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/* dosbuf.c
Copyright (C) 1992, 1997-2002, 2004-2016 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 3, 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., 51 Franklin Street - Fifth Floor, Boston, MA
02110-1301, USA. */
/* Messy DOS-specific code for correctly treating binary, Unix text
and DOS text files.
This has several aspects:
* Guessing the file type (unless the user tells us);
* Stripping CR characters from DOS text files (otherwise regex
functions won't work correctly);
* Reporting correct byte count with -b for any kind of file.
*/
#include <config.h>
typedef enum {
UNKNOWN, DOS_BINARY, DOS_TEXT, UNIX_TEXT
} File_type;
struct dos_map {
off_t pos; /* position in buffer passed to matcher */
off_t add; /* how much to add when reporting char position */
};
static int dos_report_unix_offset = 0;
static File_type dos_file_type = UNKNOWN;
static File_type dos_use_file_type = UNKNOWN;
static off_t dos_stripped_crs = 0;
static struct dos_map *dos_pos_map;
static int dos_pos_map_size = 0;
static int dos_pos_map_used = 0;
static int inp_map_idx = 0, out_map_idx = 1;
/* Set default DOS file type to binary. */
static void
dos_binary (void)
{
if (O_BINARY)
dos_use_file_type = DOS_BINARY;
}
/* Tell DOS routines to report Unix offset. */
static void
dos_unix_byte_offsets (void)
{
if (O_BINARY)
dos_report_unix_offset = 1;
}
/* Guess DOS file type by looking at its contents. */
static File_type
guess_type (char *buf, size_t buflen)
{
int crlf_seen = 0;
char *bp = buf;
while (buflen--)
{
/* Treat a file as binary if it has a NUL character. */
if (!*bp)
return DOS_BINARY;
/* CR before LF means DOS text file (unless we later see
binary characters). */
else if (*bp == '\r' && buflen && bp[1] == '\n')
crlf_seen = 1;
bp++;
}
return crlf_seen ? DOS_TEXT : UNIX_TEXT;
}
/* Convert external DOS file representation to internal.
Return the count of bytes left in the buffer.
Build table to map character positions when reporting byte counts. */
static size_t
undossify_input (char *buf, size_t buflen)
{
if (! O_BINARY)
return buflen;
size_t bytes_left = 0;
if (totalcc == 0)
{
/* New file: forget everything we knew about character
position mapping table and file type. */
inp_map_idx = 0;
out_map_idx = 1;
dos_pos_map_used = 0;
dos_stripped_crs = 0;
dos_file_type = dos_use_file_type;
}
/* Guess if this file is binary, unless we already know that. */
if (dos_file_type == UNKNOWN)
dos_file_type = guess_type(buf, buflen);
/* If this file is to be treated as DOS Text, strip the CR characters
and maybe build the table for character position mapping on output. */
if (dos_file_type == DOS_TEXT)
{
char *destp = buf;
while (buflen--)
{
if (*buf != '\r')
{
*destp++ = *buf++;
bytes_left++;
}
else
{
buf++;
if (out_byte && !dos_report_unix_offset)
{
dos_stripped_crs++;
while (buflen && *buf == '\r')
{
dos_stripped_crs++;
buflen--;
buf++;
}
if (inp_map_idx >= dos_pos_map_size - 1)
{
dos_pos_map_size = inp_map_idx ? inp_map_idx * 2 : 1000;
dos_pos_map = xrealloc(dos_pos_map,
dos_pos_map_size *
sizeof(struct dos_map));
}
if (!inp_map_idx)
{
/* Add sentinel entry. */
dos_pos_map[inp_map_idx].pos = 0;
dos_pos_map[inp_map_idx++].add = 0;
/* Initialize first real entry. */
dos_pos_map[inp_map_idx].add = 0;
}
/* Put the new entry. If the stripped CR characters
precede a Newline (the usual case), pretend that
they were found *after* the Newline. This makes
displayed byte offsets more reasonable in some
cases, and fits better the intuitive notion that
the line ends *before* the CR, not *after* it. */
inp_map_idx++;
dos_pos_map[inp_map_idx-1].pos =
(*buf == '\n' ? destp + 1 : destp ) - bufbeg + totalcc;
dos_pos_map[inp_map_idx].add = dos_stripped_crs;
dos_pos_map_used = inp_map_idx;
/* The following will be updated on the next pass. */
dos_pos_map[inp_map_idx].pos = destp - bufbeg + totalcc + 1;
}
}
}
return bytes_left;
}
return buflen;
}
/* Convert internal byte count into external. */
static off_t
dossified_pos (off_t byteno)
{
if (! O_BINARY)
return byteno;
off_t pos_lo;
off_t pos_hi;
if (dos_file_type != DOS_TEXT || dos_report_unix_offset)
return byteno;
/* Optimization: usually the file will be scanned sequentially.
So in most cases, this byte position will be found in the
table near the previous one, as recorded in 'out_map_idx'. */
pos_lo = dos_pos_map[out_map_idx-1].pos;
pos_hi = dos_pos_map[out_map_idx].pos;
/* If the initial guess failed, search up or down, as
appropriate, beginning with the previous place. */
if (byteno >= pos_hi)
{
out_map_idx++;
while (out_map_idx < dos_pos_map_used
&& byteno >= dos_pos_map[out_map_idx].pos)
out_map_idx++;
}
else if (byteno < pos_lo)
{
out_map_idx--;
while (out_map_idx > 1 && byteno < dos_pos_map[out_map_idx-1].pos)
out_map_idx--;
}
return byteno + dos_pos_map[out_map_idx].add;
}
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