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