*
* Copyright (C) 2003 Manuel Novoa III <mjn3@codepoet.org>
*
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * 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-$(CONFIG_HEAD) += head.o
/* BB_AUDIT SUSv3 compliant */
/* BB_AUDIT GNU compatible -c, -q, and -v options in 'fancy' configuration. */
/* http://www.opengroup.org/onlinepubs/007904975/utilities/head.html */
+//usage:#define head_trivial_usage
+//usage: "[OPTIONS] [FILE]..."
+//usage:#define head_full_usage "\n\n"
+//usage: "Print first 10 lines of each FILE (or stdin) to stdout.\n"
+//usage: "With more than one FILE, precede each with a filename header.\n"
+//usage: "\n -n N[kbm] Print first N lines"
+//usage: IF_FEATURE_FANCY_HEAD(
+//usage: "\n -n -N[kbm] Print all except N last lines"
+//usage: "\n -c [-]N[kbm] Print first N bytes"
+//usage: "\n -q Never print headers"
+//usage: "\n -v Always print headers"
+//usage: )
+//usage: "\n"
+//usage: "\nN may be suffixed by k (x1024), b (x512), or m (x1024^2)."
+//usage:
+//usage:#define head_example_usage
+//usage: "$ 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"
-static const char head_opts[] =
- "n:"
+/* 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);
+ }
+}
+
#if ENABLE_FEATURE_FANCY_HEAD
- "c:qv"
+static void
+print_except_N_last_bytes(FILE *fp, unsigned count)
+{
+ 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);
+}
+
+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;
+ }
+ 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
- ;
+#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
-static const struct suffix_mult head_suffixes[] = {
- { "b", 512 },
- { "k", 1024 },
- { "m", 1024*1024 },
- { NULL, 0 }
-};
+ "c:qv"
#endif
+ ;
-static const char header_fmt_str[] = "\n==> %s <==\n";
+#define header_fmt_str "\n==> %s <==\n"
-int head_main(int argc, char **argv);
+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;
+ bool count_bytes = 0;
+ bool negative_N = 0;
+#else
+# define header_threshhold 1
+# define count_bytes 0
+# define negative_N 0
#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 (argc > 1 && argv[1][0] == '-'
+ if (argv[1] && argv[1][0] == '-'
&& isdigit(argv[1][1])
) {
--argc;
++argv;
- p = (*argv) + 1;
+ p = argv[0] + 1;
goto GET_COUNT;
}
#endif
#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
+ count = eat_num(&negative_N, p);
break;
default:
bb_show_usage();
}
}
+ argc -= optind;
argv += optind;
- if (!*argv) {
+ if (!*argv)
*--argv = (char*)"-";
- }
fmt = header_fmt_str + 1;
+ if (argc <= header_threshhold) {
#if ENABLE_FEATURE_FANCY_HEAD
- if (argc - optind <= header_threshhold) {
header_threshhold = 0;
- }
#else
- if (argc <= optind + 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
+ 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 (header_threshhold) {
printf(fmt, *argv);
}
- i = count;
- while (i && ((c = getc(fp)) != EOF)) {
- if (count_bytes || (c == '\n')) {
- --i;
+ if (negative_N) {
+ if (count_bytes) {
+ print_except_N_last_bytes(fp, count);
+ } else {
+ print_except_N_last_lines(fp, count);
}
- putchar(c);
+ } else {
+ print_first_N(fp, count, count_bytes);
}
+ die_if_ferror_stdout();
if (fclose_if_not_stdin(fp)) {
- bb_perror_msg("%s", *argv); /* Avoid multibyte problems. */
+ bb_simple_perror_msg(*argv);
retval = EXIT_FAILURE;
}
- die_if_ferror_stdout();
+ } else {
+ retval = EXIT_FAILURE;
}
fmt = header_fmt_str;
} while (*++argv);
projects / oweals / busybox.git / blobdiff