/* Detect write error on a stream.
- Copyright (C) 2003-2005 Free Software Foundation, Inc.
+ Copyright (C) 2003-2006, 2008-2014 Free Software Foundation, Inc.
Written by Bruno Haible <bruno@clisp.org>, 2003.
- 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
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/>. */
-#if HAVE_CONFIG_H
-# include <config.h>
-#endif
+#include <config.h>
/* Specification. */
#include "fwriteerror.h"
#include <errno.h>
#include <stdbool.h>
-int
-fwriteerror (FILE *fp)
+static int
+do_fwriteerror (FILE *fp, bool ignore_ebadf)
{
/* State to allow multiple calls to fwriteerror (stdout). */
static bool stdout_closed = false;
- if (fp == stdout && stdout_closed)
- return 0;
+ if (fp == stdout)
+ {
+ if (stdout_closed)
+ return 0;
- /* Need to
+ /* If we are closing stdout, don't attempt to do it later again. */
+ stdout_closed = true;
+ }
+
+ /* This function returns an error indication if there was a previous failure
+ or if fclose failed, with two exceptions:
+ - Ignore an fclose failure if there was no previous error, no data
+ remains to be flushed, and fclose failed with EBADF. That can
+ happen when a program like cp is invoked like this 'cp a b >&-'
+ (i.e., with standard output closed) and doesn't generate any
+ output (hence no previous error and nothing to be flushed).
+ - Ignore an fclose failure due to EPIPE. That can happen when a
+ program blocks or ignores SIGPIPE, and the output pipe or socket
+ has no readers now. The EPIPE tells us that we should stop writing
+ to this output. That's what we are doing anyway here.
+
+ Need to
1. test the error indicator of the stream,
2. flush the buffers both in userland and in the kernel, through fclose,
testing for error again. */
if (ferror (fp))
{
if (fflush (fp))
- return -1; /* errno is set here */
+ goto close_preserving_errno; /* errno is set here */
/* The stream had an error earlier, but its errno was lost. If the
- error was not temporary, we can get the same errno by writing and
- flushing one more byte. We can do so because at this point the
- stream's contents is garbage anyway. */
+ error was not temporary, we can get the same errno by writing and
+ flushing one more byte. We can do so because at this point the
+ stream's contents is garbage anyway. */
if (fputc ('\0', fp) == EOF)
- return -1; /* errno is set here */
+ goto close_preserving_errno; /* errno is set here */
if (fflush (fp))
- return -1; /* errno is set here */
+ goto close_preserving_errno; /* errno is set here */
/* Give up on errno. */
errno = 0;
- return -1;
+ goto close_preserving_errno;
}
- /* If we are closing stdout, don't attempt to do it later again. */
- if (fp == stdout)
- stdout_closed = true;
-
- if (fclose (fp))
- return -1; /* errno is set here */
+ if (ignore_ebadf)
+ {
+ /* We need an explicit fflush to tell whether some output was already
+ done on FP. */
+ if (fflush (fp))
+ goto close_preserving_errno; /* errno is set here */
+ if (fclose (fp) && errno != EBADF)
+ goto got_errno; /* errno is set here */
+ }
+ else
+ {
+ if (fclose (fp))
+ goto got_errno; /* errno is set here */
+ }
return 0;
+
+ close_preserving_errno:
+ /* There's an error. Nevertheless call fclose(fp), for consistency
+ with the other cases. */
+ {
+ int saved_errno = errno;
+ fclose (fp);
+ errno = saved_errno;
+ }
+ got_errno:
+ /* There's an error. Ignore EPIPE. */
+ if (errno == EPIPE)
+ return 0;
+ else
+ return -1;
+}
+
+int
+fwriteerror (FILE *fp)
+{
+ return do_fwriteerror (fp, false);
+}
+
+int
+fwriteerror_no_ebadf (FILE *fp)
+{
+ return do_fwriteerror (fp, true);
}
#if TEST
/* Name of a file on which writing fails. On systems without /dev/full,
- you can choose a filename on a full filesystem. */
+ you can choose a filename on a full file system. */
#define UNWRITABLE_FILE "/dev/full"
int
size_t size = sizes[i];
for (j = 0; j < 2; j++)
- {
- /* Run a test depending on i and j:
- Write size bytes and then calls fflush if j==1. */
- FILE *stream = fopen (UNWRITABLE_FILE, "w");
-
- if (stream == NULL)
- {
- fprintf (stderr, "Test %u:%u: could not open file\n", i, j);
- continue;
- }
-
- fwrite (dummy, 347, 1, stream);
- fwrite (dummy, size - 347, 1, stream);
- if (j)
- fflush (stream);
-
- if (fwriteerror (stream) == -1)
- {
- if (errno != ENOSPC)
- fprintf (stderr, "Test %u:%u: fwriteerror ok, errno = %d\n",
- i, j, errno);
- }
- else
- fprintf (stderr, "Test %u:%u: fwriteerror found no error!\n",
- i, j);
- }
+ {
+ /* Run a test depending on i and j:
+ Write size bytes and then calls fflush if j==1. */
+ FILE *stream = fopen (UNWRITABLE_FILE, "w");
+
+ if (stream == NULL)
+ {
+ fprintf (stderr, "Test %u:%u: could not open file\n", i, j);
+ continue;
+ }
+
+ fwrite (dummy, 347, 1, stream);
+ fwrite (dummy, size - 347, 1, stream);
+ if (j)
+ fflush (stream);
+
+ if (fwriteerror (stream) == -1)
+ {
+ if (errno != ENOSPC)
+ fprintf (stderr, "Test %u:%u: fwriteerror ok, errno = %d\n",
+ i, j, errno);
+ }
+ else
+ fprintf (stderr, "Test %u:%u: fwriteerror found no error!\n",
+ i, j);
+ }
}
return 0;
projects / gnulib.git / blobdiff