(gl_MACROS): Require gl_ULLONG_MAX.

[gnulib.git] / lib / same.c

diff --git a/lib/same.c b/lib/same.c
index 725cf61..f018c62 100644 (file)
--- a/lib/same.c
+++ b/lib/same.c
@@ -1,5 +1,7 @@
 /* Determine whether two file names refer to the same file.
-   Copyright (C) 1997-2000, 2002-2003 Free Software Foundation, Inc.
+
+   Copyright (C) 1997, 1998, 1999, 2000, 2002, 2003, 2004 Free
+   Software Foundation, Inc.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -21,25 +23,22 @@
 # include <config.h>
 #endif
 
+#include <stdbool.h>
 #include <stdio.h>
 #ifdef HAVE_UNISTD_H
 # include <unistd.h>
 #endif
-#if HAVE_STDLIB_H
-# include <stdlib.h>
-#endif
+#include <stdlib.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <ctype.h>
 #include <errno.h>
-#ifndef errno
-extern int errno;
-#endif
 
-#if HAVE_STRING_H
-# include <string.h>
-#else
-# include <strings.h>
+#include <string.h>
+
+#include <limits.h>
+#ifndef _POSIX_NAME_MAX
+# define _POSIX_NAME_MAX 14
 #endif
 
 #include "same.h"
@@ -47,11 +46,8 @@ extern int errno;
 #include "error.h"
 #include "xalloc.h"
 
-#ifndef HAVE_DECL_FREE
-"this configure-time declaration test was not run"
-#endif
-#if !HAVE_DECL_FREE
-void free ();
+#ifndef MIN
+# define MIN(a, b) ((a) < (b) ? (a) : (b))
 #endif
 
 #define SAME_INODE(Stat_buf_1, Stat_buf_2) \
@@ -61,25 +57,38 @@ void free ();
 /* Return nonzero if SOURCE and DEST point to the same name in the same
    directory.  */
 
-int
+bool
 same_name (const char *source, const char *dest)
 {
-  char *source_basename, *dest_basename;
-  size_t source_baselen, dest_baselen;
-
   /* Compare the basenames.  */
-  source_basename = base_name (source);
-  dest_basename = base_name (dest);
-  source_baselen = base_len (source_basename);
-  dest_baselen = base_len (dest_basename);
-  if (source_baselen == dest_baselen
-      && memcmp (source_basename, dest_basename, dest_baselen) == 0)
+  char const *source_basename = base_name (source);
+  char const *dest_basename = base_name (dest);
+  size_t source_baselen = base_len (source_basename);
+  size_t dest_baselen = base_len (dest_basename);
+  bool identical_basenames =
+    (source_baselen == dest_baselen
+     && memcmp (source_basename, dest_basename, dest_baselen) == 0);
+  bool compare_dirs = identical_basenames;
+  bool same = false;
+
+#if ! _POSIX_NO_TRUNC && HAVE_PATHCONF && defined _PC_NAME_MAX
+  /* This implementation silently truncates pathname components.  If
+     the base names might be truncated, check whether the truncated
+     base names are the same, while checking the directories.  */
+  size_t slen_max = HAVE_LONG_FILE_NAMES ? 255 : _POSIX_NAME_MAX;
+  size_t min_baselen = MIN (source_baselen, dest_baselen);
+  if (slen_max <= min_baselen
+      && memcmp (source_basename, dest_basename, slen_max) == 0)
+    compare_dirs = true;
+#endif
+
+  if (compare_dirs)
     {
       struct stat source_dir_stats;
       struct stat dest_dir_stats;
       char *source_dirname, *dest_dirname;
 
-      /* Compare the directories (by comparing their inodes).  */
+      /* Compare the parent directories (via the device and inode numbers).  */
       source_dirname = dir_name (source);
       dest_dirname = dir_name (dest);
 
@@ -95,12 +104,30 @@ same_name (const char *source, const char *dest)
          error (1, errno, "%s", dest_dirname);
        }
 
+      same = SAME_INODE (source_dir_stats, dest_dir_stats);
+
+#if ! _POSIX_NO_TRUNC && HAVE_PATHCONF && defined _PC_NAME_MAX
+      if (same && ! identical_basenames)
+       {
+         long name_max = (errno = 0, pathconf (dest_dirname, _PC_NAME_MAX));
+         if (name_max < 0)
+           {
+             if (errno)
+               {
+                 /* Shouldn't happen.  */
+                 error (1, errno, "%s", dest_dirname);
+               }
+             same = false;
+           }
+         else
+           same = (name_max <= min_baselen
+                   && memcmp (source_basename, dest_basename, name_max) == 0);
+       }
+#endif
+
       free (source_dirname);
       free (dest_dirname);
-
-      if (SAME_INODE (source_dir_stats, dest_dir_stats))
-       return 1;
     }
 
-  return 0;
+  return same;
 }