1 /* vi: set sw=4 ts=4: */
3 * head implementation for busybox
5 * Copyright (C) 2003 Manuel Novoa III <mjn3@codepoet.org>
7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
10 /* BB_AUDIT SUSv3 compliant */
11 /* BB_AUDIT GNU compatible -c, -q, and -v options in 'fancy' configuration. */
12 /* http://www.opengroup.org/onlinepubs/007904975/utilities/head.html */
14 //kbuild:lib-$(CONFIG_HEAD) += head.o
16 //usage:#define head_trivial_usage
17 //usage: "[OPTIONS] [FILE]..."
18 //usage:#define head_full_usage "\n\n"
19 //usage: "Print first 10 lines of each FILE (or stdin) to stdout.\n"
20 //usage: "With more than one FILE, precede each with a filename header.\n"
21 //usage: "\n -n N[kbm] Print first N lines"
22 //usage: IF_FEATURE_FANCY_HEAD(
23 //usage: "\n -n -N[kbm] Print all except N last lines"
24 //usage: "\n -c [-]N[kbm] Print first N bytes"
25 //usage: "\n -q Never print headers"
26 //usage: "\n -v Always print headers"
29 //usage: "\nN may be suffixed by k (x1024), b (x512), or m (x1024^2)."
31 //usage:#define head_example_usage
32 //usage: "$ head -n 2 /etc/passwd\n"
33 //usage: "root:x:0:0:root:/root:/bin/bash\n"
34 //usage: "daemon:x:1:1:daemon:/usr/sbin:/bin/sh\n"
38 /* This is a NOEXEC applet. Be very careful! */
40 #if !ENABLE_FEATURE_FANCY_HEAD
41 # define print_first_N(fp,count,bytes) print_first_N(fp,count)
44 print_first_N(FILE *fp
, unsigned long count
, bool count_bytes
)
46 #if !ENABLE_FEATURE_FANCY_HEAD
47 const int count_bytes
= 0;
53 if (count_bytes
|| (c
== '\n'))
59 #if ENABLE_FEATURE_FANCY_HEAD
61 print_except_N_last_bytes(FILE *fp
, unsigned count
)
63 unsigned char *circle
= xmalloc(++count
);
78 putchar(circle
[head
]);
90 print_except_N_last_lines(FILE *fp
, unsigned count
)
92 char **circle
= xzalloc((++count
) * sizeof(circle
[0]));
96 c
= xmalloc_fgets(fp
);
107 fputs(circle
[head
], stdout
);
108 c
= xmalloc_fgets(fp
);
117 free(circle
[head
++]);
124 /* Must never be called */
125 void print_except_N_last_bytes(FILE *fp
, unsigned count
);
126 void print_except_N_last_lines(FILE *fp
, unsigned count
);
129 #if !ENABLE_FEATURE_FANCY_HEAD
130 # define eat_num(negative_N,p) eat_num(p)
133 eat_num(bool *negative_N
, const char *p
)
135 #if ENABLE_FEATURE_FANCY_HEAD
141 return xatoul_sfx(p
, bkm_suffixes
);
144 static const char head_opts
[] ALIGN1
=
146 #if ENABLE_FEATURE_FANCY_HEAD
151 #define header_fmt_str "\n==> %s <==\n"
153 int head_main(int argc
, char **argv
) MAIN_EXTERNALLY_VISIBLE
;
154 int head_main(int argc
, char **argv
)
156 unsigned long count
= 10;
157 #if ENABLE_FEATURE_FANCY_HEAD
158 int header_threshhold
= 1;
159 bool count_bytes
= 0;
162 # define header_threshhold 1
163 # define count_bytes 0
164 # define negative_N 0
170 int retval
= EXIT_SUCCESS
;
172 #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
173 /* Allow legacy syntax of an initial numeric option without -n. */
174 if (argv
[1] && argv
[1][0] == '-'
175 && isdigit(argv
[1][1])
184 /* No size benefit in converting this to getopt32 */
185 while ((opt
= getopt(argc
, argv
, head_opts
)) > 0) {
187 #if ENABLE_FEATURE_FANCY_HEAD
189 header_threshhold
= INT_MAX
;
192 header_threshhold
= -1;
200 #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
203 count
= eat_num(&negative_N
, p
);
213 *--argv
= (char*)"-";
215 fmt
= header_fmt_str
+ 1;
216 if (argc
<= header_threshhold
) {
217 #if ENABLE_FEATURE_FANCY_HEAD
218 header_threshhold
= 0;
224 if (count
>= INT_MAX
/ sizeof(char*))
225 bb_error_msg("count is too big: %lu", count
);
229 fp
= fopen_or_warn_stdin(*argv
);
232 *argv
= (char *) bb_msg_standard_input
;
234 if (header_threshhold
) {
239 print_except_N_last_bytes(fp
, count
);
241 print_except_N_last_lines(fp
, count
);
244 print_first_N(fp
, count
, count_bytes
);
246 die_if_ferror_stdout();
247 if (fclose_if_not_stdin(fp
)) {
248 bb_simple_perror_msg(*argv
);
249 retval
= EXIT_FAILURE
;
252 retval
= EXIT_FAILURE
;
254 fmt
= header_fmt_str
;
257 fflush_stdout_and_exit(retval
);