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/* SPDX-License-Identifier: GPL-3.0-or-later */
/*
* istream.c
*
* Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
*/
#include "internal.h"
sqfs_s32 istream_read(istream_t *strm, void *data, size_t size)
{
sqfs_s32 total = 0;
size_t diff;
if (size > 0x7FFFFFFF)
size = 0x7FFFFFFF;
while (size > 0) {
if (strm->buffer_offset >= strm->buffer_used) {
if (istream_precache(strm))
return -1;
if (strm->buffer_used == 0)
break;
}
diff = strm->buffer_used - strm->buffer_offset;
if (diff > size)
diff = size;
memcpy(data, strm->buffer + strm->buffer_offset, diff);
data = (char *)data + diff;
strm->buffer_offset += diff;
size -= diff;
total += diff;
}
return total;
}
int istream_precache(istream_t *strm)
{
if (strm->buffer_offset >= strm->buffer_used) {
strm->buffer_offset = 0;
strm->buffer_used = 0;
} else if (strm->buffer_offset > 0) {
memmove(strm->buffer,
strm->buffer + strm->buffer_offset,
strm->buffer_used - strm->buffer_offset);
strm->buffer_used -= strm->buffer_offset;
strm->buffer_offset = 0;
}
if (strm->eof)
return 0;
return strm->precache(strm);
}
int istream_skip(istream_t *strm, sqfs_u64 size)
{
size_t diff;
while (size > 0) {
if (strm->buffer_offset >= strm->buffer_used) {
if (istream_precache(strm))
return -1;
if (strm->buffer_used == 0) {
fprintf(stderr, "%s: unexpected end-of-file\n",
strm->get_filename(strm));
return -1;
}
}
diff = strm->buffer_used - strm->buffer_offset;
if ((sqfs_u64)diff > size)
diff = size;
strm->buffer_offset += diff;
size -= diff;
}
return 0;
}
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