xref: /freebsd/bin/echo/echo.c (revision 792bbaba989533a1fc93823df1720c8c4aaf0442)
1 /*-
2  * Copyright (c) 1989, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 4. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #if 0
31 #ifndef lint
32 static 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
38 static char sccsid[] = "@(#)echo.c	8.1 (Berkeley) 5/31/93";
39 #endif /* not lint */
40 #endif
41 #include <sys/cdefs.h>
42 __FBSDID("$FreeBSD$");
43 
44 #include <sys/types.h>
45 #include <sys/uio.h>
46 
47 #include <assert.h>
48 #include <capsicum_helpers.h>
49 #include <err.h>
50 #include <errno.h>
51 #include <limits.h>
52 #include <stdlib.h>
53 #include <string.h>
54 #include <unistd.h>
55 
56 /*
57  * Report an error and exit.
58  * Use it instead of err(3) to avoid linking-in stdio.
59  */
60 static __dead2 void
61 errexit(const char *prog, const char *reason)
62 {
63 	char *errstr = strerror(errno);
64 	write(STDERR_FILENO, prog, strlen(prog));
65 	write(STDERR_FILENO, ": ", 2);
66 	write(STDERR_FILENO, reason, strlen(reason));
67 	write(STDERR_FILENO, ": ", 2);
68 	write(STDERR_FILENO, errstr, strlen(errstr));
69 	write(STDERR_FILENO, "\n", 1);
70 	exit(1);
71 }
72 
73 int
74 main(int argc, char *argv[])
75 {
76 	int nflag;	/* if not set, output a trailing newline. */
77 	int veclen;	/* number of writev arguments. */
78 	struct iovec *iov, *vp; /* Elements to write, current element. */
79 	char space[] = " ";
80 	char newline[] = "\n";
81 	char *progname = argv[0];
82 
83 	if (caph_limit_stdio() < 0 || (cap_enter() < 0 && errno != ENOSYS))
84 		err(1, "capsicum");
85 
86 	/* This utility may NOT do getopt(3) option parsing. */
87 	if (*++argv && !strcmp(*argv, "-n")) {
88 		++argv;
89 		--argc;
90 		nflag = 1;
91 	} else
92 		nflag = 0;
93 
94 	veclen = (argc >= 2) ? (argc - 2) * 2 + 1 : 0;
95 
96 	if ((vp = iov = malloc((veclen + 1) * sizeof(struct iovec))) == NULL)
97 		errexit(progname, "malloc");
98 
99 	while (argv[0] != NULL) {
100 		size_t len;
101 
102 		len = strlen(argv[0]);
103 
104 		/*
105 		 * If the next argument is NULL then this is this
106 		 * the last argument, therefore we need to check
107 		 * for a trailing \c.
108 		 */
109 		if (argv[1] == NULL) {
110 			/* is there room for a '\c' and is there one? */
111 			if (len >= 2 &&
112 			    argv[0][len - 2] == '\\' &&
113 			    argv[0][len - 1] == 'c') {
114 				/* chop it and set the no-newline flag. */
115 				len -= 2;
116 				nflag = 1;
117 			}
118 		}
119 		vp->iov_base = *argv;
120 		vp++->iov_len = len;
121 		if (*++argv) {
122 			vp->iov_base = space;
123 			vp++->iov_len = 1;
124 		}
125 	}
126 	if (!nflag) {
127 		veclen++;
128 		vp->iov_base = newline;
129 		vp++->iov_len = 1;
130 	}
131 	/* assert(veclen == (vp - iov)); */
132 	while (veclen) {
133 		int nwrite;
134 
135 		nwrite = (veclen > IOV_MAX) ? IOV_MAX : veclen;
136 		if (writev(STDOUT_FILENO, iov, nwrite) == -1)
137 			errexit(progname, "write");
138 		iov += nwrite;
139 		veclen -= nwrite;
140 	}
141 	return 0;
142 }
143