223 lines
6.4 KiB
C
223 lines
6.4 KiB
C
/* $RCSfile: dcache.c,v $
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-- $Revision: 1.9 $
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-- last change: $Author: ihi $ $Date: 2007-10-15 15:52:47 $
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--
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-- SYNOPSIS
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-- Directory cache management routines.
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--
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-- DESCRIPTION
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-- This is the code that maintains a directory cache for each directory
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-- that dmake visits. The entire directory is thus only read once and
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-- the need for performing costly 'stat' calls when performing target
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-- inference is much reduced. The improvement in performance should be
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-- significant for NFS or remote mounted file systems.
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--
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-- AUTHOR
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-- Dennis Vadura, dvadura@dmake.wticorp.com
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--
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-- WWW
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-- http://dmake.wticorp.com/
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--
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-- COPYRIGHT
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-- Copyright (c) 1996,1997 by WTI Corp. All rights reserved.
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--
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-- This program is NOT free software; you can redistribute it and/or
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-- modify it under the terms of the Software License Agreement Provided
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-- in the file <distribution-root>/readme/license.txt.
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--
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-- LOG
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-- Use cvs log to obtain detailed change logs.
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*/
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/* For Borland 5.00 compile, for some reason they seem to insist on pulling
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* in the winnt.h if __WIN32__ is defined and you include <dirent.h>. This
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* is, in my opinion, a BUG! on Borland's part.
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*/
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#if defined(__BORLANDC__) && defined(__WIN32__)
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#undef __WIN32__
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#endif
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#ifdef __APPLE__
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#include <sys/types.h>
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#endif
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#include <dirent.h>
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#include "extern.h"
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#include "sysintf.h"
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typedef struct ent {
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char *name;
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uint32 hkey;
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time_t mtime;
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int isdir;
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struct ent *next;
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} Entry, *EntryPtr;
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typedef struct mydir {
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char *path;
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uint32 hkey;
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EntryPtr entries;
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struct mydir *next;
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} DirEntry, *DirEntryPtr;
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static DirEntryPtr dtab[HASH_TABLE_SIZE];
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/* Stat a path using the directory cache.
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*
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* We build a cannonical representation of the path using either an absolute
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* path name if that is what 'path' is or the relative path name constructed
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* from 'path' and the present value of Pwd.
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*
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* The present value of Pwd then gives a directory path that we search for
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* in our cache using a hash lookup. If the directory component is located
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* then we search the basename component of the path and return the result of
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* the search: 0L if the component is not in the cache and it's time stamp
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* otherwise.
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*
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* If the directory is not in our cache we insert it into the cache by
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* openning the directory and reading all of the files within. Once read
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* then we return the result of the above search.
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*
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* Optionally, if force is TRUE, and we did NOT read the directory to provide
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* the result then stat the file anyway and update the internal cache.
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*/
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PUBLIC time_t
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CacheStat(path, force)
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char *path;
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int force;
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{
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struct stat stbuf;
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DirEntryPtr dp;
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EntryPtr ep;
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uint32 hkey;
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uint16 hv;
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char *fpath;
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char *spath;
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char *comp;
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char *dir;
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char *udir; /* Hold the unchanged (DcacheRespCase) directory. */
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int loaded=FALSE;
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if (If_root_path(path))
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spath = path;
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else
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spath = Build_path(Pwd,path);
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fpath = DmStrDup(spath);
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comp = Basename(fpath); /* Use before the Filedir() call. */
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dir = Filedir(fpath);
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/* do caching and comparing lower case if told so. */
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if( !STOBOOL(DcacheRespCase) ) {
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udir = DmStrDup(dir);
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strlwr(comp);
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strlwr(dir);
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} else
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udir = dir;
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hv = Hash(dir,&hkey);
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for(dp=dtab[hv]; dp; dp=dp->next)
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if (hkey == dp->hkey && strcmp(dp->path,dir) == 0)
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break;
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if (!dp) {
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/* Not cached yet, doing it now. */
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DIR *dirp;
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struct dirent *direntp;
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if( Verbose & V_DIR_CACHE )
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printf( "%s: Caching directory [%s]\n", Pname, dir );
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/* Load the directory, we have the right hash position already */
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loaded = TRUE;
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TALLOC(dp,1,DirEntry);
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dp->next = dtab[hv];
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dtab[hv] = dp;
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dp->path = DmStrDup(dir);
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dp->hkey = hkey;
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/* We use the unchanged (not potentially lowercased because of
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* DcacheRespCase) directory as this would fail on a case sensitive
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* file system.
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* Note: Using case insensitive directory caching on case sensitive
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* file systems is a *BAD* idea. If in doubt use case sensitive
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* directory caching even on case insensitive file systems as the
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* worst case in this szenario is that /foo/bar/ and /foo/BAR/ are
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* cached separately (with the same content) even though they are
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* the same directory. This would only happen if different targets
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* using different upper/lower case spellings for the same directory
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* and is *never* a good idea. */
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if (Set_dir(udir) == 0) {
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if((dirp=opendir(".")) != NIL(DIR)) {
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while((direntp=readdir(dirp)) != NULL) {
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TALLOC(ep,1,Entry);
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ep->name = DmStrDup(direntp->d_name); /* basename only */
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if( !STOBOOL(DcacheRespCase) )
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strlwr(ep->name);
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Hash(ep->name, &ep->hkey); /* This sets ep->hkey. */
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ep->next = dp->entries;
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dp->entries = ep;
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DMSTAT(direntp->d_name,&stbuf);
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ep->isdir = (stbuf.st_mode & S_IFDIR);
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ep->mtime = stbuf.st_mtime;
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}
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closedir(dirp);
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}
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Set_dir(Pwd);
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}
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}
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Hash(comp, &hkey); /* Calculate hkey. */
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/* search in dp->entries for comp. */
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if (dp) {
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for(ep=dp->entries; ep; ep=ep->next)
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if(hkey == ep->hkey && strcmp(ep->name,comp) == 0)
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break;
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}
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else
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ep = NULL;
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if( force && !loaded) {
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if (strlen(comp) > NameMax || DMSTAT(spath,&stbuf) != 0) {
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/* Either file to long or the stat failed. */
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if (strlen(comp) > NameMax)
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Warning( "File [%s] longer than value of NAMEMAX [%d].\n\
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Assume unix time 0.\n", comp, NameMax );
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if(ep)
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ep->mtime = 0L;
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}
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else {
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if (!ep) {
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TALLOC(ep,1,Entry);
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ep->name = DmStrDup(comp);
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if( !STOBOOL(DcacheRespCase) )
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strlwr(ep->name);
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Hash(ep->name, &ep->hkey);
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ep->next = dp->entries;
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ep->isdir = (stbuf.st_mode & S_IFDIR);
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dp->entries = ep;
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}
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ep->mtime = stbuf.st_mtime;
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}
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if( Verbose & V_DIR_CACHE )
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printf("%s: Updating dir cache entry for [%s], new time is %ld\n",
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Pname, spath, ep ? ep->mtime : 0L);
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}
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if( udir != dir )
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FREE(udir); /* Keep this before the free of fpath. */
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FREE(fpath);
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return(!ep ? (time_t)0L : ((STOBOOL(Augmake) && ep->isdir)?0L:ep->mtime));
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}
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