source: branches/3.2/mindi-busybox/findutils/xargs.c @ 3232

Last change on this file since 3232 was 3232, checked in by bruno, 5 years ago
  • Update mindi-busybox to 1.21.1
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1/* vi: set sw=4 ts=4: */
2/*
3 * Mini xargs implementation for busybox
4 *
5 * (C) 2002,2003 by Vladimir Oleynik <dzo@simtreas.ru>
6 *
7 * Special thanks
8 * - Mark Whitley and Glenn McGrath for stimulus to rewrite :)
9 * - Mike Rendell <michael@cs.mun.ca>
10 * and David MacKenzie <djm@gnu.ai.mit.edu>.
11 *
12 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
13 *
14 * xargs is described in the Single Unix Specification v3 at
15 * http://www.opengroup.org/onlinepubs/007904975/utilities/xargs.html
16 */
17
18//config:config XARGS
19//config:   bool "xargs"
20//config:   default y
21//config:   help
22//config:     xargs is used to execute a specified command for
23//config:     every item from standard input.
24//config:
25//config:config FEATURE_XARGS_SUPPORT_CONFIRMATION
26//config:   bool "Enable -p: prompt and confirmation"
27//config:   default y
28//config:   depends on XARGS
29//config:   help
30//config:     Support -p: prompt the user whether to run each command
31//config:     line and read a line from the terminal.
32//config:
33//config:config FEATURE_XARGS_SUPPORT_QUOTES
34//config:   bool "Enable single and double quotes and backslash"
35//config:   default y
36//config:   depends on XARGS
37//config:   help
38//config:     Support quoting in the input.
39//config:
40//config:config FEATURE_XARGS_SUPPORT_TERMOPT
41//config:   bool "Enable -x: exit if -s or -n is exceeded"
42//config:   default y
43//config:   depends on XARGS
44//config:   help
45//config:     Support -x: exit if the command size (see the -s or -n option)
46//config:     is exceeded.
47//config:
48//config:config FEATURE_XARGS_SUPPORT_ZERO_TERM
49//config:   bool "Enable -0: NUL-terminated input"
50//config:   default y
51//config:   depends on XARGS
52//config:   help
53//config:     Support -0: input items are terminated by a NUL character
54//config:     instead of whitespace, and the quotes and backslash
55//config:     are not special.
56
57//applet:IF_XARGS(APPLET_NOEXEC(xargs, xargs, BB_DIR_USR_BIN, BB_SUID_DROP, xargs))
58
59//kbuild:lib-$(CONFIG_XARGS) += xargs.o
60
61#include "libbb.h"
62
63/* This is a NOEXEC applet. Be very careful! */
64
65
66//#define dbg_msg(...) bb_error_msg(__VA_ARGS__)
67#define dbg_msg(...) ((void)0)
68
69
70#ifdef TEST
71# ifndef ENABLE_FEATURE_XARGS_SUPPORT_CONFIRMATION
72#  define ENABLE_FEATURE_XARGS_SUPPORT_CONFIRMATION 1
73# endif
74# ifndef ENABLE_FEATURE_XARGS_SUPPORT_QUOTES
75#  define ENABLE_FEATURE_XARGS_SUPPORT_QUOTES 1
76# endif
77# ifndef ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT
78#  define ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT 1
79# endif
80# ifndef ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
81#  define ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM 1
82# endif
83#endif
84
85
86struct globals {
87    char **args;
88    const char *eof_str;
89    int idx;
90} FIX_ALIASING;
91#define G (*(struct globals*)&bb_common_bufsiz1)
92#define INIT_G() do { \
93    G.eof_str = NULL; /* need to clear by hand because we are NOEXEC applet */ \
94} while (0)
95
96
97/*
98 * This function has special algorithm.
99 * Don't use fork and include to main!
100 */
101static int xargs_exec(void)
102{
103    int status;
104
105    status = spawn_and_wait(G.args);
106    if (status < 0) {
107        bb_simple_perror_msg(G.args[0]);
108        return errno == ENOENT ? 127 : 126;
109    }
110    if (status == 255) {
111        bb_error_msg("%s: exited with status 255; aborting", G.args[0]);
112        return 124;
113    }
114    if (status >= 0x180) {
115        bb_error_msg("%s: terminated by signal %d",
116            G.args[0], status - 0x180);
117        return 125;
118    }
119    if (status)
120        return 123;
121    return 0;
122}
123
124/* In POSIX/C locale isspace is only these chars: "\t\n\v\f\r" and space.
125 * "\t\n\v\f\r" happen to have ASCII codes 9,10,11,12,13.
126 */
127#define ISSPACE(a) ({ unsigned char xargs__isspace = (a) - 9; xargs__isspace == (' ' - 9) || xargs__isspace <= (13 - 9); })
128
129static void store_param(char *s)
130{
131    /* Grow by 256 elements at once */
132    if (!(G.idx & 0xff)) { /* G.idx == N*256 */
133        /* Enlarge, make G.args[(N+1)*256 - 1] last valid idx */
134        G.args = xrealloc(G.args, sizeof(G.args[0]) * (G.idx + 0x100));
135    }
136    G.args[G.idx++] = s;
137}
138
139/* process[0]_stdin:
140 * Read characters into buf[n_max_chars+1], and when parameter delimiter
141 * is seen, store the address of a new parameter to args[].
142 * If reading discovers that last chars do not form the complete
143 * parameter, the pointer to the first such "tail character" is returned.
144 * (buf has extra byte at the end to accomodate terminating NUL
145 * of "tail characters" string).
146 * Otherwise, the returned pointer points to NUL byte.
147 * On entry, buf[] may contain some "seed chars" which are to become
148 * the beginning of the first parameter.
149 */
150
151#if ENABLE_FEATURE_XARGS_SUPPORT_QUOTES
152static char* FAST_FUNC process_stdin(int n_max_chars, int n_max_arg, char *buf)
153{
154#define NORM      0
155#define QUOTE     1
156#define BACKSLASH 2
157#define SPACE     4
158    char q = '\0';             /* quote char */
159    char state = NORM;
160    char *s = buf;             /* start of the word */
161    char *p = s + strlen(buf); /* end of the word */
162
163    buf += n_max_chars;        /* past buffer's end */
164
165    /* "goto ret" is used instead of "break" to make control flow
166     * more obvious: */
167
168    while (1) {
169        int c = getchar();
170        if (c == EOF) {
171            if (p != s)
172                goto close_word;
173            goto ret;
174        }
175        if (state == BACKSLASH) {
176            state = NORM;
177            goto set;
178        }
179        if (state == QUOTE) {
180            if (c != q)
181                goto set;
182            q = '\0';
183            state = NORM;
184        } else { /* if (state == NORM) */
185            if (ISSPACE(c)) {
186                if (p != s) {
187 close_word:
188                    state = SPACE;
189                    c = '\0';
190                    goto set;
191                }
192            } else {
193                if (c == '\\') {
194                    state = BACKSLASH;
195                } else if (c == '\'' || c == '"') {
196                    q = c;
197                    state = QUOTE;
198                } else {
199 set:
200                    *p++ = c;
201                }
202            }
203        }
204        if (state == SPACE) {   /* word's delimiter or EOF detected */
205            if (q) {
206                bb_error_msg_and_die("unmatched %s quote",
207                    q == '\'' ? "single" : "double");
208            }
209            /* A full word is loaded */
210            if (G.eof_str) {
211                if (strcmp(s, G.eof_str) == 0) {
212                    while (getchar() != EOF)
213                        continue;
214                    p = s;
215                    goto ret;
216                }
217            }
218            store_param(s);
219            dbg_msg("args[]:'%s'", s);
220            s = p;
221            n_max_arg--;
222            if (n_max_arg == 0) {
223                goto ret;
224            }
225            state = NORM;
226        }
227        if (p == buf) {
228            goto ret;
229        }
230    }
231 ret:
232    *p = '\0';
233    /* store_param(NULL) - caller will do it */
234    dbg_msg("return:'%s'", s);
235    return s;
236}
237#else
238/* The variant does not support single quotes, double quotes or backslash */
239static char* FAST_FUNC process_stdin(int n_max_chars, int n_max_arg, char *buf)
240{
241    char *s = buf;             /* start of the word */
242    char *p = s + strlen(buf); /* end of the word */
243
244    buf += n_max_chars;        /* past buffer's end */
245
246    while (1) {
247        int c = getchar();
248        if (c == EOF) {
249            if (p == s)
250                goto ret;
251        }
252        if (c == EOF || ISSPACE(c)) {
253            if (p == s)
254                continue;
255            c = EOF;
256        }
257        *p++ = (c == EOF ? '\0' : c);
258        if (c == EOF) { /* word's delimiter or EOF detected */
259            /* A full word is loaded */
260            if (G.eof_str) {
261                if (strcmp(s, G.eof_str) == 0) {
262                    while (getchar() != EOF)
263                        continue;
264                    p = s;
265                    goto ret;
266                }
267            }
268            store_param(s);
269            dbg_msg("args[]:'%s'", s);
270            s = p;
271            n_max_arg--;
272            if (n_max_arg == 0) {
273                goto ret;
274            }
275        }
276        if (p == buf) {
277            goto ret;
278        }
279    }
280 ret:
281    *p = '\0';
282    /* store_param(NULL) - caller will do it */
283    dbg_msg("return:'%s'", s);
284    return s;
285}
286#endif /* FEATURE_XARGS_SUPPORT_QUOTES */
287
288#if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
289static char* FAST_FUNC process0_stdin(int n_max_chars, int n_max_arg, char *buf)
290{
291    char *s = buf;             /* start of the word */
292    char *p = s + strlen(buf); /* end of the word */
293
294    buf += n_max_chars;        /* past buffer's end */
295
296    while (1) {
297        int c = getchar();
298        if (c == EOF) {
299            if (p == s)
300                goto ret;
301            c = '\0';
302        }
303        *p++ = c;
304        if (c == '\0') {   /* word's delimiter or EOF detected */
305            /* A full word is loaded */
306            store_param(s);
307            dbg_msg("args[]:'%s'", s);
308            s = p;
309            n_max_arg--;
310            if (n_max_arg == 0) {
311                goto ret;
312            }
313        }
314        if (p == buf) {
315            goto ret;
316        }
317    }
318 ret:
319    *p = '\0';
320    /* store_param(NULL) - caller will do it */
321    dbg_msg("return:'%s'", s);
322    return s;
323}
324#endif /* FEATURE_XARGS_SUPPORT_ZERO_TERM */
325
326#if ENABLE_FEATURE_XARGS_SUPPORT_CONFIRMATION
327/* Prompt the user for a response, and
328   if the user responds affirmatively, return true;
329   otherwise, return false. Uses "/dev/tty", not stdin. */
330static int xargs_ask_confirmation(void)
331{
332    FILE *tty_stream;
333    int c, savec;
334
335    tty_stream = xfopen_for_read(CURRENT_TTY);
336    fputs(" ?...", stderr);
337    fflush_all();
338    c = savec = getc(tty_stream);
339    while (c != EOF && c != '\n')
340        c = getc(tty_stream);
341    fclose(tty_stream);
342    return (savec == 'y' || savec == 'Y');
343}
344#else
345# define xargs_ask_confirmation() 1
346#endif
347
348//usage:#define xargs_trivial_usage
349//usage:       "[OPTIONS] [PROG ARGS]"
350//usage:#define xargs_full_usage "\n\n"
351//usage:       "Run PROG on every item given by stdin\n"
352//usage:    IF_FEATURE_XARGS_SUPPORT_CONFIRMATION(
353//usage:     "\n    -p  Ask user whether to run each command"
354//usage:    )
355//usage:     "\n    -r  Don't run command if input is empty"
356//usage:    IF_FEATURE_XARGS_SUPPORT_ZERO_TERM(
357//usage:     "\n    -0  Input is separated by NUL characters"
358//usage:    )
359//usage:     "\n    -t  Print the command on stderr before execution"
360//usage:     "\n    -e[STR] STR stops input processing"
361//usage:     "\n    -n N    Pass no more than N args to PROG"
362//usage:     "\n    -s N    Pass command line of no more than N bytes"
363//usage:    IF_FEATURE_XARGS_SUPPORT_TERMOPT(
364//usage:     "\n    -x  Exit if size is exceeded"
365//usage:    )
366//usage:#define xargs_example_usage
367//usage:       "$ ls | xargs gzip\n"
368//usage:       "$ find . -name '*.c' -print | xargs rm\n"
369
370/* Correct regardless of combination of CONFIG_xxx */
371enum {
372    OPTBIT_VERBOSE = 0,
373    OPTBIT_NO_EMPTY,
374    OPTBIT_UPTO_NUMBER,
375    OPTBIT_UPTO_SIZE,
376    OPTBIT_EOF_STRING,
377    OPTBIT_EOF_STRING1,
378    IF_FEATURE_XARGS_SUPPORT_CONFIRMATION(OPTBIT_INTERACTIVE,)
379    IF_FEATURE_XARGS_SUPPORT_TERMOPT(     OPTBIT_TERMINATE  ,)
380    IF_FEATURE_XARGS_SUPPORT_ZERO_TERM(   OPTBIT_ZEROTERM   ,)
381
382    OPT_VERBOSE     = 1 << OPTBIT_VERBOSE    ,
383    OPT_NO_EMPTY    = 1 << OPTBIT_NO_EMPTY   ,
384    OPT_UPTO_NUMBER = 1 << OPTBIT_UPTO_NUMBER,
385    OPT_UPTO_SIZE   = 1 << OPTBIT_UPTO_SIZE  ,
386    OPT_EOF_STRING  = 1 << OPTBIT_EOF_STRING , /* GNU: -e[<param>] */
387    OPT_EOF_STRING1 = 1 << OPTBIT_EOF_STRING1, /* SUS: -E<param> */
388    OPT_INTERACTIVE = IF_FEATURE_XARGS_SUPPORT_CONFIRMATION((1 << OPTBIT_INTERACTIVE)) + 0,
389    OPT_TERMINATE   = IF_FEATURE_XARGS_SUPPORT_TERMOPT(     (1 << OPTBIT_TERMINATE  )) + 0,
390    OPT_ZEROTERM    = IF_FEATURE_XARGS_SUPPORT_ZERO_TERM(   (1 << OPTBIT_ZEROTERM   )) + 0,
391};
392#define OPTION_STR "+trn:s:e::E:" \
393    IF_FEATURE_XARGS_SUPPORT_CONFIRMATION("p") \
394    IF_FEATURE_XARGS_SUPPORT_TERMOPT(     "x") \
395    IF_FEATURE_XARGS_SUPPORT_ZERO_TERM(   "0")
396
397int xargs_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
398int xargs_main(int argc, char **argv)
399{
400    int i;
401    int child_error = 0;
402    char *max_args;
403    char *max_chars;
404    char *buf;
405    unsigned opt;
406    int n_max_chars;
407    int n_max_arg;
408#if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
409    char* FAST_FUNC (*read_args)(int, int, char*) = process_stdin;
410#else
411#define read_args process_stdin
412#endif
413
414    INIT_G();
415
416#if ENABLE_DESKTOP && ENABLE_LONG_OPTS
417    /* For example, Fedora's build system uses --no-run-if-empty */
418    applet_long_options =
419        "no-run-if-empty\0" No_argument "r"
420        ;
421#endif
422    opt = getopt32(argv, OPTION_STR, &max_args, &max_chars, &G.eof_str, &G.eof_str);
423
424    /* -E ""? You may wonder why not just omit -E?
425     * This is used for portability:
426     * old xargs was using "_" as default for -E / -e */
427    if ((opt & OPT_EOF_STRING1) && G.eof_str[0] == '\0')
428        G.eof_str = NULL;
429
430    if (opt & OPT_ZEROTERM)
431        IF_FEATURE_XARGS_SUPPORT_ZERO_TERM(read_args = process0_stdin);
432
433    argv += optind;
434    argc -= optind;
435    if (!argv[0]) {
436        /* default behavior is to echo all the filenames */
437        *--argv = (char*)"echo";
438        argc++;
439    }
440
441    /* -s NUM default. fileutils-4.4.2 uses 128k, but I heasitate
442     * to use such a big value - first need to change code to use
443     * growable buffer instead of fixed one.
444     */
445    n_max_chars = 32 * 1024;
446    /* Make smaller if system does not allow our default value.
447     * The Open Group Base Specifications Issue 6:
448     * "The xargs utility shall limit the command line length such that
449     * when the command line is invoked, the combined argument
450     * and environment lists (see the exec family of functions
451     * in the System Interfaces volume of IEEE Std 1003.1-2001)
452     * shall not exceed {ARG_MAX}-2048 bytes".
453     */
454    {
455        long arg_max = 0;
456#if defined _SC_ARG_MAX
457        arg_max = sysconf(_SC_ARG_MAX) - 2048;
458#elif defined ARG_MAX
459        arg_max = ARG_MAX - 2048;
460#endif
461        if (arg_max > 0 && n_max_chars > arg_max)
462            n_max_chars = arg_max;
463    }
464    if (opt & OPT_UPTO_SIZE) {
465        n_max_chars = xatou_range(max_chars, 1, INT_MAX);
466    }
467    /* Account for prepended fixed arguments */
468    {
469        size_t n_chars = 0;
470        for (i = 0; argv[i]; i++) {
471            n_chars += strlen(argv[i]) + 1;
472        }
473        n_max_chars -= n_chars;
474    }
475    /* Sanity check */
476    if (n_max_chars <= 0) {
477        bb_error_msg_and_die("can't fit single argument within argument list size limit");
478    }
479
480    buf = xzalloc(n_max_chars + 1);
481
482    n_max_arg = n_max_chars;
483    if (opt & OPT_UPTO_NUMBER) {
484        n_max_arg = xatou_range(max_args, 1, INT_MAX);
485        /* Not necessary, we use growable args[]: */
486        /* if (n_max_arg > n_max_chars) n_max_arg = n_max_chars */
487    }
488
489    /* Allocate pointers for execvp */
490    /* We can statically allocate (argc + n_max_arg + 1) elements
491     * and do not bother with resizing args[], but on 64-bit machines
492     * this results in args[] vector which is ~8 times bigger
493     * than n_max_chars! That is, with n_max_chars == 20k,
494     * args[] will take 160k (!), which will most likely be
495     * almost entirely unused.
496     */
497    /* See store_param() for matching 256-step growth logic */
498    G.args = xmalloc(sizeof(G.args[0]) * ((argc + 0xff) & ~0xff));
499
500    /* Store the command to be executed, part 1 */
501    for (i = 0; argv[i]; i++)
502        G.args[i] = argv[i];
503
504    while (1) {
505        char *rem;
506
507        G.idx = argc;
508        rem = read_args(n_max_chars, n_max_arg, buf);
509        store_param(NULL);
510
511        if (!G.args[argc]) {
512            if (*rem != '\0')
513                bb_error_msg_and_die("argument line too long");
514            if (opt & OPT_NO_EMPTY)
515                break;
516        }
517        opt |= OPT_NO_EMPTY;
518
519        if (opt & (OPT_INTERACTIVE | OPT_VERBOSE)) {
520            const char *fmt = " %s" + 1;
521            char **args = G.args;
522            for (i = 0; args[i]; i++) {
523                fprintf(stderr, fmt, args[i]);
524                fmt = " %s";
525            }
526            if (!(opt & OPT_INTERACTIVE))
527                bb_putchar_stderr('\n');
528        }
529
530        if (!(opt & OPT_INTERACTIVE) || xargs_ask_confirmation()) {
531            child_error = xargs_exec();
532        }
533
534        if (child_error > 0 && child_error != 123) {
535            break;
536        }
537
538        overlapping_strcpy(buf, rem);
539    } /* while */
540
541    if (ENABLE_FEATURE_CLEAN_UP) {
542        free(G.args);
543        free(buf);
544    }
545
546    return child_error;
547}
548
549
550#ifdef TEST
551
552const char *applet_name = "debug stuff usage";
553
554void bb_show_usage(void)
555{
556    fprintf(stderr, "Usage: %s [-p] [-r] [-t] -[x] [-n max_arg] [-s max_chars]\n",
557        applet_name);
558    exit(EXIT_FAILURE);
559}
560
561int main(int argc, char **argv)
562{
563    return xargs_main(argc, argv);
564}
565#endif /* TEST */
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