| /* vi: set sw=4 ts=4: */ |
| /* |
| * head implementation for busybox |
| * |
| * Copyright (C) 2003 Manuel Novoa III <mjn3@codepoet.org> |
| * |
| * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. |
| */ |
| |
| /* BB_AUDIT SUSv3 compliant */ |
| /* BB_AUDIT GNU compatible -c, -q, and -v options in 'fancy' configuration. */ |
| /* http://www.opengroup.org/onlinepubs/007904975/utilities/head.html */ |
| |
| #include "libbb.h" |
| |
| static const char head_opts[] ALIGN1 = |
| "n:" |
| #if ENABLE_FEATURE_FANCY_HEAD |
| "c:qv" |
| #endif |
| ; |
| |
| #if ENABLE_FEATURE_FANCY_HEAD |
| static const struct suffix_mult head_suffixes[] = { |
| { "b", 512 }, |
| { "k", 1024 }, |
| { "m", 1024*1024 }, |
| { } |
| }; |
| #endif |
| |
| static const char header_fmt_str[] ALIGN1 = "\n==> %s <==\n"; |
| |
| int head_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
| int head_main(int argc, char **argv) |
| { |
| unsigned long count = 10; |
| unsigned long i; |
| #if ENABLE_FEATURE_FANCY_HEAD |
| int count_bytes = 0; |
| int header_threshhold = 1; |
| #endif |
| FILE *fp; |
| const char *fmt; |
| char *p; |
| int opt; |
| int c; |
| int retval = EXIT_SUCCESS; |
| |
| #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD |
| /* Allow legacy syntax of an initial numeric option without -n. */ |
| if (argv[1] && argv[1][0] == '-' |
| && isdigit(argv[1][1]) |
| ) { |
| --argc; |
| ++argv; |
| p = (*argv) + 1; |
| goto GET_COUNT; |
| } |
| #endif |
| |
| /* No size benefit in converting this to getopt32 */ |
| while ((opt = getopt(argc, argv, head_opts)) > 0) { |
| switch (opt) { |
| #if ENABLE_FEATURE_FANCY_HEAD |
| case 'q': |
| header_threshhold = INT_MAX; |
| break; |
| case 'v': |
| header_threshhold = -1; |
| break; |
| case 'c': |
| count_bytes = 1; |
| /* fall through */ |
| #endif |
| case 'n': |
| p = optarg; |
| #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD |
| GET_COUNT: |
| #endif |
| #if !ENABLE_FEATURE_FANCY_HEAD |
| count = xatoul(p); |
| #else |
| count = xatoul_sfx(p, head_suffixes); |
| #endif |
| break; |
| default: |
| bb_show_usage(); |
| } |
| } |
| |
| argc -= optind; |
| argv += optind; |
| if (!*argv) |
| *--argv = (char*)"-"; |
| |
| fmt = header_fmt_str + 1; |
| #if ENABLE_FEATURE_FANCY_HEAD |
| if (argc <= header_threshhold) { |
| header_threshhold = 0; |
| } |
| #else |
| if (argc <= 1) { |
| fmt += 11; /* "" */ |
| } |
| /* Now define some things here to avoid #ifdefs in the code below. |
| * These should optimize out of the if conditions below. */ |
| #define header_threshhold 1 |
| #define count_bytes 0 |
| #endif |
| |
| do { |
| fp = fopen_or_warn_stdin(*argv); |
| if (fp) { |
| if (fp == stdin) { |
| *argv = (char *) bb_msg_standard_input; |
| } |
| if (header_threshhold) { |
| printf(fmt, *argv); |
| } |
| i = count; |
| while (i && ((c = getc(fp)) != EOF)) { |
| if (count_bytes || (c == '\n')) { |
| --i; |
| } |
| putchar(c); |
| } |
| if (fclose_if_not_stdin(fp)) { |
| bb_simple_perror_msg(*argv); |
| retval = EXIT_FAILURE; |
| } |
| die_if_ferror_stdout(); |
| } else { |
| retval = EXIT_FAILURE; |
| } |
| fmt = header_fmt_str; |
| } while (*++argv); |
| |
| fflush_stdout_and_exit(retval); |
| } |