DIR_DEBUG1("Searching for %s ...", name);

    if (path == NULL) {
        DIR_DEBUG0("couldn't open path, file not found\n");
        misses++;
        return NULL;
    }

    if ((ln = path->first) != NULL) {
        CachedDir *dir = ln->datum;
        if (dir == dotLast) {
            hasLastDot = TRUE;
            DIR_DEBUG0("[dot last]...");
        }
    }
    DIR_DEBUG0("\n");

    /*
     * If there's no leading directory components or if the leading
     * directory component is exactly `./', consult the cached contents
     * of each of the directories on the search path.
     */
    if (!hasSlash || (base - name == 2 && *name == '.')) {
        /*
         * We look through all the directories on the path seeking one which
         * contains the final component of the given name.  If such a beast
         * is found, we concatenate the directory name and the final
         * component and return the resulting string. If we don't find any
         * such thing, we go on to phase two...
         *
         * No matter what, we always look for the file in the current
         * directory before anywhere else (unless we found the magic
         * DOTLAST path, in which case we search it last) and we *do not*
         * add the ./ to it if it exists.
         * This is so there are no conflicts between what the user
         * specifies (fish.c) and what pmake finds (./fish.c).
         */
        if (!hasLastDot && (file = DirFindDot(name, base)) != NULL)
            return file;

        for (; ln != NULL; ln = ln->next) {
            CachedDir *dir = ln->datum;
            if (dir == dotLast)
                continue;
            if ((file = DirLookup(dir, base)) != NULL)
                return file;
        }

        if (hasLastDot && (file = DirFindDot(name, base)) != NULL)
            return file;
    }

    /*
     * We didn't find the file on any directory in the search path.
     * If the name doesn't contain a slash, that means it doesn't exist.
     * If it *does* contain a slash, however, there is still hope: it
     * could be in a subdirectory of one of the members of the search
     * path. (eg. /usr/include and sys/types.h. The above search would
     * fail to turn up types.h in /usr/include, but it *is* in
     * /usr/include/sys/types.h).
     * [ This no longer applies: If we find such a beast, we assume there
     * will be more (what else can we assume?) and add all but the last
     * component of the resulting name onto the search path (at the
     * end).]
     * This phase is only performed if the file is *not* absolute.
     */
    if (!hasSlash) {
        DIR_DEBUG0("   failed.\n");
        misses++;
        return NULL;
    }

    if (*base == '\0') {
        /* we were given a trailing "/" */
        base = trailing_dot;
    }

    if (name[0] != '/') {
        Boolean checkedDot = FALSE;

        DIR_DEBUG0("   Trying subdirectories...\n");

        if (!hasLastDot) {
            if (dot) {
                checkedDot = TRUE;
                if ((file = DirLookupSubdir(dot, name)) != NULL)
                    return file;
            }
            if (cur && (file = DirLookupSubdir(cur, name)) != NULL)
                return file;
        }

        for (ln = path->first; ln != NULL; ln = ln->next) {
            CachedDir *dir = ln->datum;
            if (dir == dotLast)
                continue;
            if (dir == dot) {
                if (checkedDot)
                    continue;
                checkedDot = TRUE;
            }
            if ((file = DirLookupSubdir(dir, name)) != NULL)
                return file;
        }

        if (hasLastDot) {
            if (dot && !checkedDot) {
                checkedDot = TRUE;
                if ((file = DirLookupSubdir(dot, name)) != NULL)
                    return file;
            }
            if (cur && (file = DirLookupSubdir(cur, name)) != NULL)
                return file;
        }

        if (checkedDot) {
            /*
             * Already checked by the given name, since . was in the path,
             * so no point in proceeding...
             */
            DIR_DEBUG0("   Checked . already, returning NULL\n");
            return NULL;
        }

    } else { /* name[0] == '/' */

        /*
         * For absolute names, compare directory path prefix against the
         * the directory path of each member on the search path for an exact
         * match. If we have an exact match on any member of the search path,
         * use the cached contents of that member to lookup the final file
         * component. If that lookup fails we can safely assume that the
         * file does not exist at all.  This is signified by DirLookupAbs()
         * returning an empty string.
         */
        DIR_DEBUG0("   Trying exact path matches...\n");

        if (!hasLastDot && cur &&
            ((file = DirLookupAbs(cur, name, base)) != NULL)) {
            if (file[0] == '\0') {
                free(file);
                return NULL;
            }
            return file;
        }

        for (ln = path->first; ln != NULL; ln = ln->next) {
            CachedDir *dir = ln->datum;
            if (dir == dotLast)
                continue;
            if ((file = DirLookupAbs(dir, name, base)) != NULL) {
                if (file[0] == '\0') {
                    free(file);
                    return NULL;
                }
                return file;
            }
        }

        if (hasLastDot && cur &&
            ((file = DirLookupAbs(cur, name, base)) != NULL)) {
            if (file[0] == '\0') {
                free(file);
                return NULL;
            }
            return file;
        }
    }

    /*
     * Didn't find it that way, either. Sigh. Phase 3. Add its directory
     * onto the search path in any case, just in case, then look for the
     * thing in the hash table. If we find it, grand. We return a new
     * copy of the name. Otherwise we sadly return a NULL pointer. Sigh.
     * Note that if the directory holding the file doesn't exist, this will
     * do an extra search of the final directory on the path. Unless something
     * weird happens, this search won't succeed and life will be groovy.
     *
     * Sigh. We cannot add the directory onto the search path because
     * of this amusing case:
     * $(INSTALLDIR)/$(FILE): $(FILE)
     *
     * $(FILE) exists in $(INSTALLDIR) but not in the current one.
     * When searching for $(FILE), we will find it in $(INSTALLDIR)
     * b/c we added it here. This is not good...
     */
#ifdef notdef
    if (base == trailing_dot) {
        base = strrchr(name, '/');
        base++;
    }
    base[-1] = '\0';
    (void)Dir_AddDir(path, name);
    base[-1] = '/';

    bigmisses++;
    ln = Lst_Last(path);
    if (ln == NULL) {
        return NULL;
    } else {
        dir = LstNode_Datum(ln);
    }

    if (Hash_FindEntry(&dir->files, base) != NULL) {
        return bmake_strdup(name);
    } else {
        return NULL;
    }
#else /* !notdef */
    DIR_DEBUG1("   Looking for \"%s\" ...\n", name);

    bigmisses++;
    if (cached_stat(name, &mst) == 0) {
        return bmake_strdup(name);
    }

    DIR_DEBUG0("   failed. Returning NULL\n");
    return NULL;
#endif /* notdef */
}


/* Search for a path starting at a given directory and then working our way
 * up towards the root.
 *
 * Input:
 *      here            starting directory
 *      search_path     the relative path we are looking for
 *
 * Results:
 *      The found path, or NULL.
 */
char *
Dir_FindHereOrAbove(const char *here, const char *search_path)
{
    struct make_stat mst;
    char *dirbase, *dirbase_end;
    char *try, *try_end;

    /* copy out our starting point */
    dirbase = bmake_strdup(here);
    dirbase_end = dirbase + strlen(dirbase);

    /* loop until we determine a result */
    for (;;) {

        /* try and stat(2) it ... */
        try = str_concat3(dirbase, "/", search_path);
        if (cached_stat(try, &mst) != -1) {
            /*
             * success!  if we found a file, chop off
             * the filename so we return a directory.
             */
            if ((mst.mst_mode & S_IFMT) != S_IFDIR) {
                try_end = try + strlen(try);
                while (try_end > try && *try_end != '/')
                    try_end--;
                if (try_end > try)
                    *try_end = '\0';    /* chop! */
            }

            free(dirbase);
            return try;
        }
        free(try);

        /*
         * nope, we didn't find it.  if we used up dirbase we've
         * reached the root and failed.
         */
        if (dirbase_end == dirbase)
            break;              /* failed! */

        /*
         * truncate dirbase from the end to move up a dir
         */
        while (dirbase_end > dirbase && *dirbase_end != '/')
            dirbase_end--;
        *dirbase_end = '\0';    /* chop! */
    }

    free(dirbase);
    return NULL;
}

/*-
 *-----------------------------------------------------------------------
 * Dir_MTime  --
 *      Find the modification time of the file described by gn along the
 *      search path dirSearchPath.
 *
 * Input:
 *      gn              the file whose modification time is desired
 *
 * Results:
 *      The modification time or 0 if it doesn't exist
 *
 * Side Effects:
 *      The modification time is placed in the node's mtime slot.
 *      If the node didn't have a path entry before, and Dir_FindFile
 *      found one for it, the full name is placed in the path slot.
 *-----------------------------------------------------------------------
 */
time_t
Dir_MTime(GNode *gn, Boolean recheck)
{
    char *fullName;             /* the full pathname of name */
    struct make_stat mst;       /* buffer for finding the mod time */

    if (gn->type & OP_ARCHV) {
        return Arch_MTime(gn);
    } else if (gn->type & OP_PHONY) {
        gn->mtime = 0;
        return 0;
    } else if (gn->path == NULL) {
        if (gn->type & OP_NOPATH)
            fullName = NULL;
        else {
            fullName = Dir_FindFile(gn->name, Suff_FindPath(gn));
            if (fullName == NULL && gn->flags & FROM_DEPEND &&
                !Lst_IsEmpty(gn->implicitParents)) {
                char *cp;

                cp = strrchr(gn->name, '/');
                if (cp) {
                    /*
                     * This is an implied source, and it may have moved,
                     * see if we can find it via the current .PATH
                     */
                    cp++;

                    fullName = Dir_FindFile(cp, Suff_FindPath(gn));
                    if (fullName) {
                        /*
                         * Put the found file in gn->path
                         * so that we give that to the compiler.
                         */
                        gn->path = bmake_strdup(fullName);
                        if (!Job_RunTarget(".STALE", gn->fname))
                            fprintf(stdout,
                                    "%s: %s, %d: ignoring stale %s for %s, "
                                    "found %s\n", progname, gn->fname,
                                    gn->lineno,
                                    makeDependfile, gn->name, fullName);
                    }
                }
            }
            DIR_DEBUG2("Found '%s' as '%s'\n",
                       gn->name, fullName ? fullName : "(not found)");
        }
    } else {
        fullName = gn->path;
    }

    if (fullName == NULL) {
        fullName = bmake_strdup(gn->name);
    }

    if (cached_stats(&mtimes, fullName, &mst, recheck ? CST_UPDATE : 0) < 0) {
        if (gn->type & OP_MEMBER) {
            if (fullName != gn->path)
                free(fullName);
            return Arch_MemMTime(gn);
        } else {
            mst.mst_mtime = 0;
        }
    }

    if (fullName != NULL && gn->path == NULL)
        gn->path = fullName;

    gn->mtime = mst.mst_mtime;
    return gn->mtime;
}

/* Read the list of filenames in the directory and store the result
 * in openDirectories.
 *
 * If a path is given, append the directory to that path.
 *
 * Input:
 *      path            The path to which the directory should be
 *                      added, or NULL to only add the directory to
 *                      openDirectories
 *      name            The name of the directory to add.
 *                      The name is not normalized in any way.
 */
CachedDir *
Dir_AddDir(SearchPath *path, const char *name)
{
    CachedDir *dir = NULL;      /* the added directory */
    DIR *d;
    struct dirent *dp;

    if (path != NULL && strcmp(name, ".DOTLAST") == 0) {
        SearchPathNode *ln;

        for (ln = path->first; ln != NULL; ln = ln->next) {
            CachedDir *pathDir = ln->datum;
            if (strcmp(pathDir->name, name) == 0)
                return pathDir;
        }

        dotLast->refCount++;
        Lst_Prepend(path, dotLast);
    }

    if (path != NULL)
        dir = OpenDirs_Find(&openDirs, name);
    if (dir != NULL) {
        if (Lst_FindDatum(path, dir) == NULL) {
            dir->refCount++;
            Lst_Append(path, dir);
        }
        return dir;
    }

    DIR_DEBUG1("Caching %s ...", name);

    if ((d = opendir(name)) != NULL) {
        dir = bmake_malloc(sizeof(CachedDir));
        dir->name = bmake_strdup(name);
        dir->hits = 0;
        dir->refCount = 1;
        HashTable_Init(&dir->files);

        while ((dp = readdir(d)) != NULL) {
#if defined(sun) && defined(d_ino) /* d_ino is a sunos4 #define for d_fileno */
            /*
             * The sun directory library doesn't check for a 0 inode
             * (0-inode slots just take up space), so we have to do
             * it ourselves.
             */
            if (dp->d_fileno == 0) {
                continue;
            }
#endif /* sun && d_ino */
            (void)HashTable_CreateEntry(&dir->files, dp->d_name, NULL);
        }
        (void)closedir(d);
        OpenDirs_Add(&openDirs, dir);
        if (path != NULL)
            Lst_Append(path, dir);
    }
    DIR_DEBUG0("done\n");
    return dir;
}

/* Return a copy of dirSearchPath, incrementing the reference counts for
 * the contained directories. */
SearchPath *
Dir_CopyDirSearchPath(void)
{
    SearchPath *path = Lst_New();
    SearchPathNode *ln;
    for (ln = dirSearchPath->first; ln != NULL; ln = ln->next) {
        CachedDir *dir = ln->datum;
        dir->refCount++;
        Lst_Append(path, dir);
    }
    return path;
}

/*-
 *-----------------------------------------------------------------------
 * Dir_MakeFlags --
 *      Make a string by taking all the directories in the given search
 *      path and preceding them by the given flag. Used by the suffix
 *      module to create variables for compilers based on suffix search
 *      paths.
 *
 * Input:
 *      flag            flag which should precede each directory
 *      path            list of directories
 *
 * Results:
 *      The string mentioned above. Note that there is no space between
 *      the given flag and each directory. The empty string is returned if
 *      Things don't go well.
 *
 * Side Effects:
 *      None
 *-----------------------------------------------------------------------
 */
char *
Dir_MakeFlags(const char *flag, SearchPath *path)
{
    Buffer buf;
    SearchPathNode *ln;

    Buf_Init(&buf, 0);

    if (path != NULL) {
        for (ln = path->first; ln != NULL; ln = ln->next) {
            CachedDir *dir = ln->datum;
            Buf_AddStr(&buf, " ");
            Buf_AddStr(&buf, flag);
            Buf_AddStr(&buf, dir->name);
        }
    }

    return Buf_Destroy(&buf, FALSE);
}

/* Nuke a directory descriptor, if possible. Callback procedure for the
 * suffixes module when destroying a search path.
 *
 * Input:
 *      dirp            The directory descriptor to nuke
 */
void
Dir_Destroy(void *dirp)
{
    CachedDir *dir = dirp;
    dir->refCount--;

    if (dir->refCount == 0) {
        OpenDirs_Remove(&openDirs, dir->name);

        HashTable_Done(&dir->files);
        free(dir->name);
        free(dir);
    }
}

/* Clear out all elements from the given search path.
 * The path is set to the empty list but is not destroyed. */
void
Dir_ClearPath(SearchPath *path)
{
    while (!Lst_IsEmpty(path)) {
        CachedDir *dir = Lst_Dequeue(path);
        Dir_Destroy(dir);
    }
}


/* Concatenate two paths, adding the second to the end of the first,
 * skipping duplicates. */
void
Dir_Concat(SearchPath *dst, SearchPath *src)
{
    SearchPathNode *ln;

    for (ln = src->first; ln != NULL; ln = ln->next) {
        CachedDir *dir = ln->datum;
        if (Lst_FindDatum(dst, dir) == NULL) {
            dir->refCount++;
            Lst_Append(dst, dir);
        }
    }
}

static int
percentage(int num, int den)
{
    return den != 0 ? num * 100 / den : 0;
}

/********** DEBUG INFO **********/
void
Dir_PrintDirectories(void)
{
    CachedDirListNode *ln;

    debug_printf("#*** Directory Cache:\n");
    debug_printf("# Stats: %d hits %d misses %d near misses %d losers (%d%%)\n",
                 hits, misses, nearmisses, bigmisses,
                 percentage(hits, hits + bigmisses + nearmisses));
    debug_printf("# %-20s referenced\thits\n", "directory");

    for (ln = openDirs.list->first; ln != NULL; ln = ln->next) {
        CachedDir *dir = ln->datum;
        debug_printf("# %-20s %10d\t%4d\n", dir->name, dir->refCount,
                     dir->hits);
    }
}

void
Dir_PrintPath(SearchPath *path)
{
    SearchPathNode *node;
    for (node = path->first; node != NULL; node = node->next) {
        const CachedDir *dir = node->datum;
        debug_printf("%s ", dir->name);
    }
}