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Diffstat (limited to 'src/shuf.c')
| -rw-r--r-- | src/shuf.c | 599 |
1 files changed, 599 insertions, 0 deletions
diff --git a/src/shuf.c b/src/shuf.c new file mode 100644 index 0000000..68ca609 --- /dev/null +++ b/src/shuf.c @@ -0,0 +1,599 @@ +/* Shuffle lines of text. + + Copyright (C) 2006-2022 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 <https://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, which is guaranteed + to end in EOLBYTE. */ + +static char * +next_line (char *line, char eolbyte) +{ + char *p = rawmemchr (line, eolbyte); + 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) +{ + for (size_t 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 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, 0, &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)) + n_lines++; + + *pline = line = xnmalloc (n_lines + 1, sizeof *line); + + line[0] = p = buf; + for (size_t i = 1; i <= n_lines; i++) + line[i] = p = next_line (p, eolbyte); + + 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) +{ + for (size_t 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) +{ + for (size_t 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) +{ + const randint range = hi_input - lo_input + 1; + + for (size_t 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) +{ + for (size_t 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': + { + uintmax_t argval; + strtol_error e = xstrtoumax (optarg, NULL, 10, &argval, ""); + + 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 (head_lines == 0) + { + n_lines = 0; + line = NULL; + } + else 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 + && ! (STREQ (operand[0], "-") + || freopen (operand[0], "r", stdin))) + die (EXIT_FAILURE, errno, "%s", quotef (operand[0])); + + fadvise (stdin, FADVISE_SEQUENTIAL); + + if (repeat || head_lines == SIZE_MAX + || input_size () <= RESERVOIR_MIN_INPUT) + { + n_lines = read_input (stdin, eolbyte, &input_lines); + line = input_lines; + } + else + { + use_reservoir_sampling = true; + n_lines = SIZE_MAX; /* unknown number of input lines, for now. */ + } + } + + /* The adjusted head line count; can be less than HEAD_LINES if the + input is small and if not repeating. */ + size_t ahead_lines = repeat || head_lines < n_lines ? head_lines : n_lines; + + randint_source = randint_all_new (random_source, + (use_reservoir_sampling || repeat + ? SIZE_MAX + : randperm_bound (ahead_lines, n_lines))); + if (! randint_source) + die (EXIT_FAILURE, errno, "%s", + quotef (random_source ? random_source : "getrandom")); + + if (use_reservoir_sampling) + { + /* Instead of reading the entire file into 'line', + use reservoir-sampling to store just AHEAD_LINES random lines. */ + n_lines = read_input_reservoir_sampling (stdin, eolbyte, ahead_lines, + randint_source, &reservoir); + ahead_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 (! (head_lines == 0 || echo || input_range || fclose (stdin) == 0)) + die (EXIT_FAILURE, errno, _("read error")); + + if (!repeat) + permutation = randperm_new (randint_source, ahead_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, ahead_lines, + lo_input, hi_input, eolbyte); + else + i = write_random_lines (randint_source, ahead_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 (ahead_lines, lo_input, + permutation, eolbyte); + else + i = write_permuted_lines (ahead_lines, line, permutation); + } + + if (i != 0) + die (EXIT_FAILURE, errno, _("write error")); + + main_exit (EXIT_SUCCESS); +} |