/* 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) 1999,2000 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.
*/
+//config:config HEAD
+//config: bool "head (3.8 kb)"
+//config: default y
+//config: help
+//config: head is used to print the first specified number of lines
+//config: from files.
+//config:
+//config:config FEATURE_FANCY_HEAD
+//config: bool "Enable -c, -q, and -v"
+//config: default y
+//config: depends on HEAD
+
+//applet:IF_HEAD(APPLET_NOEXEC(head, head, BB_DIR_USR_BIN, BB_SUID_DROP, head))
+
+//kbuild:lib-$(CONFIG_HEAD) += head.o
-#include "busybox.h"
-#include <errno.h>
-#include <stdio.h>
+/* BB_AUDIT SUSv3 compliant */
+/* BB_AUDIT GNU compatible -c, -q, and -v options in 'fancy' configuration. */
+/* http://www.opengroup.org/onlinepubs/007904975/utilities/head.html */
+
+//usage:#define head_trivial_usage
+//usage: "[OPTIONS] [FILE]..."
+//usage:#define head_full_usage "\n\n"
+//usage: "Print first 10 lines of each FILE (or stdin) to stdout.\n"
+//usage: "With more than one FILE, precede each with a filename header.\n"
+//usage: "\n -n N[kbm] Print first N lines"
+//usage: IF_FEATURE_FANCY_HEAD(
+//usage: "\n -n -N[kbm] Print all except N last lines"
+//usage: "\n -c [-]N[kbm] Print first N bytes"
+//usage: "\n -q Never print headers"
+//usage: "\n -v Always print headers"
+//usage: )
+//usage: "\n"
+//usage: "\nN may be suffixed by k (x1024), b (x512), or m (x1024^2)."
+//usage:
+//usage:#define head_example_usage
+//usage: "$ 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"
+
+#include "libbb.h"
+
+/* This is a NOEXEC applet. Be very careful! */
+
+#if !ENABLE_FEATURE_FANCY_HEAD
+# define print_first_N(fp,count,bytes) print_first_N(fp,count)
+#endif
+static void
+print_first_N(FILE *fp, unsigned long count, bool count_bytes)
+{
+#if !ENABLE_FEATURE_FANCY_HEAD
+ const int count_bytes = 0;
+#endif
+ while (count) {
+ int c = getc(fp);
+ if (c == EOF)
+ break;
+ if (count_bytes || (c == '\n'))
+ --count;
+ putchar(c);
+ }
+}
-int head(int len, FILE *fp)
+#if ENABLE_FEATURE_FANCY_HEAD
+static void
+print_except_N_last_bytes(FILE *fp, unsigned count)
{
- int i;
- char *input;
+ unsigned char *circle = xmalloc(++count);
+ unsigned head = 0;
+ for(;;) {
+ int c;
+ c = getc(fp);
+ if (c == EOF)
+ goto ret;
+ circle[head++] = c;
+ if (head == count)
+ break;
+ }
+ for (;;) {
+ int c;
+ if (head == count)
+ head = 0;
+ putchar(circle[head]);
+ c = getc(fp);
+ if (c == EOF)
+ goto ret;
+ circle[head] = c;
+ head++;
+ }
+ ret:
+ free(circle);
+}
- for (i = 0; i < len; i++) {
- if ((input = get_line_from_file(fp)) == NULL)
+static void
+print_except_N_last_lines(FILE *fp, unsigned count)
+{
+ char **circle = xzalloc((++count) * sizeof(circle[0]));
+ unsigned head = 0;
+ for(;;) {
+ char *c;
+ c = xmalloc_fgets(fp);
+ if (!c)
+ goto ret;
+ circle[head++] = c;
+ if (head == count)
+ break;
+ }
+ for (;;) {
+ char *c;
+ if (head == count)
+ head = 0;
+ fputs(circle[head], stdout);
+ c = xmalloc_fgets(fp);
+ if (!c)
+ goto ret;
+ free(circle[head]);
+ circle[head++] = c;
+ }
+ ret:
+ head = 0;
+ for(;;) {
+ free(circle[head++]);
+ if (head == count)
break;
- fputs(input, stdout);
- free(input);
}
- return 0;
+ free(circle);
}
+#else
+/* Must never be called */
+void print_except_N_last_bytes(FILE *fp, unsigned count);
+void print_except_N_last_lines(FILE *fp, unsigned count);
+#endif
-/* BusyBoxed head(1) */
+#if !ENABLE_FEATURE_FANCY_HEAD
+# define eat_num(negative_N,p) eat_num(p)
+#endif
+static unsigned long
+eat_num(bool *negative_N, const char *p)
+{
+#if ENABLE_FEATURE_FANCY_HEAD
+ if (*p == '-') {
+ *negative_N = 1;
+ p++;
+ }
+#endif
+ return xatoul_sfx(p, bkm_suffixes);
+}
+
+static const char head_opts[] ALIGN1 =
+ "n:"
+#if ENABLE_FEATURE_FANCY_HEAD
+ "c:qv"
+#endif
+ ;
+
+#define header_fmt_str "\n==> %s <==\n"
+
+int head_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int head_main(int argc, char **argv)
{
+ unsigned long count = 10;
+#if ENABLE_FEATURE_FANCY_HEAD
+ int header_threshhold = 1;
+ bool count_bytes = 0;
+ bool negative_N = 0;
+#else
+# define header_threshhold 1
+# define count_bytes 0
+# define negative_N 0
+#endif
FILE *fp;
- int need_headers, opt, len = 10, status = EXIT_SUCCESS;
+ const char *fmt;
+ char *p;
+ int opt;
+ int retval = EXIT_SUCCESS;
- /* parse argv[] */
- while ((opt = getopt(argc, argv, "n:")) > 0) {
+#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[0] + 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':
- len = atoi(optarg);
- if (len >= 1)
- break;
- /* fallthrough */
+ p = optarg;
+#if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
+ GET_COUNT:
+#endif
+ count = eat_num(&negative_N, p);
+ break;
default:
- usage(head_usage);
+ bb_show_usage();
}
}
- /* get rest of argv[] or stdin if nothing's left */
- if (argv[optind] == NULL) {
- head(len, stdin);
- return status;
- }
-
- need_headers = optind != (argc - 1);
- while (argv[optind]) {
- if (strcmp(argv[optind], "-") == 0) {
- fp = stdin;
- argv[optind] = "standard input";
- } else {
- if ((fp = wfopen(argv[optind], "r")) == NULL)
- status = EXIT_FAILURE;
- }
+ argc -= optind;
+ argv += optind;
+ if (!*argv)
+ *--argv = (char*)"-";
+
+ fmt = header_fmt_str + 1;
+ if (argc <= header_threshhold) {
+#if ENABLE_FEATURE_FANCY_HEAD
+ header_threshhold = 0;
+#else
+ fmt += 11; /* "" */
+#endif
+ }
+ if (negative_N) {
+ if (count >= INT_MAX / sizeof(char*))
+ bb_error_msg("count is too big: %lu", count);
+ }
+
+ do {
+ fp = fopen_or_warn_stdin(*argv);
if (fp) {
- if (need_headers) {
- fprintf(stdout, "==> %s <==\n", argv[optind]);
+ if (fp == stdin) {
+ *argv = (char *) bb_msg_standard_input;
+ }
+ if (header_threshhold) {
+ printf(fmt, *argv);
+ }
+ if (negative_N) {
+ if (count_bytes) {
+ print_except_N_last_bytes(fp, count);
+ } else {
+ print_except_N_last_lines(fp, count);
+ }
+ } else {
+ print_first_N(fp, count, count_bytes);
}
- head(len, fp);
- if (errno) {
- errorMsg("%s: %s\n", argv[optind], strerror(errno));
- status = EXIT_FAILURE;
- errno = 0;
+ die_if_ferror_stdout();
+ if (fclose_if_not_stdin(fp)) {
+ bb_simple_perror_msg(*argv);
+ retval = EXIT_FAILURE;
}
- if (optind < argc - 1)
- fprintf(stdout, "\n");
- if (fp != stdin)
- fclose(fp);
+ } else {
+ retval = EXIT_FAILURE;
}
- optind++;
- }
+ fmt = header_fmt_str;
+ } while (*++argv);
- return status;
+ fflush_stdout_and_exit(retval);
}
projects / oweals / busybox.git / blobdiff