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 -n and -e options"
31 //config: depends on ECHO || ASH_ECHO || HUSH_ECHO
33 //applet:IF_ECHO(APPLET_NOFORK(echo, echo, BB_DIR_BIN, BB_SUID_DROP, echo))
35 //kbuild:lib-$(CONFIG_ECHO) += echo.o
37 //kbuild:lib-$(CONFIG_ASH_ECHO) += echo.o
38 //kbuild:lib-$(CONFIG_HUSH_ECHO) += echo.o
40 /* BB_AUDIT SUSv3 compliant -- unless configured as fancy echo. */
41 /* http://www.opengroup.org/onlinepubs/007904975/utilities/echo.html */
43 //usage:#define echo_trivial_usage
44 //usage: IF_FEATURE_FANCY_ECHO("[-neE] ") "[ARG]..."
45 //usage:#define echo_full_usage "\n\n"
46 //usage: "Print the specified ARGs to stdout"
47 //usage: IF_FEATURE_FANCY_ECHO( "\n"
48 //usage: "\n -n Suppress trailing newline"
49 //usage: "\n -e Interpret backslash escapes (i.e., \\t=tab)"
50 //usage: "\n -E Don't interpret backslash escapes (default)"
53 //usage:#define echo_example_usage
54 //usage: "$ echo \"Erik is cool\"\n"
55 //usage: "Erik is cool\n"
56 //usage: IF_FEATURE_FANCY_ECHO("$ echo -e \"Erik\\nis\\ncool\"\n"
60 //usage: "$ echo \"Erik\\nis\\ncool\"\n"
61 //usage: "Erik\\nis\\ncool\n")
65 /* This is a NOFORK applet. Be very careful! */
67 /* NB: can be used by shell even if not enabled as applet */
70 * NB2: we don't use stdio, we need better error handing.
71 * Examples include writing into non-opened stdout and error on write.
73 * With stdio, output gets shoveled into stdout buffer, and even
74 * fflush cannot clear it out. It seems that even if libc receives
75 * EBADF on write attempts, it feels determined to output data no matter what.
76 * If echo is called by shell, it will try writing again later, and possibly
77 * will clobber future output. Not good.
79 * Solaris has fpurge which discards buffered input. glibc has __fpurge.
80 * But this function is not standard.
83 int echo_main(int argc UNUSED_PARAM, char **argv)
90 #if !ENABLE_FEATURE_FANCY_ECHO
92 eflag = 0, /* 0 -- disable escape sequences */
93 nflag = 1, /* 1 -- print '\n' */
101 while ((arg = *++argv) != NULL) {
105 break; /* not an option arg, echo it */
107 /* If it appears that we are handling options, then make sure
108 * that all of the options specified are actually valid.
109 * Otherwise, the string should just be echoed.
117 else if (*arg == 'e')
119 else if (*arg != 'E') {
120 /* "-ccc" arg with one of c's invalid, echo it */
121 /* arg consisting from just "-" also handled here */
133 while ((arg = *pp) != NULL) {
134 buflen += strlen(arg) + 1;
137 out = buffer = xmalloc(buflen + 1); /* +1 is needed for "no args" case */
139 while ((arg = *argv) != NULL) {
143 /* optimization for very common case */
144 out = stpcpy(out, arg);
146 while ((c = *arg++) != '\0') {
148 /* This is an "\x" sequence */
151 /* "\c" means cancel newline and
152 * ignore all subsequent chars. */
155 /* Since SUSv3 mandates a first digit of 0, 4-digit octals
156 * of the form \0### are accepted. */
158 if ((unsigned char)(arg[1] - '0') < 8) {
159 /* 2nd char is 0..7: skip leading '0' */
163 /* bb_process_escape_sequence handles NUL correctly
166 /* optimization: don't force arg to be on-stack,
167 * use another variable for that. ~30 bytes win */
169 c = bb_process_escape_sequence(&z);
186 /* Careful to error out on partial writes too (think ENOSPC!) */
188 /*r =*/ full_write(STDOUT_FILENO, buffer, out - buffer);
190 if (/*WRONG:r < 0*/ errno) {
191 bb_perror_msg(bb_msg_write_error);
198 * Copyright (c) 1991, 1993
199 * The Regents of the University of California. All rights reserved.
201 * This code is derived from software contributed to Berkeley by
204 * Redistribution and use in source and binary forms, with or without
205 * modification, are permitted provided that the following conditions
207 * 1. Redistributions of source code must retain the above copyright
208 * notice, this list of conditions and the following disclaimer.
209 * 2. Redistributions in binary form must reproduce the above copyright
210 * notice, this list of conditions and the following disclaimer in the
211 * documentation and/or other materials provided with the distribution.
213 * 3. <BSD Advertising Clause omitted per the July 22, 1999 licensing change
214 * ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change>
216 * California, Berkeley and its contributors.
217 * 4. Neither the name of the University nor the names of its contributors
218 * may be used to endorse or promote products derived from this software
219 * without specific prior written permission.
221 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ''AS IS'' AND
222 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
223 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
224 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
225 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
226 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
227 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
228 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
229 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
230 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
233 * @(#)echo.c 8.1 (Berkeley) 5/31/93
236 #ifdef VERSION_WITH_WRITEV
237 /* We can't use stdio.
238 * The reason for this is highly non-obvious.
239 * echo_main is used from shell. Shell must correctly handle "echo foo"
240 * if stdout is closed. With stdio, output gets shoveled into
241 * stdout buffer, and even fflush cannot clear it out. It seems that
242 * even if libc receives EBADF on write attempts, it feels determined
243 * to output data no matter what. So it will try later,
244 * and possibly will clobber future output. Not good.
246 * Using writev instead, with 'direct' conversion of argv vector.
249 int echo_main(int argc, char **argv)
251 struct iovec io[argc];
252 struct iovec *cur_io = io;
255 #if !ENABLE_FEATURE_FANCY_ECHO
258 nflag = 1, /* 1 -- print '\n' */
274 /* If it appears that we are handling options, then make sure
275 * that all of the options specified are actually valid.
276 * Otherwise, the string should just be echoed.
279 if (!*p) /* A single '-', so echo it. */
283 if (!strchr("neE", *p))
287 /* All of the options in this arg are valid, so handle them. */
300 /* arg is already == *argv and isn't NULL */
303 cur_io->iov_base = p = arg;
306 /* optimization for very common case */
308 } else while ((c = *arg++)) {
310 /* This is an "\x" sequence */
313 /* "\c" means cancel newline and
314 * ignore all subsequent chars. */
315 cur_io->iov_len = p - (char*)cur_io->iov_base;
319 /* Since SUSv3 mandates a first digit of 0, 4-digit octals
320 * of the form \0### are accepted. */
321 if (*arg == '0' && (unsigned char)(arg[1] - '0') < 8) {
324 /* bb_process_escape_sequence can handle nul correctly */
325 c = bb_process_escape_sequence( (void*) &arg);
333 cur_io->iov_len = p - (char*)cur_io->iov_base;
341 cur_io->iov_base = (char*)"\n";
346 /* TODO: implement and use full_writev? */
347 return writev(1, io, (cur_io - io)) >= 0;