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Revision 1.5, Mon Sep 2 16:04:09 1996 UTC (27 years, 8 months ago) by briggs
Branch: MAIN
CVS Tags: OPENBSD_2_0_BASE, OPENBSD_2_0
Changes since 1.4: +12 -12 lines

Sync up with NetBSD:
(christos)
	Fix bug reported by Greg Hudson where leaf (source only) nodes were
	referenced only by their basename and not by their full pathname. This
	breaks when .PATH or MAKEOBJDIR are used. There might be Makefiles
	around that try to work around this bug by prepending ${.CURDIR} to
	the sources, and they should be found and fixed. Also a lot of the gunk
	in suff.c that was attempting to work around the same problem could be
	removed.
(christos)
	- Move -D flags from Makefile to config.h and explain what they do. Add
	  -Wall -Wno-unused to CFLAGS. Add new define SYSVVARSUB to enable SysV
	  style variable substitutions and enable them.
	- Add SunOS style command substitutions via SUNSHCMD
	- Fix core dump with '{variable = value'
(christos)
	Fix bug where make will always exit with 0, even when one or more
	parallel jobs failed. (Only affects parallel make code)
(christos)
	Protect __P from being multiply defined (for systems that already
	define it)
(christos) Add strdup() since ultrix is missing it.
	From Larry Schwimmer <rosebud@cyclone.Stanford.EDU>
(christos) Add estrdup(), a checked version of strdup and use it.
(christos) Recognize SVR4 style long filename entries in archives.
(thorpej) Tidy up some RCS ids a bit.

/*	$OpenBSD: dir.c,v 1.5 1996/09/02 16:04:09 briggs Exp $	*/
/*	$NetBSD: dir.c,v 1.11 1996/08/13 16:42:02 christos Exp $	*/

/*
 * Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
 * 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.
 */

#ifndef lint
#if 0
static char sccsid[] = "@(#)dir.c	5.6 (Berkeley) 12/28/90";
#else
static char rcsid[] = "$OpenBSD: dir.c,v 1.5 1996/09/02 16:04:09 briggs Exp $";
#endif
#endif /* not lint */

/*-
 * dir.c --
 *	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_End  	    Cleanup the module.
 *
 *	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_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 <stdio.h>
#include <sys/types.h>
#include <dirent.h>
#include <sys/stat.h>
#include "make.h"
#include "hash.h"
#include "dir.h"

/*
 *	A search path consists of a Lst of Path structures. A Path structure
 *	has in it the name of the directory and a hash table 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.
 *
 *	A list of all previously-read directories is kept in the
 *	openDirectories Lst. This list 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 hashing 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 Path structure and
 *	       verify the directory hasn't changed since the contents were
 *	       hashed. 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
 *	       rehashing could seriously degrade performance. It might be
 *	       good in such cases to keep track of the number of rehashes
 *	       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.
 */

Lst          dirSearchPath;	/* main search path */

static Lst   openDirectories;	/* the list of all open directories */

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

static Path    	  *dot;	    /* contents of current directory */
static Hash_Table mtimes;   /* 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 int DirFindName __P((ClientData, ClientData));
static int DirMatchFiles __P((char *, Path *, Lst));
static void DirExpandCurly __P((char *, char *, Lst, Lst));
static void DirExpandInt __P((char *, Lst, Lst));
static int DirPrintWord __P((ClientData, ClientData));
static int DirPrintDir __P((ClientData, ClientData));

/*-
 *-----------------------------------------------------------------------
 * Dir_Init --
 *	initialize things for this module
 *
 * Results:
 *	none
 *
 * Side Effects:
 *	some directories may be opened.
 *-----------------------------------------------------------------------
 */
void
Dir_Init ()
{
    dirSearchPath = Lst_Init (FALSE);
    openDirectories = Lst_Init (FALSE);
    Hash_InitTable(&mtimes, 0);
    
    /*
     * Since the Path structure is placed on both openDirectories and
     * the path we give Dir_AddDir (which in this case is openDirectories),
     * we need to remove "." from openDirectories and what better time to
     * do it than when we have to fetch the thing anyway?
     */
    Dir_AddDir (openDirectories, ".");
    dot = (Path *) Lst_DeQueue (openDirectories);

    /*
     * We always need to have dot around, so we increment its reference count
     * to make sure it's not destroyed.
     */
    dot->refCount += 1;
}

/*-
 *-----------------------------------------------------------------------
 * Dir_End --
 *	cleanup things for this module
 *
 * Results:
 *	none
 *
 * Side Effects:
 *	none
 *-----------------------------------------------------------------------
 */
void
Dir_End()
{
    dot->refCount -= 1;
    Dir_Destroy((ClientData) dot);
    Dir_ClearPath(dirSearchPath);
    Lst_Destroy(dirSearchPath, NOFREE);
    Dir_ClearPath(openDirectories);
    Lst_Destroy(openDirectories, NOFREE);
    Hash_DeleteTable(&mtimes);
}

/*-
 *-----------------------------------------------------------------------
 * DirFindName --
 *	See if the Path structure describes the same directory as the
 *	given one by comparing their names. Called from Dir_AddDir via
 *	Lst_Find when searching the list of open directories.
 *
 * Results:
 *	0 if it is the same. Non-zero otherwise
 *
 * Side Effects:
 *	None
 *-----------------------------------------------------------------------
 */
static int
DirFindName (p, dname)
    ClientData    p;	      /* Current name */
    ClientData	  dname;      /* Desired name */
{
    return (strcmp (((Path *)p)->name, (char *) dname));
}

/*-
 *-----------------------------------------------------------------------
 * Dir_HasWildcards  --
 *	see if the given name has any wildcard characters in it
 *
 * Results:
 *	returns TRUE if the word should be expanded, FALSE otherwise
 *
 * Side Effects:
 *	none
 *-----------------------------------------------------------------------
 */
Boolean
Dir_HasWildcards (name)
    char          *name;	/* name to check */
{
    register char *cp;
    
    for (cp = name; *cp; cp++) {
	switch(*cp) {
	case '{':
	case '[':
	case '?':
	case '*':
	    return (TRUE);
	}
    }
    return (FALSE);
}

/*-
 *-----------------------------------------------------------------------
 * DirMatchFiles --
 * 	Given a pattern and a Path structure, see if any files
 *	match the pattern and add their names to the 'expansions' list if
 *	any do. This is incomplete -- it doesn't take care of patterns like
 *	src / *src / *.c properly (just *.c on any of the directories), but it
 *	will do for now.
 *
 * Results:
 *	Always returns 0
 *
 * Side Effects:
 *	File names are added to the expansions lst. The directory will be
 *	fully hashed when this is done.
 *-----------------------------------------------------------------------
 */
static int
DirMatchFiles (pattern, p, expansions)
    char	  *pattern;   	/* Pattern to look for */
    Path	  *p;         	/* Directory to search */
    Lst	    	  expansions;	/* Place to store the results */
{
    Hash_Search	  search;   	/* Index into the directory's table */	
    Hash_Entry	  *entry;   	/* Current entry in the table */
    Boolean 	  isDot;    	/* TRUE if the directory being searched is . */
    
    isDot = (*p->name == '.' && p->name[1] == '\0');
    
    for (entry = Hash_EnumFirst(&p->files, &search);
	 entry != (Hash_Entry *)NULL;
	 entry = Hash_EnumNext(&search))
    {
	/*
	 * See if the file matches the given pattern. Note we follow the UNIX
	 * convention that dot files will only be found if the pattern
	 * begins with a dot (note also that as a side effect of the hashing
	 * scheme, .* won't match . or .. since they aren't hashed).
	 */
	if (Str_Match(entry->name, pattern) &&
	    ((entry->name[0] != '.') ||
	     (pattern[0] == '.')))
	{
	    (void)Lst_AtEnd(expansions,
			    (isDot ? estrdup(entry->name) :
			     str_concat(p->name, entry->name,
					STR_ADDSLASH)));
	}
    }
    return (0);
}

/*-
 *-----------------------------------------------------------------------
 * DirExpandCurly --
 *	Expand curly braces like the C shell. Does this recursively.
 *	Note the special case: if after the piece of the curly brace is
 *	done there are no wildcard characters in the result, the result is
 *	placed on the list WITHOUT CHECKING FOR ITS EXISTENCE.
 *
 * Results:
 *	None.
 *
 * Side Effects:
 *	The given list is filled with the expansions...
 *
 *-----------------------------------------------------------------------
 */
static void
DirExpandCurly(word, brace, path, expansions)
    char    	  *word;    	/* Entire word to expand */
    char    	  *brace;   	/* First curly brace in it */
    Lst	    	  path;	    	/* Search path to use */
    Lst	    	  expansions;	/* Place to store the expansions */
{
    char    	  *end;	    	/* Character after the closing brace */
    char    	  *cp;	    	/* Current position in brace clause */
    char    	  *start;   	/* Start of current piece of brace clause */
    int	    	  bracelevel;	/* Number of braces we've seen. If we see a
				 * right brace when this is 0, we've hit the
				 * end of the clause. */
    char    	  *file;    	/* Current expansion */
    int	    	  otherLen; 	/* The length of the other pieces of the
				 * expansion (chars before and after the
				 * clause in 'word') */
    char    	  *cp2;	    	/* Pointer for checking for wildcards in
				 * expansion before calling Dir_Expand */

    start = brace+1;

    /*
     * Find the end of the brace clause first, being wary of nested brace
     * clauses.
     */
    for (end = start, bracelevel = 0; *end != '\0'; end++) {
	if (*end == '{') {
	    bracelevel++;
	} else if ((*end == '}') && (bracelevel-- == 0)) {
	    break;
	}
    }
    if (*end == '\0') {
	Error("Unterminated {} clause \"%s\"", start);
	return;
    } else {
	end++;
    }
    otherLen = brace - word + strlen(end);

    for (cp = start; cp < end; cp++) {
	/*
	 * Find the end of this piece of the clause.
	 */
	bracelevel = 0;
	while (*cp != ',') {
	    if (*cp == '{') {
		bracelevel++;
	    } else if ((*cp == '}') && (bracelevel-- <= 0)) {
		break;
	    }
	    cp++;
	}
	/*
	 * Allocate room for the combination and install the three pieces.
	 */
	file = emalloc(otherLen + cp - start + 1);
	if (brace != word) {
	    strncpy(file, word, brace-word);
	}
	if (cp != start) {
	    strncpy(&file[brace-word], start, cp-start);
	}
	strcpy(&file[(brace-word)+(cp-start)], end);

	/*
	 * See if the result has any wildcards in it. If we find one, call
	 * Dir_Expand right away, telling it to place the result on our list
	 * of expansions.
	 */
	for (cp2 = file; *cp2 != '\0'; cp2++) {
	    switch(*cp2) {
	    case '*':
	    case '?':
	    case '{':
	    case '[':
		Dir_Expand(file, path, expansions);
		goto next;
	    }
	}
	if (*cp2 == '\0') {
	    /*
	     * Hit the end w/o finding any wildcards, so stick the expansion
	     * on the end of the list.
	     */
	    (void)Lst_AtEnd(expansions, file);
	} else {
	next:
	    free(file);
	}
	start = cp+1;
    }
}


/*-
 *-----------------------------------------------------------------------
 * DirExpandInt --
 *	Internal expand routine. Passes through the directories in the
 *	path one by one, calling DirMatchFiles for each. NOTE: This still
 *	doesn't handle patterns in directories...
 *
 * Results:
 *	None.
 *
 * Side Effects:
 *	Things are added to the expansions list.
 *
 *-----------------------------------------------------------------------
 */
static void
DirExpandInt(word, path, expansions)
    char    	  *word;    	/* Word to expand */
    Lst	    	  path;	    	/* Path on which to look */
    Lst	    	  expansions;	/* Place to store the result */
{
    LstNode 	  ln;	    	/* Current node */
    Path	  *p;	    	/* Directory in the node */

    if (Lst_Open(path) == SUCCESS) {
	while ((ln = Lst_Next(path)) != NILLNODE) {
	    p = (Path *)Lst_Datum(ln);
	    DirMatchFiles(word, p, expansions);
	}
	Lst_Close(path);
    }
}

/*-
 *-----------------------------------------------------------------------
 * DirPrintWord --
 *	Print a word in the list of expansions. Callback for Dir_Expand
 *	when DEBUG(DIR), via Lst_ForEach.
 *
 * Results:
 *	=== 0
 *
 * Side Effects:
 *	The passed word is printed, followed by a space.
 *
 *-----------------------------------------------------------------------
 */
static int
DirPrintWord(word, dummy)
    ClientData  word;
    ClientData  dummy;
{
    printf("%s ", (char *) word);

    return(dummy ? 0 : 0);
}

/*-
 *-----------------------------------------------------------------------
 * Dir_Expand  --
 *	Expand the given word into a list of words by globbing it looking
 *	in the directories on the given search path.
 *
 * Results:
 *	A list of words consisting of the files which exist along the search
 *	path matching the given pattern.
 *
 * Side Effects:
 *	Directories may be opened. Who knows?
 *-----------------------------------------------------------------------
 */
void
Dir_Expand (word, path, expansions)
    char    *word;      /* the word to expand */
    Lst     path;   	/* the list of directories in which to find
			 * the resulting files */
    Lst	    expansions;	/* the list on which to place the results */
{
    char    	  *cp;

    if (DEBUG(DIR)) {
	printf("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 == '*' || *cp == '{') {
		    break;
		}
	    }
	    if (*cp == '{') {
		/*
		 * This one will be fun.
		 */
		DirExpandCurly(word, cp, path, expansions);
		return;
	    } else if (*cp != '\0') {
		/*
		 * Back up to the start of the component
		 */
		char  *dirpath;

		while (cp > word && *cp != '/') {
		    cp--;
		}
		if (cp != word) {
		    char sc;
		    /*
		     * If the glob isn't in the first component, try and find
		     * all the components up to the one with a wildcard.
		     */
		    sc = cp[1];
		    cp[1] = '\0';
		    dirpath = Dir_FindFile(word, path);
		    cp[1] = sc;
		    /*
		     * 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 != (char *)NULL) {
			char *dp = &dirpath[strlen(dirpath) - 1];
			if (*dp == '/')
			    *dp = '\0';
			path = Lst_Init(FALSE);
			Dir_AddDir(path, dirpath);
			DirExpandInt(cp+1, path, expansions);
			Lst_Destroy(path, NOFREE);
		    }
		} else {
		    /*
		     * Start the search from the local directory
		     */
		    DirExpandInt(word, path, expansions);
		}
	    } else {
		/*
		 * Return the file -- this should never happen.
		 */
		DirExpandInt(word, path, expansions);
	    }
	} else {
	    /*
	     * First the files in dot
	     */
	    DirMatchFiles(word, dot, expansions);
    
	    /*
	     * Then the files in every other directory on the path.
	     */
	    DirExpandInt(word, path, expansions);
	}
    }
    if (DEBUG(DIR)) {
	Lst_ForEach(expansions, DirPrintWord, (ClientData) 0);
	fputc('\n', stdout);
    }
}

/*-
 *-----------------------------------------------------------------------
 * Dir_FindFile  --
 *	Find the file with the given name along the given search path.
 *
 * Results:
 *	The path to the file or NULL. This path is guaranteed to be in a
 *	different part of memory than name and so may be safely free'd.
 *
 * Side Effects:
 *	If the file is found in a directory which 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.
 *-----------------------------------------------------------------------
 */
char *
Dir_FindFile (name, path)
    char    	  *name;    /* the file to find */
    Lst           path;	    /* the Lst of directories to search */
{
    register char *p1;	    /* pointer into p->name */
    register char *p2;	    /* pointer into name */
    LstNode       ln;	    /* a list element */
    register char *file;    /* the current filename to check */
    register Path *p;	    /* current path member */
    register char *cp;	    /* index of first slash, if any */
    Boolean	  hasSlash; /* true if 'name' contains a / */
    struct stat	  stb;	    /* Buffer for stat, if necessary */
    Hash_Entry	  *entry;   /* Entry for mtimes table */
    
    /*
     * Find the final component of the name and note whether it has a
     * slash in it (the name, I mean)
     */
    cp = strrchr (name, '/');
    if (cp) {
	hasSlash = TRUE;
	cp += 1;
    } else {
	hasSlash = FALSE;
	cp = name;
    }
    
    if (DEBUG(DIR)) {
	printf("Searching for %s...", name);
    }
    /*
     * No matter what, we always look for the file in the current directory
     * before anywhere else 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 ((!hasSlash || (cp - name == 2 && *name == '.')) &&
	(Hash_FindEntry (&dot->files, cp) != (Hash_Entry *)NULL)) {
	    if (DEBUG(DIR)) {
		printf("in '.'\n");
	    }
	    hits += 1;
	    dot->hits += 1;
	    return (estrdup (name));
    }
    
    if (Lst_Open (path) == FAILURE) {
	if (DEBUG(DIR)) {
	    printf("couldn't open path, file not found\n");
	}
	misses += 1;
	return ((char *) NULL);
    }
    
    /*
     * We look through all the directories on the path seeking one which
     * contains the final component of the given name and whose final
     * component(s) match the name's initial component(s). 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...
     */
    while ((ln = Lst_Next (path)) != NILLNODE) {
	p = (Path *) Lst_Datum (ln);
	if (DEBUG(DIR)) {
	    printf("%s...", p->name);
	}
	if (Hash_FindEntry (&p->files, cp) != (Hash_Entry *)NULL) {
	    if (DEBUG(DIR)) {
		printf("here...");
	    }
	    if (hasSlash) {
		/*
		 * If the name had a slash, its initial components and p's
		 * final components must match. This is false if a mismatch
		 * is encountered before all of the initial components
		 * have been checked (p2 > name at the end of the loop), or
		 * we matched only part of one of the components of p
		 * along with all the rest of them (*p1 != '/').
		 */
		p1 = p->name + strlen (p->name) - 1;
		p2 = cp - 2;
		while (p2 >= name && p1 >= p->name && *p1 == *p2) {
		    p1 -= 1; p2 -= 1;
		}
		if (p2 >= name || (p1 >= p->name && *p1 != '/')) {
		    if (DEBUG(DIR)) {
			printf("component mismatch -- continuing...");
		    }
		    continue;
		}
	    }
	    file = str_concat (p->name, cp, STR_ADDSLASH);
	    if (DEBUG(DIR)) {
		printf("returning %s\n", file);
	    }
	    Lst_Close (path);
	    p->hits += 1;
	    hits += 1;
	    return (file);
	} else if (hasSlash) {
	    /*
	     * If the file has a leading path component and that component
	     * exactly matches the entire name of the current search
	     * directory, we assume the file doesn't exist and return NULL.
	     */
	    for (p1 = p->name, p2 = name; *p1 && *p1 == *p2; p1++, p2++) {
		continue;
	    }
	    if (*p1 == '\0' && p2 == cp - 1) {
		if (DEBUG(DIR)) {
		    printf("must be here but isn't -- returing NULL\n");
		}
		Lst_Close (path);
		return ((char *) NULL);
	    }
	}
    }
    
    /*
     * We didn't find the file on any existing members of the directory.
     * 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) 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) {
	if (DEBUG(DIR)) {
	    printf("failed.\n");
	}
	misses += 1;
	return ((char *) NULL);
    }
    
    if (*name != '/') {
	Boolean	checkedDot = FALSE;
	
	if (DEBUG(DIR)) {
	    printf("failed. Trying subdirectories...");
	}
	(void) Lst_Open (path);
	while ((ln = Lst_Next (path)) != NILLNODE) {
	    p = (Path *) Lst_Datum (ln);
	    if (p != dot) {
		file = str_concat (p->name, name, STR_ADDSLASH);
	    } else {
		/*
		 * Checking in dot -- DON'T put a leading ./ on the thing.
		 */
		file = estrdup(name);
		checkedDot = TRUE;
	    }
	    if (DEBUG(DIR)) {
		printf("checking %s...", file);
	    }
	    
		
	    if (stat (file, &stb) == 0) {
		if (DEBUG(DIR)) {
		    printf("got it.\n");
		}
		
		Lst_Close (path);
		
		/*
		 * We've found another directory to search. We know there's
		 * a slash in 'file' because we put one there. We nuke it after
		 * finding it and call Dir_AddDir to add this new directory
		 * onto the existing search path. Once that's done, we restore
		 * the slash and triumphantly return the file name, knowing
		 * that should a file in this directory every be referenced
		 * again in such a manner, we will find it without having to do
		 * numerous numbers of access calls. Hurrah!
		 */
		cp = strrchr (file, '/');
		*cp = '\0';
		Dir_AddDir (path, file);
		*cp = '/';
		
		/*
		 * Save the modification time so if it's needed, we don't have
		 * to fetch it again.
		 */
		if (DEBUG(DIR)) {
		    printf("Caching %s for %s\n", Targ_FmtTime(stb.st_mtime),
			    file);
		}
		entry = Hash_CreateEntry(&mtimes, (char *) file,
					 (Boolean *)NULL);
		Hash_SetValue(entry, (long)stb.st_mtime);
		nearmisses += 1;
		return (file);
	    } else {
		free (file);
	    }
	}
	
	if (DEBUG(DIR)) {
	    printf("failed. ");
	}
	Lst_Close (path);

	if (checkedDot) {
	    /*
	     * Already checked by the given name, since . was in the path,
	     * so no point in proceeding...
	     */
	    if (DEBUG(DIR)) {
		printf("Checked . already, returning NULL\n");
	    }
	    return(NULL);
	}
    }
    
    /*
     * 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
    cp[-1] = '\0';
    Dir_AddDir (path, name);
    cp[-1] = '/';
    
    bigmisses += 1;
    ln = Lst_Last (path);
    if (ln == NILLNODE) {
	return ((char *) NULL);
    } else {
	p = (Path *) Lst_Datum (ln);
    }
    
    if (Hash_FindEntry (&p->files, cp) != (Hash_Entry *)NULL) {
	return (estrdup (name));
    } else {
	return ((char *) NULL);
    }
#else /* !notdef */
    if (DEBUG(DIR)) {
	printf("Looking for \"%s\"...", name);
    }
    
    bigmisses += 1;
    entry = Hash_FindEntry(&mtimes, name);
    if (entry != (Hash_Entry *)NULL) {
	if (DEBUG(DIR)) {
	    printf("got it (in mtime cache)\n");
	}
	return(estrdup(name));
    } else if (stat (name, &stb) == 0) {
	entry = Hash_CreateEntry(&mtimes, name, (Boolean *)NULL);
	if (DEBUG(DIR)) {
	    printf("Caching %s for %s\n", Targ_FmtTime(stb.st_mtime),
		    name);
	}
	Hash_SetValue(entry, (long)stb.st_mtime);
	return (estrdup (name));
    } else {
	if (DEBUG(DIR)) {
	    printf("failed. Returning NULL\n");
	}
	return ((char *)NULL);
    }
#endif /* notdef */
}

/*-
 *-----------------------------------------------------------------------
 * Dir_MTime  --
 *	Find the modification time of the file described by gn along the
 *	search path dirSearchPath.
 * 
 * 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.
 *-----------------------------------------------------------------------
 */
int
Dir_MTime (gn)
    GNode         *gn;	      /* the file whose modification time is
			       * desired */
{
    char          *fullName;  /* the full pathname of name */
    struct stat	  stb;	      /* buffer for finding the mod time */
    Hash_Entry	  *entry;
    
    if (gn->type & OP_ARCHV) {
	return Arch_MTime (gn);
    } else if (gn->path == (char *)NULL) {
	fullName = Dir_FindFile (gn->name, dirSearchPath);
    } else {
	fullName = gn->path;
    }
    
    if (fullName == (char *)NULL) {
	fullName = estrdup(gn->name);
    }

    entry = Hash_FindEntry(&mtimes, fullName);
    if (entry != (Hash_Entry *)NULL) {
	/*
	 * Only do this once -- the second time folks are checking to
	 * see if the file was actually updated, so we need to actually go
	 * to the file system.
	 */
	if (DEBUG(DIR)) {
	    printf("Using cached time %s for %s\n",
		    Targ_FmtTime((time_t)(long)Hash_GetValue(entry)), fullName);
	}
	stb.st_mtime = (time_t)(long)Hash_GetValue(entry);
	Hash_DeleteEntry(&mtimes, entry);
    } else if (stat (fullName, &stb) < 0) {
	if (gn->type & OP_MEMBER) {
	    if (fullName != gn->path)
		free(fullName);
	    return Arch_MemMTime (gn);
	} else {
	    stb.st_mtime = 0;
	}
    }
    if (fullName && gn->path == (char *)NULL) {
	gn->path = fullName;
    }
    
    gn->mtime = stb.st_mtime;
    return (gn->mtime);
}

/*-
 *-----------------------------------------------------------------------
 * Dir_AddDir --
 *	Add the given name to the end of the given path. The order of
 *	the arguments is backwards so ParseDoDependency can do a
 *	Lst_ForEach of its list of paths...
 *
 * Results:
 *	none
 *
 * Side Effects:
 *	A structure is added to the list and the directory is 
 *	read and hashed.
 *-----------------------------------------------------------------------
 */
void
Dir_AddDir (path, name)
    Lst           path;	      /* the path to which the directory should be
			       * added */
    char          *name;      /* the name of the directory to add */
{
    LstNode       ln;	      /* node in case Path structure is found */
    register Path *p;	      /* pointer to new Path structure */
    DIR     	  *d;	      /* for reading directory */
    register struct dirent *dp; /* entry in directory */
    
    ln = Lst_Find (openDirectories, (ClientData)name, DirFindName);
    if (ln != NILLNODE) {
	p = (Path *)Lst_Datum (ln);
	if (Lst_Member(path, (ClientData)p) == NILLNODE) {
	    p->refCount += 1;
	    (void)Lst_AtEnd (path, (ClientData)p);
	}
    } else {
	if (DEBUG(DIR)) {
	    printf("Caching %s...", name);
	    fflush(stdout);
	}
	
	if ((d = opendir (name)) != (DIR *) NULL) {
	    p = (Path *) emalloc (sizeof (Path));
	    p->name = estrdup (name);
	    p->hits = 0;
	    p->refCount = 1;
	    Hash_InitTable (&p->files, -1);
	    
	    /*
	     * Skip the first two entries -- these will *always* be . and ..
	     */
	    (void)readdir(d);
	    (void)readdir(d);
	    
	    while ((dp = readdir (d)) != (struct dirent *) 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)Hash_CreateEntry(&p->files, dp->d_name, (Boolean *)NULL);
	    }
	    (void) closedir (d);
	    (void)Lst_AtEnd (openDirectories, (ClientData)p);
	    (void)Lst_AtEnd (path, (ClientData)p);
	}
	if (DEBUG(DIR)) {
	    printf("done\n");
	}
    }
}

/*-
 *-----------------------------------------------------------------------
 * Dir_CopyDir --
 *	Callback function for duplicating a search path via Lst_Duplicate.
 *	Ups the reference count for the directory.
 *
 * Results:
 *	Returns the Path it was given.
 *
 * Side Effects:
 *	The refCount of the path is incremented.
 *
 *-----------------------------------------------------------------------
 */
ClientData
Dir_CopyDir(p)
    ClientData p;
{
    ((Path *) p)->refCount += 1;

    return ((ClientData)p);
}

/*-
 *-----------------------------------------------------------------------
 * 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.
 *
 * 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 (flag, path)
    char	  *flag;  /* flag which should precede each directory */
    Lst	    	  path;	  /* list of directories */
{
    char	  *str;	  /* the string which will be returned */
    char	  *tstr;  /* the current directory preceded by 'flag' */
    LstNode	  ln;	  /* the node of the current directory */
    Path	  *p;	  /* the structure describing the current directory */
    
    str = estrdup ("");
    
    if (Lst_Open (path) == SUCCESS) {
	while ((ln = Lst_Next (path)) != NILLNODE) {
	    p = (Path *) Lst_Datum (ln);
	    tstr = str_concat (flag, p->name, 0);
	    str = str_concat (str, tstr, STR_ADDSPACE | STR_DOFREE);
	}
	Lst_Close (path);
    }
    
    return (str);
}

/*-
 *-----------------------------------------------------------------------
 * Dir_Destroy --
 *	Nuke a directory descriptor, if possible. Callback procedure
 *	for the suffixes module when destroying a search path.
 *
 * Results:
 *	None.
 *
 * Side Effects:
 *	If no other path references this directory (refCount == 0),
 *	the Path and all its data are freed.
 *
 *-----------------------------------------------------------------------
 */
void
Dir_Destroy (pp)
    ClientData 	  pp;	    /* The directory descriptor to nuke */
{
    Path    	  *p = (Path *) pp;
    p->refCount -= 1;

    if (p->refCount == 0) {
	LstNode	ln;

	ln = Lst_Member (openDirectories, (ClientData)p);
	(void) Lst_Remove (openDirectories, ln);

	Hash_DeleteTable (&p->files);
	free((Address)p->name);
	free((Address)p);
    }
}

/*-
 *-----------------------------------------------------------------------
 * Dir_ClearPath --
 *	Clear out all elements of the given search path. This is different
 *	from destroying the list, notice.
 *
 * Results:
 *	None.
 *
 * Side Effects:
 *	The path is set to the empty list.
 *
 *-----------------------------------------------------------------------
 */
void
Dir_ClearPath(path)
    Lst	    path; 	/* Path to clear */
{
    Path    *p;
    while (!Lst_IsEmpty(path)) {
	p = (Path *)Lst_DeQueue(path);
	Dir_Destroy((ClientData) p);
    }
}
	    

/*-
 *-----------------------------------------------------------------------
 * Dir_Concat --
 *	Concatenate two paths, adding the second to the end of the first.
 *	Makes sure to avoid duplicates.
 *
 * Results:
 *	None
 *
 * Side Effects:
 *	Reference counts for added dirs are upped.
 *
 *-----------------------------------------------------------------------
 */
void
Dir_Concat(path1, path2)
    Lst	    path1;  	/* Dest */
    Lst	    path2;  	/* Source */
{
    LstNode ln;
    Path    *p;

    for (ln = Lst_First(path2); ln != NILLNODE; ln = Lst_Succ(ln)) {
	p = (Path *)Lst_Datum(ln);
	if (Lst_Member(path1, (ClientData)p) == NILLNODE) {
	    p->refCount += 1;
	    (void)Lst_AtEnd(path1, (ClientData)p);
	}
    }
}

/********** DEBUG INFO **********/
void
Dir_PrintDirectories()
{
    LstNode	ln;
    Path	*p;
    
    printf ("#*** Directory Cache:\n");
    printf ("# Stats: %d hits %d misses %d near misses %d losers (%d%%)\n",
	      hits, misses, nearmisses, bigmisses,
	      (hits+bigmisses+nearmisses ?
	       hits * 100 / (hits + bigmisses + nearmisses) : 0));
    printf ("# %-20s referenced\thits\n", "directory");
    if (Lst_Open (openDirectories) == SUCCESS) {
	while ((ln = Lst_Next (openDirectories)) != NILLNODE) {
	    p = (Path *) Lst_Datum (ln);
	    printf ("# %-20s %10d\t%4d\n", p->name, p->refCount, p->hits);
	}
	Lst_Close (openDirectories);
    }
}

static int DirPrintDir (p, dummy)
    ClientData	p;
    ClientData	dummy;
{ 
    printf ("%s ", ((Path *) p)->name);
    return (dummy ? 0 : 0);
}

void
Dir_PrintPath (path)
    Lst	path;
{
    Lst_ForEach (path, DirPrintDir, (ClientData)0);
}