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* fhandler.h (struct part_t): New type. 

(class fhandler_dev_floppy): Convert partitions to part_t pointer.
	Add lock_partition method.
	* fhandler_floppy.cc (fhandler_dev_floppy::lock_partition): New method
	to implement ondemand partition locking.
	(fhandler_dev_floppy::write_file): Call lock_partition from here if
	writing failed due to a potential write restriction on a disk
	partition.
	(fhandler_dev_floppy::open): Don't lock partitions here.
	(fhandler_dev_floppy::close): Keep track of partition handle reference
	count.  Close handles and remove partitions pointer ony if count is 0.
	(fhandler_dev_floppy::dup): Just copy partitions pointer and increment
	reference count.
This commit is contained in:
Corinna Vinschen 2011-01-12 09:16:51 +00:00
parent 95a5c969ab
commit 667f187146
3 changed files with 193 additions and 67 deletions
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16
winsup/cygwin/ChangeLog
View File

@ -1,3 +1,19 @@
2011-01-12 Corinna Vinschen <corinna@vinschen.de>
* fhandler.h (struct part_t): New type.
(class fhandler_dev_floppy): Convert partitions to part_t pointer.
Add lock_partition method.
* fhandler_floppy.cc (fhandler_dev_floppy::lock_partition): New method
to implement ondemand partition locking.
(fhandler_dev_floppy::write_file): Call lock_partition from here if
writing failed due to a potential write restriction on a disk
partition.
(fhandler_dev_floppy::open): Don't lock partitions here.
(fhandler_dev_floppy::close): Keep track of partition handle reference
count. Close handles and remove partitions pointer ony if count is 0.
(fhandler_dev_floppy::dup): Just copy partitions pointer and increment
reference count.
2011-01-11 Corinna Vinschen <corinna@vinschen.de>
* fhandler.h (MAX_PARTITIONS): New definition.

10
winsup/cygwin/fhandler.h
View File

@ -689,12 +689,18 @@ class fhandler_dev_raw: public fhandler_base
#define MAX_PARTITIONS 15
struct part_t
{
LONG refcnt;
HANDLE hdl[MAX_PARTITIONS];
};
class fhandler_dev_floppy: public fhandler_dev_raw
{
private:
_off64_t drive_size;
unsigned long bytes_per_sector;
HANDLE partitions[MAX_PARTITIONS];
part_t *partitions;
struct status_flags
{
unsigned eom_detected : 1;
@ -707,6 +713,8 @@ class fhandler_dev_floppy: public fhandler_dev_raw
inline _off64_t get_current_position ();
int get_drive_info (struct hd_geometry *geo);
int lock_partition (DWORD to_write);
BOOL write_file (const void *buf, DWORD to_write, DWORD *written, int *err);
BOOL read_file (void *buf, DWORD to_read, DWORD *read, int *err);

234
winsup/cygwin/fhandler_floppy.cc
View File

@ -11,6 +11,7 @@ Cygwin license. Please consult the file "CYGWIN_LICENSE" for
details. */
#include "winsup.h"
#include <alloca.h>
#include <unistd.h>
#include <winioctl.h>
#include <cygwin/rdevio.h>
@ -32,7 +33,6 @@ details. */
fhandler_dev_floppy::fhandler_dev_floppy ()
: fhandler_dev_raw (), status ()
{
memset (partitions, 0, sizeof partitions);
}
int
@ -180,6 +180,143 @@ fhandler_dev_floppy::read_file (void *buf, DWORD to_read, DWORD *read, int *err)
return ret;
}
/* See comment in write_file below. */
BOOL
fhandler_dev_floppy::lock_partition (DWORD to_write)
{
DWORD bytes_read;
/* The simple case. We have only a single partition open anyway.
Try to lock the partition so that a subsequent write succeeds.
If there's some file handle open on one of the affected partitions,
this fails, but that's how it works on Vista and later... */
if (get_minor () % 16 != 0)
{
if (!DeviceIoControl (get_handle (), FSCTL_LOCK_VOLUME,
NULL, 0, NULL, 0, &bytes_read, NULL))
{
debug_printf ("DeviceIoControl (FSCTL_LOCK_VOLUME) failed, %E");
return FALSE;
}
return TRUE;
}
/* The tricky case. We're writing to the entire disk. What this code
basically does is to find out if the current write operation affects
one or more partitions on the disk. If so, it tries to lock all these
partitions and stores the handles for a subsequent close(). */
NTSTATUS status;
IO_STATUS_BLOCK io;
FILE_POSITION_INFORMATION fpi;
/* Allocate space for 4 times the maximum partition count we can handle.
The reason is that for *every* single logical drive in an extended
partition on an MBR drive, 3 filler entries with partition number set
to 0 are added into the partition table returned by
IOCTL_DISK_GET_DRIVE_LAYOUT_EX. The first of them reproduces the data
of the next partition entry, if any, except for the partiton number.
Then two entries with everything set to 0 follow. Well, the
documentation states that for MBR drives the number of partition entries
in the PARTITION_INFORMATION_EX array is always a multiple of 4, but,
nevertheless, how crappy is that layout? */
const DWORD size = sizeof (DRIVE_LAYOUT_INFORMATION_EX)
+ 4 * MAX_PARTITIONS * sizeof (PARTITION_INFORMATION_EX);
PDRIVE_LAYOUT_INFORMATION_EX pdlix = (PDRIVE_LAYOUT_INFORMATION_EX)
alloca (size);
BOOL found = FALSE;
/* Fetch current file pointer position on disk. */
status = NtQueryInformationFile (get_handle (), &io, &fpi, sizeof fpi,
FilePositionInformation);
if (!NT_SUCCESS (status))
{
debug_printf ("NtQueryInformationFile(FilePositionInformation): %p",
status);
return FALSE;
}
/* Fetch drive layout to get start and end positions of partitions on disk. */
if (!DeviceIoControl (get_handle (), IOCTL_DISK_GET_DRIVE_LAYOUT_EX, NULL, 0,
pdlix, size, &bytes_read, NULL))
{
debug_printf ("DeviceIoControl(IOCTL_DISK_GET_DRIVE_LAYOUT_EX): %E");
return FALSE;
}
/* Scan through partition info to find the partition(s) into which we're
currently trying to write. */
PARTITION_INFORMATION_EX *ppie = pdlix->PartitionEntry;
for (DWORD i = 0; i < pdlix->PartitionCount; ++i, ++ppie)
{
/* A partition number of 0 denotes an extended partition or one of the
aforementioned filler entries. Just skip. */
if (ppie->PartitionNumber == 0)
continue;
/* Check if our writing range affects this partition. */
if (fpi.CurrentByteOffset.QuadPart < ppie->StartingOffset.QuadPart
+ ppie->PartitionLength.QuadPart
&& ppie->StartingOffset.QuadPart < fpi.CurrentByteOffset.QuadPart
+ to_write)
{
/* Yes. Now check if we can handle it. We can only handle
up to MAX_PARTITIONS partitions. The partition numbering is
one-based, so we decrement the partition number by 1 when using
as index into the partition array. */
DWORD &part_no = ppie->PartitionNumber;
if (part_no >= MAX_PARTITIONS)
return FALSE;
found = TRUE;
debug_printf ("%d %D->%D : %D->%D", part_no,
ppie->StartingOffset.QuadPart,
ppie->StartingOffset.QuadPart
+ ppie->PartitionLength.QuadPart,
fpi.CurrentByteOffset.QuadPart,
fpi.CurrentByteOffset.QuadPart + to_write);
/* Do we already have partitions? If not, create it. */
if (!partitions)
{
partitions = (part_t *) ccalloc_abort (HEAP_FHANDLER, 1,
sizeof (part_t));
partitions->refcnt = 1;
}
/* Next, check if the partition is already open. If so, skip it. */
if (partitions->hdl[part_no - 1])
continue;
/* Now open the partition and lock it. */
WCHAR part[MAX_PATH], *p;
NTSTATUS status;
UNICODE_STRING upart;
OBJECT_ATTRIBUTES attr;
IO_STATUS_BLOCK io;
sys_mbstowcs (part, MAX_PATH, get_win32_name ());
p = wcschr (part, L'\0') - 1;
__small_swprintf (p, L"%d", part_no);
RtlInitUnicodeString (&upart, part);
InitializeObjectAttributes (&attr, &upart,
OBJ_CASE_INSENSITIVE
| ((get_flags () & O_CLOEXEC)
? 0 : OBJ_INHERIT),
NULL, NULL);
status = NtOpenFile (&partitions->hdl[part_no - 1],
GENERIC_READ | GENERIC_WRITE, &attr,
&io, FILE_SHARE_READ | FILE_SHARE_WRITE, 0);
if (!NT_SUCCESS (status))
{
debug_printf ("NtCreateFile(%W): %p", part, status);
return FALSE;
}
if (!DeviceIoControl (partitions->hdl[part_no - 1], FSCTL_LOCK_VOLUME,
NULL, 0, NULL, 0, &bytes_read, NULL))
{
debug_printf ("DeviceIoControl (%W, FSCTL_LOCK_VOLUME) "
"failed, %E", part);
return FALSE;
}
}
}
/* If we didn't find a single matching partition, the "Access denied"
had another reason, so return FALSE in that case. */
return found;
}
BOOL
fhandler_dev_floppy::write_file (const void *buf, DWORD to_write,
DWORD *written, int *err)
@ -189,6 +326,24 @@ fhandler_dev_floppy::write_file (const void *buf, DWORD to_write,
*err = 0;
if (!(ret = WriteFile (get_handle (), buf, to_write, written, 0)))
*err = GetLastError ();
/* When writing to a disk or partition on Vista, an "Access denied" error
is potentially a result of the raw disk write restriction. See
http://support.microsoft.com/kb/942448 for details. What we have to
do here is to lock the partition and retry. The previous solution
locked one or all partitions immediately in open. Which is overly
wasteful, given that the user might only want to change, say, the boot
sector. */
if (*err == ERROR_ACCESS_DENIED
&& wincap.has_restricted_raw_disk_access ()
&& get_major () != DEV_FLOPPY_MAJOR
&& get_major () != DEV_CDROM_MAJOR
&& (get_flags () & O_ACCMODE) != O_RDONLY
&& lock_partition (to_write))
{
*err = 0;
if (!(ret = WriteFile (get_handle (), buf, to_write, written, 0)))
*err = GetLastError ();
}
syscall_printf ("%d (err %d) = WriteFile (%d, %d, write %d, written %d, 0)",
ret, *err, get_handle (), buf, to_write, *written);
return ret;
@ -227,52 +382,6 @@ fhandler_dev_floppy::open (int flags, mode_t)
NULL, 0, NULL, 0, &bytes_read, NULL))
debug_printf ("DeviceIoControl (FSCTL_ALLOW_EXTENDED_DASD_IO) "
"failed, %E");
/* If we're trying to write to a disk partition, lock the partition,
otherwise we will get "Access denied" starting with Vista. */
if (wincap.has_restricted_raw_disk_access ()
&& get_major () != DEV_FLOPPY_MAJOR
&& get_major () != DEV_CDROM_MAJOR
&& (flags & O_ACCMODE) != O_RDONLY)
{
/* Special case: If we try to write to the entire disk, we have to
lock all partitions, otherwise writing fails as soon as we cross
a partition boundary. */
if (get_minor () % 16 == 0)
{
WCHAR part[MAX_PATH], *p;
sys_mbstowcs (part, MAX_PATH, get_win32_name ());
p = wcschr (part, L'\0') - 1;
for (int i = 0; i < MAX_PARTITIONS; ++i)
{
NTSTATUS status;
UNICODE_STRING upart;
OBJECT_ATTRIBUTES attr;
IO_STATUS_BLOCK io;
__small_swprintf (p, L"%d", i + 1);
RtlInitUnicodeString (&upart, part);
InitializeObjectAttributes (&attr, &upart,
OBJ_INHERIT|OBJ_CASE_INSENSITIVE,
NULL, NULL);
status = NtOpenFile (&partitions[i], GENERIC_WRITE, &attr,
&io, FILE_SHARE_VALID_FLAGS, 0);
if (status == STATUS_OBJECT_NAME_NOT_FOUND ||
status == STATUS_OBJECT_PATH_NOT_FOUND)
break;
else if (!NT_SUCCESS (status))
debug_printf ("NtCreateFile(%W): status %p", part, status);
else if (!DeviceIoControl (partitions[i], FSCTL_LOCK_VOLUME,
NULL, 0, NULL, 0,
&bytes_read, NULL))
debug_printf ("DeviceIoControl (%W, FSCTL_LOCK_VOLUME) "
"failed, %E", part);
}
}
else if (!DeviceIoControl (get_handle (), FSCTL_LOCK_VOLUME,
NULL, 0, NULL, 0, &bytes_read, NULL))
debug_printf ("DeviceIoControl (FSCTL_LOCK_VOLUME) failed, %E");
}
}
return ret;
@ -283,11 +392,13 @@ fhandler_dev_floppy::close ()
{
int ret = fhandler_dev_raw::close ();
/* See "Special case" comment in fhandler_dev_floppy::open. */
if (wincap.has_restricted_raw_disk_access ())
for (int i = 0; i < MAX_PARTITIONS && partitions[i]; ++i)
NtClose (partitions[i]);
if (partitions && InterlockedDecrement (&partitions->refcnt) == 0)
{
for (int i = 0; i < MAX_PARTITIONS; ++i)
if (partitions->hdl[i])
NtClose (partitions->hdl[i]);
cfree (partitions);
}
return ret;
}
@ -296,26 +407,17 @@ fhandler_dev_floppy::dup (fhandler_base *child)
{
fhandler_dev_floppy *fhc = (fhandler_dev_floppy *) child;
/* See "Special case" comment in fhandler_dev_floppy::open. */
memset (fhc->partitions, 0, sizeof fhc->partitions);
if (wincap.has_restricted_raw_disk_access ())
for (int i = 0; i < MAX_PARTITIONS && partitions[i]; ++i)
if (!DuplicateHandle (GetCurrentProcess (), partitions[i],
GetCurrentProcess (), &fhc->partitions[i],
0, TRUE, DUPLICATE_SAME_ACCESS))
{
__seterrno ();
while (--i >= 0)
NtClose (partitions[i]);
return -1;
}
int ret = fhandler_dev_raw::dup (child);
if (!ret)
{
fhc->drive_size = drive_size;
fhc->bytes_per_sector = bytes_per_sector;
if (partitions)
{
InterlockedIncrement (&partitions->refcnt);
fhc->partitions = partitions;
}
fhc->eom_detected (eom_detected ());
}
return ret;