summaryrefslogtreecommitdiff
path: root/coreutils/echo.c
blob: 4c7a91743f017e11e8fd7040f45b3d2b91c59e54 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
/* vi: set sw=4 ts=4: */
/*
 * echo implementation for busybox
 *
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 *
 * Original copyright notice is retained at the end of this file.
 */

/* BB_AUDIT SUSv3 compliant -- unless configured as fancy echo. */
/* http://www.opengroup.org/onlinepubs/007904975/utilities/echo.html */

/* Mar 16, 2003      Manuel Novoa III   (mjn3@codepoet.org)
 *
 * Because of behavioral differences, implemented configurable SUSv3
 * or 'fancy' gnu-ish behaviors.  Also, reduced size and fixed bugs.
 * 1) In handling '\c' escape, the previous version only suppressed the
 *     trailing newline.  SUSv3 specifies _no_ output after '\c'.
 * 2) SUSv3 specifies that octal escapes are of the form \0{#{#{#}}}.
 *    The previous version did not allow 4-digit octals.
 */

#include "libbb.h"

/* argc is unused, but removing it precludes compiler from
 * using call -> jump optimization */
int bb_echo(int argc, char **argv)
{
	const char *arg;
#if !ENABLE_FEATURE_FANCY_ECHO
	enum {
		eflag = '\\',
		nflag = 1,  /* 1 -- print '\n' */
	};

	/* We must check that stdout is not closed.
	 * The reason for this is highly non-obvious.
	 * bb_echo is used from shell. Shell must correctly handle "echo foo"
	 * if stdout is closed. With stdio, output gets shoveled into
	 * stdout buffer, and even fflush cannot clear it out. It seems that
	 * even if libc receives EBADF on write attempts, it feels determined
	 * to output data no matter what. So it will try later,
	 * and possibly will clobber future output. Not good. */
	if (dup2(1, 1) != 1)
		return -1;

	arg = *++argv;
	if (!arg)
		goto newline_ret;
#else
	const char *p;
	char nflag = 1;
	char eflag = 0;

	/* We must check that stdout is not closed. */
	if (dup2(1, 1) != 1)
		return -1;

	while (1) {
		arg = *++argv;
		if (!arg)
			goto newline_ret;
		if (*arg != '-')
			break;

		/* If it appears that we are handling options, then make sure
		 * that all of the options specified are actually valid.
		 * Otherwise, the string should just be echoed.
		 */
		p = arg + 1;
		if (!*p)	/* A single '-', so echo it. */
			goto just_echo;

		do {
			if (!strrchr("neE", *p))
				goto just_echo;
		} while (*++p);

		/* All of the options in this arg are valid, so handle them. */
		p = arg + 1;
		do {
			if (*p == 'n')
				nflag = 0;
			if (*p == 'e')
				eflag = '\\';
		} while (*++p);
	}
 just_echo:
#endif
	while (1) {
		/* arg is already == *argv and isn't NULL */
		int c;

		if (!eflag) {
			/* optimization for very common case */
			fputs(arg, stdout);
		} else while ((c = *arg++)) {
			if (c == eflag) {	/* Check for escape seq. */
				if (*arg == 'c') {
					/* '\c' means cancel newline and
					 * ignore all subsequent chars. */
					goto ret;
				}
#if !ENABLE_FEATURE_FANCY_ECHO
				/* SUSv3 specifies that octal escapes must begin with '0'. */
				if ( (((unsigned char)*arg) - '1') >= 7)
#endif
				{
					/* Since SUSv3 mandates a first digit of 0, 4-digit octals
					* of the form \0### are accepted. */
					if (*arg == '0' && ((unsigned char)(arg[1]) - '0') < 8) {
						arg++;
					}
					/* bb_process_escape_sequence can handle nul correctly */
					c = bb_process_escape_sequence(&arg);
				}
			}
			bb_putchar(c);
		}

		arg = *++argv;
		if (!arg)
			break;
		bb_putchar(' ');
	}

 newline_ret:
	if (nflag) {
		bb_putchar('\n');
	}
 ret:
	return fflush(stdout);
}

/* This is a NOFORK applet. Be very careful! */

int echo_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int echo_main(int argc, char **argv)
{
	return bb_echo(argc, argv);
}

/*-
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. <BSD Advertising Clause omitted per the July 22, 1999 licensing change
 *		ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change>
 *
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)echo.c	8.1 (Berkeley) 5/31/93
 */

#ifdef VERSION_WITH_WRITEV
/* We can't use stdio.
 * The reason for this is highly non-obvious.
 * bb_echo is used from shell. Shell must correctly handle "echo foo"
 * if stdout is closed. With stdio, output gets shoveled into
 * stdout buffer, and even fflush cannot clear it out. It seems that
 * even if libc receives EBADF on write attempts, it feels determined
 * to output data no matter what. So it will try later,
 * and possibly will clobber future output. Not good.
 *
 * Using writev instead, with 'direct' conversion of argv vector.
 */

int bb_echo(int argc, char **argv)
{
	struct iovec io[argc];
	struct iovec *cur_io = io;
	char *arg;
	char *p;
#if !ENABLE_FEATURE_FANCY_ECHO
	enum {
		eflag = '\\',
		nflag = 1,  /* 1 -- print '\n' */
	};
	arg = *++argv;
	if (!arg)
		goto newline_ret;
#else
	char nflag = 1;
	char eflag = 0;

	while (1) {
		arg = *++argv;
		if (!arg)
			goto newline_ret;
		if (*arg != '-')
			break;

		/* If it appears that we are handling options, then make sure
		 * that all of the options specified are actually valid.
		 * Otherwise, the string should just be echoed.
		 */
		p = arg + 1;
		if (!*p)	/* A single '-', so echo it. */
			goto just_echo;

		do {
			if (!strrchr("neE", *p))
				goto just_echo;
		} while (*++p);

		/* All of the options in this arg are valid, so handle them. */
		p = arg + 1;
		do {
			if (*p == 'n')
				nflag = 0;
			if (*p == 'e')
				eflag = '\\';
		} while (*++p);
	}
 just_echo:
#endif

	while (1) {
		/* arg is already == *argv and isn't NULL */
		int c;

		cur_io->iov_base = p = arg;

		if (!eflag) {
			/* optimization for very common case */
			p += strlen(arg);
		} else while ((c = *arg++)) {
			if (c == eflag) {	/* Check for escape seq. */
				if (*arg == 'c') {
					/* '\c' means cancel newline and
					 * ignore all subsequent chars. */
					cur_io->iov_len = p - (char*)cur_io->iov_base;
					cur_io++;
					goto ret;
				}
#if !ENABLE_FEATURE_FANCY_ECHO
				/* SUSv3 specifies that octal escapes must begin with '0'. */
				if ( (((unsigned char)*arg) - '1') >= 7)
#endif
				{
					/* Since SUSv3 mandates a first digit of 0, 4-digit octals
					* of the form \0### are accepted. */
					if (*arg == '0' && ((unsigned char)(arg[1]) - '0') < 8) {
						arg++;
					}
					/* bb_process_escape_sequence can handle nul correctly */
					c = bb_process_escape_sequence( (void*) &arg);
				}
			}
			*p++ = c;
		}

		arg = *++argv;
		if (arg)
			*p++ = ' ';
		cur_io->iov_len = p - (char*)cur_io->iov_base;
		cur_io++;
		if (!arg)
			break;
	}

 newline_ret:
	if (nflag) {
		cur_io->iov_base = (char*)"\n";
		cur_io->iov_len = 1;
		cur_io++;
	}
 ret:
	/* TODO: implement and use full_writev? */
	return writev(1, io, (cur_io - io)) >= 0; 
}
#endif