Refactor AppendToFile and WriteFileDescriptor

base/files/file_util_posix.cc

Index: base/files/file_util_posix.cc
diff --git a/base/files/file_util_posix.cc b/base/files/file_util_posix.cc
index 07c21d1430f94527d4c3faf87078913bb265ab2e..86eada5a4b9344c21f2acf64c8ca01ddb7c89fea 100644
--- a/base/files/file_util_posix.cc
+++ b/base/files/file_util_posix.cc
@@ -682,13 +682,13 @@ int WriteFile(const FilePath& filename, const char* data, int size) {
   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;
@@ -697,22 +697,37 @@ int WriteFileDescriptor(const int fd, const char* data, int size) {
         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.