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-rw-r--r--coreutils/head.c139
1 files changed, 139 insertions, 0 deletions
diff --git a/coreutils/head.c b/coreutils/head.c
new file mode 100644
index 000000000..f2c948300
--- /dev/null
+++ b/coreutils/head.c
@@ -0,0 +1,139 @@
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 "busybox.h"
15
16static const char head_opts[] =
17 "n:"
18#if ENABLE_FEATURE_FANCY_HEAD
19 "c:qv"
20#endif
21 ;
22
23#if ENABLE_FEATURE_FANCY_HEAD
24static const struct suffix_mult head_suffixes[] = {
25 { "b", 512 },
26 { "k", 1024 },
27 { "m", 1024*1024 },
28 { NULL, 0 }
29};
30#endif
31
32static const char header_fmt_str[] = "\n==> %s <==\n";
33
34int head_main(int argc, char **argv)
35{
36 unsigned long count = 10;
37 unsigned long i;
38#if ENABLE_FEATURE_FANCY_HEAD
39 int count_bytes = 0;
40 int header_threshhold = 1;
41#endif
42
43 FILE *fp;
44 const char *fmt;
45 char *p;
46 int opt;
47 int c;
48 int retval = EXIT_SUCCESS;
49
50#if !ENABLE_DEBUG_YANK_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
51 /* Allow legacy syntax of an initial numeric option without -n. */
52 if (argc > 1 && argv[1][0] == '-'
53 && isdigit(argv[1][1])
54 ) {
55 --argc;
56 ++argv;
57 p = (*argv) + 1;
58 goto GET_COUNT;
59 }
60#endif
61
62 /* No size benefit in converting this to getopt32 */
63 while ((opt = getopt(argc, argv, head_opts)) > 0) {
64 switch (opt) {
65#if ENABLE_FEATURE_FANCY_HEAD
66 case 'q':
67 header_threshhold = INT_MAX;
68 break;
69 case 'v':
70 header_threshhold = -1;
71 break;
72 case 'c':
73 count_bytes = 1;
74 /* fall through */
75#endif
76 case 'n':
77 p = optarg;
78#if !ENABLE_DEBUG_YANK_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
79 GET_COUNT:
80#endif
81
82#if !ENABLE_FEATURE_FANCY_HEAD
83 count = xatoul(p);
84#else
85 count = xatoul_sfx(p, head_suffixes);
86#endif
87 break;
88 default:
89 bb_show_usage();
90 }
91 }
92
93 argv += optind;
94 if (!*argv) {
95 *--argv = "-";
96 }
97
98 fmt = header_fmt_str + 1;
99#if ENABLE_FEATURE_FANCY_HEAD
100 if (argc - optind <= header_threshhold) {
101 header_threshhold = 0;
102 }
103#else
104 if (argc <= optind + 1) {
105 fmt += 11;
106 }
107 /* Now define some things here to avoid #ifdefs in the code below.
108 * These should optimize out of the if conditions below. */
109#define header_threshhold 1
110#define count_bytes 0
111#endif
112
113 do {
114 fp = fopen_or_warn_stdin(*argv);
115 if (fp) {
116 if (fp == stdin) {
117 *argv = (char *) bb_msg_standard_input;
118 }
119 if (header_threshhold) {
120 printf(fmt, *argv);
121 }
122 i = count;
123 while (i && ((c = getc(fp)) != EOF)) {
124 if (count_bytes || (c == '\n')) {
125 --i;
126 }
127 putchar(c);
128 }
129 if (fclose_if_not_stdin(fp)) {
130 bb_perror_msg("%s", *argv); /* Avoid multibyte problems. */
131 retval = EXIT_FAILURE;
132 }
133 die_if_ferror_stdout();
134 }
135 fmt = header_fmt_str;
136 } while (*++argv);
137
138 fflush_stdout_and_exit(retval);
139}