[Bug libc/5998] New: fwrite returns -1 and errno EINTR instead of a short write when sigaction without SA_RESTART is used

[zlynx at acm dot org]

I first ran into this in a C++ program.  The program was using a periodic timer
without setting SA_RESTART in the sigaction call.

The result in the C++ program was that entire blocks of output to std::cout
would vanish because it never checks the return value of fwrite.

Then I tested with a C program and fwrite.  I discovered that it returns -1 and
EINTR after the write syscall gets interrupted.  So even if libstdc++ wanted to
check its return value, there is nothing useful there!

>From fwrite's man-page I'd expect it to return the number of items written, or
detect the EINTR and retry.

C++'s file stream operations do check for short writes and retry, I noticed. 
But not the cout and cerr objects!

I believe fwrite's current implementation is not optimal.  Sure, the C language
definition of which fwrite is a part does not know about signals, but that's no
reason to be sloppy.

-- 
           Summary: fwrite returns -1 and errno EINTR instead of a short
                    write when sigaction without SA_RESTART is used
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: drepper at redhat dot com
        ReportedBy: zlynx at acm dot org
                CC: glibc-bugs at sources dot redhat dot com
  GCC host triplet: x86_64-pc-linux-gnu


http://sourceware.org/bugzilla/show_bug.cgi?id=5998

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