1 /* vi: set sw=4 ts=4: */
3 * echo implementation for busybox
5 * Copyright (c) 1991, 1993
6 * The Regents of the University of California. All rights reserved.
8 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
10 * Original copyright notice is retained at the end of this file.
12 /* Mar 16, 2003 Manuel Novoa III (mjn3@codepoet.org)
14 * Because of behavioral differences, implemented configurable SUSv3
15 * or 'fancy' gnu-ish behaviors. Also, reduced size and fixed bugs.
16 * 1) In handling '\c' escape, the previous version only suppressed the
17 * trailing newline. SUSv3 specifies _no_ output after '\c'.
18 * 2) SUSv3 specifies that octal escapes are of the form \0{#{#{#}}}.
19 * The previous version did not allow 4-digit octals.
22 //config: bool "echo (basic SuSv3 version taking no options)"
25 //config: echo is used to print a specified string to stdout.
27 //config:# this entry also appears in shell/Config.in, next to the echo builtin
28 //config:config FEATURE_FANCY_ECHO
29 //config: bool "Enable echo options (-n and -e)"
31 //config: depends on ECHO || ASH_BUILTIN_ECHO || HUSH
33 //config: This adds options (-n and -e) to echo.
35 //applet:IF_ECHO(APPLET_NOFORK(echo, echo, BB_DIR_BIN, BB_SUID_DROP, echo))
37 //kbuild:lib-$(CONFIG_ECHO) += echo.o
39 /* BB_AUDIT SUSv3 compliant -- unless configured as fancy echo. */
40 /* http://www.opengroup.org/onlinepubs/007904975/utilities/echo.html */
42 //usage:#define echo_trivial_usage
43 //usage: IF_FEATURE_FANCY_ECHO("[-neE] ") "[ARG]..."
44 //usage:#define echo_full_usage "\n\n"
45 //usage: "Print the specified ARGs to stdout"
46 //usage: IF_FEATURE_FANCY_ECHO( "\n"
47 //usage: "\n -n Suppress trailing newline"
48 //usage: "\n -e Interpret backslash escapes (i.e., \\t=tab)"
49 //usage: "\n -E Don't interpret backslash escapes (default)"
52 //usage:#define echo_example_usage
53 //usage: "$ echo \"Erik is cool\"\n"
54 //usage: "Erik is cool\n"
55 //usage: IF_FEATURE_FANCY_ECHO("$ echo -e \"Erik\\nis\\ncool\"\n"
59 //usage: "$ echo \"Erik\\nis\\ncool\"\n"
60 //usage: "Erik\\nis\\ncool\n")
64 /* This is a NOFORK applet. Be very careful! */
66 /* NB: can be used by shell even if not enabled as applet */
69 * NB2: we don't use stdio, we need better error handing.
70 * Examples include writing into non-opened stdout and error on write.
72 * With stdio, output gets shoveled into stdout buffer, and even
73 * fflush cannot clear it out. It seems that even if libc receives
74 * EBADF on write attempts, it feels determined to output data no matter what.
75 * If echo is called by shell, it will try writing again later, and possibly
76 * will clobber future output. Not good.
78 * Solaris has fpurge which discards buffered input. glibc has __fpurge.
79 * But this function is not standard.
82 int echo_main(int argc UNUSED_PARAM, char **argv)
89 #if !ENABLE_FEATURE_FANCY_ECHO
91 eflag = 0, /* 0 -- disable escape sequences */
92 nflag = 1, /* 1 -- print '\n' */
100 while ((arg = *++argv) != NULL) {
104 break; /* not an option arg, echo it */
106 /* If it appears that we are handling options, then make sure
107 * that all of the options specified are actually valid.
108 * Otherwise, the string should just be echoed.
116 else if (*arg == 'e')
118 else if (*arg != 'E') {
119 /* "-ccc" arg with one of c's invalid, echo it */
120 /* arg consisting from just "-" also handled here */
132 while ((arg = *pp) != NULL) {
133 buflen += strlen(arg) + 1;
136 out = buffer = xmalloc(buflen + 1); /* +1 is needed for "no args" case */
138 while ((arg = *argv) != NULL) {
142 /* optimization for very common case */
143 out = stpcpy(out, arg);
145 while ((c = *arg++) != '\0') {
147 /* This is an "\x" sequence */
150 /* "\c" means cancel newline and
151 * ignore all subsequent chars. */
154 /* Since SUSv3 mandates a first digit of 0, 4-digit octals
155 * of the form \0### are accepted. */
157 if ((unsigned char)(arg[1] - '0') < 8) {
158 /* 2nd char is 0..7: skip leading '0' */
162 /* bb_process_escape_sequence handles NUL correctly
165 /* optimization: don't force arg to be on-stack,
166 * use another variable for that. ~30 bytes win */
168 c = bb_process_escape_sequence(&z);
185 /* Careful to error out on partial writes too (think ENOSPC!) */
187 /*r =*/ full_write(STDOUT_FILENO, buffer, out - buffer);
189 if (/*WRONG:r < 0*/ errno) {
190 bb_perror_msg(bb_msg_write_error);
197 * Copyright (c) 1991, 1993
198 * The Regents of the University of California. All rights reserved.
200 * This code is derived from software contributed to Berkeley by
203 * Redistribution and use in source and binary forms, with or without
204 * modification, are permitted provided that the following conditions
206 * 1. Redistributions of source code must retain the above copyright
207 * notice, this list of conditions and the following disclaimer.
208 * 2. Redistributions in binary form must reproduce the above copyright
209 * notice, this list of conditions and the following disclaimer in the
210 * documentation and/or other materials provided with the distribution.
212 * 3. <BSD Advertising Clause omitted per the July 22, 1999 licensing change
213 * ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change>
215 * California, Berkeley and its contributors.
216 * 4. Neither the name of the University nor the names of its contributors
217 * may be used to endorse or promote products derived from this software
218 * without specific prior written permission.
220 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
221 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
222 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
223 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
224 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
225 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
226 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
227 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
228 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
229 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
232 * @(#)echo.c 8.1 (Berkeley) 5/31/93
235 #ifdef VERSION_WITH_WRITEV
236 /* We can't use stdio.
237 * The reason for this is highly non-obvious.
238 * echo_main is used from shell. Shell must correctly handle "echo foo"
239 * if stdout is closed. With stdio, output gets shoveled into
240 * stdout buffer, and even fflush cannot clear it out. It seems that
241 * even if libc receives EBADF on write attempts, it feels determined
242 * to output data no matter what. So it will try later,
243 * and possibly will clobber future output. Not good.
245 * Using writev instead, with 'direct' conversion of argv vector.
248 int echo_main(int argc, char **argv)
250 struct iovec io[argc];
251 struct iovec *cur_io = io;
254 #if !ENABLE_FEATURE_FANCY_ECHO
257 nflag = 1, /* 1 -- print '\n' */
273 /* If it appears that we are handling options, then make sure
274 * that all of the options specified are actually valid.
275 * Otherwise, the string should just be echoed.
278 if (!*p) /* A single '-', so echo it. */
282 if (!strchr("neE", *p))
286 /* All of the options in this arg are valid, so handle them. */
299 /* arg is already == *argv and isn't NULL */
302 cur_io->iov_base = p = arg;
305 /* optimization for very common case */
307 } else while ((c = *arg++)) {
309 /* This is an "\x" sequence */
312 /* "\c" means cancel newline and
313 * ignore all subsequent chars. */
314 cur_io->iov_len = p - (char*)cur_io->iov_base;
318 /* Since SUSv3 mandates a first digit of 0, 4-digit octals
319 * of the form \0### are accepted. */
320 if (*arg == '0' && (unsigned char)(arg[1] - '0') < 8) {
323 /* bb_process_escape_sequence can handle nul correctly */
324 c = bb_process_escape_sequence( (void*) &arg);
332 cur_io->iov_len = p - (char*)cur_io->iov_base;
340 cur_io->iov_base = (char*)"\n";
345 /* TODO: implement and use full_writev? */
346 return writev(1, io, (cur_io - io)) >= 0;