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/* head -- output first part of file(s)
Copyright (C) 89, 90, 91, 95, 1996 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"
/* Number of lines/chars/blocks to head. */
#define DEFAULT_NUMBER 10
/* Size of atomic reads. */
#define BUFSIZE (512 * 8)
/* Number of bytes per item we are printing.
If 0, head in lines. */
static int unit_size;
/* If nonzero, print filename headers. */
static int print_headers;
/* When to print the filename banners. */
enum header_mode
{
multiple_files, always, never
};
int safe_read ();
/* 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.ai.mit.edu"));
}
exit (status == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
}
/* Convert STR, a string of ASCII digits, into an unsigned integer.
Return -1 if STR does not represent a valid unsigned integer. */
static long
atou (const char *str)
{
int value;
for (value = 0; ISDIGIT (*str); ++str)
value = value * 10 + *str - '0';
return *str ? -1 : value;
}
static void
parse_unit (char *str)
{
int arglen = strlen (str);
if (arglen == 0)
return;
switch (str[arglen - 1])
{
case 'b':
unit_size = 512;
str[arglen - 1] = '\0';
break;
case 'k':
unit_size = 1024;
str[arglen - 1] = '\0';
break;
case 'm':
unit_size = 1048576;
str[arglen - 1] = '\0';
break;
}
}
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, long int 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, long int 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, long int number)
{
if (unit_size)
return head_bytes (filename, fd, number);
else
return head_lines (filename, fd, number);
}
static int
head_file (const char *filename, long int number)
{
int fd;
if (!strcmp (filename, "-"))
{
have_read_stdin = 1;
filename = _("standard input");
if (print_headers)
write_header (filename);
return head (filename, 0, number);
}
else
{
fd = open (filename, O_RDONLY);
if (fd >= 0)
{
int errors;
if (print_headers)
write_header (filename);
errors = head (filename, fd, number);
if (close (fd) == 0)
return errors;
}
error (0, errno, "%s", filename);
return 1;
}
}
int
main (int argc, char **argv)
{
enum header_mode header_mode = multiple_files;
int exit_status = 0;
long number = -1; /* Number of items to print (-1 if undef.). */
int c; /* Option character. */
program_name = argv[0];
setlocale (LC_ALL, "");
bindtextdomain (PACKAGE, LOCALEDIR);
textdomain (PACKAGE);
have_read_stdin = 0;
unit_size = 0;
print_headers = 0;
if (argc > 1 && argv[1][0] == '-' && ISDIGIT (argv[1][1]))
{
/* Old option syntax; a dash, one or more digits, and one or
more option letters. Move past the number. */
for (number = 0, ++argv[1]; ISDIGIT (*argv[1]); ++argv[1])
number = number * 10 + *argv[1] - '0';
/* Parse any appended option letters. */
while (*argv[1])
{
switch (*argv[1])
{
case 'b':
unit_size = 512;
break;
case 'c':
unit_size = 1;
break;
case 'k':
unit_size = 1024;
break;
case 'l':
unit_size = 0;
break;
case 'm':
unit_size = 1048576;
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];
}
/* Make the options we just parsed invisible to getopt. */
argv[1] = argv[0];
argv++;
argc--;
}
while ((c = getopt_long (argc, argv, "c:n:qv", long_options, NULL)) != -1)
{
switch (c)
{
case 0:
break;
case 'c':
unit_size = 1;
parse_unit (optarg);
goto getnum;
case 'n':
unit_size = 0;
getnum:
/* FIXME: use xstrtoul instead. */
number = atou (optarg);
if (number == -1)
error (EXIT_FAILURE, 0, _("invalid number `%s'"), 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 (number == -1)
number = DEFAULT_NUMBER;
if (unit_size > 1)
number *= unit_size;
if (header_mode == always
|| (header_mode == multiple_files && optind < argc - 1))
print_headers = 1;
if (optind == argc)
exit_status |= head_file ("-", number);
for (; optind < argc; ++optind)
exit_status |= head_file (argv[optind], number);
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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