Contents of /tags/mkinitrd-6_1_0/busybox/coreutils/head.c
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Fri Apr 24 19:09:57 2009 UTC (15 years, 5 months ago) by niro
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File size: 2866 byte(s)
Fri Apr 24 19:09:57 2009 UTC (15 years, 5 months ago) by niro
File MIME type: text/plain
File size: 2866 byte(s)
tagged 'mkinitrd-6_1_0'
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 tarball for details. |
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 | #include "libbb.h" |
15 | |
16 | static const char head_opts[] ALIGN1 = |
17 | "n:" |
18 | #if ENABLE_FEATURE_FANCY_HEAD |
19 | "c:qv" |
20 | #endif |
21 | ; |
22 | |
23 | #if ENABLE_FEATURE_FANCY_HEAD |
24 | static const struct suffix_mult head_suffixes[] = { |
25 | { "b", 512 }, |
26 | { "k", 1024 }, |
27 | { "m", 1024*1024 }, |
28 | { } |
29 | }; |
30 | #endif |
31 | |
32 | static const char header_fmt_str[] ALIGN1 = "\n==> %s <==\n"; |
33 | |
34 | int head_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
35 | int head_main(int argc, char **argv) |
36 | { |
37 | unsigned long count = 10; |
38 | unsigned long i; |
39 | #if ENABLE_FEATURE_FANCY_HEAD |
40 | int count_bytes = 0; |
41 | int header_threshhold = 1; |
42 | #endif |
43 | |
44 | FILE *fp; |
45 | const char *fmt; |
46 | char *p; |
47 | int opt; |
48 | int c; |
49 | int retval = EXIT_SUCCESS; |
50 | |
51 | #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD |
52 | /* Allow legacy syntax of an initial numeric option without -n. */ |
53 | if (argc > 1 && argv[1][0] == '-' |
54 | && isdigit(argv[1][1]) |
55 | ) { |
56 | --argc; |
57 | ++argv; |
58 | p = (*argv) + 1; |
59 | goto GET_COUNT; |
60 | } |
61 | #endif |
62 | |
63 | /* No size benefit in converting this to getopt32 */ |
64 | while ((opt = getopt(argc, argv, head_opts)) > 0) { |
65 | switch (opt) { |
66 | #if ENABLE_FEATURE_FANCY_HEAD |
67 | case 'q': |
68 | header_threshhold = INT_MAX; |
69 | break; |
70 | case 'v': |
71 | header_threshhold = -1; |
72 | break; |
73 | case 'c': |
74 | count_bytes = 1; |
75 | /* fall through */ |
76 | #endif |
77 | case 'n': |
78 | p = optarg; |
79 | #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD |
80 | GET_COUNT: |
81 | #endif |
82 | |
83 | #if !ENABLE_FEATURE_FANCY_HEAD |
84 | count = xatoul(p); |
85 | #else |
86 | count = xatoul_sfx(p, head_suffixes); |
87 | #endif |
88 | break; |
89 | default: |
90 | bb_show_usage(); |
91 | } |
92 | } |
93 | |
94 | argc -= optind; |
95 | argv += optind; |
96 | if (!*argv) |
97 | *--argv = (char*)"-"; |
98 | |
99 | fmt = header_fmt_str + 1; |
100 | #if ENABLE_FEATURE_FANCY_HEAD |
101 | if (argc <= header_threshhold) { |
102 | header_threshhold = 0; |
103 | } |
104 | #else |
105 | if (argc <= 1) { |
106 | fmt += 11; /* "" */ |
107 | } |
108 | /* Now define some things here to avoid #ifdefs in the code below. |
109 | * These should optimize out of the if conditions below. */ |
110 | #define header_threshhold 1 |
111 | #define count_bytes 0 |
112 | #endif |
113 | |
114 | do { |
115 | fp = fopen_or_warn_stdin(*argv); |
116 | if (fp) { |
117 | if (fp == stdin) { |
118 | *argv = (char *) bb_msg_standard_input; |
119 | } |
120 | if (header_threshhold) { |
121 | printf(fmt, *argv); |
122 | } |
123 | i = count; |
124 | while (i && ((c = getc(fp)) != EOF)) { |
125 | if (count_bytes || (c == '\n')) { |
126 | --i; |
127 | } |
128 | putchar(c); |
129 | } |
130 | if (fclose_if_not_stdin(fp)) { |
131 | bb_simple_perror_msg(*argv); /* Avoid multibyte problems. */ |
132 | retval = EXIT_FAILURE; |
133 | } |
134 | die_if_ferror_stdout(); |
135 | } |
136 | fmt = header_fmt_str; |
137 | } while (*++argv); |
138 | |
139 | fflush_stdout_and_exit(retval); |
140 | } |