mirror of
https://github.com/sheumann/hush.git
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af3f420116
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
274 lines
5.8 KiB
C
274 lines
5.8 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* head implementation for busybox
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*
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* Copyright (C) 2003 Manuel Novoa III <mjn3@codepoet.org>
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*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*/
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//config:config HEAD
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//config: bool "head"
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//config: default y
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//config: help
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//config: head is used to print the first specified number of lines
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//config: from files.
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//config:
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//config:config FEATURE_FANCY_HEAD
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//config: bool "Enable head options (-c, -q, and -v)"
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//config: default y
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//config: depends on HEAD
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//config: help
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//config: This enables the head options (-c, -q, and -v).
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//applet:IF_HEAD(APPLET_NOEXEC(head, head, BB_DIR_USR_BIN, BB_SUID_DROP, head))
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//kbuild:lib-$(CONFIG_HEAD) += head.o
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/* BB_AUDIT SUSv3 compliant */
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/* BB_AUDIT GNU compatible -c, -q, and -v options in 'fancy' configuration. */
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/* http://www.opengroup.org/onlinepubs/007904975/utilities/head.html */
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//usage:#define head_trivial_usage
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//usage: "[OPTIONS] [FILE]..."
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//usage:#define head_full_usage "\n\n"
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//usage: "Print first 10 lines of each FILE (or stdin) to stdout.\n"
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//usage: "With more than one FILE, precede each with a filename header.\n"
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//usage: "\n -n N[kbm] Print first N lines"
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//usage: IF_FEATURE_FANCY_HEAD(
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//usage: "\n -n -N[kbm] Print all except N last lines"
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//usage: "\n -c [-]N[kbm] Print first N bytes"
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//usage: "\n -q Never print headers"
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//usage: "\n -v Always print headers"
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//usage: )
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//usage: "\n"
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//usage: "\nN may be suffixed by k (x1024), b (x512), or m (x1024^2)."
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//usage:
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//usage:#define head_example_usage
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//usage: "$ head -n 2 /etc/passwd\n"
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//usage: "root:x:0:0:root:/root:/bin/bash\n"
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//usage: "daemon:x:1:1:daemon:/usr/sbin:/bin/sh\n"
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#include "libbb.h"
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/* This is a NOEXEC applet. Be very careful! */
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#if !ENABLE_FEATURE_FANCY_HEAD
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# define print_first_N(fp,count,bytes) print_first_N(fp,count)
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#endif
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static void
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print_first_N(FILE *fp, unsigned long count, bool count_bytes)
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{
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#if !ENABLE_FEATURE_FANCY_HEAD
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const int count_bytes = 0;
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#endif
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while (count) {
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int c = getc(fp);
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if (c == EOF)
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break;
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if (count_bytes || (c == '\n'))
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--count;
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putchar(c);
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}
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}
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#if ENABLE_FEATURE_FANCY_HEAD
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static void
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print_except_N_last_bytes(FILE *fp, unsigned count)
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{
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unsigned char *circle = xmalloc(++count);
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unsigned head = 0;
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for(;;) {
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int c;
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c = getc(fp);
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if (c == EOF)
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goto ret;
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circle[head++] = c;
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if (head == count)
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break;
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}
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for (;;) {
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int c;
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if (head == count)
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head = 0;
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putchar(circle[head]);
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c = getc(fp);
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if (c == EOF)
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goto ret;
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circle[head] = c;
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head++;
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}
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ret:
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free(circle);
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}
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static void
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print_except_N_last_lines(FILE *fp, unsigned count)
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{
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char **circle = xzalloc((++count) * sizeof(circle[0]));
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unsigned head = 0;
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for(;;) {
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char *c;
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c = xmalloc_fgets(fp);
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if (!c)
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goto ret;
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circle[head++] = c;
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if (head == count)
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break;
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}
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for (;;) {
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char *c;
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if (head == count)
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head = 0;
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fputs(circle[head], stdout);
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c = xmalloc_fgets(fp);
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if (!c)
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goto ret;
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free(circle[head]);
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circle[head++] = c;
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}
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ret:
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head = 0;
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for(;;) {
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free(circle[head++]);
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if (head == count)
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break;
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}
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free(circle);
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}
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#else
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/* Must never be called */
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void print_except_N_last_bytes(FILE *fp, unsigned count);
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void print_except_N_last_lines(FILE *fp, unsigned count);
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#endif
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#if !ENABLE_FEATURE_FANCY_HEAD
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# define eat_num(negative_N,p) eat_num(p)
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#endif
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static unsigned long
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eat_num(bool *negative_N, const char *p)
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{
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#if ENABLE_FEATURE_FANCY_HEAD
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if (*p == '-') {
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*negative_N = 1;
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p++;
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}
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#endif
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return xatoul_sfx(p, bkm_suffixes);
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}
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static const char head_opts[] ALIGN1 =
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"n:"
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#if ENABLE_FEATURE_FANCY_HEAD
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"c:qv"
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#endif
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;
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#define header_fmt_str "\n==> %s <==\n"
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int head_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int head_main(int argc, char **argv)
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{
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unsigned long count = 10;
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#if ENABLE_FEATURE_FANCY_HEAD
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int header_threshhold = 1;
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bool count_bytes = 0;
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bool negative_N = 0;
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#else
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# define header_threshhold 1
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# define count_bytes 0
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# define negative_N 0
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#endif
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FILE *fp;
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const char *fmt;
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char *p;
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int opt;
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int retval = EXIT_SUCCESS;
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#if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
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/* Allow legacy syntax of an initial numeric option without -n. */
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if (argv[1] && argv[1][0] == '-'
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&& isdigit(argv[1][1])
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) {
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--argc;
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++argv;
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p = argv[0] + 1;
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goto GET_COUNT;
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}
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#endif
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/* No size benefit in converting this to getopt32 */
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while ((opt = getopt(argc, argv, head_opts)) > 0) {
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switch (opt) {
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#if ENABLE_FEATURE_FANCY_HEAD
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case 'q':
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header_threshhold = INT_MAX;
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break;
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case 'v':
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header_threshhold = -1;
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break;
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case 'c':
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count_bytes = 1;
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/* fall through */
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#endif
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case 'n':
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p = optarg;
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#if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
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GET_COUNT:
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#endif
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count = eat_num(&negative_N, p);
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break;
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default:
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bb_show_usage();
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}
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}
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argc -= optind;
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argv += optind;
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if (!*argv)
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*--argv = (char*)"-";
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fmt = header_fmt_str + 1;
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if (argc <= header_threshhold) {
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#if ENABLE_FEATURE_FANCY_HEAD
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header_threshhold = 0;
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#else
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fmt += 11; /* "" */
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#endif
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}
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if (negative_N) {
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if (count >= INT_MAX / sizeof(char*))
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bb_error_msg("count is too big: %lu", count);
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}
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do {
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fp = fopen_or_warn_stdin(*argv);
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if (fp) {
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if (fp == stdin) {
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*argv = (char *) bb_msg_standard_input;
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}
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if (header_threshhold) {
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printf(fmt, *argv);
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}
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if (negative_N) {
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if (count_bytes) {
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print_except_N_last_bytes(fp, count);
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} else {
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print_except_N_last_lines(fp, count);
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}
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} else {
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print_first_N(fp, count, count_bytes);
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}
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die_if_ferror_stdout();
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if (fclose_if_not_stdin(fp)) {
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bb_simple_perror_msg(*argv);
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retval = EXIT_FAILURE;
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}
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} else {
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retval = EXIT_FAILURE;
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}
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fmt = header_fmt_str;
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} while (*++argv);
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fflush_stdout_and_exit(retval);
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}
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