echo/echo.c

   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: src/bin/echo/echo.c,v 1.18 2005/01/10 08:39:22 imp Exp $");
  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  */
  58 static void
  59 errexit(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
  71 int
  72 main(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 }