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bug#9574: data-loss with --batch: ignored write failure
From: |
Jim Meyering |
Subject: |
bug#9574: data-loss with --batch: ignored write failure |
Date: |
Sat, 24 Sep 2011 11:23:26 +0200 |
> Subject: Re: bug#9574: data-loss with --batch: ignored write failure
>
> Fixed.
Thanks, but even with your fix, emacs --batch would
still ignore some write errors.
I've just committed a change to fix that part properly.
Included below.
A clean fix for the entire problem (including --help and --version and
anything else that may write to stdout) would be to ensure that no other
code path explicitly closes stdout and to add this line in main:
atexit (close_stdout);
However, that would require gnulib's closeout module and would probably
end up being too invasive a change to make during a code freeze.
2011-09-24 Jim Meyering <meyering@redhat.com>
do not ignore write error for any output size
The previous change was incomplete.
While it makes emacs --batch detect the vast majority of stdout
write failures, errors were still ignored whenever the output size is
k * (BUFSIZ+1) - 4. E.g., on a system with BUFSIZ of 4096,
$ emacs --batch --eval '(print (format "%4093d" 0))' > /dev/full \
&& echo FAIL: ignored write error
FAIL: ignored write error
$ emacs --batch --eval '(print (format "%20481d" 0))' > /dev/full \
&& echo FAIL: ignored write error
FAIL: ignored write error
* emacs.c (Fkill_emacs): Also test ferror. (Bug#9574)
=== modified file 'src/emacs.c'
--- src/emacs.c 2011-09-23 09:56:55 +0000
+++ src/emacs.c 2011-09-24 08:28:32 +0000
@@ -2019,7 +2019,7 @@
unlink (SSDATA (Vauto_save_list_file_name));
exit_code = EXIT_SUCCESS;
- if (noninteractive && fflush (stdout))
+ if (noninteractive && (fflush (stdout) || ferror (stdout)))
exit_code = EXIT_FAILURE;
exit (INTEGERP (arg) ? XINT (arg) : exit_code);
}