path: root/coreutils/echo.c (plain)
blob: fd0d9b780a0076f294c29c79df927b552ac130b3

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
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
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