diff options
Diffstat (limited to 'coreutils/head.c')
-rw-r--r-- | coreutils/head.c | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/coreutils/head.c b/coreutils/head.c new file mode 100644 index 0000000..570f140 --- /dev/null +++ b/coreutils/head.c @@ -0,0 +1,140 @@ +/* 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 tarball for details. + */ + +/* 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 */ + +#include "libbb.h" + +static const char head_opts[] ALIGN1 = + "n:" +#if ENABLE_FEATURE_FANCY_HEAD + "c:qv" +#endif + ; + +#if ENABLE_FEATURE_FANCY_HEAD +static const struct suffix_mult head_suffixes[] = { + { "b", 512 }, + { "k", 1024 }, + { "m", 1024*1024 }, + { } +}; +#endif + +static const char header_fmt_str[] ALIGN1 = "\n==> %s <==\n"; + +int head_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; +int head_main(int argc, char **argv) +{ + unsigned long count = 10; + unsigned long i; +#if ENABLE_FEATURE_FANCY_HEAD + int count_bytes = 0; + int header_threshhold = 1; +#endif + + FILE *fp; + const char *fmt; + char *p; + int opt; + int c; + int retval = EXIT_SUCCESS; + +#if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD + /* Allow legacy syntax of an initial numeric option without -n. */ + if (argc > 1 && argv[1][0] == '-' + && isdigit(argv[1][1]) + ) { + --argc; + ++argv; + p = (*argv) + 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 + +#if !ENABLE_FEATURE_FANCY_HEAD + count = xatoul(p); +#else + count = xatoul_sfx(p, head_suffixes); +#endif + break; + default: + bb_show_usage(); + } + } + + argc -= optind; + argv += optind; + if (!*argv) + *--argv = (char*)"-"; + + fmt = header_fmt_str + 1; +#if ENABLE_FEATURE_FANCY_HEAD + if (argc <= header_threshhold) { + header_threshhold = 0; + } +#else + if (argc <= 1) { + fmt += 11; /* "" */ + } + /* Now define some things here to avoid #ifdefs in the code below. + * These should optimize out of the if conditions below. */ +#define header_threshhold 1 +#define count_bytes 0 +#endif + + do { + fp = fopen_or_warn_stdin(*argv); + if (fp) { + if (fp == stdin) { + *argv = (char *) bb_msg_standard_input; + } + if (header_threshhold) { + printf(fmt, *argv); + } + i = count; + while (i && ((c = getc(fp)) != EOF)) { + if (count_bytes || (c == '\n')) { + --i; + } + putchar(c); + } + if (fclose_if_not_stdin(fp)) { + bb_simple_perror_msg(*argv); /* Avoid multibyte problems. */ + retval = EXIT_FAILURE; + } + die_if_ferror_stdout(); + } + fmt = header_fmt_str; + } while (*++argv); + + fflush_stdout_and_exit(retval); +} |