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/* head -- output first part of file(s)
Copyright (C) 89, 90, 91, 95, 96, 1997, 1998 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
/* Options: (see usage)
Reads from standard input if no files are given or when a filename of
``-'' is encountered.
By default, filename headers are printed only if more than one file
is given.
By default, prints the first 10 lines (head -n 10).
David MacKenzie <djm@gnu.ai.mit.edu> */
#include <config.h>
#include <stdio.h>
#include <getopt.h>
#include <sys/types.h>
#include "system.h"
#include "error.h"
#include "xstrtoul.h"
#include "safe-read.h"
/* FIXME: someday, make this really *be* `long long'. */
typedef long int U_LONG_LONG;
/* Number of lines/chars/blocks to head. */
#define DEFAULT_NUMBER 10
/* Size of atomic reads. */
#define BUFSIZE (512 * 8)
/* If nonzero, print filename headers. */
static int print_headers;
/* When to print the filename banners. */
enum header_mode
{
multiple_files, always, never
};
/* The name this program was run with. */
char *program_name;
/* Have we ever read standard input? */
static int have_read_stdin;
/* If nonzero, display usage information and exit. */
static int show_help;
/* If nonzero, print the version on standard output then exit. */
static int show_version;
static struct option const long_options[] =
{
{"bytes", required_argument, NULL, 'c'},
{"lines", required_argument, NULL, 'n'},
{"quiet", no_argument, NULL, 'q'},
{"silent", no_argument, NULL, 'q'},
{"verbose", no_argument, NULL, 'v'},
{"help", no_argument, &show_help, 1},
{"version", no_argument, &show_version, 1},
{NULL, 0, NULL, 0}
};
static void
usage (int status)
{
if (status != 0)
fprintf (stderr, _("Try `%s --help' for more information.\n"),
program_name);
else
{
printf (_("\
Usage: %s [OPTION]... [FILE]...\n\
"),
program_name);
printf (_("\
Print first 10 lines of each FILE to standard output.\n\
With more than one FILE, precede each with a header giving the file name.\n\
With no FILE, or when FILE is -, read standard input.\n\
\n\
-c, --bytes=SIZE print first SIZE bytes\n\
-n, --lines=NUMBER print first NUMBER lines instead of first 10\n\
-q, --quiet, --silent never print headers giving file names\n\
-v, --verbose always print headers giving file names\n\
--help display this help and exit\n\
--version output version information and exit\n\
\n\
SIZE may have a multiplier suffix: b for 512, k for 1K, m for 1 Meg.\n\
If -VALUE is used as first OPTION, read -c VALUE when one of\n\
multipliers bkm follows concatenated, else read -n VALUE.\n\
"));
puts (_("\nReport bugs to <textutils-bugs@gnu.org>."));
}
exit (status == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
}
static void
write_header (const char *filename)
{
static int first_file = 1;
printf ("%s==> %s <==\n", (first_file ? "" : "\n"), filename);
first_file = 0;
}
static int
head_bytes (const char *filename, int fd, U_LONG_LONG bytes_to_write)
{
char buffer[BUFSIZE];
int bytes_read;
while (bytes_to_write)
{
bytes_read = safe_read (fd, buffer, BUFSIZE);
if (bytes_read < 0)
{
error (0, errno, "%s", filename);
return 1;
}
if (bytes_read == 0)
break;
if (bytes_read > bytes_to_write)
bytes_read = bytes_to_write;
if (fwrite (buffer, 1, bytes_read, stdout) == 0)
error (EXIT_FAILURE, errno, _("write error"));
bytes_to_write -= bytes_read;
}
return 0;
}
static int
head_lines (const char *filename, int fd, U_LONG_LONG lines_to_write)
{
char buffer[BUFSIZE];
int bytes_read;
int bytes_to_write;
while (lines_to_write)
{
bytes_read = safe_read (fd, buffer, BUFSIZE);
if (bytes_read < 0)
{
error (0, errno, "%s", filename);
return 1;
}
if (bytes_read == 0)
break;
bytes_to_write = 0;
while (bytes_to_write < bytes_read)
if (buffer[bytes_to_write++] == '\n' && --lines_to_write == 0)
break;
if (fwrite (buffer, 1, bytes_to_write, stdout) == 0)
error (EXIT_FAILURE, errno, _("write error"));
}
return 0;
}
static int
head (const char *filename, int fd, U_LONG_LONG n_units, int count_lines)
{
if (count_lines)
return head_lines (filename, fd, n_units);
else
return head_bytes (filename, fd, n_units);
}
static int
head_file (const char *filename, U_LONG_LONG n_units, int count_lines)
{
int fd;
if (!strcmp (filename, "-"))
{
have_read_stdin = 1;
filename = _("standard input");
if (print_headers)
write_header (filename);
return head (filename, 0, n_units, count_lines);
}
else
{
fd = open (filename, O_RDONLY);
if (fd >= 0)
{
int errors;
if (print_headers)
write_header (filename);
errors = head (filename, fd, n_units, count_lines);
if (close (fd) == 0)
return errors;
}
error (0, errno, "%s", filename);
return 1;
}
}
/* Convert a string of digits, N_STRING, with a single, optional suffix
character (b, k, or m) to an integral value. Upon successful conversion,
return that value. If it cannot be converted, give a diagnostic and exit.
COUNT_LINES indicates whether N_STRING is a number of bytes or a number
of lines. It is used solely to give a more specific diagnostic. */
static U_LONG_LONG
string_to_ull (int count_lines, const char *n_string)
{
strtol_error s_err;
unsigned long int tmp_ulong;
s_err = xstrtoul (n_string, NULL, 0, &tmp_ulong, "bkm");
if (s_err == LONGINT_INVALID)
{
error (EXIT_FAILURE, 0, "%s: %s", n_string,
(count_lines
? _("invalid number of lines")
: _("invalid number of bytes")));
}
if (s_err != LONGINT_OK)
{
error (EXIT_FAILURE, 0,
_("%s: %s is so large that it is not representable"), n_string,
count_lines ? _("number of lines") : _("number of bytes"));
}
return tmp_ulong;
}
int
main (int argc, char **argv)
{
enum header_mode header_mode = multiple_files;
int exit_status = 0;
char *n_string;
int c;
/* Number of items to print. */
U_LONG_LONG n_units = DEFAULT_NUMBER;
/* If nonzero, interpret the numeric argument as the number of lines.
Otherwise, interpret it as the number of bytes. */
int count_lines = 1;
program_name = argv[0];
setlocale (LC_ALL, "");
bindtextdomain (PACKAGE, LOCALEDIR);
textdomain (PACKAGE);
have_read_stdin = 0;
print_headers = 0;
if (argc > 1 && argv[1][0] == '-' && ISDIGIT (argv[1][1]))
{
char *end_n_string;
char multiplier_char = 0;
n_string = &argv[1][1];
/* Old option syntax; a dash, one or more digits, and one or
more option letters. Move past the number. */
for (++argv[1]; ISDIGIT (*argv[1]); ++argv[1])
{
/* empty */
}
/* Pointer to the byte after the last digit. */
end_n_string = argv[1];
/* Parse any appended option letters. */
while (*argv[1])
{
switch (*argv[1])
{
case 'c':
count_lines = 0;
multiplier_char = 0;
break;
case 'b':
case 'k':
case 'm':
count_lines = 0;
multiplier_char = *argv[1];
break;
case 'l':
count_lines = 1;
break;
case 'q':
header_mode = never;
break;
case 'v':
header_mode = always;
break;
default:
error (0, 0, _("unrecognized option `-%c'"), *argv[1]);
usage (1);
}
++argv[1];
}
/* Append the multiplier character (if any) onto the end of
the digit string. Then add NUL byte if necessary. */
*end_n_string = multiplier_char;
if (multiplier_char)
*(++end_n_string) = 0;
n_units = string_to_ull (count_lines, n_string);
/* Make the options we just parsed invisible to getopt. */
argv[1] = argv[0];
argv++;
argc--;
/* FIXME: allow POSIX options if there were obsolescent ones? */
}
while ((c = getopt_long (argc, argv, "c:n:qv", long_options, NULL)) != -1)
{
switch (c)
{
case 0:
break;
case 'c':
count_lines = 0;
n_units = string_to_ull (count_lines, optarg);
break;
case 'n':
count_lines = 1;
n_units = string_to_ull (count_lines, optarg);
break;
case 'q':
header_mode = never;
break;
case 'v':
header_mode = always;
break;
default:
usage (1);
}
}
if (show_version)
{
printf ("head (%s) %s\n", GNU_PACKAGE, VERSION);
exit (EXIT_SUCCESS);
}
if (show_help)
usage (0);
if (header_mode == always
|| (header_mode == multiple_files && optind < argc - 1))
print_headers = 1;
if (optind == argc)
exit_status |= head_file ("-", n_units, count_lines);
for (; optind < argc; ++optind)
exit_status |= head_file (argv[optind], n_units, count_lines);
if (have_read_stdin && close (0) < 0)
error (EXIT_FAILURE, errno, "-");
if (fclose (stdout) == EOF)
error (EXIT_FAILURE, errno, _("write error"));
exit (exit_status == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
}
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