Refactor AppendToFile and WriteFileDescriptor

base/files/file_util_posix.cc

 // Copyright (c) 2012 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/files/file_util.h"
 
 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <libgen.h>
@@ skipping 664 matching lines @@
     return -1;
   return bytes_read;
 }
 
 int WriteFile(const FilePath& filename, const char* data, int size) {
   ThreadRestrictions::AssertIOAllowed();
   int fd = HANDLE_EINTR(creat(filename.value().c_str(), 0640));
   if (fd < 0)
     return -1;
 
-  int bytes_written = WriteFileDescriptor(fd, data, size);
+  int bytes_written = WriteFileDescriptor(fd, data, size) ? size : -1;
   if (IGNORE_EINTR(close(fd)) < 0)
     return -1;
   return bytes_written;
 }
 
-int WriteFileDescriptor(const int fd, const char* data, int size) {
+bool WriteFileDescriptor(const int fd, const char* data, int size) {
   // Allow for partial writes.
   ssize_t bytes_written_total = 0;
   for (ssize_t bytes_written_partial = 0; bytes_written_total < size;
        bytes_written_total += bytes_written_partial) {
     bytes_written_partial =
         HANDLE_EINTR(write(fd, data + bytes_written_total,
                            size - bytes_written_total));
     if (bytes_written_partial < 0)
-      return -1;
+      return false;
   }
 
-  return bytes_written_total;
+  return true;
 }
 
-int AppendToFile(const FilePath& filename, const char* data, int size) {
+bool AppendToFile(const FilePath& filename, const char* data, int size) {
   ThreadRestrictions::AssertIOAllowed();
+  int saved_errno = 0;
   int fd = HANDLE_EINTR(open(filename.value().c_str(), O_WRONLY | O_APPEND));
   if (fd < 0)
-    return -1;
+    return false;
 
-  int bytes_written = WriteFileDescriptor(fd, data, size);
-  if (IGNORE_EINTR(close(fd)) < 0)
-    return -1;
-  return bytes_written;
+  // This call will either write all of the data or return false.
+  if (!WriteFileDescriptor(fd, data, size))
+    saved_errno = errno;
+
+  if (IGNORE_EINTR(close(fd)) < 0 && saved_errno == 0) {
+    // An error occurred while closing the file but the data was written
+    // successfully so it's ok to return here.
+    return false;
+  }
+
+  // Restore any error that occurred while writing the data.  This takes
+  // precedence over any error that occurred while closing the file.
+  if (saved_errno != 0) {
+    errno = saved_errno;
+    return false;
+  }
+
+  return true;
 }
 
 // Gets the current working directory for the process.
 bool GetCurrentDirectory(FilePath* dir) {
   // getcwd can return ENOENT, which implies it checks against the disk.
   ThreadRestrictions::AssertIOAllowed();
 
   char system_buffer[PATH_MAX] = "";
   if (!getcwd(system_buffer, sizeof(system_buffer))) {
     NOTREACHED();
@@ skipping 177 matching lines @@
     result = false;
   if (IGNORE_EINTR(close(outfile)) < 0)
     result = false;
 
   return result;
 }
 #endif  // !defined(OS_MACOSX)
 
 }  // namespace internal
 }  // namespace base