From: Bruno Haible Date: Mon, 6 Oct 2008 00:38:03 +0000 (+0200) Subject: Add an option for ignoring EPIPE during close_stdout. X-Git-Tag: v0.1~6887 X-Git-Url: http://erislabs.org.uk/gitweb/?a=commitdiff_plain;h=1b3b9273dc697c2fdd1fc50a2a5e4b3908225882;p=gnulib.git Add an option for ignoring EPIPE during close_stdout. --- diff --git a/ChangeLog b/ChangeLog index b5de6d886..e7db98509 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,4 +1,18 @@ 2008-10-05 Bruno Haible + Jim Meyering + + Add an option for ignoring EPIPE during close_stdout. + * lib/closeout.h: Include . + (close_stdout_set_ignore_EPIPE): New declaration. + * lib/closeout.c: Include . + (ignore_EPIPE): New variable. + (close_stdout_set_ignore_EPIPE): New function. + (close_stdout): Ignore EPIPE error if ignore_EPIPE is set. + * lib/close-stream.c (close_stream): Mention the possible EPIPE + failure. + * modules/closeout (Depends-on): Add stdbool. + +2008-10-05 Bruno Haible * modules/accept: New file. * modules/bind: New file. diff --git a/lib/close-stream.c b/lib/close-stream.c index e2c3ac0cc..59ab616b1 100644 --- a/lib/close-stream.c +++ b/lib/close-stream.c @@ -1,6 +1,6 @@ /* Close a stream, with nicer error checking than fclose's. - Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004, 2006, 2007 Free + Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004, 2006, 2007, 2008 Free Software Foundation, Inc. This program is free software: you can redistribute it and/or modify @@ -33,6 +33,10 @@ otherwise. A failure might set errno to 0 if the error number cannot be determined. + A failure with errno set to EPIPE may or may not indicate an error + situation worth signaling to the user. See the documentation of the + close_stdout_set_ignore_EPIPE function for details. + If a program writes *anything* to STREAM, that program should close STREAM and make sure that it succeeds before exiting. Otherwise, suppose that you go to the extreme of checking the return status diff --git a/lib/closeout.c b/lib/closeout.c index 69ddb8b23..6a0b82ffa 100644 --- a/lib/closeout.c +++ b/lib/closeout.c @@ -1,6 +1,6 @@ /* Close standard output and standard error, exiting with a diagnostic on error. - Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004, 2006 Free + Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004, 2006, 2008 Free Software Foundation, Inc. This program is free software: you can redistribute it and/or modify @@ -21,6 +21,7 @@ #include "closeout.h" #include +#include #include #include @@ -42,6 +43,43 @@ close_stdout_set_file_name (const char *file) file_name = file; } +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. */ + +void +close_stdout_set_ignore_EPIPE (bool ignore) +{ + ignore_EPIPE = ignore; +} + /* Close standard output. On error, issue a diagnostic and _exit with status 'exit_failure'. @@ -68,7 +106,8 @@ close_stdout_set_file_name (const char *file) void close_stdout (void) { - if (close_stream (stdout) != 0) + if (close_stream (stdout) != 0 + && !(ignore_EPIPE && errno == EPIPE)) { char const *write_error = _("write error"); if (file_name) diff --git a/lib/closeout.h b/lib/closeout.h index fa7adc311..34e61effb 100644 --- a/lib/closeout.h +++ b/lib/closeout.h @@ -1,6 +1,7 @@ /* Close standard output and standard error. - Copyright (C) 1998, 2000, 2003, 2004, 2006 Free Software Foundation, Inc. + Copyright (C) 1998, 2000, 2003, 2004, 2006, 2008 Free Software Foundation, + Inc. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -18,11 +19,14 @@ #ifndef CLOSEOUT_H # define CLOSEOUT_H 1 +# include + # ifdef __cplusplus extern "C" { # endif void close_stdout_set_file_name (const char *file); +void close_stdout_set_ignore_EPIPE (bool ignore); void close_stdout (void); # ifdef __cplusplus diff --git a/modules/closeout b/modules/closeout index 4480c7f3a..6a77cef62 100644 --- a/modules/closeout +++ b/modules/closeout @@ -12,6 +12,7 @@ gettext-h error quotearg exitfail +stdbool configure.ac: gl_CLOSEOUT