1 files changed, 153 insertions, 0 deletions

diff --git a/coreutils/shuf.c b/coreutils/shuf.c
new file mode 100644
index 000000000..6d0a68fc1
--- /dev/null
+++ b/coreutils/shuf.c
@@ -0,0 +1,153 @@
+/* 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;
+                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);
+}