/*	$shbox: cat.c,v 20220701 2022/07/02 06:02:69 leah Exp $	*/
/*	$OpenBSD: cat.c,v 1.34 2022/02/09 01:58:57 cheloha Exp $	*/
/*	$NetBSD: cat.c,v 1.11 1995/09/07 06:12:54 jtc Exp $	*/

/*
 * Copyright (c) 1989, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kevin Fall.
 *
 * 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. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
 */

#include <sys/stat.h>

#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define MAXIMUM(a, b)	(((a) > (b)) ? (a) : (b))

int status;

void cat_input(const char *path);
void cat_spew(int rfd, const char *path);

int
main(int argc, char *argv[])
{
	int ch;
	setvbuf(stdout, NULL, _IOLBF, 0);
	while ((ch = getopt(argc, argv, "u")) != -1) {
		if (ch != 'u') {
			fprintf(stderr, "usage: cat [-u] [file ...]\n");
			exit(1);
		}
		setvbuf(stdout, NULL, _IONBF, 0);
	}
	argc -= optind;
	argv += optind;

	if (argc == 0)
		cat_input(NULL);
	else while (*argv != NULL)
		cat_input(*argv++);

	if (fclose(stdout))
		err(1, "stdout");

	return status;
}

void
cat_input(const char *path)
{
	FILE *fp;
	int fd;

	if (path == NULL || strcmp(path, "-") == 0) {
		cat_spew(STDIN_FILENO, "stdin");
	} else if ((fd = open(path, O_RDONLY)) == -1) {
		warn("%s", path);
		status = 1;
	} else {
		cat_spew(fd, path);
		close(fd);
	}
}

void
cat_spew(int rfd, const char *path)
{
	int wfd;
	ssize_t nr, nw, off;
	static size_t bsize;
	static char *buf = NULL;
	struct stat sbuf;

	wfd = fileno(stdout);
	if (buf == NULL) {
		if (fstat(wfd, &sbuf) == -1)
			err(1, "stdout");
		bsize = MAXIMUM(sbuf.st_blksize, BUFSIZ);
		if ((buf = malloc(bsize)) == NULL)
			err(1, NULL);
	}

	while ((nr = read(rfd, buf, bsize)) != -1 && nr != 0)
		for (off = 0; nr; nr -= nw, off += nw)
			if ((nw = write(wfd, buf + off, nr)) == -1 || nw == 0)
				err(1, "stdout");

	if (nr == -1) {
		warn("%s", path);
		status = 1;
	}
}