blob: 9388b026af9f5374d1d26e861c0e4cbff7ba0c6d
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * head implementation for busybox |
4 | * |
5 | * Copyright (C) 2003 Manuel Novoa III <mjn3@codepoet.org> |
6 | * |
7 | * Licensed under GPLv2 or later, see file LICENSE in this source tree. |
8 | */ |
9 | |
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 */ |
13 | |
14 | //kbuild:lib-$(CONFIG_HEAD) += head.o |
15 | |
16 | //usage:#define head_trivial_usage |
17 | //usage: "[OPTIONS] [FILE]..." |
18 | //usage:#define head_full_usage "\n\n" |
19 | //usage: "Print first 10 lines of each FILE (or stdin) to stdout.\n" |
20 | //usage: "With more than one FILE, precede each with a filename header.\n" |
21 | //usage: "\n -n N[kbm] Print first N lines" |
22 | //usage: IF_FEATURE_FANCY_HEAD( |
23 | //usage: "\n -n -N[kbm] Print all except N last lines" |
24 | //usage: "\n -c [-]N[kbm] Print first N bytes" |
25 | //usage: "\n -q Never print headers" |
26 | //usage: "\n -v Always print headers" |
27 | //usage: ) |
28 | //usage: "\n" |
29 | //usage: "\nN may be suffixed by k (x1024), b (x512), or m (x1024^2)." |
30 | //usage: |
31 | //usage:#define head_example_usage |
32 | //usage: "$ 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" |
35 | |
36 | #include "libbb.h" |
37 | |
38 | /* This is a NOEXEC applet. Be very careful! */ |
39 | |
40 | #if !ENABLE_FEATURE_FANCY_HEAD |
41 | # define print_first_N(fp,count,bytes) print_first_N(fp,count) |
42 | #endif |
43 | static void |
44 | print_first_N(FILE *fp, unsigned long count, bool count_bytes) |
45 | { |
46 | #if !ENABLE_FEATURE_FANCY_HEAD |
47 | const int count_bytes = 0; |
48 | #endif |
49 | while (count) { |
50 | int c = getc(fp); |
51 | if (c == EOF) |
52 | break; |
53 | if (count_bytes || (c == '\n')) |
54 | --count; |
55 | putchar(c); |
56 | } |
57 | } |
58 | |
59 | #if ENABLE_FEATURE_FANCY_HEAD |
60 | static void |
61 | print_except_N_last_bytes(FILE *fp, unsigned count) |
62 | { |
63 | unsigned char *circle = xmalloc(++count); |
64 | unsigned head = 0; |
65 | for(;;) { |
66 | int c; |
67 | c = getc(fp); |
68 | if (c == EOF) |
69 | goto ret; |
70 | circle[head++] = c; |
71 | if (head == count) |
72 | break; |
73 | } |
74 | for (;;) { |
75 | int c; |
76 | if (head == count) |
77 | head = 0; |
78 | putchar(circle[head]); |
79 | c = getc(fp); |
80 | if (c == EOF) |
81 | goto ret; |
82 | circle[head] = c; |
83 | head++; |
84 | } |
85 | ret: |
86 | free(circle); |
87 | } |
88 | |
89 | static void |
90 | print_except_N_last_lines(FILE *fp, unsigned count) |
91 | { |
92 | char **circle = xzalloc((++count) * sizeof(circle[0])); |
93 | unsigned head = 0; |
94 | for(;;) { |
95 | char *c; |
96 | c = xmalloc_fgets(fp); |
97 | if (!c) |
98 | goto ret; |
99 | circle[head++] = c; |
100 | if (head == count) |
101 | break; |
102 | } |
103 | for (;;) { |
104 | char *c; |
105 | if (head == count) |
106 | head = 0; |
107 | fputs(circle[head], stdout); |
108 | c = xmalloc_fgets(fp); |
109 | if (!c) |
110 | goto ret; |
111 | free(circle[head]); |
112 | circle[head++] = c; |
113 | } |
114 | ret: |
115 | head = 0; |
116 | for(;;) { |
117 | free(circle[head++]); |
118 | if (head == count) |
119 | break; |
120 | } |
121 | free(circle); |
122 | } |
123 | #else |
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); |
127 | #endif |
128 | |
129 | #if !ENABLE_FEATURE_FANCY_HEAD |
130 | # define eat_num(negative_N,p) eat_num(p) |
131 | #endif |
132 | static unsigned long |
133 | eat_num(bool *negative_N, const char *p) |
134 | { |
135 | #if ENABLE_FEATURE_FANCY_HEAD |
136 | if (*p == '-') { |
137 | *negative_N = 1; |
138 | p++; |
139 | } |
140 | #endif |
141 | return xatoul_sfx(p, bkm_suffixes); |
142 | } |
143 | |
144 | static const char head_opts[] ALIGN1 = |
145 | "n:" |
146 | #if ENABLE_FEATURE_FANCY_HEAD |
147 | "c:qv" |
148 | #endif |
149 | ; |
150 | |
151 | #define header_fmt_str "\n==> %s <==\n" |
152 | |
153 | int head_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
154 | int head_main(int argc, char **argv) |
155 | { |
156 | unsigned long count = 10; |
157 | #if ENABLE_FEATURE_FANCY_HEAD |
158 | int header_threshhold = 1; |
159 | bool count_bytes = 0; |
160 | bool negative_N = 0; |
161 | #else |
162 | # define header_threshhold 1 |
163 | # define count_bytes 0 |
164 | # define negative_N 0 |
165 | #endif |
166 | FILE *fp; |
167 | const char *fmt; |
168 | char *p; |
169 | int opt; |
170 | int retval = EXIT_SUCCESS; |
171 | |
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]) |
176 | ) { |
177 | --argc; |
178 | ++argv; |
179 | p = argv[0] + 1; |
180 | goto GET_COUNT; |
181 | } |
182 | #endif |
183 | |
184 | /* No size benefit in converting this to getopt32 */ |
185 | while ((opt = getopt(argc, argv, head_opts)) > 0) { |
186 | switch (opt) { |
187 | #if ENABLE_FEATURE_FANCY_HEAD |
188 | case 'q': |
189 | header_threshhold = INT_MAX; |
190 | break; |
191 | case 'v': |
192 | header_threshhold = -1; |
193 | break; |
194 | case 'c': |
195 | count_bytes = 1; |
196 | /* fall through */ |
197 | #endif |
198 | case 'n': |
199 | p = optarg; |
200 | #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD |
201 | GET_COUNT: |
202 | #endif |
203 | count = eat_num(&negative_N, p); |
204 | break; |
205 | default: |
206 | bb_show_usage(); |
207 | } |
208 | } |
209 | |
210 | argc -= optind; |
211 | argv += optind; |
212 | if (!*argv) |
213 | *--argv = (char*)"-"; |
214 | |
215 | fmt = header_fmt_str + 1; |
216 | if (argc <= header_threshhold) { |
217 | #if ENABLE_FEATURE_FANCY_HEAD |
218 | header_threshhold = 0; |
219 | #else |
220 | fmt += 11; /* "" */ |
221 | #endif |
222 | } |
223 | if (negative_N) { |
224 | if (count >= INT_MAX / sizeof(char*)) |
225 | bb_error_msg("count is too big: %lu", count); |
226 | } |
227 | |
228 | do { |
229 | fp = fopen_or_warn_stdin(*argv); |
230 | if (fp) { |
231 | if (fp == stdin) { |
232 | *argv = (char *) bb_msg_standard_input; |
233 | } |
234 | if (header_threshhold) { |
235 | printf(fmt, *argv); |
236 | } |
237 | if (negative_N) { |
238 | if (count_bytes) { |
239 | print_except_N_last_bytes(fp, count); |
240 | } else { |
241 | print_except_N_last_lines(fp, count); |
242 | } |
243 | } else { |
244 | print_first_N(fp, count, count_bytes); |
245 | } |
246 | die_if_ferror_stdout(); |
247 | if (fclose_if_not_stdin(fp)) { |
248 | bb_simple_perror_msg(*argv); |
249 | retval = EXIT_FAILURE; |
250 | } |
251 | } else { |
252 | retval = EXIT_FAILURE; |
253 | } |
254 | fmt = header_fmt_str; |
255 | } while (*++argv); |
256 | |
257 | fflush_stdout_and_exit(retval); |
258 | } |
259 |