(make_dir): New function, factored out of make_path.

(make_path): Use make_dir rather than open-coding it twice.
This effectively reverses the order of the latter pair of stat/mkdir
calls and fixes a race condition bug whereby one of two concurrent
`mkdir -p' processes could fail with EEXIST.

diff --git a/lib/makepath.c b/lib/makepath.c
index 99119a2..cf570d9 100644 (file)
--- a/lib/makepath.c
+++ b/lib/makepath.c
@@ -1,5 +1,5 @@
 /* makepath.c -- Ensure that a directory path exists.
-   Copyright (C) 1990, 1997, 1998 Free Software Foundation, Inc.
+   Copyright (C) 1990, 1997, 1998, 1999 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
@@ -99,9 +99,9 @@ void strip_trailing_slashes ();
         Restore working directory.  */                 \
       if (do_chdir)                                    \
        {                                               \
-         int fail = restore_cwd (&cwd, NULL, NULL);    \
+         int _fail = restore_cwd (&cwd, NULL, NULL);   \
          free_cwd (&cwd);                              \
-         if (fail)                                     \
+         if (_fail)                                    \
            return 1;                                   \
        }                                               \
     }                                                  \
@@ -115,6 +115,56 @@ void strip_trailing_slashes ();
     }                                                  \
   while (0)
 
+/* Attempt to create directory DIR (aka DIRPATH) with the specified MODE.
+   If CREATED_DIR_P is non-NULL, set *CREATED_DIR_P to non-zero if this
+   function creates DIR and to zero otherwise.  Give a diagnostic and
+   return non-zero if DIR cannot be created or cannot be determined to
+   exist already.  Use DIRPATH in any diagnostic, not DIR.
+   Note that if DIR already exists, this function will return zero
+   (indicating success) and will set *CREATED_DIR_P to zero.  */
+
+static int
+make_dir (const char *dir, const char *dirpath, mode_t mode, int *created_dir_p)
+{
+  int fail = 0;
+  int created_dir;
+
+  created_dir = (mkdir (dir, mode) == 0);
+
+  if (!created_dir)
+    {
+      struct stat stats;
+
+      /* The mkdir and stat calls below may appear to be reversed.
+        They are not.  It is important to call mkdir first and then to
+        call stat (to distinguish the three cases) only if mkdir fails.
+        The alternative to this approach is to `stat' each directory,
+        then to call mkdir if it doesn't exist.  But if some other process
+        were to create the directory between the stat & mkdir, the mkdir
+        would fail with EEXIST.  */
+
+      if (stat (dir, &stats))
+       {
+         error (0, errno, "cannot create directory `%s'", dirpath);
+         fail = 1;
+       }
+      else if (!S_ISDIR (stats.st_mode))
+       {
+         error (0, 0, "`%s' exists but is not a directory", dirpath);
+         fail = 1;
+       }
+      else
+       {
+         /* DIR (aka DIRPATH) already exists and is a directory. */
+       }
+    }
+
+  if (created_dir_p)
+    *created_dir_p = created_dir;
+
+  return fail;
+}
+
 /* Ensure that the directory ARGPATH exists.
    Remove any trailing slashes from ARGPATH before calling this function.
 
@@ -203,7 +253,8 @@ make_path (const char *argpath,
 
       while (1)
        {
-         int newly_created_dir = 1;
+         int newly_created_dir;
+         int fail;
 
          /* slash points to the leftmost unprocessed component of dirpath.  */
          basename_dir = slash;
@@ -217,34 +268,12 @@ make_path (const char *argpath,
          if (!do_chdir)
            basename_dir = dirpath;
 
-         /* The mkdir and stat calls below appear to be reversed.
-            They are not.  It is important to call mkdir first and then to
-            call stat (to distinguish the three cases) only if mkdir fails.
-            The alternative to this approach is to `stat' each directory,
-            then to call mkdir if it doesn't exist.  But if some other process
-            were to create the directory between the stat & mkdir, the mkdir
-            would fail with EEXIST.  */
-
          *slash = '\0';
-         if (mkdir (basename_dir, tmp_mode))
+         fail = make_dir (basename_dir, dirpath, tmp_mode, &newly_created_dir);
+         if (fail)
            {
-             if (stat (basename_dir, &stats))
-               {
-                 error (0, errno, "cannot create directory `%s'", dirpath);
-                 CLEANUP;
-                 return 1;
-               }
-             else if (!S_ISDIR (stats.st_mode))
-               {
-                 error (0, 0, "`%s' exists but is not a directory", dirpath);
-                 CLEANUP;
-                 return 1;
-               }
-             else
-               {
-                 /* DIRPATH already exists and is a directory. */
-                 newly_created_dir = 0;
-               }
+             CLEANUP;
+             return 1;
            }
 
          if (newly_created_dir)
@@ -299,12 +328,8 @@ make_path (const char *argpath,
       /* We're done making leading directories.
         Create the final component of the path.  */
 
-      /* The path could end in "/." or contain "/..", so test
-        if we really have to create the directory.  */
-
-      if (stat (basename_dir, &stats) && mkdir (basename_dir, mode))
+      if (make_dir (basename_dir, dirpath, mode, NULL))
        {
-         error (0, errno, "cannot create directory `%s'", dirpath);
          CLEANUP;
          return 1;
        }