xref: /freebsd/bin/echo/echo.c (revision dc36d6f9bb1753f3808552f3afd30eda9a7b206a)
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 #if 0
33 #ifndef lint
34 static char const copyright[] =
35 "@(#) Copyright (c) 1989, 1993\n\
36 	The Regents of the University of California.  All rights reserved.\n";
37 #endif /* not lint */
38 
39 #endif
40 #include <sys/cdefs.h>
41 #include <sys/types.h>
42 #include <sys/uio.h>
43 
44 #include <assert.h>
45 #include <capsicum_helpers.h>
46 #include <err.h>
47 #include <errno.h>
48 #include <limits.h>
49 #include <stdlib.h>
50 #include <string.h>
51 #include <unistd.h>
52 
53 int
54 main(int argc, char *argv[])
55 {
56 	int nflag;	/* if not set, output a trailing newline. */
57 	int veclen;	/* number of writev arguments. */
58 	struct iovec *iov, *vp; /* Elements to write, current element. */
59 	char space[] = " ";
60 	char newline[] = "\n";
61 
62 	if (caph_limit_stdio() < 0 || caph_enter() < 0)
63 		err(1, "capsicum");
64 
65 	/* This utility may NOT do getopt(3) option parsing. */
66 	if (*++argv && !strcmp(*argv, "-n")) {
67 		++argv;
68 		--argc;
69 		nflag = 1;
70 	} else
71 		nflag = 0;
72 
73 	veclen = (argc >= 2) ? (argc - 2) * 2 + 1 : 0;
74 
75 	if ((vp = iov = malloc((veclen + 1) * sizeof(struct iovec))) == NULL)
76 		err(1, "malloc");
77 
78 	while (argv[0] != NULL) {
79 		size_t len;
80 
81 		len = strlen(argv[0]);
82 
83 		/*
84 		 * If the next argument is NULL then this is the last argument,
85 		 * therefore we need to check for a trailing \c.
86 		 */
87 		if (argv[1] == NULL) {
88 			/* is there room for a '\c' and is there one? */
89 			if (len >= 2 &&
90 			    argv[0][len - 2] == '\\' &&
91 			    argv[0][len - 1] == 'c') {
92 				/* chop it and set the no-newline flag. */
93 				len -= 2;
94 				nflag = 1;
95 			}
96 		}
97 		vp->iov_base = *argv;
98 		vp++->iov_len = len;
99 		if (*++argv) {
100 			vp->iov_base = space;
101 			vp++->iov_len = 1;
102 		}
103 	}
104 	if (!nflag) {
105 		veclen++;
106 		vp->iov_base = newline;
107 		vp++->iov_len = 1;
108 	}
109 	/* assert(veclen == (vp - iov)); */
110 	while (veclen) {
111 		int nwrite;
112 
113 		nwrite = (veclen > IOV_MAX) ? IOV_MAX : veclen;
114 		if (writev(STDOUT_FILENO, iov, nwrite) == -1)
115 			err(1, "write");
116 		iov += nwrite;
117 		veclen -= nwrite;
118 	}
119 	return 0;
120 }
121