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/* catdvi - get text from DVI files
Copyright (C) 1999 J.H.M. Dassen (Ray) <jdassen@wi.LeidenUniv.nl>
Copyright (C) 1999 Antti-Juhani Kaijanaho <gaia@iki.fi>
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 of the License, 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.
*/
#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stddef.h>
#include <string.h>
#include "bytesex.h"
#include "util.h"
#define SKIPBYTES_BUFLEN 128
void efread(void *ptr, size_t size, size_t nmemb,
FILE *stream, char *errmsg)
{
if (fread(ptr, size, nmemb, stream) != nmemb) {
if (feof(stream)) {
panic("Unexpected end of file\n");
} else {
panic("%s\n", strerror(errno));
}
panic(errmsg);
}
}
byte readbyte(FILE * stream)
{
byte b;
efread(&b, 1, 1, stream, "Failed to read byte\n");
return b;
}
/* A portable reader for unsigned muli-octet big-endian numbers. */
uint32 u_readbigendiannumber(byte count, FILE *stream)
{
uint32 ures = 0;
int i;
unsigned char buf[4];
assert(count <= 4);
efread(buf, count, 1, stream, "Failed to read big endian number.\n");
/* We want to read one chunk of count bytes, not count chunks
* of one byte.
*/
for (i = 0; i < count; i++) {
ures = (ures << 8) + buf[i];
}
return ures;
}
/* An extremely portable reader for signed (two's complement)
muli-octet big-endian numbers. */
sint32 s_readbigendiannumber(byte count, FILE *stream)
{
uint32 ures;
const uint32 msb_bitmask = ((uint32) 1) << (8 * count - 1);
/* Beware of overflow! 2 * msb_bitmask may be too much for
uint32. */
const uint32 allset_bitmask = msb_bitmask + (msb_bitmask - 1);
assert(count <= 4);
/* First read the octets, taking care of the bytesex. */
ures = u_readbigendiannumber(count, stream);
assert(ures <= allset_bitmask);
/* We need to handle the sign conversion ourselves, as a
simple cast is implementation-defined. The value in ures
is in two's complement format. */
if (ures >= msb_bitmask) {
/* It is negative. */
return - (sint32) (ures ^ allset_bitmask) - 1;
}
else {
/* Positive (or 0). */
return ures;
}
}
void readbcblstring(byte * buffer, uint32 slen, FILE * fp)
{
uint32 len;
len = u_readbigendiannumber(1, fp);
if (len > slen - 1) {
warning("invalid BCBL string length");
len = 0;
}
if (len > 0) {
efread(buffer, 1, len, fp, "unable to read BCBL string");
}
buffer[len] = 0;
skipbytes(slen - len - 1, fp);
}
void skipbytes(int count, FILE *stream)
{
byte buf[SKIPBYTES_BUFLEN];
while (count > 0) {
int numbytes = count > SKIPBYTES_BUFLEN
? SKIPBYTES_BUFLEN
: count;
count = count - SKIPBYTES_BUFLEN;
efread(buf, 1, numbytes, stream,
"Error while skipping bytes\n");
}
}
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