-/* Close standard output, exiting with status STATUS on failure.
- If a program writes *anything* to stdout, that program should `fflush'
- stdout and make sure that it succeeds before exiting. Otherwise,
- suppose that you go to the extreme of checking the return status
- of every function that does an explicit write to stdout. The last
- printf can succeed in writing to the internal stream buffer, and yet
- the fclose(stdout) could still fail (due e.g., to a disk full error)
- when it tries to write out that buffered data. Thus, you would be
- left with an incomplete output file and the offending program would
- exit successfully.
-
- FIXME: note the fflush suggested above is implicit in the fclose
- we actually do below. Consider doing only the fflush and/or using
- setvbuf to inhibit buffering.
-
- Besides, it's wasteful to check the return value from every call
- that writes to stdout -- just let the internal stream state record
- the failure. That's what the ferror test is checking below.
+static bool ignore_EPIPE /* = false */;
+
+/* Specify the reaction to an EPIPE error during the closing of stdout:
+ - If ignore = true, it shall be ignored.
+ - If ignore = false, it shall evoke a diagnostic, along with a nonzero
+ exit status.
+ The default is ignore = false.
+
+ This setting matters only if the SIGPIPE signal is ignored (i.e. its
+ handler set to SIG_IGN) or blocked. Only particular programs need to
+ temporarily ignore SIGPIPE. If SIGPIPE is ignored or blocked because
+ it was ignored or blocked in the parent process when it created the
+ child process, it usually is a bug in the parent process: It is bad
+ practice to have SIGPIPE ignored or blocked while creating a child
+ process.
+
+ EPIPE occurs when writing to a pipe or socket that has no readers now,
+ when SIGPIPE is ignored or blocked.
+
+ The ignore = false setting is suitable for a scenario where it is normally
+ guaranteed that the pipe writer terminates before the pipe reader. In
+ this case, an EPIPE is an indication of a premature termination of the
+ pipe reader and should lead to a diagnostic and a nonzero exit status.
+
+ The ignore = true setting is suitable for a scenario where you don't know
+ ahead of time whether the pipe writer or the pipe reader will terminate
+ first. In this case, an EPIPE is an indication that the pipe writer can
+ stop doing useless write() calls; this is what close_stdout does anyway.
+ EPIPE is part of the normal pipe/socket shutdown protocol in this case,
+ and should not lead to a diagnostic message. */