win32: emulate SIGPIPE

The code to check whether a write error is due to a broken pipe
can now either:

- return with error EPIPE;
- cause the process to exit with code 128+SIGPIPE.

The default is the latter but the behaviour can be changed by issuing
signal(SIGPIPE, SIG_IGN) and signal(SIGPIPE, SIG_DFL) calls.

No actual signal is involved so kill can't send SIGPIPE and handlers
other than SIG_IGN and SIG_DFL aren't supported.

This does, however, avoid unsightly 'broken pipe' errors from commands
like the example in GitHub issue #99:

  dd if=/dev/urandom | tr -dc _A-Z-a-z-0-9 | head -c${1:-32};echo;

1 files changed, 0 insertions, 2 deletions

diff --git a/coreutils/tee.c b/coreutils/tee.c
index d0ded58c4..f0ec791bb 100644
--- a/coreutils/tee.c
+++ b/coreutils/tee.c
@@ -69,11 +69,9 @@ int tee_main(int argc, char **argv)
                 signal(SIGINT, SIG_IGN); /* TODO - switch to sigaction. (why?) */
         }
         retval = EXIT_SUCCESS;
-#ifdef SIGPIPE
         /* gnu tee ignores SIGPIPE in case one of the output files is a pipe
          * that doesn't consume all its input.  Good idea... */
         signal(SIGPIPE, SIG_IGN);
-#endif
 
         /* Allocate an array of FILE *'s, with one extra for a sentinel. */
         fp = files = xzalloc(sizeof(FILE *) * (argc + 2));