Start using file_util symlink code, now that it's available.

base/command_line.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/command_line.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include <shellapi.h>
 #elif defined(OS_POSIX)
 #include <limits.h>
 #include <stdlib.h>
 #include <unistd.h>
 #endif
 #if defined(OS_LINUX)
 #include <sys/prctl.h>
 #endif
 
 #include <algorithm>
 
 #include "base/file_path.h"
+#include "base/file_util.h"
 #include "base/logging.h"
 #include "base/singleton.h"
 #include "base/string_split.h"
 #include "base/string_util.h"
 #include "base/sys_string_conversions.h"
 #include "base/utf_string_conversions.h"
 
 #if defined(OS_LINUX)
 // Linux/glibc doesn't natively have setproctitle().
 #include "base/setproctitle_linux.h"
@@ skipping 198 matching lines @@
   // Build a single string which consists of all the arguments separated
   // by spaces. We can't actually keep them separate due to the way the
   // setproctitle() function works.
   std::string title;
   bool have_argv0 = false;
 #if defined(OS_LINUX)
   // In Linux we sometimes exec ourselves from /proc/self/exe, but this makes us
   // show up as "exe" in process listings. Read the symlink /proc/self/exe and
   // use the path it points at for our process title. Note that this is only for
   // display purposes and has no TOCTTOU security implications.
-  char buffer[PATH_MAX];
-  // Note: readlink() does not append a null byte to terminate the string.
-  ssize_t length = readlink("/proc/self/exe", buffer, sizeof(buffer));
-  DCHECK(length <= static_cast<ssize_t>(sizeof(buffer)));
-  if (length > 0) {
+  FilePath target;
+  FilePath self_exe("/proc/self/exe");
+  if (file_util::ReadSymbolicLink(self_exe, &target)) {
     have_argv0 = true;
-    title.assign(buffer, length);
+    title = target.value();
     // If the binary has since been deleted, Linux appends " (deleted)" to the
     // symlink target. Remove it, since this is not really part of our name.
     const std::string kDeletedSuffix = " (deleted)";
     if (EndsWith(title, kDeletedSuffix, true))
       title.resize(title.size() - kDeletedSuffix.size());
 #if defined(PR_SET_NAME)
     // If PR_SET_NAME is available at compile time, we try using it. We ignore
     // any errors if the kernel does not support it at runtime though. When
     // available, this lets us set the short process name that shows when the
     // full command line is not being displayed in most process listings.
@@ skipping 278 matching lines @@
 
 // private
 CommandLine::CommandLine() {
 }
 
 // static
 CommandLine* CommandLine::ForCurrentProcessMutable() {
   DCHECK(current_process_commandline_);
   return current_process_commandline_;
 }