source: branches/3.2/mindi-busybox/coreutils/head.c @ 3232

Last change on this file since 3232 was 3232, checked in by bruno, 5 years ago
  • Update mindi-busybox to 1.21.1
File size: 3.5 KB
Line 
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//usage:#define head_trivial_usage
15//usage:       "[OPTIONS] [FILE]..."
16//usage:#define head_full_usage "\n\n"
17//usage:       "Print first 10 lines of each FILE (or stdin) to stdout.\n"
18//usage:       "With more than one FILE, precede each with a filename header.\n"
19//usage:     "\n    -n N[kbm]   Print first N lines"
20//usage:    IF_FEATURE_FANCY_HEAD(
21//usage:     "\n    -c N[kbm]   Print first N bytes"
22//usage:     "\n    -q      Never print headers"
23//usage:     "\n    -v      Always print headers"
24//usage:    )
25//usage:     "\n"
26//usage:     "\nN may be suffixed by k (x1024), b (x512), or m (x1024^2)."
27//usage:
28//usage:#define head_example_usage
29//usage:       "$ head -n 2 /etc/passwd\n"
30//usage:       "root:x:0:0:root:/root:/bin/bash\n"
31//usage:       "daemon:x:1:1:daemon:/usr/sbin:/bin/sh\n"
32
33#include "libbb.h"
34
35/* This is a NOEXEC applet. Be very careful! */
36
37static const char head_opts[] ALIGN1 =
38    "n:"
39#if ENABLE_FEATURE_FANCY_HEAD
40    "c:qv"
41#endif
42    ;
43
44static const struct suffix_mult head_suffixes[] = {
45    { "b", 512 },
46    { "k", 1024 },
47    { "m", 1024*1024 },
48    { "", 0 }
49};
50
51#define header_fmt_str "\n==> %s <==\n"
52
53int head_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
54int head_main(int argc, char **argv)
55{
56    unsigned long count = 10;
57    unsigned long i;
58#if ENABLE_FEATURE_FANCY_HEAD
59    int count_bytes = 0;
60    int header_threshhold = 1;
61#endif
62    FILE *fp;
63    const char *fmt;
64    char *p;
65    int opt;
66    int c;
67    int retval = EXIT_SUCCESS;
68
69#if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
70    /* Allow legacy syntax of an initial numeric option without -n. */
71    if (argv[1] && argv[1][0] == '-'
72     && isdigit(argv[1][1])
73    ) {
74        --argc;
75        ++argv;
76        p = (*argv) + 1;
77        goto GET_COUNT;
78    }
79#endif
80
81    /* No size benefit in converting this to getopt32 */
82    while ((opt = getopt(argc, argv, head_opts)) > 0) {
83        switch (opt) {
84#if ENABLE_FEATURE_FANCY_HEAD
85        case 'q':
86            header_threshhold = INT_MAX;
87            break;
88        case 'v':
89            header_threshhold = -1;
90            break;
91        case 'c':
92            count_bytes = 1;
93            /* fall through */
94#endif
95        case 'n':
96            p = optarg;
97#if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
98 GET_COUNT:
99#endif
100            count = xatoul_sfx(p, head_suffixes);
101            break;
102        default:
103            bb_show_usage();
104        }
105    }
106
107    argc -= optind;
108    argv += optind;
109    if (!*argv)
110        *--argv = (char*)"-";
111
112    fmt = header_fmt_str + 1;
113#if ENABLE_FEATURE_FANCY_HEAD
114    if (argc <= header_threshhold) {
115        header_threshhold = 0;
116    }
117#else
118    if (argc <= 1) {
119        fmt += 11; /* "" */
120    }
121    /* Now define some things here to avoid #ifdefs in the code below.
122     * These should optimize out of the if conditions below. */
123#define header_threshhold   1
124#define count_bytes         0
125#endif
126
127    do {
128        fp = fopen_or_warn_stdin(*argv);
129        if (fp) {
130            if (fp == stdin) {
131                *argv = (char *) bb_msg_standard_input;
132            }
133            if (header_threshhold) {
134                printf(fmt, *argv);
135            }
136            i = count;
137            while (i && ((c = getc(fp)) != EOF)) {
138                if (count_bytes || (c == '\n')) {
139                    --i;
140                }
141                putchar(c);
142            }
143            if (fclose_if_not_stdin(fp)) {
144                bb_simple_perror_msg(*argv);
145                retval = EXIT_FAILURE;
146            }
147            die_if_ferror_stdout();
148        } else {
149            retval = EXIT_FAILURE;
150        }
151        fmt = header_fmt_str;
152    } while (*++argv);
153
154    fflush_stdout_and_exit(retval);
155}
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