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