strace/tests/tprintf.c
Dmitry V. Levin c6782f144a tests: change the license to GPL-2.0-or-later
strace test suite is now provided under the terms of the GNU General
Public License version 2 or later, see tests/COPYING for more details.
2018-12-10 00:00:00 +00:00

71 lines
1.2 KiB
C

/*
* Close stdin, move stdout to a non-standard descriptor, and print.
*
* Copyright (c) 2016 Dmitry V. Levin <ldv@altlinux.org>
* All rights reserved.
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "tests.h"
#include <assert.h>
#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <unistd.h>
static ssize_t
write_retry(int fd, const void *buf, size_t count)
{
ssize_t rc;
do {
errno = 0;
rc = write(fd, buf, count);
} while (rc == -1 && EINTR == errno);
if (rc <= 0)
perror_msg_and_fail("write");
return rc;
}
static void
write_loop(int fd, const char *buf, size_t count)
{
ssize_t offset = 0;
while (count > 0) {
ssize_t block = write_retry(fd, &buf[offset], count);
offset += block;
count -= (size_t) block;
}
}
void
tprintf(const char *fmt, ...)
{
static int initialized;
if (!initialized) {
assert(dup2(1, 3) == 3);
assert(close(1) == 0);
(void) close(0);
initialized = 1;
}
va_list p;
va_start(p, fmt);
static char buf[65536];
int len = vsnprintf(buf, sizeof(buf), fmt, p);
if (len < 0)
perror_msg_and_fail("vsnprintf");
assert((unsigned) len < sizeof(buf));
write_loop(3, buf, len);
va_end(p);
}