141 lines
2.8 KiB
C
141 lines
2.8 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 tarball for details.
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*/
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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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#include "libbb.h"
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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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#if ENABLE_FEATURE_FANCY_HEAD
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static const struct suffix_mult head_suffixes[] = {
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{ "b", 512 },
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{ "k", 1024 },
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{ "m", 1024*1024 },
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{ }
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};
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#endif
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static const char header_fmt_str[] ALIGN1 = "\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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unsigned long i;
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#if ENABLE_FEATURE_FANCY_HEAD
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int count_bytes = 0;
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int header_threshhold = 1;
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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 c;
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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 (argc > 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) + 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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#if !ENABLE_FEATURE_FANCY_HEAD
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count = xatoul(p);
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#else
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count = xatoul_sfx(p, head_suffixes);
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#endif
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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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argv += optind;
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if (!*argv) {
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*--argv = (char*)"-";
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}
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fmt = header_fmt_str + 1;
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#if ENABLE_FEATURE_FANCY_HEAD
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if (argc - optind <= header_threshhold) {
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header_threshhold = 0;
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}
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#else
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if (argc <= optind + 1) {
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fmt += 11;
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}
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/* Now define some things here to avoid #ifdefs in the code below.
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* These should optimize out of the if conditions below. */
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#define header_threshhold 1
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#define count_bytes 0
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#endif
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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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i = count;
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while (i && ((c = getc(fp)) != EOF)) {
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if (count_bytes || (c == '\n')) {
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--i;
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}
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putchar(c);
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}
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if (fclose_if_not_stdin(fp)) {
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bb_simple_perror_msg(*argv); /* Avoid multibyte problems. */
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retval = EXIT_FAILURE;
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}
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die_if_ferror_stdout();
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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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