1 files changed, 150 insertions, 0 deletions
diff --git a/coreutils/shuf.c b/coreutils/shuf.c
new file mode 100644
index 000000000..f213d6759
--- /dev/null
+++ b/coreutils/shuf.c
@@ -0,0 +1,150 @@
+/* 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);
+}