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 (basic SuSv3 version taking no options)"
23 //config: default y
24 //config: help
25 //config: echo is used to print 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 echo options (-n and -e)"
30 //config: default y
31 //config: depends on ECHO || ASH_BUILTIN_ECHO || HUSH
32 //config: help
33 //config: This adds options (-n and -e) to echo.
34
35 //applet:IF_ECHO(APPLET_NOFORK(echo, echo, BB_DIR_BIN, BB_SUID_DROP, echo))
36
37 //kbuild:lib-$(CONFIG_ECHO) += echo.o
38
39 /* BB_AUDIT SUSv3 compliant -- unless configured as fancy echo. */
40 /* http://www.opengroup.org/onlinepubs/007904975/utilities/echo.html */
41
42 //usage:#define echo_trivial_usage
43 //usage: IF_FEATURE_FANCY_ECHO("[-neE] ") "[ARG]..."
44 //usage:#define echo_full_usage "\n\n"
45 //usage: "Print the specified ARGs to stdout"
46 //usage: IF_FEATURE_FANCY_ECHO( "\n"
47 //usage: "\n -n Suppress trailing newline"
48 //usage: "\n -e Interpret backslash escapes (i.e., \\t=tab)"
49 //usage: "\n -E Don't interpret backslash escapes (default)"
50 //usage: )
51 //usage:
52 //usage:#define echo_example_usage
53 //usage: "$ echo \"Erik is cool\"\n"
54 //usage: "Erik is cool\n"
55 //usage: IF_FEATURE_FANCY_ECHO("$ echo -e \"Erik\\nis\\ncool\"\n"
56 //usage: "Erik\n"
57 //usage: "is\n"
58 //usage: "cool\n"
59 //usage: "$ echo \"Erik\\nis\\ncool\"\n"
60 //usage: "Erik\\nis\\ncool\n")
61
62 #include "libbb.h"
63
64 /* This is a NOFORK applet. Be very careful! */
65
66 /* NB: can be used by shell even if not enabled as applet */
67
68 /*
69 * NB2: we don't use stdio, we need better error handing.
70 * Examples include writing into non-opened stdout and error on write.
71 *
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.
77 *
78 * Solaris has fpurge which discards buffered input. glibc has __fpurge.
79 * But this function is not standard.
80 */
81
echo_main(int argc UNUSED_PARAM,char ** argv)82 int echo_main(int argc UNUSED_PARAM, char **argv)
83 {
84 char **pp;
85 const char *arg;
86 char *out;
87 char *buffer;
88 unsigned buflen;
89 #if !ENABLE_FEATURE_FANCY_ECHO
90 enum {
91 eflag = 0, /* 0 -- disable escape sequences */
92 nflag = 1, /* 1 -- print '\n' */
93 };
94
95 argv++;
96 #else
97 char nflag = 1;
98 char eflag = 0;
99
100 while ((arg = *++argv) != NULL) {
101 char n, e;
102
103 if (arg[0] != '-')
104 break; /* not an option arg, echo it */
105
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.
109 */
110 arg++;
111 n = nflag;
112 e = eflag;
113 do {
114 if (*arg == 'n')
115 n = 0;
116 else if (*arg == 'e')
117 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 */
121 goto just_echo;
122 }
123 } while (*++arg);
124 nflag = n;
125 eflag = e;
126 }
127 just_echo:
128 #endif
129
130 buflen = 0;
131 pp = argv;
132 while ((arg = *pp) != NULL) {
133 buflen += strlen(arg) + 1;
134 pp++;
135 }
136 out = buffer = xmalloc(buflen + 1); /* +1 is needed for "no args" case */
137
138 while ((arg = *argv) != NULL) {
139 int c;
140
141 if (!eflag) {
142 /* optimization for very common case */
143 out = stpcpy(out, arg);
144 } else
145 while ((c = *arg++) != '\0') {
146 if (c == eflag) {
147 /* This is an "\x" sequence */
148
149 if (*arg == 'c') {
150 /* "\c" means cancel newline and
151 * ignore all subsequent chars. */
152 goto do_write;
153 }
154 /* Since SUSv3 mandates a first digit of 0, 4-digit octals
155 * of the form \0### are accepted. */
156 if (*arg == '0') {
157 if ((unsigned char)(arg[1] - '0') < 8) {
158 /* 2nd char is 0..7: skip leading '0' */
159 arg++;
160 }
161 }
162 /* bb_process_escape_sequence handles NUL correctly
163 * ("...\" case). */
164 {
165 /* optimization: don't force arg to be on-stack,
166 * use another variable for that. ~30 bytes win */
167 const char *z = arg;
168 c = bb_process_escape_sequence(&z);
169 arg = z;
170 }
171 }
172 *out++ = c;
173 }
174
175 if (!*++argv)
176 break;
177 *out++ = ' ';
178 }
179
180 if (nflag) {
181 *out++ = '\n';
182 }
183
184 do_write:
185 /* Careful to error out on partial writes too (think ENOSPC!) */
186 errno = 0;
187 /*r =*/ full_write(STDOUT_FILENO, buffer, out - buffer);
188 free(buffer);
189 if (/*WRONG:r < 0*/ errno) {
190 bb_perror_msg(bb_msg_write_error);
191 return 1;
192 }
193 return 0;
194 }
195
196 /*
197 * Copyright (c) 1991, 1993
198 * The Regents of the University of California. All rights reserved.
199 *
200 * This code is derived from software contributed to Berkeley by
201 * Kenneth Almquist.
202 *
203 * Redistribution and use in source and binary forms, with or without
204 * modification, are permitted provided that the following conditions
205 * are met:
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.
211 *
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>
214 *
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.
219 *
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
230 * SUCH DAMAGE.
231 *
232 * @(#)echo.c 8.1 (Berkeley) 5/31/93
233 */
234
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.
244 *
245 * Using writev instead, with 'direct' conversion of argv vector.
246 */
247
echo_main(int argc,char ** argv)248 int echo_main(int argc, char **argv)
249 {
250 struct iovec io[argc];
251 struct iovec *cur_io = io;
252 char *arg;
253 char *p;
254 #if !ENABLE_FEATURE_FANCY_ECHO
255 enum {
256 eflag = '\\',
257 nflag = 1, /* 1 -- print '\n' */
258 };
259 arg = *++argv;
260 if (!arg)
261 goto newline_ret;
262 #else
263 char nflag = 1;
264 char eflag = 0;
265
266 while (1) {
267 arg = *++argv;
268 if (!arg)
269 goto newline_ret;
270 if (*arg != '-')
271 break;
272
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.
276 */
277 p = arg + 1;
278 if (!*p) /* A single '-', so echo it. */
279 goto just_echo;
280
281 do {
282 if (!strchr("neE", *p))
283 goto just_echo;
284 } while (*++p);
285
286 /* All of the options in this arg are valid, so handle them. */
287 p = arg + 1;
288 do {
289 if (*p == 'n')
290 nflag = 0;
291 if (*p == 'e')
292 eflag = '\\';
293 } while (*++p);
294 }
295 just_echo:
296 #endif
297
298 while (1) {
299 /* arg is already == *argv and isn't NULL */
300 int c;
301
302 cur_io->iov_base = p = arg;
303
304 if (!eflag) {
305 /* optimization for very common case */
306 p += strlen(arg);
307 } else while ((c = *arg++)) {
308 if (c == eflag) {
309 /* This is an "\x" sequence */
310
311 if (*arg == 'c') {
312 /* "\c" means cancel newline and
313 * ignore all subsequent chars. */
314 cur_io->iov_len = p - (char*)cur_io->iov_base;
315 cur_io++;
316 goto ret;
317 }
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) {
321 arg++;
322 }
323 /* bb_process_escape_sequence can handle nul correctly */
324 c = bb_process_escape_sequence( (void*) &arg);
325 }
326 *p++ = c;
327 }
328
329 arg = *++argv;
330 if (arg)
331 *p++ = ' ';
332 cur_io->iov_len = p - (char*)cur_io->iov_base;
333 cur_io++;
334 if (!arg)
335 break;
336 }
337
338 newline_ret:
339 if (nflag) {
340 cur_io->iov_base = (char*)"\n";
341 cur_io->iov_len = 1;
342 cur_io++;
343 }
344 ret:
345 /* TODO: implement and use full_writev? */
346 return writev(1, io, (cur_io - io)) >= 0;
347 }
348 #endif
349