1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
|
/* 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 source tree.
*/
/* 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 */
//kbuild:lib-$(CONFIG_HEAD) += head.o
//kbuild:lib-$(CONFIG_HEAD) += head_tail.o
//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"
#include "head_tail.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);
}
}
#if ENABLE_FEATURE_FANCY_HEAD
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, head_tail_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;
const char *fmt;
char *p;
int opt;
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[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':
p = optarg;
#if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
GET_COUNT:
#endif
count = eat_num(&negative_N, p);
break;
default:
bb_show_usage();
}
}
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 (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);
}
die_if_ferror_stdout();
if (fclose_if_not_stdin(fp)) {
bb_simple_perror_msg(*argv);
retval = EXIT_FAILURE;
}
} else {
retval = EXIT_FAILURE;
}
fmt = header_fmt_str;
} while (*++argv);
fflush_stdout_and_exit(retval);
}
|
