[821] | 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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[2725] | 7 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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[821] | 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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[3232] | 14 | //usage:#define head_trivial_usage
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| 15 | //usage: "[OPTIONS] [FILE]..."
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| 16 | //usage:#define head_full_usage "\n\n"
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| 17 | //usage: "Print first 10 lines of each FILE (or stdin) to stdout.\n"
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| 18 | //usage: "With more than one FILE, precede each with a filename header.\n"
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| 19 | //usage: "\n -n N[kbm] Print first N lines"
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| 20 | //usage: IF_FEATURE_FANCY_HEAD(
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| 21 | //usage: "\n -c N[kbm] Print first N bytes"
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| 22 | //usage: "\n -q Never print headers"
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| 23 | //usage: "\n -v Always print headers"
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| 24 | //usage: )
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| 25 | //usage: "\n"
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| 26 | //usage: "\nN may be suffixed by k (x1024), b (x512), or m (x1024^2)."
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| 27 | //usage:
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| 28 | //usage:#define head_example_usage
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| 29 | //usage: "$ head -n 2 /etc/passwd\n"
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| 30 | //usage: "root:x:0:0:root:/root:/bin/bash\n"
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| 31 | //usage: "daemon:x:1:1:daemon:/usr/sbin:/bin/sh\n"
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| 32 |
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[1765] | 33 | #include "libbb.h"
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[821] | 34 |
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[2725] | 35 | /* This is a NOEXEC applet. Be very careful! */
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| 36 |
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[1765] | 37 | static const char head_opts[] ALIGN1 =
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[821] | 38 | "n:"
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| 39 | #if ENABLE_FEATURE_FANCY_HEAD
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| 40 | "c:qv"
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| 41 | #endif
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| 42 | ;
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| 43 |
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| 44 | static const struct suffix_mult head_suffixes[] = {
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| 45 | { "b", 512 },
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| 46 | { "k", 1024 },
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| 47 | { "m", 1024*1024 },
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[2725] | 48 | { "", 0 }
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[821] | 49 | };
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| 50 |
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[2725] | 51 | #define header_fmt_str "\n==> %s <==\n"
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[1765] | 52 |
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[2725] | 53 | int head_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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[821] | 54 | int head_main(int argc, char **argv)
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| 55 | {
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| 56 | unsigned long count = 10;
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| 57 | unsigned long i;
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| 58 | #if ENABLE_FEATURE_FANCY_HEAD
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| 59 | int count_bytes = 0;
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| 60 | int header_threshhold = 1;
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| 61 | #endif
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| 62 | FILE *fp;
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| 63 | const char *fmt;
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| 64 | char *p;
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| 65 | int opt;
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| 66 | int c;
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| 67 | int retval = EXIT_SUCCESS;
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| 68 |
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[1765] | 69 | #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
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[821] | 70 | /* Allow legacy syntax of an initial numeric option without -n. */
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[2725] | 71 | if (argv[1] && argv[1][0] == '-'
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[1765] | 72 | && isdigit(argv[1][1])
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[821] | 73 | ) {
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| 74 | --argc;
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| 75 | ++argv;
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| 76 | p = (*argv) + 1;
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| 77 | goto GET_COUNT;
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| 78 | }
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| 79 | #endif
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| 80 |
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[1765] | 81 | /* No size benefit in converting this to getopt32 */
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[821] | 82 | while ((opt = getopt(argc, argv, head_opts)) > 0) {
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[1765] | 83 | switch (opt) {
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[821] | 84 | #if ENABLE_FEATURE_FANCY_HEAD
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[1765] | 85 | case 'q':
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| 86 | header_threshhold = INT_MAX;
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| 87 | break;
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| 88 | case 'v':
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| 89 | header_threshhold = -1;
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| 90 | break;
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| 91 | case 'c':
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| 92 | count_bytes = 1;
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| 93 | /* fall through */
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[821] | 94 | #endif
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[1765] | 95 | case 'n':
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| 96 | p = optarg;
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| 97 | #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
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| 98 | GET_COUNT:
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[821] | 99 | #endif
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[1765] | 100 | count = xatoul_sfx(p, head_suffixes);
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| 101 | break;
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| 102 | default:
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| 103 | bb_show_usage();
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[821] | 104 | }
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| 105 | }
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| 106 |
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[2725] | 107 | argc -= optind;
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[821] | 108 | argv += optind;
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[2725] | 109 | if (!*argv)
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[1765] | 110 | *--argv = (char*)"-";
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[821] | 111 |
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| 112 | fmt = header_fmt_str + 1;
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| 113 | #if ENABLE_FEATURE_FANCY_HEAD
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[2725] | 114 | if (argc <= header_threshhold) {
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[821] | 115 | header_threshhold = 0;
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| 116 | }
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| 117 | #else
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[2725] | 118 | if (argc <= 1) {
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| 119 | fmt += 11; /* "" */
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[821] | 120 | }
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| 121 | /* Now define some things here to avoid #ifdefs in the code below.
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| 122 | * These should optimize out of the if conditions below. */
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| 123 | #define header_threshhold 1
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| 124 | #define count_bytes 0
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| 125 | #endif
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| 126 |
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| 127 | do {
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[1765] | 128 | fp = fopen_or_warn_stdin(*argv);
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| 129 | if (fp) {
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[821] | 130 | if (fp == stdin) {
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| 131 | *argv = (char *) bb_msg_standard_input;
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| 132 | }
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| 133 | if (header_threshhold) {
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[1765] | 134 | printf(fmt, *argv);
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[821] | 135 | }
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| 136 | i = count;
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| 137 | while (i && ((c = getc(fp)) != EOF)) {
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| 138 | if (count_bytes || (c == '\n')) {
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| 139 | --i;
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| 140 | }
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| 141 | putchar(c);
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| 142 | }
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[1765] | 143 | if (fclose_if_not_stdin(fp)) {
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[2725] | 144 | bb_simple_perror_msg(*argv);
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[821] | 145 | retval = EXIT_FAILURE;
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| 146 | }
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[1765] | 147 | die_if_ferror_stdout();
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[2725] | 148 | } else {
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| 149 | retval = EXIT_FAILURE;
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[821] | 150 | }
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| 151 | fmt = header_fmt_str;
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| 152 | } while (*++argv);
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| 153 |
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[1765] | 154 | fflush_stdout_and_exit(retval);
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[821] | 155 | }
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