Implement File.lastModified.

runtime/bin/file_macos.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "bin/file.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <unistd.h>
@@ skipping 157 matching lines @@
 
 off_t File::LengthFromName(const char* name) {
   struct stat st;
   if (TEMP_FAILURE_RETRY(stat(name, &st)) == 0) {
     return st.st_size;
   }
   return -1;
 }
 
 
+time_t File::LastModified(const char* name) {
+  struct stat st;
+  if (TEMP_FAILURE_RETRY(stat(name, &st)) == 0) {
+    return st.st_mtime;
+  }
+  return -1;
+}
+
+
 bool File::IsAbsolutePath(const char* pathname) {
   return (pathname != NULL && pathname[0] == '/');
 }
 
 
 char* File::GetCanonicalPath(const char* pathname) {
   char* abs_path = NULL;
   if (pathname != NULL) {
     // On some older MacOs versions the default behaviour of realpath allocating
     // space for the resolved_path when a NULL is passed in does not seem to
@@ skipping 45 matching lines @@
   int result = fstat(fd, &buf);
   if (result == -1) {
     FATAL2("Failed stat on file descriptor %d: %s", fd, strerror(errno));
   }
   if (S_ISCHR(buf.st_mode)) return kTerminal;
   if (S_ISFIFO(buf.st_mode)) return kPipe;
   if (S_ISSOCK(buf.st_mode)) return kSocket;
   if (S_ISREG(buf.st_mode)) return kFile;
   return kOther;
 }