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

base/file_util_posix.cc

Index: base/file_util_posix.cc
diff --git a/base/file_util_posix.cc b/base/file_util_posix.cc
index 579e79a34b87e5ba52aa570c624f42a3f925c98c..5be5f5b73d9a327d4259d56a10e973e643332c4a 100644
--- a/base/file_util_posix.cc
+++ b/base/file_util_posix.cc
@@ -303,24 +303,22 @@ bool PathExists(const FilePath& path) {
   return CallStat(path.value().c_str(), &file_info) == 0;
 }
 
-bool PathIsWritable(const FilePath& path) {
-  FilePath test_path(path);
-  stat_wrapper_t file_info;
-  if (CallStat(test_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.

-    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;
+    r = access(path.DirName().value().c_str(), mode);
   }
-  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 r == 0;
+}
+
+bool PathIsReadable(const FilePath& path) {
+  return PathAccess(path, R_OK);
+}
+
+bool PathIsWritable(const FilePath& path) {
+  return PathAccess(path, W_OK);
 }
 
 bool DirectoryExists(const FilePath& path) {