[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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[3621] | 14 | //kbuild:lib-$(CONFIG_HEAD) += head.o
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| 15 |
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[3232] | 16 | //usage:#define head_trivial_usage
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| 17 | //usage: "[OPTIONS] [FILE]..."
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| 18 | //usage:#define head_full_usage "\n\n"
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| 19 | //usage: "Print first 10 lines of each FILE (or stdin) to stdout.\n"
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| 20 | //usage: "With more than one FILE, precede each with a filename header.\n"
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| 21 | //usage: "\n -n N[kbm] Print first N lines"
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| 22 | //usage: IF_FEATURE_FANCY_HEAD(
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[3621] | 23 | //usage: "\n -n -N[kbm] Print all except N last lines"
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| 24 | //usage: "\n -c [-]N[kbm] Print first N bytes"
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[3232] | 25 | //usage: "\n -q Never print headers"
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| 26 | //usage: "\n -v Always print headers"
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| 27 | //usage: )
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| 28 | //usage: "\n"
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| 29 | //usage: "\nN may be suffixed by k (x1024), b (x512), or m (x1024^2)."
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| 30 | //usage:
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| 31 | //usage:#define head_example_usage
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| 32 | //usage: "$ head -n 2 /etc/passwd\n"
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| 33 | //usage: "root:x:0:0:root:/root:/bin/bash\n"
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| 34 | //usage: "daemon:x:1:1:daemon:/usr/sbin:/bin/sh\n"
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| 35 |
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[1765] | 36 | #include "libbb.h"
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[821] | 37 |
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[2725] | 38 | /* This is a NOEXEC applet. Be very careful! */
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| 39 |
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[3621] | 40 | #if !ENABLE_FEATURE_FANCY_HEAD
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| 41 | # define print_first_N(fp,count,bytes) print_first_N(fp,count)
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| 42 | #endif
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| 43 | static void
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| 44 | print_first_N(FILE *fp, unsigned long count, bool count_bytes)
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| 45 | {
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| 46 | #if !ENABLE_FEATURE_FANCY_HEAD
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| 47 | const int count_bytes = 0;
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| 48 | #endif
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| 49 | while (count) {
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| 50 | int c = getc(fp);
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| 51 | if (c == EOF)
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| 52 | break;
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| 53 | if (count_bytes || (c == '\n'))
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| 54 | --count;
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| 55 | putchar(c);
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| 56 | }
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| 57 | }
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| 58 |
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| 59 | #if ENABLE_FEATURE_FANCY_HEAD
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| 60 | static void
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| 61 | print_except_N_last_bytes(FILE *fp, unsigned count)
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| 62 | {
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| 63 | unsigned char *circle = xmalloc(++count);
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| 64 | unsigned head = 0;
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| 65 | for(;;) {
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| 66 | int c;
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| 67 | c = getc(fp);
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| 68 | if (c == EOF)
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| 69 | goto ret;
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| 70 | circle[head++] = c;
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| 71 | if (head == count)
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| 72 | break;
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| 73 | }
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| 74 | for (;;) {
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| 75 | int c;
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| 76 | if (head == count)
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| 77 | head = 0;
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| 78 | putchar(circle[head]);
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| 79 | c = getc(fp);
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| 80 | if (c == EOF)
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| 81 | goto ret;
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| 82 | circle[head] = c;
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| 83 | head++;
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| 84 | }
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| 85 | ret:
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| 86 | free(circle);
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| 87 | }
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| 88 |
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| 89 | static void
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| 90 | print_except_N_last_lines(FILE *fp, unsigned count)
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| 91 | {
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| 92 | char **circle = xzalloc((++count) * sizeof(circle[0]));
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| 93 | unsigned head = 0;
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| 94 | for(;;) {
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| 95 | char *c;
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| 96 | c = xmalloc_fgets(fp);
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| 97 | if (!c)
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| 98 | goto ret;
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| 99 | circle[head++] = c;
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| 100 | if (head == count)
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| 101 | break;
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| 102 | }
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| 103 | for (;;) {
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| 104 | char *c;
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| 105 | if (head == count)
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| 106 | head = 0;
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| 107 | fputs(circle[head], stdout);
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| 108 | c = xmalloc_fgets(fp);
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| 109 | if (!c)
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| 110 | goto ret;
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| 111 | free(circle[head]);
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| 112 | circle[head++] = c;
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| 113 | }
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| 114 | ret:
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| 115 | head = 0;
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| 116 | for(;;) {
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| 117 | free(circle[head++]);
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| 118 | if (head == count)
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| 119 | break;
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| 120 | }
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| 121 | free(circle);
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| 122 | }
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| 123 | #else
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| 124 | /* Must never be called */
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| 125 | void print_except_N_last_bytes(FILE *fp, unsigned count);
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| 126 | void print_except_N_last_lines(FILE *fp, unsigned count);
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| 127 | #endif
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| 128 |
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| 129 | #if !ENABLE_FEATURE_FANCY_HEAD
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| 130 | # define eat_num(negative_N,p) eat_num(p)
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| 131 | #endif
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| 132 | static unsigned long
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| 133 | eat_num(bool *negative_N, const char *p)
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| 134 | {
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| 135 | #if ENABLE_FEATURE_FANCY_HEAD
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| 136 | if (*p == '-') {
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| 137 | *negative_N = 1;
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| 138 | p++;
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| 139 | }
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| 140 | #endif
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| 141 | return xatoul_sfx(p, bkm_suffixes);
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| 142 | }
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| 143 |
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[1765] | 144 | static const char head_opts[] ALIGN1 =
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[821] | 145 | "n:"
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| 146 | #if ENABLE_FEATURE_FANCY_HEAD
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| 147 | "c:qv"
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| 148 | #endif
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| 149 | ;
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| 150 |
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[2725] | 151 | #define header_fmt_str "\n==> %s <==\n"
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[1765] | 152 |
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[2725] | 153 | int head_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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[821] | 154 | int head_main(int argc, char **argv)
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| 155 | {
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| 156 | unsigned long count = 10;
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| 157 | #if ENABLE_FEATURE_FANCY_HEAD
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| 158 | int header_threshhold = 1;
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[3621] | 159 | bool count_bytes = 0;
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| 160 | bool negative_N = 0;
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| 161 | #else
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| 162 | # define header_threshhold 1
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| 163 | # define count_bytes 0
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| 164 | # define negative_N 0
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[821] | 165 | #endif
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| 166 | FILE *fp;
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| 167 | const char *fmt;
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| 168 | char *p;
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| 169 | int opt;
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| 170 | int retval = EXIT_SUCCESS;
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| 171 |
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[1765] | 172 | #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
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[821] | 173 | /* Allow legacy syntax of an initial numeric option without -n. */
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[2725] | 174 | if (argv[1] && argv[1][0] == '-'
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[1765] | 175 | && isdigit(argv[1][1])
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[821] | 176 | ) {
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| 177 | --argc;
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| 178 | ++argv;
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[3621] | 179 | p = argv[0] + 1;
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[821] | 180 | goto GET_COUNT;
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| 181 | }
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| 182 | #endif
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| 183 |
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[1765] | 184 | /* No size benefit in converting this to getopt32 */
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[821] | 185 | while ((opt = getopt(argc, argv, head_opts)) > 0) {
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[1765] | 186 | switch (opt) {
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[821] | 187 | #if ENABLE_FEATURE_FANCY_HEAD
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[1765] | 188 | case 'q':
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| 189 | header_threshhold = INT_MAX;
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| 190 | break;
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| 191 | case 'v':
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| 192 | header_threshhold = -1;
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| 193 | break;
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| 194 | case 'c':
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| 195 | count_bytes = 1;
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| 196 | /* fall through */
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[821] | 197 | #endif
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[1765] | 198 | case 'n':
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| 199 | p = optarg;
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| 200 | #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
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| 201 | GET_COUNT:
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[821] | 202 | #endif
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[3621] | 203 | count = eat_num(&negative_N, p);
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[1765] | 204 | break;
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| 205 | default:
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| 206 | bb_show_usage();
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[821] | 207 | }
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| 208 | }
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| 209 |
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[2725] | 210 | argc -= optind;
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[821] | 211 | argv += optind;
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[2725] | 212 | if (!*argv)
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[1765] | 213 | *--argv = (char*)"-";
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[821] | 214 |
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| 215 | fmt = header_fmt_str + 1;
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[3621] | 216 | if (argc <= header_threshhold) {
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[821] | 217 | #if ENABLE_FEATURE_FANCY_HEAD
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| 218 | header_threshhold = 0;
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| 219 | #else
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[2725] | 220 | fmt += 11; /* "" */
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[3621] | 221 | #endif
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[821] | 222 | }
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[3621] | 223 | if (negative_N) {
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| 224 | if (count >= INT_MAX / sizeof(char*))
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| 225 | bb_error_msg("count is too big: %lu", count);
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| 226 | }
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[821] | 227 |
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| 228 | do {
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[1765] | 229 | fp = fopen_or_warn_stdin(*argv);
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| 230 | if (fp) {
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[821] | 231 | if (fp == stdin) {
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| 232 | *argv = (char *) bb_msg_standard_input;
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| 233 | }
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| 234 | if (header_threshhold) {
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[1765] | 235 | printf(fmt, *argv);
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[821] | 236 | }
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[3621] | 237 | if (negative_N) {
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| 238 | if (count_bytes) {
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| 239 | print_except_N_last_bytes(fp, count);
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| 240 | } else {
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| 241 | print_except_N_last_lines(fp, count);
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[821] | 242 | }
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[3621] | 243 | } else {
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| 244 | print_first_N(fp, count, count_bytes);
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[821] | 245 | }
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[3621] | 246 | die_if_ferror_stdout();
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[1765] | 247 | if (fclose_if_not_stdin(fp)) {
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[2725] | 248 | bb_simple_perror_msg(*argv);
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[821] | 249 | retval = EXIT_FAILURE;
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| 250 | }
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[2725] | 251 | } else {
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| 252 | retval = EXIT_FAILURE;
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[821] | 253 | }
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| 254 | fmt = header_fmt_str;
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| 255 | } while (*++argv);
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| 256 |
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[1765] | 257 | fflush_stdout_and_exit(retval);
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[821] | 258 | }
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