1/* vi: set sw=4 ts=4: */
2/*
3 * Mini xargs implementation for busybox
4 * Options are supported: "-prtx -n max_arg -s max_chars -e[ouf_str]"
5 *
6 * (C) 2002,2003 by Vladimir Oleynik <dzo@simtreas.ru>
7 *
8 * Special thanks
9 * - Mark Whitley and Glenn McGrath for stimulus to rewrite :)
10 * - Mike Rendell <michael@cs.mun.ca>
11 * and David MacKenzie <djm@gnu.ai.mit.edu>.
12 *
13 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
14 *
15 * xargs is described in the Single Unix Specification v3 at
16 * http://www.opengroup.org/onlinepubs/007904975/utilities/xargs.html
17 *
18 */
19
20#include "libbb.h"
21
22/* This is a NOEXEC applet. Be very careful! */
23
24
25/* COMPAT:  SYSV version defaults size (and has a max value of) to 470.
26   We try to make it as large as possible. */
27#if !defined(ARG_MAX) && defined(_SC_ARG_MAX)
28#define ARG_MAX sysconf (_SC_ARG_MAX)
29#endif
30#ifndef ARG_MAX
31#define ARG_MAX 470
32#endif
33
34
35#ifdef TEST
36# ifndef ENABLE_FEATURE_XARGS_SUPPORT_CONFIRMATION
37#  define ENABLE_FEATURE_XARGS_SUPPORT_CONFIRMATION 1
38# endif
39# ifndef ENABLE_FEATURE_XARGS_SUPPORT_QUOTES
40#  define ENABLE_FEATURE_XARGS_SUPPORT_QUOTES 1
41# endif
42# ifndef ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT
43#  define ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT 1
44# endif
45# ifndef ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
46#  define ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM 1
47# endif
48#endif
49
50/*
51   This function has special algorithm.
52   Don't use fork and include to main!
53*/
54static int xargs_exec(char **args)
55{
56	int status;
57
58	status = spawn_and_wait(args);
59	if (status < 0) {
60		bb_perror_msg("%s", args[0]);
61		return errno == ENOENT ? 127 : 126;
62	}
63	if (status == 255) {
64		bb_error_msg("%s: exited with status 255; aborting", args[0]);
65		return 124;
66	}
67/* Huh? I think we won't see this, ever. We don't wait with WUNTRACED!
68	if (WIFSTOPPED(status)) {
69		bb_error_msg("%s: stopped by signal %d",
70			args[0], WSTOPSIG(status));
71		return 125;
72	}
73*/
74	if (status >= 1000) {
75		bb_error_msg("%s: terminated by signal %d",
76			args[0], status - 1000);
77		return 125;
78	}
79	if (status)
80		return 123;
81	return 0;
82}
83
84
85typedef struct xlist_t {
86	struct xlist_t *link;
87	size_t length;
88	char xstr[1];
89} xlist_t;
90
91static smallint eof_stdin_detected;
92
93#define ISBLANK(c) ((c) == ' ' || (c) == '\t')
94#define ISSPACE(c) (ISBLANK(c) || (c) == '\n' || (c) == '\r' \
95		    || (c) == '\f' || (c) == '\v')
96
97#if ENABLE_FEATURE_XARGS_SUPPORT_QUOTES
98static xlist_t *process_stdin(xlist_t *list_arg,
99	const char *eof_str, size_t mc, char *buf)
100{
101#define NORM      0
102#define QUOTE     1
103#define BACKSLASH 2
104#define SPACE     4
105
106	char *s = NULL;         /* start word */
107	char *p = NULL;         /* pointer to end word */
108	char q = '\0';          /* quote char */
109	char state = NORM;
110	char eof_str_detected = 0;
111	size_t line_l = 0;      /* size loaded args line */
112	int c;                  /* current char */
113	xlist_t *cur;
114	xlist_t *prev;
115
116	prev = cur = list_arg;
117	while (1) {
118		if (!cur) break;
119		prev = cur;
120		line_l += cur->length;
121		cur = cur->link;
122	}
123
124	while (!eof_stdin_detected) {
125		c = getchar();
126		if (c == EOF) {
127			eof_stdin_detected = 1;
128			if (s)
129				goto unexpected_eof;
130			break;
131		}
132		if (eof_str_detected)
133			continue;
134		if (state == BACKSLASH) {
135			state = NORM;
136			goto set;
137		} else if (state == QUOTE) {
138			if (c != q)
139				goto set;
140			q = '\0';
141			state = NORM;
142		} else { /* if (state == NORM) */
143			if (ISSPACE(c)) {
144				if (s) {
145 unexpected_eof:
146					state = SPACE;
147					c = '\0';
148					goto set;
149				}
150			} else {
151				if (s == NULL)
152					s = p = buf;
153				if (c == '\\') {
154					state = BACKSLASH;
155				} else if (c == '\'' || c == '"') {
156					q = c;
157					state = QUOTE;
158				} else {
159 set:
160					if ((size_t)(p - buf) >= mc)
161						bb_error_msg_and_die("argument line too long");
162					*p++ = c;
163				}
164			}
165		}
166		if (state == SPACE) {   /* word's delimiter or EOF detected */
167			if (q) {
168				bb_error_msg_and_die("unmatched %s quote",
169					q == '\'' ? "single" : "double");
170			}
171			/* word loaded */
172			if (eof_str) {
173				eof_str_detected = (strcmp(s, eof_str) == 0);
174			}
175			if (!eof_str_detected) {
176				size_t length = (p - buf);
177				/* Dont xzalloc - it can be quite big */
178				cur = xmalloc(offsetof(xlist_t, xstr) + length);
179				cur->link = NULL;
180				cur->length = length;
181				memcpy(cur->xstr, s, length);
182				if (prev == NULL) {
183					list_arg = cur;
184				} else {
185					prev->link = cur;
186				}
187				prev = cur;
188				line_l += length;
189				if (line_l > mc) {
190					/* stop memory usage :-) */
191					break;
192				}
193			}
194			s = NULL;
195			state = NORM;
196		}
197	}
198	return list_arg;
199}
200#else
201/* The variant does not support single quotes, double quotes or backslash */
202static xlist_t *process_stdin(xlist_t *list_arg,
203		const char *eof_str, size_t mc, char *buf)
204{
205
206	int c;                  /* current char */
207	char eof_str_detected = 0;
208	char *s = NULL;         /* start word */
209	char *p = NULL;         /* pointer to end word */
210	size_t line_l = 0;      /* size loaded args line */
211	xlist_t *cur;
212	xlist_t *prev;
213
214	prev = cur = list_arg;
215	while (1) {
216		if (!cur) break;
217		prev = cur;
218		line_l += cur->length;
219		cur = cur->link;
220	}
221
222	while (!eof_stdin_detected) {
223		c = getchar();
224		if (c == EOF) {
225			eof_stdin_detected = 1;
226		}
227		if (eof_str_detected)
228			continue;
229		if (c == EOF || ISSPACE(c)) {
230			if (s == NULL)
231				continue;
232			c = EOF;
233		}
234		if (s == NULL)
235			s = p = buf;
236		if ((p - buf) >= mc)
237			bb_error_msg_and_die("argument line too long");
238		*p++ = (c == EOF ? '\0' : c);
239		if (c == EOF) { /* word's delimiter or EOF detected */
240			/* word loaded */
241			if (eof_str) {
242				eof_str_detected = (strcmp(s, eof_str) == 0);
243			}
244			if (!eof_str_detected) {
245				size_t length = (p - buf);
246				/* Dont xzalloc - it can be quite big */
247				cur = xmalloc(offsetof(xlist_t, xstr) + length);
248				cur->link = NULL;
249				cur->length = length;
250				memcpy(cur->xstr, s, length);
251				if (prev == NULL) {
252					list_arg = cur;
253				} else {
254					prev->link = cur;
255				}
256				prev = cur;
257				line_l += length;
258				if (line_l > mc) {
259					/* stop memory usage :-) */
260					break;
261				}
262				s = NULL;
263			}
264		}
265	}
266	return list_arg;
267}
268#endif /* FEATURE_XARGS_SUPPORT_QUOTES */
269
270
271#if ENABLE_FEATURE_XARGS_SUPPORT_CONFIRMATION
272/* Prompt the user for a response, and
273   if the user responds affirmatively, return true;
274   otherwise, return false. Uses "/dev/tty", not stdin. */
275static int xargs_ask_confirmation(void)
276{
277	FILE *tty_stream;
278	int c, savec;
279
280	tty_stream = xfopen(CURRENT_TTY, "r");
281	fputs(" ?...", stderr);
282	fflush(stderr);
283	c = savec = getc(tty_stream);
284	while (c != EOF && c != '\n')
285		c = getc(tty_stream);
286	fclose(tty_stream);
287	return (savec == 'y' || savec == 'Y');
288}
289#else
290# define xargs_ask_confirmation() 1
291#endif /* FEATURE_XARGS_SUPPORT_CONFIRMATION */
292
293#if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
294static xlist_t *process0_stdin(xlist_t *list_arg,
295		const char *eof_str ATTRIBUTE_UNUSED, size_t mc, char *buf)
296{
297	int c;                  /* current char */
298	char *s = NULL;         /* start word */
299	char *p = NULL;         /* pointer to end word */
300	size_t line_l = 0;      /* size loaded args line */
301	xlist_t *cur;
302	xlist_t *prev;
303
304	prev = cur = list_arg;
305	while (1) {
306		if (!cur) break;
307		prev = cur;
308		line_l += cur->length;
309		cur = cur->link;
310	}
311
312	while (!eof_stdin_detected) {
313		c = getchar();
314		if (c == EOF) {
315			eof_stdin_detected = 1;
316			if (s == NULL)
317				break;
318			c = '\0';
319		}
320		if (s == NULL)
321			s = p = buf;
322		if ((size_t)(p - buf) >= mc)
323			bb_error_msg_and_die("argument line too long");
324		*p++ = c;
325		if (c == '\0') {   /* word's delimiter or EOF detected */
326			/* word loaded */
327			size_t length = (p - buf);
328			/* Dont xzalloc - it can be quite big */
329			cur = xmalloc(offsetof(xlist_t, xstr) + length);
330			cur->link = NULL;
331			cur->length = length;
332			memcpy(cur->xstr, s, length);
333			if (prev == NULL) {
334				list_arg = cur;
335			} else {
336				prev->link = cur;
337			}
338			prev = cur;
339			line_l += length;
340			if (line_l > mc) {
341				/* stop memory usage :-) */
342				break;
343			}
344			s = NULL;
345		}
346	}
347	return list_arg;
348}
349#endif /* FEATURE_XARGS_SUPPORT_ZERO_TERM */
350
351/* Correct regardless of combination of CONFIG_xxx */
352enum {
353	OPTBIT_VERBOSE = 0,
354	OPTBIT_NO_EMPTY,
355	OPTBIT_UPTO_NUMBER,
356	OPTBIT_UPTO_SIZE,
357	OPTBIT_EOF_STRING,
358	USE_FEATURE_XARGS_SUPPORT_CONFIRMATION(OPTBIT_INTERACTIVE,)
359	USE_FEATURE_XARGS_SUPPORT_TERMOPT(     OPTBIT_TERMINATE  ,)
360	USE_FEATURE_XARGS_SUPPORT_ZERO_TERM(   OPTBIT_ZEROTERM   ,)
361
362	OPT_VERBOSE     = 1<<OPTBIT_VERBOSE    ,
363	OPT_NO_EMPTY    = 1<<OPTBIT_NO_EMPTY   ,
364	OPT_UPTO_NUMBER = 1<<OPTBIT_UPTO_NUMBER,
365	OPT_UPTO_SIZE   = 1<<OPTBIT_UPTO_SIZE  ,
366	OPT_EOF_STRING  = 1<<OPTBIT_EOF_STRING ,
367	OPT_INTERACTIVE = USE_FEATURE_XARGS_SUPPORT_CONFIRMATION((1<<OPTBIT_INTERACTIVE)) + 0,
368	OPT_TERMINATE   = USE_FEATURE_XARGS_SUPPORT_TERMOPT(     (1<<OPTBIT_TERMINATE  )) + 0,
369	OPT_ZEROTERM    = USE_FEATURE_XARGS_SUPPORT_ZERO_TERM(   (1<<OPTBIT_ZEROTERM   )) + 0,
370};
371#define OPTION_STR "+trn:s:e::" \
372	USE_FEATURE_XARGS_SUPPORT_CONFIRMATION("p") \
373	USE_FEATURE_XARGS_SUPPORT_TERMOPT(     "x") \
374	USE_FEATURE_XARGS_SUPPORT_ZERO_TERM(   "0")
375
376int xargs_main(int argc, char **argv);
377int xargs_main(int argc, char **argv)
378{
379	char **args;
380	int i, n;
381	xlist_t *list = NULL;
382	xlist_t *cur;
383	int child_error = 0;
384	char *max_args, *max_chars;
385	int n_max_arg;
386	size_t n_chars = 0;
387	long orig_arg_max;
388	const char *eof_str = "_";
389	unsigned opt;
390	size_t n_max_chars;
391#if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
392	xlist_t* (*read_args)(xlist_t*, const char*, size_t, char*) = process_stdin;
393#else
394#define read_args process_stdin
395#endif
396
397	opt = getopt32(argv, OPTION_STR, &max_args, &max_chars, &eof_str);
398
399	if (opt & OPT_ZEROTERM)
400		USE_FEATURE_XARGS_SUPPORT_ZERO_TERM(read_args = process0_stdin);
401
402	argv += optind;
403	argc -= optind;
404	if (!argc) {
405		/* default behavior is to echo all the filenames */
406		*argv = (char*)"echo";
407		argc++;
408	}
409
410	orig_arg_max = ARG_MAX;
411	if (orig_arg_max == -1)
412		orig_arg_max = LONG_MAX;
413	orig_arg_max -= 2048;   /* POSIX.2 requires subtracting 2048 */
414
415	if (opt & OPT_UPTO_SIZE) {
416		n_max_chars = xatoul_range(max_chars, 1, orig_arg_max);
417		for (i = 0; i < argc; i++) {
418			n_chars += strlen(*argv) + 1;
419		}
420		if (n_max_chars < n_chars) {
421			bb_error_msg_and_die("cannot fit single argument within argument list size limit");
422		}
423		n_max_chars -= n_chars;
424	} else {
425		/* Sanity check for systems with huge ARG_MAX defines (e.g., Suns which
426		   have it at 1 meg).  Things will work fine with a large ARG_MAX but it
427		   will probably hurt the system more than it needs to; an array of this
428		   size is allocated.  */
429		if (orig_arg_max > 20 * 1024)
430			orig_arg_max = 20 * 1024;
431		n_max_chars = orig_arg_max;
432	}
433	max_chars = xmalloc(n_max_chars);
434
435	if (opt & OPT_UPTO_NUMBER) {
436		n_max_arg = xatoul_range(max_args, 1, INT_MAX);
437	} else {
438		n_max_arg = n_max_chars;
439	}
440
441	while ((list = read_args(list, eof_str, n_max_chars, max_chars)) != NULL ||
442		!(opt & OPT_NO_EMPTY))
443	{
444		opt |= OPT_NO_EMPTY;
445		n = 0;
446		n_chars = 0;
447#if ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT
448		for (cur = list; cur;) {
449			n_chars += cur->length;
450			n++;
451			cur = cur->link;
452			if (n_chars > n_max_chars || (n == n_max_arg && cur)) {
453				if (opt & OPT_TERMINATE)
454					bb_error_msg_and_die("argument list too long");
455				break;
456			}
457		}
458#else
459		for (cur = list; cur; cur = cur->link) {
460			n_chars += cur->length;
461			n++;
462			if (n_chars > n_max_chars || n == n_max_arg) {
463				break;
464			}
465		}
466#endif /* FEATURE_XARGS_SUPPORT_TERMOPT */
467
468		/* allocate pointers for execvp:
469		   argc*arg, n*arg from stdin, NULL */
470		args = xzalloc((n + argc + 1) * sizeof(char *));
471
472		/* store the command to be executed
473		   (taken from the command line) */
474		for (i = 0; i < argc; i++)
475			args[i] = argv[i];
476		/* (taken from stdin) */
477		for (cur = list; n; cur = cur->link) {
478			args[i++] = cur->xstr;
479			n--;
480		}
481
482		if (opt & (OPT_INTERACTIVE | OPT_VERBOSE)) {
483			for (i = 0; args[i]; i++) {
484				if (i)
485					fputc(' ', stderr);
486				fputs(args[i], stderr);
487			}
488			if (!(opt & OPT_INTERACTIVE))
489				fputc('\n', stderr);
490		}
491		if (!(opt & OPT_INTERACTIVE) || xargs_ask_confirmation()) {
492			child_error = xargs_exec(args);
493		}
494
495		/* clean up */
496		for (i = argc; args[i]; i++) {
497			cur = list;
498			list = list->link;
499			free(cur);
500		}
501		free(args);
502		if (child_error > 0 && child_error != 123) {
503			break;
504		}
505	}
506	if (ENABLE_FEATURE_CLEAN_UP)
507		free(max_chars);
508	return child_error;
509}
510
511
512#ifdef TEST
513
514const char *applet_name = "debug stuff usage";
515
516void bb_show_usage(void)
517{
518	fprintf(stderr, "Usage: %s [-p] [-r] [-t] -[x] [-n max_arg] [-s max_chars]\n",
519		applet_name);
520	exit(1);
521}
522
523int main(int argc, char **argv)
524{
525	return xargs_main(argc, argv);
526}
527#endif /* TEST */
528