1 /* vi: set sw=4 ts=4: */
2 /*
3 * echo implementation for busybox
4 *
5 * Copyright (c) 1991, 1993
6 * The Regents of the University of California. All rights reserved.
7 *
8 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
9 *
10 * Original copyright notice is retained at the end of this file.
11 */
12 /* Mar 16, 2003 Manuel Novoa III (mjn3@codepoet.org)
13 *
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.
20 */
21 //config:config ECHO
22 //config: bool "echo (1.8 kb)"
23 //config: default y
24 //config: help
25 //config: echo prints a specified string to stdout.
26 //config:
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"
30 //config: default y
31 //config: depends on ECHO || ASH_ECHO || HUSH_ECHO
32
33 //applet:IF_ECHO(APPLET_NOFORK(echo, echo, BB_DIR_BIN, BB_SUID_DROP, echo))
34
35 //kbuild:lib-$(CONFIG_ECHO) += echo.o
36
37 //kbuild:lib-$(CONFIG_ASH_ECHO) += echo.o
38 //kbuild:lib-$(CONFIG_HUSH_ECHO) += echo.o
39
40 /* BB_AUDIT SUSv3 compliant -- unless configured as fancy echo. */
41 /* http://www.opengroup.org/onlinepubs/007904975/utilities/echo.html */
42
43 //usage:#define echo_trivial_usage
44 //usage: IF_FEATURE_FANCY_ECHO("[-neE] ") "[ARG]..."
45 //usage:#define echo_full_usage "\n\n"
46 //usage: "Print ARGs to stdout"
47 //usage: IF_FEATURE_FANCY_ECHO( "\n"
48 //usage: "\n -n No trailing newline"
49 //usage: "\n -e Interpret backslash escapes (\\t=tab etc)"
50 //usage: "\n -E Don't interpret backslash escapes (default)"
51 //usage: )
52 //usage:
53 //usage:#define echo_example_usage
54 //usage: "$ echo \"Erik is cool\"\n"
55 //usage: "Erik is cool\n"
56 //usage: IF_FEATURE_FANCY_ECHO("$ echo -e \"Erik\\nis\\ncool\"\n"
57 //usage: "Erik\n"
58 //usage: "is\n"
59 //usage: "cool\n"
60 //usage: "$ echo \"Erik\\nis\\ncool\"\n"
61 //usage: "Erik\\nis\\ncool\n")
62
63 #include "libbb.h"
64
65 /* This is a NOFORK applet. Be very careful! */
66
67 /* NB: can be used by shell even if not enabled as applet */
68
69 /*
70 * NB2: we don't use stdio, we need better error handing.
71 * Examples include writing into non-opened stdout and error on write.
72 *
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.
78 *
79 * Solaris has fpurge which discards buffered input. glibc has __fpurge.
80 * But this function is not standard.
81 */
82
echo_main(int argc UNUSED_PARAM,char ** argv)83 int echo_main(int argc UNUSED_PARAM, char **argv)
84 {
85 char **pp;
86 const char *arg;
87 char *out;
88 char *buffer;
89 unsigned buflen;
90 int err;
91 #if !ENABLE_FEATURE_FANCY_ECHO
92 enum {
93 eflag = 0, /* 0 -- disable escape sequences */
94 nflag = 1, /* 1 -- print '\n' */
95 };
96
97 argv++;
98 #else
99 char nflag = 1;
100 char eflag = 0;
101
102 while ((arg = *++argv) != NULL) {
103 char n, e;
104
105 if (arg[0] != '-')
106 break; /* not an option arg, echo it */
107
108 /* If it appears that we are handling options, then make sure
109 * that all of the options specified are actually valid.
110 * Otherwise, the string should just be echoed.
111 */
112 arg++;
113 n = nflag;
114 e = eflag;
115 do {
116 if (*arg == 'n')
117 n = 0;
118 else if (*arg == 'e')
119 e = '\\';
120 else if (*arg != 'E') {
121 /* "-ccc" arg with one of c's invalid, echo it */
122 /* arg consisting from just "-" also handled here */
123 goto just_echo;
124 }
125 } while (*++arg);
126 nflag = n;
127 eflag = e;
128 }
129 just_echo:
130 #endif
131
132 buflen = 0;
133 pp = argv;
134 while ((arg = *pp) != NULL) {
135 buflen += strlen(arg) + 1;
136 pp++;
137 }
138 out = buffer = xmalloc(buflen + 1); /* +1 is needed for "no args" case */
139
140 while ((arg = *argv) != NULL) {
141 int c;
142
143 if (!eflag) {
144 /* optimization for very common case */
145 out = stpcpy(out, arg);
146 } else
147 while ((c = *arg++) != '\0') {
148 if (c == eflag) {
149 /* This is an "\x" sequence */
150
151 if (*arg == 'c') {
152 /* "\c" means cancel newline and
153 * ignore all subsequent chars. */
154 goto do_write;
155 }
156 /* Since SUSv3 mandates a first digit of 0, 4-digit octals
157 * of the form \0### are accepted. */
158 if (*arg == '0') {
159 if ((unsigned char)(arg[1] - '0') < 8) {
160 /* 2nd char is 0..7: skip leading '0' */
161 arg++;
162 }
163 }
164 /* bb_process_escape_sequence handles NUL correctly
165 * ("...\" case). */
166 {
167 /* optimization: don't force arg to be on-stack,
168 * use another variable for that. ~30 bytes win */
169 const char *z = arg;
170 c = bb_process_escape_sequence(&z);
171 arg = z;
172 }
173 }
174 *out++ = c;
175 }
176
177 if (!*++argv)
178 break;
179 *out++ = ' ';
180 }
181
182 if (nflag) {
183 *out++ = '\n';
184 }
185
186 do_write:
187 /* Careful to error out on partial writes too (think ENOSPC!) */
188 errno = 0;
189 err = full_write(STDOUT_FILENO, buffer, out - buffer) != out - buffer;
190 if (err) {
191 bb_simple_perror_msg(bb_msg_write_error);
192 }
193 free(buffer);
194 return err;
195 }
196
197 /*
198 * Copyright (c) 1991, 1993
199 * The Regents of the University of California. All rights reserved.
200 *
201 * This code is derived from software contributed to Berkeley by
202 * Kenneth Almquist.
203 *
204 * Redistribution and use in source and binary forms, with or without
205 * modification, are permitted provided that the following conditions
206 * are met:
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.
212 *
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>
215 *
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.
220 *
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
231 * SUCH DAMAGE.
232 *
233 * @(#)echo.c 8.1 (Berkeley) 5/31/93
234 */
235
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.
245 *
246 * Using writev instead, with 'direct' conversion of argv vector.
247 */
248
echo_main(int argc,char ** argv)249 int echo_main(int argc, char **argv)
250 {
251 struct iovec io[argc];
252 struct iovec *cur_io = io;
253 char *arg;
254 char *p;
255 #if !ENABLE_FEATURE_FANCY_ECHO
256 enum {
257 eflag = '\\',
258 nflag = 1, /* 1 -- print '\n' */
259 };
260 arg = *++argv;
261 if (!arg)
262 goto newline_ret;
263 #else
264 char nflag = 1;
265 char eflag = 0;
266
267 while (1) {
268 arg = *++argv;
269 if (!arg)
270 goto newline_ret;
271 if (*arg != '-')
272 break;
273
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.
277 */
278 p = arg + 1;
279 if (!*p) /* A single '-', so echo it. */
280 goto just_echo;
281
282 do {
283 if (!strchr("neE", *p))
284 goto just_echo;
285 } while (*++p);
286
287 /* All of the options in this arg are valid, so handle them. */
288 p = arg + 1;
289 do {
290 if (*p == 'n')
291 nflag = 0;
292 if (*p == 'e')
293 eflag = '\\';
294 } while (*++p);
295 }
296 just_echo:
297 #endif
298
299 while (1) {
300 /* arg is already == *argv and isn't NULL */
301 int c;
302
303 cur_io->iov_base = p = arg;
304
305 if (!eflag) {
306 /* optimization for very common case */
307 p += strlen(arg);
308 } else while ((c = *arg++)) {
309 if (c == eflag) {
310 /* This is an "\x" sequence */
311
312 if (*arg == 'c') {
313 /* "\c" means cancel newline and
314 * ignore all subsequent chars. */
315 cur_io->iov_len = p - (char*)cur_io->iov_base;
316 cur_io++;
317 goto ret;
318 }
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) {
322 arg++;
323 }
324 /* bb_process_escape_sequence can handle nul correctly */
325 c = bb_process_escape_sequence( (void*) &arg);
326 }
327 *p++ = c;
328 }
329
330 arg = *++argv;
331 if (arg)
332 *p++ = ' ';
333 cur_io->iov_len = p - (char*)cur_io->iov_base;
334 cur_io++;
335 if (!arg)
336 break;
337 }
338
339 newline_ret:
340 if (nflag) {
341 cur_io->iov_base = (char*)"\n";
342 cur_io->iov_len = 1;
343 cur_io++;
344 }
345 ret:
346 /* TODO: implement and use full_writev? */
347 return writev(1, io, (cur_io - io)) >= 0;
348 }
349 #endif
350