mirror of git://sourceware.org/git/glibc.git
90 lines
3.1 KiB
C
90 lines
3.1 KiB
C
/* Test fwrite against bug 29459.
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Copyright (C) 2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* This test is based on the code attached to bug 29459.
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It depends on stdout being redirected to a specific process via a script
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with the same name. Because of this, we cannot use the features from
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test_driver.c. */
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include <unistd.h>
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#include <support/check.h>
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#include <support/xsignal.h>
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/* Usually this test reproduces in a few iterations. However, keep a high
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number of iterations in order to avoid return false-positives due to an
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overwhelmed/slow system. */
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#define ITERATIONS 500000
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/* The goal of this test is to use fwrite () on a redirected and closed
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stdout. A script will guarantee that stdout is redirected to another
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process that closes it during the execution. The process reading from
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the pipe must read at least the first line in order to guarantee that
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flag _IO_CURRENTLY_PUTTING is set in the write end of the pipe, triggering
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important parts of the code that flushes lines from fwrite's internal
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buffer. The underlying write () returns EPIPE, which fwrite () must
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propagate. */
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int
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main (void)
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{
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int i;
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size_t rc;
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/* Ensure the string we send has a new line because we're dealing
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with a lined-buffered stream. */
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const char *s = "hello world\n";
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const size_t len = strlen(s);
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/* Ensure that fwrite buffers the output before writing to stdout. */
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setlinebuf(stdout);
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/* Ignore SIGPIPE in order to catch the EPIPE returned by the
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underlying call to write(). */
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xsignal(SIGPIPE, SIG_IGN);
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for (i = 1; i <= ITERATIONS; i++)
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{
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/* Keep writing to stdout. The test succeeds if fwrite () returns an
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error. */
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if ((rc = fwrite(s, 1, len, stdout)) < len)
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{
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/* An error happened. Check if ferror () does return an error
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and that it is indeed EPIPE. */
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TEST_COMPARE (ferror (stdout), 1);
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TEST_COMPARE (errno, EPIPE);
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fprintf(stderr, "Success: i=%d. fwrite returned %zu < %zu "
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"and errno=EPIPE\n",
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i, rc, len);
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/* The test succeeded! */
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return 0;
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}
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else
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{
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/* fwrite () was able to write all the contents. Check if no errors
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have been reported and try again. */
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TEST_COMPARE (ferror (stdout), 0);
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TEST_COMPARE (errno, 0);
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}
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}
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fprintf(stderr, "Error: fwrite did not return an error\n");
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return 1;
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}
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