+/* vi: set sw=4 ts=4: */
/*
- * Mini head implementation for busybox
+ * head implementation for busybox
*
+ * Copyright (C) 2003 Manuel Novoa III <mjn3@codepoet.org>
*
- * Copyright (C) 1999 by Lineo, inc.
- * Written by John Beppu <beppu@lineo.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
- *
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
-#include "internal.h"
-#include <errno.h>
-#include <stdio.h>
+/* 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 */
-const char head_usage[] =
-"Usage: head [FILE]...\n\n"
-"Print first 10 lines of each FILE to standard output.\n"
-"With more than one FILE, precede each with a header giving the\n"
-"file name. With no FILE, or when FILE is -, read standard input.\n";
+//usage:#define head_trivial_usage
+//usage: "[OPTIONS] [FILE]..."
+//usage:#define head_full_usage "\n\n"
+//usage: "Print first 10 lines of each FILE (or stdin) to stdout.\n"
+//usage: "With more than one FILE, precede each with a filename header.\n"
+//usage: "\n -n N[kbm] Print first N lines"
+//usage: IF_FEATURE_FANCY_HEAD(
+//usage: "\n -c N[kbm] Print first N bytes"
+//usage: "\n -q Never print headers"
+//usage: "\n -v Always print headers"
+//usage: )
+//usage: "\n"
+//usage: "\nN may be suffixed by k (x1024), b (x512), or m (x1024^2)."
+//usage:
+//usage:#define head_example_usage
+//usage: "$ head -n 2 /etc/passwd\n"
+//usage: "root:x:0:0:root:/root:/bin/bash\n"
+//usage: "daemon:x:1:1:daemon:/usr/sbin:/bin/sh\n"
-int
-head(int len, FILE *src)
-{
- int i;
- char buffer[1024];
+#include "libbb.h"
- for (i = 0; i < len; i++) {
- fgets(buffer, 1024, src);
- if (feof(src)) { break; }
- fputs(buffer, stdout);
- }
- return 0;
-}
+/* This is a NOEXEC applet. Be very careful! */
+
+static const char head_opts[] ALIGN1 =
+ "n:"
+#if ENABLE_FEATURE_FANCY_HEAD
+ "c:qv"
+#endif
+ ;
+
+static const struct suffix_mult head_suffixes[] = {
+ { "b", 512 },
+ { "k", 1024 },
+ { "m", 1024*1024 },
+ { "", 0 }
+};
+
+#define header_fmt_str "\n==> %s <==\n"
-/* BusyBoxed head(1) */
-int
-head_main(int argc, char **argv)
+int head_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int head_main(int argc, char **argv)
{
- int i = 1;
- char opt;
- int len = 10;
+ 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;
- /* 1st option is potentially special */
- if ((argc > 1) && (argv[1][0] == '-') && isDecimal(argv[1][1])) {
- int tmplen = atoi(&argv[1][1]);
- if (tmplen) { len = tmplen; }
- i = 2;
- }
+#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
- /* parse argv[] */
- for ( ; i < argc; i++) {
- if (argv[i][0] == '-') {
- opt = argv[i][1];
- switch (opt) {
- case '-':
- case 'h':
- usage(head_usage);
+ /* 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
+ count = xatoul_sfx(p, head_suffixes);
+ break;
default:
- fprintf(stderr, "head: invalid option -- %c\n", opt);
- usage(head_usage);
- }
- } else {
- break;
+ bb_show_usage();
+ }
}
- }
- /* get rest of argv[] or stdin if nothing's left */
- if (i >= argc) {
- head(len, stdin);
+ argc -= optind;
+ argv += optind;
+ if (!*argv)
+ *--argv = (char*)"-";
- } else {
- int need_headers = ((argc - i) > 1);
- for ( ; i < argc; i++) {
- FILE *src;
- src = fopen(argv[i], "r");
- if (!src) {
- fprintf(stderr,"head: %s: %s\n", argv[i], strerror(errno));
- } else {
- /* emulating GNU behaviour */
- if (need_headers) {
- fprintf(stdout, "==> %s <==\n", argv[i]);
- }
- head(len, src);
- if (i < argc - 1) {
- fprintf(stdout, "\n");
- }
- }
+ fmt = header_fmt_str + 1;
+#if ENABLE_FEATURE_FANCY_HEAD
+ if (argc <= header_threshhold) {
+ header_threshhold = 0;
}
- }
- exit(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);
-/* $Id: head.c,v 1.4 1999/12/17 18:52:06 erik Exp $ */
+ fflush_stdout_and_exit(retval);
+}
projects / oweals / busybox.git / blobdiff