strace/error_prints.c

/*
 * Copyright (c) 1999-2017 The strace developers.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <errno.h>
#include <stdarg.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>

#include "error_prints.h"

#ifndef HAVE_PROGRAM_INVOCATION_NAME
extern char *program_invocation_name;
#endif

static void
verror_msg(int err_no, const char *fmt, va_list p)
{
	char *msg;

	fflush(NULL);

	/* We want to print entire message with single fprintf to ensure
	 * message integrity if stderr is shared with other programs.
	 * Thus we use vasprintf + single fprintf.
	 */
	msg = NULL;
	if (vasprintf(&msg, fmt, p) >= 0) {
		if (err_no)
			fprintf(stderr, "%s: %s: %s\n",
				program_invocation_name, msg, strerror(err_no));
		else
			fprintf(stderr, "%s: %s\n",
				program_invocation_name, msg);
		free(msg);
	} else {
		/* malloc in vasprintf failed, try it without malloc */
		fprintf(stderr, "%s: ", program_invocation_name);
		vfprintf(stderr, fmt, p);
		if (err_no)
			fprintf(stderr, ": %s\n", strerror(err_no));
		else
			putc('\n', stderr);
	}
	/* We don't switch stderr to buffered, thus fprintf(stderr)
	 * always flushes its output and this is not necessary: */
	/* fflush(stderr); */
}

void
error_msg(const char *fmt, ...)
{
	va_list p;
	va_start(p, fmt);
	verror_msg(0, fmt, p);
	va_end(p);
}

void
error_msg_and_die(const char *fmt, ...)
{
	va_list p;
	va_start(p, fmt);
	verror_msg(0, fmt, p);
	die();
}

void
error_msg_and_help(const char *fmt, ...)
{
	if (fmt != NULL) {
		va_list p;
		va_start(p, fmt);
		verror_msg(0, fmt, p);
	}
	fprintf(stderr, "Try '%s -h' for more information.\n",
		program_invocation_name);
	die();
}

void
perror_msg(const char *fmt, ...)
{
	va_list p;
	va_start(p, fmt);
	verror_msg(errno, fmt, p);
	va_end(p);
}

void
perror_msg_and_die(const char *fmt, ...)
{
	va_list p;
	va_start(p, fmt);
	verror_msg(errno, fmt, p);
	die();
}