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- /* vi: set sw=4 ts=4: */
- /*
- * shuf: Write a random permutation of the input lines to standard output.
- *
- * Copyright (C) 2014 by Bartosz Golaszewski <bartekgola@gmail.com>
- *
- * Licensed under GPLv2 or later, see file LICENSE in this source tree.
- */
- //config:config SHUF
- //config: bool "shuf"
- //config: default y
- //config: help
- //config: Generate random permutations
- //kbuild:lib-$(CONFIG_SHUF) += shuf.o
- //applet:IF_SHUF(APPLET_NOEXEC(shuf, shuf, BB_DIR_USR_BIN, BB_SUID_DROP, shuf))
- //usage:#define shuf_trivial_usage
- //usage: "[-e|-i L-H] [-n NUM] [-o FILE] [-z] [FILE|ARG...]"
- //usage:#define shuf_full_usage "\n\n"
- //usage: "Randomly permute lines\n"
- //usage: "\n -e Treat ARGs as lines"
- //usage: "\n -i L-H Treat numbers L-H as lines"
- //usage: "\n -n NUM Output at most NUM lines"
- //usage: "\n -o FILE Write to FILE, not standard output"
- //usage: "\n -z End lines with zero byte, not newline"
- #include "libbb.h"
- /* This is a NOEXEC applet. Be very careful! */
- #define OPT_e (1 << 0)
- #define OPT_i (1 << 1)
- #define OPT_n (1 << 2)
- #define OPT_o (1 << 3)
- #define OPT_z (1 << 4)
- #define OPT_STR "ei:n:o:z"
- /*
- * Use the Fisher-Yates shuffle algorithm on an array of lines.
- */
- static void shuffle_lines(char **lines, unsigned numlines)
- {
- unsigned i;
- unsigned r;
- char *tmp;
- srand(monotonic_us());
- for (i = numlines-1; i > 0; i--) {
- r = rand();
- /* RAND_MAX can be as small as 32767 */
- if (i > RAND_MAX)
- r ^= rand() << 15;
- r %= i + 1;
- tmp = lines[i];
- lines[i] = lines[r];
- lines[r] = tmp;
- }
- }
- int shuf_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
- int shuf_main(int argc, char **argv)
- {
- unsigned opts;
- char *opt_i_str, *opt_n_str, *opt_o_str;
- unsigned i;
- char **lines;
- unsigned numlines;
- char eol;
- opt_complementary = "e--i:i--e"; /* mutually exclusive */
- opts = getopt32(argv, OPT_STR, &opt_i_str, &opt_n_str, &opt_o_str);
- argc -= optind;
- argv += optind;
- /* Prepare lines for shuffling - either: */
- if (opts & OPT_e) {
- /* make lines from command-line arguments */
- numlines = argc;
- lines = argv;
- } else
- if (opts & OPT_i) {
- /* create a range of numbers */
- char *dash;
- unsigned lo, hi;
- dash = strchr(opt_i_str, '-');
- if (!dash) {
- bb_error_msg_and_die("bad range '%s'", opt_i_str);
- }
- *dash = '\0';
- lo = xatou(opt_i_str);
- hi = xatou(dash + 1);
- *dash = '-';
- if (hi < lo) {
- bb_error_msg_and_die("bad range '%s'", opt_i_str);
- }
- numlines = (hi+1) - lo;
- lines = xmalloc(numlines * sizeof(lines[0]));
- for (i = 0; i < numlines; i++) {
- lines[i] = (char*)(uintptr_t)lo;
- lo++;
- }
- } else {
- /* default - read lines from stdin or the input file */
- FILE *fp;
- if (argc > 1)
- bb_show_usage();
- fp = xfopen_stdin(argv[0] ? argv[0] : "-");
- lines = NULL;
- numlines = 0;
- for (;;) {
- char *line = xmalloc_fgetline(fp);
- if (!line)
- break;
- lines = xrealloc_vector(lines, 6, numlines);
- lines[numlines++] = line;
- }
- fclose_if_not_stdin(fp);
- }
- if (numlines != 0)
- shuffle_lines(lines, numlines);
- if (opts & OPT_o)
- xmove_fd(xopen(opt_o_str, O_WRONLY|O_CREAT|O_TRUNC), STDOUT_FILENO);
- if (opts & OPT_n) {
- unsigned maxlines;
- maxlines = xatou(opt_n_str);
- if (numlines > maxlines)
- numlines = maxlines;
- }
- eol = '\n';
- if (opts & OPT_z)
- eol = '\0';
- for (i = 0; i < numlines; i++) {
- if (opts & OPT_i)
- printf("%u%c", (unsigned)(uintptr_t)lines[i], eol);
- else
- printf("%s%c", lines[i], eol);
- }
- fflush_stdout_and_exit(EXIT_SUCCESS);
- }
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