1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * shuf: Write a random permutation of the input lines to standard output.
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4 | *
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5 | * Copyright (C) 2014 by Bartosz Golaszewski <bartekgola@gmail.com>
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6 | *
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7 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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8 | */
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9 |
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10 | //config:config SHUF
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11 | //config: bool "shuf"
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12 | //config: default y
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13 | //config: help
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14 | //config: Generate random permutations
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15 |
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16 | //kbuild:lib-$(CONFIG_SHUF) += shuf.o
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17 | //applet:IF_SHUF(APPLET_NOEXEC(shuf, shuf, BB_DIR_USR_BIN, BB_SUID_DROP, shuf))
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18 |
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19 | //usage:#define shuf_trivial_usage
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20 | //usage: "[-e|-i L-H] [-n NUM] [-o FILE] [-z] [FILE|ARG...]"
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21 | //usage:#define shuf_full_usage "\n\n"
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22 | //usage: "Randomly permute lines\n"
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23 | //usage: "\n -e Treat ARGs as lines"
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24 | //usage: "\n -i L-H Treat numbers L-H as lines"
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25 | //usage: "\n -n NUM Output at most NUM lines"
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26 | //usage: "\n -o FILE Write to FILE, not standard output"
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27 | //usage: "\n -z End lines with zero byte, not newline"
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28 |
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29 | #include "libbb.h"
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30 |
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31 | /* This is a NOEXEC applet. Be very careful! */
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32 |
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33 | #define OPT_e (1 << 0)
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34 | #define OPT_i (1 << 1)
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35 | #define OPT_n (1 << 2)
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36 | #define OPT_o (1 << 3)
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37 | #define OPT_z (1 << 4)
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38 | #define OPT_STR "ei:n:o:z"
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39 |
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40 | /*
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41 | * Use the Fisher-Yates shuffle algorithm on an array of lines.
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42 | */
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43 | static void shuffle_lines(char **lines, unsigned numlines)
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44 | {
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45 | unsigned i;
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46 | unsigned r;
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47 | char *tmp;
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48 |
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49 | srand(monotonic_us());
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50 |
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51 | for (i = numlines-1; i > 0; i--) {
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52 | r = rand();
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53 | /* RAND_MAX can be as small as 32767 */
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54 | if (i > RAND_MAX)
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55 | r ^= rand() << 15;
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56 | r %= i;
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57 | tmp = lines[i];
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58 | lines[i] = lines[r];
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59 | lines[r] = tmp;
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60 | }
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61 | }
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62 |
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63 | int shuf_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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64 | int shuf_main(int argc, char **argv)
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65 | {
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66 | unsigned opts;
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67 | char *opt_i_str, *opt_n_str, *opt_o_str;
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68 | unsigned i;
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69 | char **lines;
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70 | unsigned numlines;
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71 | char eol;
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72 |
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73 | opt_complementary = "e--i:i--e"; /* mutually exclusive */
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74 | opts = getopt32(argv, OPT_STR, &opt_i_str, &opt_n_str, &opt_o_str);
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75 |
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76 | argc -= optind;
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77 | argv += optind;
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78 |
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79 | /* Prepare lines for shuffling - either: */
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80 | if (opts & OPT_e) {
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81 | /* make lines from command-line arguments */
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82 | numlines = argc;
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83 | lines = argv;
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84 | } else
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85 | if (opts & OPT_i) {
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86 | /* create a range of numbers */
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87 | char *dash;
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88 | unsigned lo, hi;
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89 |
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90 | dash = strchr(opt_i_str, '-');
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91 | if (!dash) {
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92 | bb_error_msg_and_die("bad range '%s'", opt_i_str);
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93 | }
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94 | *dash = '\0';
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95 | lo = xatou(opt_i_str);
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96 | hi = xatou(dash + 1);
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97 | *dash = '-';
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98 | if (hi < lo) {
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99 | bb_error_msg_and_die("bad range '%s'", opt_i_str);
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100 | }
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101 |
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102 | numlines = (hi+1) - lo;
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103 | lines = xmalloc(numlines * sizeof(lines[0]));
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104 | for (i = 0; i < numlines; i++) {
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105 | lines[i] = (char*)(uintptr_t)lo;
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106 | lo++;
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107 | }
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108 | } else {
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109 | /* default - read lines from stdin or the input file */
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110 | FILE *fp;
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111 |
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112 | if (argc > 1)
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113 | bb_show_usage();
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114 |
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115 | fp = xfopen_stdin(argv[0] ? argv[0] : "-");
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116 | lines = NULL;
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117 | numlines = 0;
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118 | for (;;) {
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119 | char *line = xmalloc_fgetline(fp);
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120 | if (!line)
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121 | break;
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122 | lines = xrealloc_vector(lines, 6, numlines);
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123 | lines[numlines++] = line;
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124 | }
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125 | fclose_if_not_stdin(fp);
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126 | }
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127 |
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128 | if (numlines != 0)
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129 | shuffle_lines(lines, numlines);
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130 |
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131 | if (opts & OPT_o)
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132 | xmove_fd(xopen(opt_o_str, O_WRONLY|O_CREAT|O_TRUNC), STDOUT_FILENO);
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133 |
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134 | if (opts & OPT_n) {
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135 | unsigned maxlines;
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136 | maxlines = xatou(opt_n_str);
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137 | if (numlines > maxlines)
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138 | numlines = maxlines;
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139 | }
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140 |
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141 | eol = '\n';
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142 | if (opts & OPT_z)
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143 | eol = '\0';
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144 |
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145 | for (i = 0; i < numlines; i++) {
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146 | if (opts & OPT_i)
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147 | printf("%u%c", (unsigned)(uintptr_t)lines[i], eol);
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148 | else
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149 | printf("%s%c", lines[i], eol);
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150 | }
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151 |
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152 | fflush_stdout_and_exit(EXIT_SUCCESS);
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153 | }
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