[llvm-commits] [llvm] r103085 - /llvm/trunk/lib/Support/raw_ostream.cpp

[Dan Gohman]

On May 5, 2010, at 8:17 AM, Benjamin Kramer wrote:

> Author: d0k
> Date: Wed May  5 10:17:47 2010
> New Revision: 103085
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=103085&view=rev
> Log:
> Try again if write(2) reports an recoverable error.
> 
> This should fix mysteriously crashing boost regression tests when stderr is
> managed by bjam (PR7043).
> 
> Modified:
>    llvm/trunk/lib/Support/raw_ostream.cpp
> 
> Modified: llvm/trunk/lib/Support/raw_ostream.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/raw_ostream.cpp?rev=103085&r1=103084&r2=103085&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Support/raw_ostream.cpp (original)
> +++ llvm/trunk/lib/Support/raw_ostream.cpp Wed May  5 10:17:47 2010
> @@ -21,6 +21,7 @@
> #include "llvm/Support/ErrorHandling.h"
> #include "llvm/ADT/STLExtras.h"
> #include <cctype>
> +#include <cerrno>
> #include <sys/stat.h>
> #include <sys/types.h>
> 
> @@ -420,7 +421,11 @@
> void raw_fd_ostream::write_impl(const char *Ptr, size_t Size) {
>   assert(FD >= 0 && "File already closed.");
>   pos += Size;
> -  if (::write(FD, Ptr, Size) != (ssize_t) Size)
> +  ssize_t ret;
> +  do {
> +    ret = ::write(FD, Ptr, Size);
> +  } while (ret < 0 && (errno == EAGAIN || errno == EINTR));

Is EAGAIN really a recoverable error? According to the documentation I
have, EAGAIN is only used for non-blocking I/O (O_NONBLOCK), so
immediately retrying the write in that case is likely to send the process
into a spin. raw_ostream isn't really designed to be used with non-blocking
I/O, so it seems better to just fail.

EINTR is recoverable, but it's not the only way that write can fail
when interrupted.  Another possibility is that the write could be interrupted
after some bytes have already been written, in which case it'll return
a positive value less than Size to indicate the number of bytes written.

Dan

> +  if (ret != (ssize_t) Size)
>     error_detected();
> }
> 
> 
> 
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits