Fix the case where the browser livelocks if we cannot open a file.

base/file_util_posix.cc

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/file_util.h"
 
 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <fnmatch.h>
@@ skipping 285 matching lines @@
   }
 
   return success;
 }
 
 bool PathExists(const FilePath& path) {
   stat_wrapper_t file_info;
   return CallStat(path.value().c_str(), &file_info) == 0;
 }
 
+static bool PathAccess(const FilePath& path, int mode) {
+  int r = access(path.value().c_str(), mode);
+  if (r == -1 && errno == ENOENT) {
+    // If the path doesn't exist, test the parent dir.

[wtc, 2010/01/12 19:51:02]

Do you know why we do this?  This behavior is not specified
in file_util.h.

The Windows implementation doesn't seem to do this.

+    r = access(path.DirName().value().c_str(), mode);
+  }
+
+  return r == 0;
+}
+
+bool PathIsReadable(const FilePath& path) {
+  return PathAccess(path, R_OK);
+}
+
 bool PathIsWritable(const FilePath& path) {
-  FilePath test_path(path);
-  stat_wrapper_t file_info;
-  if (CallStat(test_path.value().c_str(), &file_info) != 0) {
-    // If the path doesn't exist, test the parent dir.
-    test_path = test_path.DirName();
-    // If the parent dir doesn't exist, then return false (the path is not
-    // directly writable).
-    if (CallStat(test_path.value().c_str(), &file_info) != 0)
-      return false;
-  }
-  if (S_IWOTH & file_info.st_mode)
-    return true;
-  if (getegid() == file_info.st_gid && (S_IWGRP & file_info.st_mode))
-    return true;
-  if (geteuid() == file_info.st_uid && (S_IWUSR & file_info.st_mode))
-    return true;
-  return false;
+  return PathAccess(path, W_OK);
 }
 
 bool DirectoryExists(const FilePath& path) {
   stat_wrapper_t file_info;
   if (CallStat(path.value().c_str(), &file_info) == 0)
     return S_ISDIR(file_info.st_mode);
   return false;
 }
 
 // TODO(erikkay): implement
@@ skipping 368 matching lines @@
   length_ = 0;
   file_ = base::kInvalidPlatformFileValue;
 }
 
 bool HasFileBeenModifiedSince(const FileEnumerator::FindInfo& find_info,
                               const base::Time& cutoff_time) {
   return find_info.stat.st_mtime >= cutoff_time.ToTimeT();
 }
 
 } // namespace file_util