Some additions to support symlinks better on platforms that support them.

base/file_util_posix.cc

 // Copyright (c) 2010 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 355 matching lines @@
   while (total_read < bytes) {
     ssize_t bytes_read =
         HANDLE_EINTR(read(fd, buffer + total_read, bytes - total_read));
     if (bytes_read <= 0)
       break;
     total_read += bytes_read;
   }
   return total_read == bytes;
 }
 
+bool CreateSymbolicLink(const FilePath& target_path,
+                        const FilePath& symlink_path) {
+  DCHECK(!symlink_path.empty());
+  DCHECK(!target_path.empty());
+  return ::symlink(target_path.value().c_str(),
+                   symlink_path.value().c_str()) != -1;
+}
+
+bool ReadSymbolicLink(const FilePath& symlink_path,
+                      FilePath* target_path) {
+  DCHECK(!symlink_path.empty());
+  DCHECK(target_path);
+  char buf[PATH_MAX];
+  ssize_t count = ::readlink(symlink_path.value().c_str(), buf, arraysize(buf));
+  if (count > 0) {

[Evan Martin, 2010/11/29 21:21:14]

Consider an early return pattern here instead (if (count <= 0) return false;)

[Greg Spencer (Chromium), 2010/11/29 21:34:11]

Done.

+    *target_path = FilePath(FilePath::StringType(buf, count));

[Evan Martin, 2010/11/29 21:21:14]

Can use std::string here, since we know the string type.

[Greg Spencer (Chromium), 2010/11/29 21:34:11]

I prefer to use the actual type that FilePath expects, actually.  I'm aware that
StringType is just a typedef for std::string on posix, but if that ever changed,
or this code were ported to other platforms, using the StringType here makes it
a lot easier to find instances that are supposed to be interpreted as FilePaths
as opposed to strings used for other purposes (i.e. it's more self documenting).

For this particular instance, this isn't a huge deal, but as a coding practice,
I think it is.

+  } else {
+    return false;
+  }
+  return true;
+}
+
 // Creates and opens a temporary file in |directory|, returning the
 // file descriptor. |path| is set to the temporary file path.
 // This function does NOT unlink() the file.
 int CreateAndOpenFdForTemporaryFile(FilePath directory, FilePath* path) {
   base::ThreadRestrictions::AssertIOAllowed();  // For call to mkstemp().
   *path = directory.Append(kTempFileName);
   const std::string& tmpdir_string = path->value();
   // this should be OK since mkstemp just replaces characters in place
   char* buffer = const_cast<char*>(tmpdir_string.c_str());
 
@@ skipping 471 matching lines @@
   if (HANDLE_EINTR(close(infile)) < 0)
     result = false;
   if (HANDLE_EINTR(close(outfile)) < 0)
     result = false;
 
   return result;
 }
 #endif  // defined(OS_MACOSX)
 
 }  // namespace file_util