1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * head implementation for busybox
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4 | *
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5 | * Copyright (C) 2003 Manuel Novoa III <mjn3@codepoet.org>
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6 | *
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7 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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8 | */
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9 |
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10 | /* BB_AUDIT SUSv3 compliant */
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11 | /* BB_AUDIT GNU compatible -c, -q, and -v options in 'fancy' configuration. */
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12 | /* http://www.opengroup.org/onlinepubs/007904975/utilities/head.html */
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13 |
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14 | #include "libbb.h"
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15 |
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16 | static const char head_opts[] ALIGN1 =
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17 | "n:"
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18 | #if ENABLE_FEATURE_FANCY_HEAD
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19 | "c:qv"
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20 | #endif
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21 | ;
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22 |
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23 | #if ENABLE_FEATURE_FANCY_HEAD
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24 | static const struct suffix_mult head_suffixes[] = {
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25 | { "b", 512 },
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26 | { "k", 1024 },
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27 | { "m", 1024*1024 },
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28 | { }
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29 | };
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30 | #endif
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31 |
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32 | static const char header_fmt_str[] ALIGN1 = "\n==> %s <==\n";
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33 |
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34 | int head_main(int argc, char **argv);
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35 | int head_main(int argc, char **argv)
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36 | {
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37 | unsigned long count = 10;
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38 | unsigned long i;
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39 | #if ENABLE_FEATURE_FANCY_HEAD
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40 | int count_bytes = 0;
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41 | int header_threshhold = 1;
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42 | #endif
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43 |
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44 | FILE *fp;
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45 | const char *fmt;
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46 | char *p;
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47 | int opt;
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48 | int c;
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49 | int retval = EXIT_SUCCESS;
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50 |
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51 | #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
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52 | /* Allow legacy syntax of an initial numeric option without -n. */
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53 | if (argc > 1 && argv[1][0] == '-'
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54 | && isdigit(argv[1][1])
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55 | ) {
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56 | --argc;
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57 | ++argv;
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58 | p = (*argv) + 1;
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59 | goto GET_COUNT;
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60 | }
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61 | #endif
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62 |
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63 | /* No size benefit in converting this to getopt32 */
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64 | while ((opt = getopt(argc, argv, head_opts)) > 0) {
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65 | switch (opt) {
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66 | #if ENABLE_FEATURE_FANCY_HEAD
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67 | case 'q':
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68 | header_threshhold = INT_MAX;
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69 | break;
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70 | case 'v':
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71 | header_threshhold = -1;
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72 | break;
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73 | case 'c':
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74 | count_bytes = 1;
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75 | /* fall through */
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76 | #endif
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77 | case 'n':
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78 | p = optarg;
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79 | #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
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80 | GET_COUNT:
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81 | #endif
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82 |
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83 | #if !ENABLE_FEATURE_FANCY_HEAD
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84 | count = xatoul(p);
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85 | #else
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86 | count = xatoul_sfx(p, head_suffixes);
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87 | #endif
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88 | break;
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89 | default:
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90 | bb_show_usage();
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91 | }
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92 | }
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93 |
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94 | argv += optind;
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95 | if (!*argv) {
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96 | *--argv = (char*)"-";
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97 | }
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98 |
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99 | fmt = header_fmt_str + 1;
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100 | #if ENABLE_FEATURE_FANCY_HEAD
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101 | if (argc - optind <= header_threshhold) {
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102 | header_threshhold = 0;
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103 | }
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104 | #else
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105 | if (argc <= optind + 1) {
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106 | fmt += 11;
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107 | }
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108 | /* Now define some things here to avoid #ifdefs in the code below.
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109 | * These should optimize out of the if conditions below. */
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110 | #define header_threshhold 1
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111 | #define count_bytes 0
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112 | #endif
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113 |
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114 | do {
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115 | fp = fopen_or_warn_stdin(*argv);
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116 | if (fp) {
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117 | if (fp == stdin) {
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118 | *argv = (char *) bb_msg_standard_input;
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119 | }
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120 | if (header_threshhold) {
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121 | printf(fmt, *argv);
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122 | }
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123 | i = count;
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124 | while (i && ((c = getc(fp)) != EOF)) {
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125 | if (count_bytes || (c == '\n')) {
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126 | --i;
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127 | }
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128 | putchar(c);
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129 | }
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130 | if (fclose_if_not_stdin(fp)) {
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131 | bb_perror_msg("%s", *argv); /* Avoid multibyte problems. */
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132 | retval = EXIT_FAILURE;
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133 | }
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134 | die_if_ferror_stdout();
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135 | }
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136 | fmt = header_fmt_str;
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137 | } while (*++argv);
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138 |
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139 | fflush_stdout_and_exit(retval);
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140 | }
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