Improve error handling in the process library.

runtime/bin/file_macos.cc

Index: runtime/bin/file_macos.cc
diff --git a/runtime/bin/file_macos.cc b/runtime/bin/file_macos.cc
index 7a976070ea53355598818b4dfc565de8fc4ee0c1..303824912f440458f240a27adb9927b8675e6e84 100644
--- a/runtime/bin/file_macos.cc
+++ b/runtime/bin/file_macos.cc
@@ -36,7 +36,7 @@ File::~File() {
 
 
 void File::Close() {
-  assert(handle_->fd() >= 0);
+  ASSERT(handle_->fd() >= 0);
   int err = close(handle_->fd());
   if (err != 0) {
     const int kBufferSize = 1024;
@@ -54,31 +54,31 @@ bool File::IsClosed() {
 
 
 int64_t File::Read(void* buffer, int64_t num_bytes) {
-  assert(handle_->fd() >= 0);
+  ASSERT(handle_->fd() >= 0);
   return read(handle_->fd(), buffer, num_bytes);
 }
 
 
 int64_t File::Write(const void* buffer, int64_t num_bytes) {
-  assert(handle_->fd() >= 0);
+  ASSERT(handle_->fd() >= 0);
   return write(handle_->fd(), buffer, num_bytes);
 }
 
 
 off_t File::Position() {
-  assert(handle_->fd() >= 0);
+  ASSERT(handle_->fd() >= 0);
   return lseek(handle_->fd(), 0, SEEK_CUR);
 }
 
 
 void File::Flush() {
-  assert(handle_->fd() >= 0);
+  ASSERT(handle_->fd() >= 0);
   fsync(handle_->fd());
 }
 
 
 off_t File::Length() {
-  assert(handle_->fd() >= 0);
+  ASSERT(handle_->fd() >= 0);
   off_t position = lseek(handle_->fd(), 0, SEEK_CUR);
   if (position < 0) {
     // The file is not capable of seeking. Return an error.