openat: detect Solaris fchownat bug

[pspp] / lib / open.c

diff --git a/lib/open.c b/lib/open.c
index 13af274602661bb5b628c6d225d51ad2f4673007..8027b473a5a385816248b638a486abce5071aaf5 100644 (file)
--- a/lib/open.c
+++ b/lib/open.c
@@ -1,5 +1,5 @@
 /* Open a descriptor to a file.
-   Copyright (C) 2007-2008 Free Software Foundation, Inc.
+   Copyright (C) 2007-2009 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
@@ -38,6 +38,11 @@ orig_open (const char *filename, int flags, mode_t mode)
 #include <string.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <unistd.h>
+
+#ifndef REPLACE_OPEN_DIRECTORY
+# define REPLACE_OPEN_DIRECTORY 0
+#endif
 
 int
 open (const char *filename, int flags, ...)
@@ -51,12 +56,9 @@ open (const char *filename, int flags, ...)
       va_list arg;
       va_start (arg, flags);
 
-      /* If mode_t is narrower than int, use the promoted type (int),
-        not mode_t.  Use sizeof to guess whether mode_t is narrower;
-        we don't know of any practical counterexamples.  */
-      mode = (sizeof (mode_t) < sizeof (int)
-             ? va_arg (arg, int)
-             : va_arg (arg, mode_t));
+      /* We have to use PROMOTED_MODE_T instead of mode_t, otherwise GCC 4
+        creates crashing code when 'mode_t' is smaller than 'int'.  */
+      mode = va_arg (arg, PROMOTED_MODE_T);
 
       va_end (arg);
     }
@@ -101,6 +103,29 @@ open (const char *filename, int flags, ...)
 
   fd = orig_open (filename, flags, mode);
 
+#if REPLACE_FCHDIR
+  /* Implementing fchdir and fdopendir requires the ability to open a
+     directory file descriptor.  If open doesn't support that (as on
+     mingw), we use a dummy file that behaves the same as directories
+     on Linux (ie. always reports EOF on attempts to read()), and
+     override fstat() in fchdir.c to hide the fact that we have a
+     dummy.  */
+  if (REPLACE_OPEN_DIRECTORY && fd < 0 && errno == EACCES
+      && (flags & O_ACCMODE) == O_RDONLY)
+    {
+      struct stat statbuf;
+      if (stat (filename, &statbuf) == 0 && S_ISDIR (statbuf.st_mode))
+        {
+          /* Maximum recursion depth of 1.  */
+          fd = open ("/dev/null", flags, mode);
+          if (0 <= fd)
+            fd = _gl_register_fd (fd, filename);
+        }
+      else
+        errno = EACCES;
+    }
+#endif
+
 #if OPEN_TRAILING_SLASH_BUG
   /* If the filename ends in a slash and fd does not refer to a directory,
      then fail.
@@ -116,8 +141,9 @@ open (const char *filename, int flags, ...)
      with ENOTDIR.  */
   if (fd >= 0)
     {
+      /* We know len is positive, since open did not fail with ENOENT.  */
       size_t len = strlen (filename);
-      if (len > 0 && filename[len - 1] == '/')
+      if (filename[len - 1] == '/')
        {
          struct stat statbuf;
 
@@ -131,9 +157,9 @@ open (const char *filename, int flags, ...)
     }
 #endif
 
-#ifdef FCHDIR_REPLACEMENT
-  if (fd >= 0)
-    _gl_register_fd (fd, filename);
+#if REPLACE_FCHDIR
+  if (!REPLACE_OPEN_DIRECTORY && 0 <= fd)
+    fd = _gl_register_fd (fd, filename);
 #endif
 
   return fd;