xref: /freebsd/bin/echo/echo.c (revision 7899f917b1c0ea178f1d2be0cfb452086d079d23)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1989, 1993
5  *	The Regents of the University of California.  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. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #include <sys/types.h>
33 #include <sys/uio.h>
34 
35 #include <assert.h>
36 #include <capsicum_helpers.h>
37 #include <err.h>
38 #include <errno.h>
39 #include <limits.h>
40 #include <stdlib.h>
41 #include <string.h>
42 #include <unistd.h>
43 
44 int
45 main(int argc, char *argv[])
46 {
47 	int nflag;	/* if not set, output a trailing newline. */
48 	int veclen;	/* number of writev arguments. */
49 	struct iovec *iov, *vp; /* Elements to write, current element. */
50 	char space[] = " ";
51 	char newline[] = "\n";
52 
53 	if (caph_limit_stdio() < 0 || caph_enter() < 0)
54 		err(1, "capsicum");
55 
56 	/* This utility may NOT do getopt(3) option parsing. */
57 	if (*++argv && !strcmp(*argv, "-n")) {
58 		++argv;
59 		--argc;
60 		nflag = 1;
61 	} else
62 		nflag = 0;
63 
64 	veclen = (argc >= 2) ? (argc - 2) * 2 + 1 : 0;
65 
66 	if ((vp = iov = malloc((veclen + 1) * sizeof(struct iovec))) == NULL)
67 		err(1, "malloc");
68 
69 	while (argv[0] != NULL) {
70 		size_t len;
71 
72 		len = strlen(argv[0]);
73 
74 		/*
75 		 * If the next argument is NULL then this is the last argument,
76 		 * therefore we need to check for a trailing \c.
77 		 */
78 		if (argv[1] == NULL) {
79 			/* is there room for a '\c' and is there one? */
80 			if (len >= 2 &&
81 			    argv[0][len - 2] == '\\' &&
82 			    argv[0][len - 1] == 'c') {
83 				/* chop it and set the no-newline flag. */
84 				len -= 2;
85 				nflag = 1;
86 			}
87 		}
88 		vp->iov_base = *argv;
89 		vp++->iov_len = len;
90 		if (*++argv) {
91 			vp->iov_base = space;
92 			vp++->iov_len = 1;
93 		}
94 	}
95 	if (!nflag) {
96 		veclen++;
97 		vp->iov_base = newline;
98 		vp++->iov_len = 1;
99 	}
100 	/* assert(veclen == (vp - iov)); */
101 	while (veclen) {
102 		int nwrite;
103 
104 		nwrite = (veclen > IOV_MAX) ? IOV_MAX : veclen;
105 		if (writev(STDOUT_FILENO, iov, nwrite) == -1)
106 			err(1, "write");
107 		iov += nwrite;
108 		veclen -= nwrite;
109 	}
110 	return 0;
111 }
112