dir.c

早期freebsd实现

/*
 * Copyright (c) 1988, 1989, 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 * 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
static char sccsid[] = "@(#)dir.c	8.2 (Berkeley) 1/2/94";
#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_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((Path *, char *));
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((char *));
static int DirPrintDir __P((Path *));

/*-
 *-----------------------------------------------------------------------
 * 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;
}

/*-
 *-----------------------------------------------------------------------
 * 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)
    Path          *p;	      /* Current name */
    char	  *dname;     /* Desired name */
{
    return (strcmp (p->name, 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 ? strdup(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);