X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fcloseout.c;h=674db787eab6404eb129baf099ad57fc88b64761;hb=1276a2c5f24c0c932426aca9c899fa524d2443f2;hp=5d0509dedecdb8c424ed72ec12dca757228c0517;hpb=222b0486b7db1b09293e05512873d633440efcb3;p=gnulib.git

diff --git a/lib/closeout.c b/lib/closeout.c
index 5d0509ded..674db787e 100644
--- a/lib/closeout.c
+++ b/lib/closeout.c
@@ -1,12 +1,12 @@
-/* closeout.c - close standard output
+/* Close standard output and standard error, exiting with a diagnostic on error.
 
-   Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004 Free Software
-   Foundation, Inc.
+   Copyright (C) 1998-2002, 2004, 2006, 2008-2014 Free Software Foundation,
+   Inc.
 
-   This program is free software; you can redistribute it and/or modify
+   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
-   the Free Software Foundation; either version 2, or (at your option)
-   any later version.
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
 
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -14,30 +14,24 @@
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
-   along with this program; if not, write to the Free Software Foundation,
-   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-#ifdef HAVE_CONFIG_H
-# include <config.h>
-#endif
+#include <config.h>
 
 #include "closeout.h"
 
-#include <stdio.h>
-#include <stdbool.h>
 #include <errno.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <unistd.h>
 
 #include "gettext.h"
 #define _(msgid) gettext (msgid)
 
+#include "close-stream.h"
 #include "error.h"
 #include "exitfail.h"
 #include "quotearg.h"
-#include "__fpending.h"
-
-#if USE_UNLOCKED_IO
-# include "unlocked-io.h"
-#endif
 
 static const char *file_name;
 
@@ -49,53 +43,82 @@ close_stdout_set_file_name (const char *file)
   file_name = file;
 }
 
-/* Close standard output, exiting with status 'exit_failure' on failure.
-   If a program writes *anything* to stdout, that program should close
-   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.  Even calling fflush is not always sufficient,
-   since some file systems (NFS and CODA) buffer written/flushed data
-   until an actual close call.
-
-   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.  */
+
+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'.
+
+   Also close standard error.  On error, _exit with status 'exit_failure'.
+
+   Since close_stdout is commonly registered via 'atexit', POSIX
+   and the C standard both say that it should not call 'exit',
+   because the behavior is undefined if 'exit' is called more than
+   once.  So it calls '_exit' instead of 'exit'.  If close_stdout
+   is registered via atexit before other functions are registered,
+   the other functions can act before this _exit is invoked.
+
+   Applications that use close_stdout should flush any streams
+   other than stdout and stderr before exiting, since the call to
+   _exit will bypass other buffer flushing.  Applications should
+   be flushing and closing other streams anyway, to check for I/O
+   errors.  Also, applications should not use tmpfile, since _exit
+   can bypass the removal of these files.
 
    It's important to detect such failures and exit nonzero because many
-   tools (most notably `make' and other build-management systems) depend
+   tools (most notably 'make' and other build-management systems) depend
    on being able to detect failure in other tools via their exit status.  */
 
 void
 close_stdout (void)
 {
-  bool prev_fail = ferror (stdout);
-  bool none_pending = (0 == __fpending (stdout));
-  bool fclose_fail = fclose (stdout);
-
-  if (prev_fail || fclose_fail)
+  if (close_stream (stdout) != 0
+      && !(ignore_EPIPE && errno == EPIPE))
     {
-      int e = fclose_fail ? errno : 0;
-      char const *write_error;
-
-      /* If ferror returned zero, no data remains to be flushed, and we'd
-	 otherwise fail with EBADF due to a failed fclose, then assume that
-	 it's ok to ignore the fclose failure.  That can happen when a
-	 program like cp is invoked like this `cp a b >&-' (i.e., with
-	 stdout closed) and doesn't generate any output (hence no previous
-	 error and nothing to be flushed).  */
-      if (e == EBADF && !prev_fail && none_pending)
-	return;
-
-      write_error = _("write error");
+      char const *write_error = _("write error");
       if (file_name)
-	error (exit_failure, e, "%s: %s", quotearg_colon (file_name),
-	       write_error);
+        error (0, errno, "%s: %s", quotearg_colon (file_name),
+               write_error);
       else
-	error (exit_failure, e, "%s", write_error);
+        error (0, errno, "%s", write_error);
+
+      _exit (exit_failure);
     }
+
+   if (close_stream (stderr) != 0)
+     _exit (exit_failure);
 }