| 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 <stdio.h>
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| 15 | #include <stdlib.h>
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| 16 | #include <limits.h>
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| 17 | #include <ctype.h>
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| 18 | #include <unistd.h>
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| 19 | #include "busybox.h"
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| 20 |
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| 21 | static const char head_opts[] =
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| 22 | "n:"
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| 23 | #if ENABLE_FEATURE_FANCY_HEAD
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| 24 | "c:qv"
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| 25 | #endif
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| 26 | ;
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| 27 |
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| 28 | #if ENABLE_FEATURE_FANCY_HEAD
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| 29 | static const struct suffix_mult head_suffixes[] = {
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| 30 | { "b", 512 },
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| 31 | { "k", 1024 },
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| 32 | { "m", 1024*1024 },
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| 33 | { NULL, 0 }
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| 34 | };
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| 35 | #endif
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| 36 |
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| 37 | static const char header_fmt_str[] = "\n==> %s <==\n";
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| 38 |
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| 39 | int head_main(int argc, char **argv)
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| 40 | {
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| 41 | unsigned long count = 10;
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| 42 | unsigned long i;
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| 43 | #if ENABLE_FEATURE_FANCY_HEAD
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| 44 | int count_bytes = 0;
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| 45 | int header_threshhold = 1;
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| 46 | #endif
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| 47 |
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| 48 | FILE *fp;
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| 49 | const char *fmt;
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| 50 | char *p;
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| 51 | int opt;
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| 52 | int c;
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| 53 | int retval = EXIT_SUCCESS;
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| 54 |
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| 55 | #if !ENABLE_DEBUG_YANK_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
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| 56 | /* Allow legacy syntax of an initial numeric option without -n. */
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| 57 | if ((argc > 1) && (argv[1][0] == '-')
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| 58 | /* && (isdigit)(argv[1][1]) */
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| 59 | && (((unsigned int)(argv[1][1] - '0')) <= 9)
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| 60 | ) {
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| 61 | --argc;
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| 62 | ++argv;
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| 63 | p = (*argv) + 1;
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| 64 | goto GET_COUNT;
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| 65 | }
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| 66 | #endif
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| 67 |
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| 68 | /* No size benefit in converting this to bb_getopt_ulflags */
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| 69 | while ((opt = getopt(argc, argv, head_opts)) > 0) {
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| 70 | switch(opt) {
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| 71 | #if ENABLE_FEATURE_FANCY_HEAD
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| 72 | case 'q':
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| 73 | header_threshhold = INT_MAX;
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| 74 | break;
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| 75 | case 'v':
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| 76 | header_threshhold = -1;
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| 77 | break;
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| 78 | case 'c':
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| 79 | count_bytes = 1;
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| 80 | /* fall through */
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| 81 | #endif
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| 82 | case 'n':
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| 83 | p = optarg;
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| 84 | #if !ENABLE_DEBUG_YANK_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
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| 85 | GET_COUNT:
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| 86 | #endif
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| 87 |
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| 88 | #if !ENABLE_FEATURE_FANCY_HEAD
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| 89 | count = bb_xgetularg10(p);
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| 90 | #else
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| 91 | count = bb_xgetularg_bnd_sfx(p, 10,
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| 92 | 0, ULONG_MAX,
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| 93 | head_suffixes);
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| 94 | #endif
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| 95 | break;
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| 96 | default:
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| 97 | bb_show_usage();
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| 98 | }
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| 99 | }
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| 100 |
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| 101 | argv += optind;
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| 102 | if (!*argv) {
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| 103 | *--argv = "-";
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| 104 | }
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| 105 |
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| 106 | fmt = header_fmt_str + 1;
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| 107 | #if ENABLE_FEATURE_FANCY_HEAD
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| 108 | if (argc - optind <= header_threshhold) {
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| 109 | header_threshhold = 0;
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| 110 | }
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| 111 | #else
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| 112 | if (argc <= optind + 1) {
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| 113 | fmt += 11;
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| 114 | }
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| 115 | /* Now define some things here to avoid #ifdefs in the code below.
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| 116 | * These should optimize out of the if conditions below. */
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| 117 | #define header_threshhold 1
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| 118 | #define count_bytes 0
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| 119 | #endif
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| 120 |
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| 121 | do {
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| 122 | if ((fp = bb_wfopen_input(*argv)) != NULL) {
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| 123 | if (fp == stdin) {
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| 124 | *argv = (char *) bb_msg_standard_input;
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| 125 | }
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| 126 | if (header_threshhold) {
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| 127 | bb_printf(fmt, *argv);
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| 128 | }
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| 129 | i = count;
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| 130 | while (i && ((c = getc(fp)) != EOF)) {
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| 131 | if (count_bytes || (c == '\n')) {
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| 132 | --i;
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| 133 | }
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| 134 | putchar(c);
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| 135 | }
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| 136 | if (bb_fclose_nonstdin(fp)) {
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| 137 | bb_perror_msg("%s", *argv); /* Avoid multibyte problems. */
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| 138 | retval = EXIT_FAILURE;
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| 139 | }
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| 140 | bb_xferror_stdout();
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| 141 | }
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| 142 | fmt = header_fmt_str;
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| 143 | } while (*++argv);
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| 144 |
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| 145 | bb_fflush_stdout_and_exit(retval);
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| 146 | }
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