summaryrefslogtreecommitdiff
path: root/src/shuf.c
blob: 85ad5940834a9babc97650e8805fd443efe7e495 (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
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
/* Shuffle lines of text.

   Copyright (C) 2006-2016 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.

   Written by Paul Eggert.  */

#include <config.h>

#include <sys/types.h>
#include "system.h"

#include "die.h"
#include "error.h"
#include "fadvise.h"
#include "getopt.h"
#include "linebuffer.h"
#include "quote.h"
#include "randint.h"
#include "randperm.h"
#include "read-file.h"
#include "stdio--.h"
#include "xdectoint.h"
#include "xstrtol.h"

/* The official name of this program (e.g., no 'g' prefix).  */
#define PROGRAM_NAME "shuf"

#define AUTHORS proper_name ("Paul Eggert")

/* For reservoir-sampling, allocate the reservoir lines in batches.  */
enum { RESERVOIR_LINES_INCREMENT = 1024 };

/* reservoir-sampling introduces CPU overhead for small inputs.
   So only enable it for inputs >= this limit.
   This limit was determined using these commands:
     $ for p in $(seq 7); do src/seq $((10**$p)) > 10p$p.in; done
     $ for p in $(seq 7); do time shuf-nores -n10 10p$p.in >/dev/null; done
     $ for p in $(seq 7); do time shuf -n10 10p$p.in >/dev/null; done  .*/
enum { RESERVOIR_MIN_INPUT = 8192 * 1024 };


void
usage (int status)
{
  if (status != EXIT_SUCCESS)
    emit_try_help ();
  else
    {
      printf (_("\
Usage: %s [OPTION]... [FILE]\n\
  or:  %s -e [OPTION]... [ARG]...\n\
  or:  %s -i LO-HI [OPTION]...\n\
"),
              program_name, program_name, program_name);
      fputs (_("\
Write a random permutation of the input lines to standard output.\n\
"), stdout);

      emit_stdin_note ();
      emit_mandatory_arg_note ();

      fputs (_("\
  -e, --echo                treat each ARG as an input line\n\
  -i, --input-range=LO-HI   treat each number LO through HI as an input line\n\
  -n, --head-count=COUNT    output at most COUNT lines\n\
  -o, --output=FILE         write result to FILE instead of standard output\n\
      --random-source=FILE  get random bytes from FILE\n\
  -r, --repeat              output lines can be repeated\n\
"), stdout);
      fputs (_("\
  -z, --zero-terminated     line delimiter is NUL, not newline\n\
"), stdout);
      fputs (HELP_OPTION_DESCRIPTION, stdout);
      fputs (VERSION_OPTION_DESCRIPTION, stdout);
      emit_ancillary_info (PROGRAM_NAME);
    }

  exit (status);
}

/* For long options that have no equivalent short option, use a
   non-character as a pseudo short option, starting with CHAR_MAX + 1.  */
enum
{
  RANDOM_SOURCE_OPTION = CHAR_MAX + 1
};

static struct option const long_opts[] =
{
  {"echo", no_argument, NULL, 'e'},
  {"input-range", required_argument, NULL, 'i'},
  {"head-count", required_argument, NULL, 'n'},
  {"output", required_argument, NULL, 'o'},
  {"random-source", required_argument, NULL, RANDOM_SOURCE_OPTION},
  {"repeat", no_argument, NULL, 'r'},
  {"zero-terminated", no_argument, NULL, 'z'},
  {GETOPT_HELP_OPTION_DECL},
  {GETOPT_VERSION_OPTION_DECL},
  {0, 0, 0, 0},
};

static void
input_from_argv (char **operand, int n_operands, char eolbyte)
{
  char *p;
  size_t size = n_operands;
  int i;

  for (i = 0; i < n_operands; i++)
    size += strlen (operand[i]);
  p = xmalloc (size);

  for (i = 0; i < n_operands; i++)
    {
      char *p1 = stpcpy (p, operand[i]);
      operand[i] = p;
      p = p1;
      *p++ = eolbyte;
    }

  operand[n_operands] = p;
}

/* Return the start of the next line after LINE.  The current line
   ends in EOLBYTE, and is guaranteed to end before LINE + N.  */

static char *
next_line (char *line, char eolbyte, size_t n)
{
  char *p = memchr (line, eolbyte, n);
  return p + 1;
}

/* Return the size of the input if possible or OFF_T_MAX if not.  */

static off_t
input_size (void)
{
  off_t file_size;

  struct stat stat_buf;
  if (fstat (STDIN_FILENO, &stat_buf) != 0)
    return OFF_T_MAX;
  if (usable_st_size (&stat_buf))
    file_size = stat_buf.st_size;
  else
    return OFF_T_MAX;

  off_t input_offset = lseek (STDIN_FILENO, 0, SEEK_CUR);
  if (input_offset < 0)
    return OFF_T_MAX;

  file_size -= input_offset;

  return file_size;
}

/* Read all lines and store up to K permuted lines in *OUT_RSRV.
   Return the number of lines read, up to a maximum of K.  */

static size_t
read_input_reservoir_sampling (FILE *in, char eolbyte, size_t k,
                               struct randint_source *s,
                               struct linebuffer **out_rsrv)
{
  randint n_lines = 0;
  size_t n_alloc_lines = MIN (k, RESERVOIR_LINES_INCREMENT);
  struct linebuffer *line = NULL;
  struct linebuffer *rsrv;

  rsrv = xcalloc (n_alloc_lines, sizeof (struct linebuffer));

  /* Fill the first K lines, directly into the reservoir.  */
  while (n_lines < k
         && (line =
             readlinebuffer_delim (&rsrv[n_lines], in, eolbyte)) != NULL)
    {
      n_lines++;

      /* Enlarge reservoir.  */
      if (n_lines >= n_alloc_lines)
        {
          n_alloc_lines += RESERVOIR_LINES_INCREMENT;
          rsrv = xnrealloc (rsrv, n_alloc_lines, sizeof (struct linebuffer));
          memset (&rsrv[n_lines], 0,
                  RESERVOIR_LINES_INCREMENT * sizeof (struct linebuffer));
        }
    }

  /* last line wasn't NULL - so there may be more lines to read.  */
  if (line != NULL)
    {
      struct linebuffer dummy;
      initbuffer (&dummy);  /* space for lines not put in reservoir.  */

      /* Choose the fate of the next line, with decreasing probability (as
         n_lines increases in size).

         If the line will be used, store it directly in the reservoir.
         Otherwise, store it in dummy space.

         With 'struct linebuffer', storing into existing buffer will reduce
         re-allocations (will only re-allocate if the new line is longer than
         the currently allocated space).  */
      do
        {
          randint j = randint_choose (s, n_lines + 1);  /* 0 .. n_lines.  */
          line = (j < k) ? (&rsrv[j]) : (&dummy);
        }
      while (readlinebuffer_delim (line, in, eolbyte) != NULL && n_lines++);

      if (! n_lines)
        die (EXIT_FAILURE, EOVERFLOW, _("too many input lines"));

      freebuffer (&dummy);
    }

  /* no more input lines, or an input error.  */
  if (ferror (in))
    die (EXIT_FAILURE, errno, _("read error"));

  *out_rsrv = rsrv;
  return MIN (k, n_lines);
}

static int
write_permuted_output_reservoir (size_t n_lines, struct linebuffer *lines,
                                 size_t const *permutation)
{
  size_t i;

  for (i = 0; i < n_lines; i++)
    {
      const struct linebuffer *p = &lines[permutation[i]];
      if (fwrite (p->buffer, sizeof (char), p->length, stdout) != p->length)
        return -1;
    }

  return 0;
}

/* Read data from file IN.  Input lines are delimited by EOLBYTE;
   silently append a trailing EOLBYTE if the file ends in some other
   byte.  Store a pointer to the resulting array of lines into *PLINE.
   Return the number of lines read.  Report an error and exit on
   failure.  */

static size_t
read_input (FILE *in, char eolbyte, char ***pline)
{
  char *p;
  char *buf = NULL;
  size_t used;
  char *lim;
  char **line;
  size_t i;
  size_t n_lines;

  /* TODO: We should limit the amount of data read here,
     to less than RESERVOIR_MIN_INPUT.  I.e., adjust fread_file() to support
     taking a byte limit.  We'd then need to ensure we handle a line spanning
     this boundary.  With that in place we could set use_reservoir_sampling
     when used==RESERVOIR_MIN_INPUT, and have read_input_reservoir_sampling()
     call a wrapper function to populate a linebuffer from the internal pline
     or if none left, stdin.  Doing that would give better performance by
     avoiding the reservoir CPU overhead when reading < RESERVOIR_MIN_INPUT
     from a pipe, and allow us to dispense with the input_size() function.  */
  if (!(buf = fread_file (in, &used)))
    die (EXIT_FAILURE, errno, _("read error"));

  if (used && buf[used - 1] != eolbyte)
    buf[used++] = eolbyte;

  lim = buf + used;

  n_lines = 0;
  for (p = buf; p < lim; p = next_line (p, eolbyte, lim - p))
    n_lines++;

  *pline = line = xnmalloc (n_lines + 1, sizeof *line);

  line[0] = p = buf;
  for (i = 1; i <= n_lines; i++)
    line[i] = p = next_line (p, eolbyte, lim - p);

  return n_lines;
}

/* Output N_LINES lines to stdout from LINE array,
   chosen by the indices in PERMUTATION.
   PERMUTATION and LINE must have at least N_LINES elements.
   Strings in LINE must include the line-terminator character.  */
static int
write_permuted_lines (size_t n_lines, char *const *line,
                      size_t const *permutation)
{
  size_t i;

  for (i = 0; i < n_lines; i++)
    {
      char *const *p = line + permutation[i];
      size_t len = p[1] - p[0];
      if (fwrite (p[0], sizeof *p[0], len, stdout) != len)
        return -1;
    }

  return 0;
}

/* Output N_LINES of numbers to stdout, from PERMUTATION array.
   PERMUTATION must have at least N_LINES elements.  */
static int
write_permuted_numbers (size_t n_lines, size_t lo_input,
                        size_t const *permutation, char eolbyte)
{
  size_t i;

  for (i = 0; i < n_lines; i++)
    {
      unsigned long int n = lo_input + permutation[i];
      if (printf ("%lu%c", n, eolbyte) < 0)
        return -1;
    }

  return 0;
}

/* Output COUNT numbers to stdout, chosen randomly from range
   LO_INPUT through HI_INPUT.  */
static int
write_random_numbers (struct randint_source *s, size_t count,
                      size_t lo_input, size_t hi_input, char eolbyte)
{
  size_t i;
  const randint range = hi_input - lo_input + 1;

  for (i = 0; i < count; i++)
    {
      unsigned long int j = lo_input + randint_choose (s, range);
      if (printf ("%lu%c", j, eolbyte) < 0)
        return -1;
    }

  return 0;
}

/* Output COUNT lines to stdout from LINES array.
   LINES must have at least N_LINES elements in it.
   Strings in LINES_ must include the line-terminator character.  */
static int
write_random_lines (struct randint_source *s, size_t count,
                    char *const *lines, size_t n_lines)
{
  size_t i;

  for (i = 0; i < count; i++)
    {
      const randint j = randint_choose (s, n_lines);
      char *const *p = lines + j;
      size_t len = p[1] - p[0];
      if (fwrite (p[0], sizeof *p[0], len, stdout) != len)
        return -1;
    }

  return 0;
}

int
main (int argc, char **argv)
{
  bool echo = false;
  bool input_range = false;
  size_t lo_input = SIZE_MAX;
  size_t hi_input = 0;
  size_t head_lines = SIZE_MAX;
  char const *outfile = NULL;
  char *random_source = NULL;
  char eolbyte = '\n';
  char **input_lines = NULL;
  bool use_reservoir_sampling = false;
  bool repeat = false;

  int optc;
  int n_operands;
  char **operand;
  size_t n_lines;
  char **line = NULL;
  struct linebuffer *reservoir = NULL;
  struct randint_source *randint_source;
  size_t *permutation = NULL;
  int i;

  initialize_main (&argc, &argv);
  set_program_name (argv[0]);
  setlocale (LC_ALL, "");
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);

  atexit (close_stdout);

  while ((optc = getopt_long (argc, argv, "ei:n:o:rz", long_opts, NULL)) != -1)
    switch (optc)
      {
      case 'e':
        echo = true;
        break;

      case 'i':
        {
          char *p = strchr (optarg, '-');
          char const *hi_optarg = optarg;
          bool invalid = !p;

          if (input_range)
            die (EXIT_FAILURE, 0, _("multiple -i options specified"));
          input_range = true;

          if (p)
            {
              *p = '\0';
              lo_input = xdectoumax (optarg, 0, SIZE_MAX, "",
                                     _("invalid input range"), 0);
              *p = '-';
              hi_optarg = p + 1;
            }

          hi_input = xdectoumax (hi_optarg, 0, SIZE_MAX, "",
                                 _("invalid input range"), 0);

          n_lines = hi_input - lo_input + 1;
          invalid |= ((lo_input <= hi_input) == (n_lines == 0));
          if (invalid)
            die (EXIT_FAILURE, errno, "%s: %s", _("invalid input range"),
                 quote (optarg));
        }
        break;

      case 'n':
        {
          unsigned long int argval;
          strtol_error e = xstrtoul (optarg, NULL, 10, &argval, NULL);

          if (e == LONGINT_OK)
            head_lines = MIN (head_lines, argval);
          else if (e != LONGINT_OVERFLOW)
            die (EXIT_FAILURE, 0, _("invalid line count: %s"),
                 quote (optarg));
        }
        break;

      case 'o':
        if (outfile && !STREQ (outfile, optarg))
          die (EXIT_FAILURE, 0, _("multiple output files specified"));
        outfile = optarg;
        break;

      case RANDOM_SOURCE_OPTION:
        if (random_source && !STREQ (random_source, optarg))
          die (EXIT_FAILURE, 0, _("multiple random sources specified"));
        random_source = optarg;
        break;

      case 'r':
        repeat = true;
        break;

      case 'z':
        eolbyte = '\0';
        break;

      case_GETOPT_HELP_CHAR;
      case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
      default:
        usage (EXIT_FAILURE);
      }

  n_operands = argc - optind;
  operand = argv + optind;

  /* Check invalid usage.  */
  if (echo && input_range)
    {
      error (0, 0, _("cannot combine -e and -i options"));
      usage (EXIT_FAILURE);
    }
  if (input_range ? 0 < n_operands : !echo && 1 < n_operands)
    {
      error (0, 0, _("extra operand %s"), quote (operand[!input_range]));
      usage (EXIT_FAILURE);
    }

  /* Prepare input.  */
  if (echo)
    {
      input_from_argv (operand, n_operands, eolbyte);
      n_lines = n_operands;
      line = operand;
    }
  else if (input_range)
    {
      n_lines = hi_input - lo_input + 1;
      line = NULL;
    }
  else
    {
      /* If an input file is specified, re-open it as stdin.  */
      if (n_operands == 1)
        if (! (STREQ (operand[0], "-") || ! head_lines
               || freopen (operand[0], "r", stdin)))
          die (EXIT_FAILURE, errno, "%s", quotef (operand[0]));

      fadvise (stdin, FADVISE_SEQUENTIAL);

      if (! repeat && head_lines != SIZE_MAX
          && (! head_lines || input_size () > RESERVOIR_MIN_INPUT))
        {
          use_reservoir_sampling = true;
          n_lines = SIZE_MAX;   /* unknown number of input lines, for now.  */
        }
      else
        {
          n_lines = read_input (stdin, eolbyte, &input_lines);
          line = input_lines;
        }
    }

  if (! repeat)
    head_lines = MIN (head_lines, n_lines);

  randint_source = randint_all_new (random_source,
                                    (use_reservoir_sampling || repeat
                                     ? SIZE_MAX
                                     : randperm_bound (head_lines, n_lines)));
  if (! randint_source)
    die (EXIT_FAILURE, errno, "%s", quotef (random_source));

  if (use_reservoir_sampling)
    {
      /* Instead of reading the entire file into 'line',
         use reservoir-sampling to store just "head_lines" random lines.  */
      n_lines = read_input_reservoir_sampling (stdin, eolbyte, head_lines,
                                               randint_source, &reservoir);
      head_lines = n_lines;
    }

  /* Close stdin now, rather than earlier, so that randint_all_new
     doesn't have to worry about opening something other than
     stdin.  */
  if (! (echo || input_range)
      && (fclose (stdin) != 0))
    die (EXIT_FAILURE, errno, _("read error"));

  if (!repeat)
    permutation = randperm_new (randint_source, head_lines, n_lines);

  if (outfile && ! freopen (outfile, "w", stdout))
    die (EXIT_FAILURE, errno, "%s", quotef (outfile));

  /* Generate output according to requested method */
  if (repeat)
    {
      if (head_lines == 0)
        i = 0;
      else
        {
          if (n_lines == 0)
            die (EXIT_FAILURE, 0, _("no lines to repeat"));
          if (input_range)
            i = write_random_numbers (randint_source, head_lines,
                                      lo_input, hi_input, eolbyte);
          else
            i = write_random_lines (randint_source, head_lines, line, n_lines);
        }
    }
  else
    {
      if (use_reservoir_sampling)
        i = write_permuted_output_reservoir (n_lines, reservoir, permutation);
      else if (input_range)
        i = write_permuted_numbers (head_lines, lo_input,
                                    permutation, eolbyte);
      else
        i = write_permuted_lines (head_lines, line, permutation);
    }

  if (i != 0)
    die (EXIT_FAILURE, errno, _("write error"));

#ifdef lint
  free (permutation);
  randint_all_free (randint_source);
  if (input_lines)
    {
      free (input_lines[0]);
      free (input_lines);
    }
  if (reservoir)
    {
      size_t j;
      for (j = 0; j < n_lines; ++j)
        freebuffer (&reservoir[j]);
      free (reservoir);
    }
#endif

  return EXIT_SUCCESS;
}