Source code of cat command of Unix

/* $OpenBSD: cat.c,v 1.14 2002/07/04 04:26:39 deraadt 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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.
*/


#ifndef lint
static char copyright[] =
"@(#) Copyright (c) 1989, 1993\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)cat.c 8.2 (Berkeley) 4/27/95";
#else
static char rcsid[] = "$OpenBSD: cat.c,v 1.14 2002/07/04 04:26:39 deraadt Exp $";
#endif
#endif /* not lint */

#include <sys/param.h>
#include <sys/stat.h>

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

extern char *__progname;

int bflag, eflag, nflag, sflag, tflag, vflag;
int rval;
char *filename;

void cook_args(char *argv[]);
void cook_buf(FILE *);
void raw_args(char *argv[]);
void raw_cat(int);

int
main(int argc, char *argv[])
{
int ch;

setlocale(LC_ALL, "");

while ((ch = getopt(argc, argv, "benstuv")) != -1)
switch (ch) {
case 'b':
bflag = nflag = 1; /* -b implies -n */
break;
case 'e':
eflag = vflag = 1; /* -e implies -v */
break;
case 'n':
nflag = 1;
break;
case 's':
sflag = 1;
break;
case 't':
tflag = vflag = 1; /* -t implies -v */
break;
case 'u':
setbuf(stdout, NULL);
break;
case 'v':
vflag = 1;
break;
default:
(void)fprintf(stderr,
"usage: %s [-benstuv] [-] [file ...]\n", __progname);
exit(1);
/* NOTREACHED */
}
argv += optind;

if (bflag || eflag || nflag || sflag || tflag || vflag)
cook_args(argv);
else
raw_args(argv);
if (fclose(stdout))
err(1, "stdout");
exit(rval);
}

void
cook_args(char **argv)
{
FILE *fp;

fp = stdin;
filename = "stdin";
do {
if (*argv) {
if (!strcmp(*argv, "-"))
fp = stdin;
else if ((fp = fopen(*argv, "r")) == NULL) {
warn("%s", *argv);
rval = 1;
++argv;
continue;
}
filename = *argv++;
}
cook_buf(fp);
if (fp != stdin)
(void)fclose(fp);
} while (*argv);
}


void
cook_buf(FILE *fp)
{
int ch, gobble, line, prev;

line = gobble = 0;
for (prev = '\n'; (ch = getc(fp)) != EOF; prev = ch) {
if (prev == '\n') {
if (sflag) {
if (ch == '\n') {
if (gobble)
continue;
gobble = 1;
} else
gobble = 0;
}
if (nflag && (!bflag || ch != '\n')) {
(void)fprintf(stdout, "%6d\t", ++line);
if (ferror(stdout))
break;
}
}
if (ch == '\n') {
if (eflag && putchar('$') == EOF)
break;
} else if (ch == '\t') {
if (tflag) {
if (putchar('^') == EOF || putchar('I') == EOF)
break;
continue;
}
} else if (vflag) {
if (!isascii(ch)) {
if (putchar('M') == EOF || putchar('-') == EOF)
break;
ch = toascii(ch);
}
if (iscntrl(ch)) {
if (putchar('^') == EOF ||
putchar(ch == '\177' ? '?' :
ch | 0100) == EOF)
break;
continue;
}
}
if (putchar(ch) == EOF)
break;
}
if (ferror(fp)) {
warn("%s", filename);
rval = 1;
clearerr(fp);
}
if (ferror(stdout))
err(1, "stdout");
}


void
raw_args(char **argv)
{
int fd;

fd = fileno(stdin);
filename = "stdin";
do {
if (*argv) {
if (!strcmp(*argv, "-"))
fd = fileno(stdin);
else if ((fd = open(*argv, O_RDONLY, 0)) < rval =" 1;" filename =" *argv++;" wfd =" fileno(stdout);" buf ="=" bsize =" MAX(sbuf.st_blksize," buf =" malloc((u_int)bsize))" nr =" read(rfd,"> 0)
for (off = 0; nr; nr -= nw, off += nw)
if ((nw = write(wfd, buf + off, nr)) < rval =" 1;">