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      1 /*
      2  * Close stdin, move stdout to a non-standard descriptor, and print.
      3  *
      4  * Copyright (c) 2016 Dmitry V. Levin <ldv (at) altlinux.org>
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. The name of the author may not be used to endorse or promote products
     16  *    derived from this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     28  */
     29 
     30 #include "tests.h"
     31 
     32 #include <assert.h>
     33 #include <errno.h>
     34 #include <stdarg.h>
     35 #include <stdio.h>
     36 #include <unistd.h>
     37 
     38 static ssize_t
     39 write_retry(int fd, const void *buf, size_t count)
     40 {
     41 	ssize_t rc;
     42 
     43 	do {
     44 		errno = 0;
     45 		rc = write(fd, buf, count);
     46 	} while (rc == -1 && EINTR == errno);
     47 
     48 	if (rc <= 0)
     49 		perror_msg_and_fail("write");
     50 
     51 	return rc;
     52 }
     53 
     54 static void
     55 write_loop(int fd, const char *buf, size_t count)
     56 {
     57 	ssize_t offset = 0;
     58 
     59 	while (count > 0) {
     60 		ssize_t block = write_retry(fd, &buf[offset], count);
     61 
     62 		offset += block;
     63 		count -= (size_t) block;
     64 	}
     65 }
     66 
     67 void
     68 tprintf(const char *fmt, ...)
     69 {
     70 	static int initialized;
     71 	if (!initialized) {
     72 		assert(dup2(1, 3) == 3);
     73 		assert(close(1) == 0);
     74 		(void) close(0);
     75 		initialized = 1;
     76 	}
     77 
     78 	va_list p;
     79 	va_start(p, fmt);
     80 
     81 	static char buf[65536];
     82 	int len = vsnprintf(buf, sizeof(buf), fmt, p);
     83 	if (len < 0)
     84 		perror_msg_and_fail("vsnprintf");
     85 	assert((unsigned) len < sizeof(buf));
     86 
     87 	write_loop(3, buf, len);
     88 
     89 	va_end(p);
     90 }
     91