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-rw-r--r--coreutils/shuf.c150
1 files changed, 150 insertions, 0 deletions
diff --git a/coreutils/shuf.c b/coreutils/shuf.c
new file mode 100644
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+++ b/coreutils/shuf.c
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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 LO-HI] [-n NUM] [-o FILE] [-z] [FILE|ARG...]"
+//usage:#define shuf_full_usage "\n\n"
+//usage: "Write a random permutation of the input lines to standard output\n"
+//usage: "\n -e Treat each ARG as an input line"
+//usage: "\n -i L-H Treat each number L through H as an input line"
+//usage: "\n -n NUM Output at most NUM lines"
+//usage: "\n -o Write result to FILE instead of 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;
+ 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] = xstrdup(utoa(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);
+ }
+
+ 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++) {
+ printf("%s%c", lines[i], eol);
+ }
+
+ fflush_stdout_and_exit(EXIT_SUCCESS);
+}