Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Allow large VHD files #79

Merged
merged 3 commits into from
Sep 19, 2023
Merged

Allow large VHD files #79

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
0696f2e
Allow large VHD files
fysnet Sep 18, 2023
66095eb
Merge branch 'master' into vpc
fysnet Sep 18, 2023
057fe31
Add Error message for too large VHD images
fysnet Sep 18, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
39 changes: 36 additions & 3 deletions bochs/iodev/hdimage/vpc.cc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -166,11 +166,44 @@ int vpc_image_t::open(const char* _pathname, int flags)
cylinders = be16_to_cpu(footer->cyls);
heads = footer->heads;
spt = footer->secs_per_cyl;
sector_count = (Bit64u)(cylinders * heads * spt);
sector_count = (Bit64u)((Bit64u)cylinders * heads * spt);
sect_size = 512;
hd_size = sector_count * sect_size;

if (sector_count >= 65535 * 16 * 255) {
/* Microsoft Virtual PC and Microsoft Hyper-V produce and read
* VHD image sizes differently. VPC will rely on CHS geometry,
* while Hyper-V and disk2vhd use the size specified in the footer.
*
* We use a couple of approaches to try and determine the correct method:
* look at the Creator App field, and look for images that have CHS
* geometry that is the maximum value.
*
* If the CHS geometry is the maximum CHS geometry, then we assume that
* the size is the footer->size to avoid truncation. Otherwise,
* we follow the table based on footer->creator_app:
*
* Known creator apps:
* 'vpc ' : CHS Virtual PC (uses disk geometry)
* 'qemu' : CHS QEMU (uses disk geometry)
* 'qem2' : current_size QEMU (uses current_size)
* 'win ' : current_size Hyper-V
* 'd2v ' : current_size Disk2vhd
* 'tap\0' : current_size XenServer
* 'CTXS' : current_size XenConverter
*/
bool use_chs = (!!strncmp(footer->creator_app, "win ", 4) &&
!!strncmp(footer->creator_app, "qem2", 4) &&
!!strncmp(footer->creator_app, "d2v ", 4) &&
!!strncmp(footer->creator_app, "CTXS", 4) &&
!!memcmp (footer->creator_app, "tap", 4));

if (!use_chs || sector_count == (65535 * 16 * 255)) {
sector_count = be64_to_cpu(footer->size) / sect_size;
}
hd_size = sector_count * sect_size;

/* Allow a maximum disk size of 2040 GiB */
if (sector_count > 0xff000000) {
BX_ERROR(("VHD Emulated Image too large. " FMT_LL "i > 4278190080", sector_count));
bx_close_image(fd, pathname);
return -EFBIG;
}
Expand Down
6 changes: 3 additions & 3 deletions bochs/iodev/hdimage/vpc.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -69,7 +69,7 @@ typedef
__declspec(align(1))
#endif
struct vhd_footer_t {
Bit8u creator[8]; // "conectix"
char creator[8]; // "conectix"
Bit32u features;
Bit32u version;

Expand All @@ -79,10 +79,10 @@ struct vhd_footer_t {
// Seconds since Jan 1, 2000 0:00:00 (UTC)
Bit32u timestamp;

Bit8u creator_app[4]; // "vpc "
char creator_app[4]; // "vpc "
Bit16u major;
Bit16u minor;
Bit8u creator_os[4]; // "Wi2k"
char creator_os[4]; // "Wi2k"

Bit64u orig_size;
Bit64u size;
Expand Down