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winedos: Limit reported disk space to 1GB.

This commit is contained in:
Dan Kegel 2006-07-23 17:29:31 -07:00 committed by Alexandre Julliard
parent 75950b5bf8
commit 91f9746d2f
1 changed files with 52 additions and 3 deletions
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55
dlls/winedos/int21.c
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@ -3475,16 +3475,65 @@ static int INT21_GetFreeDiskSpace( CONTEXT86 *context )
{
DWORD cluster_sectors, sector_bytes, free_clusters, total_clusters;
WCHAR root[] = {'A',':','\\',0};
const DWORD max_clusters = 0x3d83;
const DWORD max_sectors_per_cluster = 0x7f;
const DWORD max_bytes_per_sector = 0x200;
root[0] += INT21_MapDrive(DL_reg(context));
if (!GetDiskFreeSpaceW( root, &cluster_sectors, &sector_bytes,
&free_clusters, &total_clusters )) return 0;
/* make sure that the number of clusters fits in a 16 bits value */
while( total_clusters & 0xffff0000) {
/* Some old win31 apps (Lotus SmartSuite 5.1) crap out if there's too
* much disk space, so Windows XP seems to apply the following limits:
* cluster_sectors <= 0x7f
* sector size <= 0x200
* clusters <= 0x3D83
* This means total reported space is limited to about 1GB.
*/
/* Make sure bytes-per-sector is in [, max] */
while (sector_bytes > max_bytes_per_sector) {
sector_bytes >>= 1;
free_clusters <<= 1;
total_clusters <<= 1;
}
/* Then make sure sectors-per-cluster is in [max/2, max]. */
while (cluster_sectors <= max_sectors_per_cluster/2) {
cluster_sectors <<= 1;
free_clusters >>= 1;
total_clusters >>= 1;
}
while (cluster_sectors > max_sectors_per_cluster) {
cluster_sectors >>= 1;
free_clusters <<= 1;
total_clusters <<= 1;
}
/* scale up sectors_per_cluster to exactly max_sectors_per_cluster.
* We could skip this, but that would impose an artificially low
* limit on reported disk space.
* To avoid overflow, first apply a preliminary cap on sector count;
* this will not affect the correctness of the final result,
* because if the preliminary cap hits, the final one will, too.
*/
if (total_clusters > 4 * max_clusters)
total_clusters = 4 * max_clusters;
if (free_clusters > 4 * max_clusters)
free_clusters = 4 * max_clusters;
if (cluster_sectors < max_sectors_per_cluster) {
free_clusters *= cluster_sectors;
free_clusters /= max_sectors_per_cluster;
total_clusters *= cluster_sectors;
total_clusters /= max_sectors_per_cluster;
cluster_sectors = max_sectors_per_cluster;
}
/* Finally, apply real cluster count cap. */
if (total_clusters > max_clusters)
total_clusters = max_clusters;
if (free_clusters > max_clusters)
free_clusters = max_clusters;
SET_AX( context, cluster_sectors );
SET_BX( context, free_clusters );
SET_CX( context, sector_bytes );
@ -4625,7 +4674,7 @@ void WINAPI DOSVM_Int21Handler( CONTEXT86 *context )
break;
case 0x36: /* GET FREE DISK SPACE */
TRACE("GET FREE DISK SPACE FOR DRIVE %s\n",
TRACE("GET FREE DISK SPACE FOR DRIVE %s (limited to about 1GB)\n",
INT21_DriveName( DL_reg(context) ));
if (!INT21_GetFreeDiskSpace(context)) SET_AX( context, 0xffff );
break;