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fileutil.zip
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HEAD.C
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1992-02-22
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/* head -- output first part of file(s)
Copyright (C) 1989, 1990 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 1, 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., 675 Mass Ave, Cambridge, MA 02139, USA. */
/* MS-DOS port (c) 1990 by Thorsten Ohl, ohl@gnu.ai.mit.edu
This port is also distributed under the terms of the
GNU General Public License as published by the
Free Software Foundation.
Please note that this file is not identical to the
original GNU release, you should have received this
code as patch to the official release. */
#ifdef MSDOS
static char RCS_Id[] =
"$Header: e:/gnu/fileutil/RCS/head.c 1.4.0.3 90/09/19 11:17:59 tho Exp $";
static char Program_Id[] = "head";
static char RCS_Revision[] = "$Revision: 1.4.0.3 $";
#define VERSION \
"GNU %s, Version %.*s (compiled %s %s for MS-DOS)\n", Program_Id, \
(sizeof RCS_Revision - 14), (RCS_Revision + 11), __DATE__, __TIME__
#define COPYING \
"This is free software, distributed under the terms of the\n" \
"GNU General Public License. For details, see the file COPYING.\n"
#endif /* MSDOS */
/* Usage: head [-b #] [-c #] [-n #] [-qv] [+blocks #] [+bytes #] [+lines #]
[+quiet] [+silent] [+verbose] [file...]
head [-#bclqv] [file...]
Options:
-b, +blocks # Print first # 512-byte blocks.
-c, +bytes # Print first # bytes.
-l, -n, +lines # Print first # lines.
-q, +quiet, +silent Never print filename headers.
-v, +verbose Always print filename headers.
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@ai.mit.edu> */
#include <stdio.h>
#include <getopt.h>
#include <ctype.h>
#include <sys/types.h>
#include "system.h"
#ifdef STDC_HEADERS
#include <errno.h>
#include <stdlib.h>
#define ISDIGIT(c) (isdigit ((unsigned char) (c)))
#else
#define ISDIGIT(c) (isascii (c) && isdigit (c))
extern int errno;
#endif
/* Number of lines/chars/blocks to head. */
#define DEFAULT_NUMBER 10
#define BLOCKSIZE 512
/* Size of atomic reads. */
#define BUFSIZE (BLOCKSIZE*8)
/* Masks for the operation mode. If neither BYTES nor BLOCKS is set,
head operates by lines. */
#define BYTES 1 /* Head in bytes. */
#define BLOCKS 2 /* Head in blocks. */
#define HEADERS 4 /* Write filename headers. */
#ifdef MSDOS
#define BINARY 32 /* Suppress crlf translation. */
#endif
/* When to print the filename banners. */
enum header_mode
{
multiple_files, always, never
};
#ifdef MSDOS
#include <string.h>
#include <stdarg.h>
#include <io.h>
#include <gnulib.h>
extern void main (int, char **);
extern int head_file (char *, int, long);
extern void write_header (char *);
extern int head (char *, int, int, long);
extern int head_bytes (char *, int, long);
extern int head_lines (char *, int, long);
extern void xwrite (int, char *, int);
extern long atou (char *);
extern char *basename (char *);
extern void usage (void);
#else /* not MSDOS */
int head ();
int head_bytes ();
int head_file ();
int head_lines ();
long atou ();
void error ();
void usage ();
void write_header ();
void xwrite ();
#endif /* MSDOS */
/* The name this program was run with. */
char *program_name;
struct option long_options[] =
{
#ifdef MSDOS
{"binary", 1, NULL, 'B'},
{"copying", 0, NULL, 30},
{"version", 0, NULL, 31},
#endif
{"blocks", 1, NULL, 'b'},
{"bytes", 1, NULL, 'c'},
{"lines", 1, NULL, 'n'},
{"quiet", 0, NULL, 'q'},
{"silent", 0, NULL, 'q'},
{"verbose", 0, NULL, 'v'},
{NULL, 0, NULL, 0}
};
void
main (argc, argv)
int argc;
char **argv;
{
enum header_mode header_mode = multiple_files;
int errors = 0; /* Exit status. */
int mode = 0; /* Flags. */
long number = -1; /* Number of items to print (-1 if undef.). */
int c; /* Option character. */
int longind; /* Index in `long_options' of option found. */
program_name = argv[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':
mode |= BLOCKS;
mode &= ~BYTES;
break;
case 'c':
mode |= BYTES;
mode &= ~BLOCKS;
break;
case 'l':
mode &= ~(BYTES | BLOCKS);
break;
case 'q':
header_mode = never;
break;
case 'v':
header_mode = always;
break;
default:
error (0, 0, "unrecognized option `-%c'", *argv[1]);
usage ();
}
++argv[1];
}
/* Make the options we just parsed invisible to getopt. */
argv[1] = argv[0];
argv++;
argc--;
}
#ifdef MSDOS
while ((c = getopt_long (argc, argv, "Bb:c:n:qv", long_options, &longind))
#else
while ((c = getopt_long (argc, argv, "b:c:n:qv", long_options, &longind))
#endif
!= EOF)
{
switch (c)
{
#ifdef MSDOS
case 30:
fprintf (stderr, COPYING);
exit (0);
break;
case 31:
fprintf (stderr, VERSION);
exit (0);
break;
case 'B':
mode |= BINARY;
break;
#endif
case 'b':
mode |= BLOCKS;
mode &= ~BYTES;
number = atou (optarg);
if (number == -1)
error (1, 0, "invalid number `%s'", optarg);
break;
case 'c':
mode |= BYTES;
mode &= ~BLOCKS;
number = atou (optarg);
if (number == -1)
error (1, 0, "invalid number `%s'", optarg);
break;
case 'n':
mode &= ~(BYTES | BLOCKS);
number = atou (optarg);
if (number == -1)
error (1, 0, "invalid number `%s'", optarg);
break;
case 'q':
header_mode = never;
break;
case 'v':
header_mode = always;
break;
default:
usage ();
}
}
if (number == -1)
number = DEFAULT_NUMBER;
if (mode & BLOCKS)
number *= BLOCKSIZE;
if (header_mode == always
|| header_mode == multiple_files && optind < argc - 1)
mode |= HEADERS;
if (optind == argc)
errors |= head_file ("-", mode, number);
for (; optind < argc; ++optind)
errors |= head_file (argv[optind], mode, number);
exit (errors);
}
int
head_file (filename, mode, number)
char *filename;
int mode;
long number;
{
int fd;
if (!strcmp (filename, "-"))
{
filename = "standard input";
if (mode & HEADERS)
write_header (filename);
return head (filename, 0, mode, number);
}
else
{
fd = open (filename, O_RDONLY);
if (fd == -1)
{
error (0, errno, "%s", filename);
return 1;
}
else
{
int errors;
if (mode & HEADERS)
write_header (filename);
errors = head (filename, fd, mode, number);
close (fd);
return errors;
}
}
}
void
write_header (filename)
char *filename;
{
static int first_file = 1;
if (first_file)
{
xwrite (1, "==> ", 4);
first_file = 0;
}
else
xwrite (1, "\n==> ", 5);
xwrite (1, filename, strlen (filename));
xwrite (1, " <==\n", 5);
}
int
head (filename, fd, mode, number)
char *filename;
int fd;
int mode;
long number;
{
#ifdef MSDOS
int errors;
if (mode & BINARY)
{
setmode (fileno (stdout), O_BINARY);
setmode (fd, O_BINARY);
}
if (mode & (BYTES | BLOCKS))
errors = head_bytes (filename, fd, number);
else
errors = head_lines (filename, fd, number);
if (mode & BINARY)
setmode (fileno (stdout), O_TEXT);
return errors;
#else /* not MSDOS */
if (mode & (BYTES | BLOCKS))
return head_bytes (filename, fd, number);
else
return head_lines (filename, fd, number);
#endif /* not MSDOS */
}
int
head_bytes (filename, fd, bytes_to_write)
char *filename;
int fd;
long bytes_to_write;
{
char buffer[BUFSIZE];
int bytes_read;
while (bytes_to_write)
{
bytes_read = read (fd, buffer, BUFSIZE);
if (bytes_read == -1)
{
error (0, errno, "%s", filename);
return 1;
}
if (bytes_read == 0)
break;
#ifdef MSDOS
if ((long) bytes_read > bytes_to_write)
bytes_read = (int) bytes_to_write;
xwrite (1, buffer, bytes_read);
bytes_to_write -= (long) bytes_read;
#else /* not MSDOS */
if (bytes_read > bytes_to_write)
bytes_read = bytes_to_write;
xwrite (1, buffer, bytes_read);
bytes_to_write -= bytes_read;
#endif /* not MSDOS */
}
return 0;
}
int
head_lines (filename, fd, lines_to_write)
char *filename;
int fd;
long lines_to_write;
{
char buffer[BUFSIZE];
int bytes_read;
int bytes_to_write;
while (lines_to_write)
{
bytes_read = read (fd, buffer, BUFSIZE);
if (bytes_read == -1)
{
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;
xwrite (1, buffer, bytes_to_write);
}
return 0;
}
/* Write plus error check. */
void
xwrite (fd, buffer, count)
int fd;
int count;
char *buffer;
{
fd = write (fd, buffer, count);
if (fd != count)
error (1, errno, "write error");
}
/* Convert `str', a string of ASCII digits, into an unsigned integer.
Return -1 if `str' does not represent a valid unsigned integer. */
long
atou (str)
char *str;
{
long value;
for (value = 0; ISDIGIT (*str); ++str)
value = value * 10 + *str - '0';
return *str ? -1L : value;
}
void
usage ()
{
#ifdef MSDOS
fprintf (stderr, "\
Usage: %s [-b #] [-c #] [-n #] [-qvB] [+blocks #] [+bytes #]\n\
[+lines #] [+quiet] [+silent] [+verbose] [+binary] [+version]\n\
[+copying] [file...]\n\
\n\
%s [-#bclqv] [file...]\n", program_name, program_name);
exit (1);
#else
fprintf (stderr, "\
Usage: %s [-b #] [-c #] [-n #] [-qv] [+blocks #] [+bytes #] [+lines #]\n\
[+quiet] [+silent] [+verbose] [file...]\n\
\n\
%s [-#bclqv] [file...]\n", program_name, program_name);
exit (1);
#endif
}