Make std* blocking file-descriptors.

runtime/bin/file_linux.cc

Index: runtime/bin/file_linux.cc
diff --git a/runtime/bin/file_linux.cc b/runtime/bin/file_linux.cc
index bc6f6109a5d708cb4dd0938b2fd70b7bf16bd3e2..b75ee5715f4d2801d887d73f22a236fd3f0c4241 100644
--- a/runtime/bin/file_linux.cc
+++ b/runtime/bin/file_linux.cc
@@ -38,21 +38,26 @@ class FileHandle {
 
 
 File::~File() {
-  // Close the file (unless it's a standard stream).
-  if (handle_->fd() > STDERR_FILENO) {
-    Close();
-  }
+  Close();
   delete handle_;
 }
 
 
 void File::Close() {
   ASSERT(handle_->fd() >= 0);
-  int err = TEMP_FAILURE_RETRY_BLOCK_SIGNALS(close(handle_->fd()));
-  if (err != 0) {
-    const int kBufferSize = 1024;
-    char error_buf[kBufferSize];
-    Log::PrintErr("%s\n", strerror_r(errno, error_buf, kBufferSize));
+  if (handle_->fd() == STDOUT_FILENO) {

[Søren Gjesse, 2014/02/07 11:05:11]

Why is stderr not handled here as well?

[Anders Johnsen, 2014/02/14 08:43:28]

It's only to work around print printing to file/socket, that's reusing the
stdout fd.

+    // If stdout, redirect fd to /dev/null.
+    int null_fd = TEMP_FAILURE_RETRY(open("/dev/null", O_WRONLY));
+    ASSERT(null_fd >= 0);

[Søren Gjesse, 2014/02/07 11:05:11]

So this will still affect "printf debugging".

[Anders Johnsen, 2014/02/14 08:43:28]

Yes, intentionally. :)

+    VOID_TEMP_FAILURE_RETRY(dup2(null_fd, STDOUT_FILENO));

[Søren Gjesse, 2014/02/07 11:05:11]

Use handle_->fd() instead of STDOUT_FILENO here.

[Ivan Posva, 2014/02/11 04:08:37]

I am wondering whether we should have duped the stdout and stderr fds at the
beginning when opening them from dart:io.

[Anders Johnsen, 2014/02/14 08:43:28]

Done.

[Anders Johnsen, 2014/02/14 08:43:28]

That would still have given us this scenario where stdout.close and print can do
bad things. Note that the fact that we can close stdout is a feature.

+    VOID_TEMP_FAILURE_RETRY(close(null_fd));
+  } else {
+    int err = TEMP_FAILURE_RETRY_BLOCK_SIGNALS(close(handle_->fd()));
+    if (err != 0) {
+      const int kBufferSize = 1024;
+      char error_buf[kBufferSize];
+      Log::PrintErr("%s\n", strerror_r(errno, error_buf, kBufferSize));
+    }
   }
   handle_->set_fd(kClosedFd);
 }