| 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 source tree.
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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 | /* This is a NOEXEC applet. Be very careful! */
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| 17 |
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| 18 | static const char head_opts[] ALIGN1 =
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| 19 | "n:"
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| 20 | #if ENABLE_FEATURE_FANCY_HEAD
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| 21 | "c:qv"
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| 22 | #endif
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| 23 | ;
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| 24 |
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| 25 | static const struct suffix_mult head_suffixes[] = {
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| 26 | { "b", 512 },
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| 27 | { "k", 1024 },
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| 28 | { "m", 1024*1024 },
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| 29 | { "", 0 }
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| 30 | };
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| 31 |
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| 32 | #define header_fmt_str "\n==> %s <==\n"
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| 33 |
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| 34 | int head_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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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 | FILE *fp;
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| 44 | const char *fmt;
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| 45 | char *p;
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| 46 | int opt;
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| 47 | int c;
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| 48 | int retval = EXIT_SUCCESS;
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| 49 |
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| 50 | #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
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| 51 | /* Allow legacy syntax of an initial numeric option without -n. */
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| 52 | if (argv[1] && argv[1][0] == '-'
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| 53 | && isdigit(argv[1][1])
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| 54 | ) {
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| 55 | --argc;
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| 56 | ++argv;
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| 57 | p = (*argv) + 1;
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| 58 | goto GET_COUNT;
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| 59 | }
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| 60 | #endif
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| 61 |
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| 62 | /* No size benefit in converting this to getopt32 */
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| 63 | while ((opt = getopt(argc, argv, head_opts)) > 0) {
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| 64 | switch (opt) {
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| 65 | #if ENABLE_FEATURE_FANCY_HEAD
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| 66 | case 'q':
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| 67 | header_threshhold = INT_MAX;
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| 68 | break;
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| 69 | case 'v':
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| 70 | header_threshhold = -1;
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| 71 | break;
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| 72 | case 'c':
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| 73 | count_bytes = 1;
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| 74 | /* fall through */
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| 75 | #endif
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| 76 | case 'n':
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| 77 | p = optarg;
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| 78 | #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
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| 79 | GET_COUNT:
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| 80 | #endif
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| 81 | count = xatoul_sfx(p, head_suffixes);
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| 82 | break;
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| 83 | default:
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| 84 | bb_show_usage();
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| 85 | }
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| 86 | }
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| 87 |
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| 88 | argc -= optind;
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| 89 | argv += optind;
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| 90 | if (!*argv)
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| 91 | *--argv = (char*)"-";
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| 92 |
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| 93 | fmt = header_fmt_str + 1;
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| 94 | #if ENABLE_FEATURE_FANCY_HEAD
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| 95 | if (argc <= header_threshhold) {
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| 96 | header_threshhold = 0;
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| 97 | }
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| 98 | #else
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| 99 | if (argc <= 1) {
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| 100 | fmt += 11; /* "" */
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| 101 | }
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| 102 | /* Now define some things here to avoid #ifdefs in the code below.
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| 103 | * These should optimize out of the if conditions below. */
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| 104 | #define header_threshhold 1
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| 105 | #define count_bytes 0
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| 106 | #endif
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| 107 |
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| 108 | do {
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| 109 | fp = fopen_or_warn_stdin(*argv);
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| 110 | if (fp) {
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| 111 | if (fp == stdin) {
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| 112 | *argv = (char *) bb_msg_standard_input;
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| 113 | }
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| 114 | if (header_threshhold) {
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| 115 | printf(fmt, *argv);
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| 116 | }
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| 117 | i = count;
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| 118 | while (i && ((c = getc(fp)) != EOF)) {
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| 119 | if (count_bytes || (c == '\n')) {
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| 120 | --i;
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| 121 | }
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| 122 | putchar(c);
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| 123 | }
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| 124 | if (fclose_if_not_stdin(fp)) {
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| 125 | bb_simple_perror_msg(*argv);
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| 126 | retval = EXIT_FAILURE;
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| 127 | }
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| 128 | die_if_ferror_stdout();
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| 129 | } else {
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| 130 | retval = EXIT_FAILURE;
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| 131 | }
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| 132 | fmt = header_fmt_str;
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| 133 | } while (*++argv);
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| 134 |
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| 135 | fflush_stdout_and_exit(retval);
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| 136 | }
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