echo.c revision 331722 
1179221Sjb/*-
2179221Sjb * Copyright (c) 1989, 1993
3204597Suqs *	The Regents of the University of California.  All rights reserved.
4179221Sjb *
5179221Sjb * Redistribution and use in source and binary forms, with or without
6204597Suqs * modification, are permitted provided that the following conditions
7179221Sjb * are met:
8179221Sjb * 1. Redistributions of source code must retain the above copyright
9204597Suqs *    notice, this list of conditions and the following disclaimer.
10179221Sjb * 2. Redistributions in binary form must reproduce the above copyright
11179221Sjb *    notice, this list of conditions and the following disclaimer in the
12179221Sjb *    documentation and/or other materials provided with the distribution.
13179221Sjb * 4. Neither the name of the University nor the names of its contributors
14179221Sjb *    may be used to endorse or promote products derived from this software
15179221Sjb *    without specific prior written permission.
16179221Sjb *
17179221Sjb * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18179221Sjb * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19179221Sjb * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20179221Sjb * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21179221Sjb * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22179221Sjb * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23210691Srpaulo * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24210691Srpaulo * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25210691Srpaulo * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26210691Srpaulo * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27179221Sjb * SUCH DAMAGE.
28179221Sjb */
29
30#if 0
31#ifndef lint
32static char const copyright[] =
33"@(#) Copyright (c) 1989, 1993\n\
34	The Regents of the University of California.  All rights reserved.\n";
35#endif /* not lint */
36
37#ifndef lint
38static char sccsid[] = "@(#)echo.c	8.1 (Berkeley) 5/31/93";
39#endif /* not lint */
40#endif
41#include <sys/cdefs.h>
42__FBSDID("$FreeBSD: stable/11/bin/echo/echo.c 331722 2018-03-29 02:50:57Z eadler $");
43
44#include <sys/types.h>
45#include <sys/uio.h>
46
47#include <assert.h>
48#include <errno.h>
49#include <limits.h>
50#include <stdlib.h>
51#include <string.h>
52#include <unistd.h>
53
54/*
55 * Report an error and exit.
56 * Use it instead of err(3) to avoid linking-in stdio.
57 */
58static __dead2 void
59errexit(const char *prog, const char *reason)
60{
61	char *errstr = strerror(errno);
62	write(STDERR_FILENO, prog, strlen(prog));
63	write(STDERR_FILENO, ": ", 2);
64	write(STDERR_FILENO, reason, strlen(reason));
65	write(STDERR_FILENO, ": ", 2);
66	write(STDERR_FILENO, errstr, strlen(errstr));
67	write(STDERR_FILENO, "\n", 1);
68	exit(1);
69}
70
71int
72main(int argc, char *argv[])
73{
74	int nflag;	/* if not set, output a trailing newline. */
75	int veclen;	/* number of writev arguments. */
76	struct iovec *iov, *vp; /* Elements to write, current element. */
77	char space[] = " ";
78	char newline[] = "\n";
79	char *progname = argv[0];
80
81	/* This utility may NOT do getopt(3) option parsing. */
82	if (*++argv && !strcmp(*argv, "-n")) {
83		++argv;
84		--argc;
85		nflag = 1;
86	} else
87		nflag = 0;
88
89	veclen = (argc >= 2) ? (argc - 2) * 2 + 1 : 0;
90
91	if ((vp = iov = malloc((veclen + 1) * sizeof(struct iovec))) == NULL)
92		errexit(progname, "malloc");
93
94	while (argv[0] != NULL) {
95		size_t len;
96
97		len = strlen(argv[0]);
98
99		/*
100		 * If the next argument is NULL then this is this
101		 * the last argument, therefore we need to check
102		 * for a trailing \c.
103		 */
104		if (argv[1] == NULL) {
105			/* is there room for a '\c' and is there one? */
106			if (len >= 2 &&
107			    argv[0][len - 2] == '\\' &&
108			    argv[0][len - 1] == 'c') {
109				/* chop it and set the no-newline flag. */
110				len -= 2;
111				nflag = 1;
112			}
113		}
114		vp->iov_base = *argv;
115		vp++->iov_len = len;
116		if (*++argv) {
117			vp->iov_base = space;
118			vp++->iov_len = 1;
119		}
120	}
121	if (!nflag) {
122		veclen++;
123		vp->iov_base = newline;
124		vp++->iov_len = 1;
125	}
126	/* assert(veclen == (vp - iov)); */
127	while (veclen) {
128		int nwrite;
129
130		nwrite = (veclen > IOV_MAX) ? IOV_MAX : veclen;
131		if (writev(STDOUT_FILENO, iov, nwrite) == -1)
132			errexit(progname, "write");
133		iov += nwrite;
134		veclen -= nwrite;
135	}
136	return 0;
137}
138