* path.cc (struct _FAST_CWD): Redefine to new layout used since patch
for KB 2393802. Adjust comments throughout. (struct _FAST_CWD_OLD): Rename former definition. (cwdstuff::override_win32_cwd): Check if the OS is using the old or the new FAST_CWD structure layout and handle accordingly.
This commit is contained in:
Corinna Vinschen
parent
8447bf9f9f
commit
32d86d2ab2
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@ -1,3 +1,11 @@
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2011-02-13 Corinna Vinschen <corinna@vinschen.de>
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* path.cc (struct _FAST_CWD): Redefine to new layout used since patch
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for KB 2393802. Adjust comments throughout.
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(struct _FAST_CWD_OLD): Rename former definition.
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(cwdstuff::override_win32_cwd): Check if the OS is using the old or the
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new FAST_CWD structure layout and handle accordingly.
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2011-02-11 Christopher Faylor <me+cygwin@cgf.cx>
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* mkstatic: Make sure that we are not cd'ed to temporary directory on
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@ -3432,6 +3432,20 @@ cygwin_split_path (const char *path, char *dir, char *file)
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minimal locking and it's much more multi-thread friendly. Presumably
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it minimizes contention when accessing the CWD. */
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typedef struct _FAST_CWD {
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UNICODE_STRING Path; /* Path's Buffer member always refers
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to the following Buffer array. */
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HANDLE DirectoryHandle;
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LONG FSCharacteristics; /* Taken from FileFsDeviceInformation */
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LONG ReferenceCount; /* Only release when this is 0. */
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ULONG OldDismountCount; /* Reflects the system DismountCount
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at the time the CWD has been set. */
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WCHAR Buffer[MAX_PATH];
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} FAST_CWD, *PFAST_CWD;
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/* This is the old FAST_CWD structure up to the patch from KB 2393802,
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release in February 2011. Hopefully it's not used for long anymore,
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but for quite some time we can't rely on this fact. */
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typedef struct _FAST_CWD_OLD {
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LONG ReferenceCount; /* Only release when this is 0. */
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HANDLE DirectoryHandle;
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ULONG OldDismountCount; /* Reflects the system DismountCount
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@ -3439,7 +3453,7 @@ typedef struct _FAST_CWD {
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UNICODE_STRING Path; /* Path's Buffer member always refers
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to the following Buffer array. */
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WCHAR Buffer[MAX_PATH];
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} FAST_CWD, *PFAST_CWD;
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} FAST_CWD_OLD, *PFAST_CWD_OLD;
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/* fast_cwd_ptr is a pointer to the global pointer in ntdll.dll pointing
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to the FAST_CWD structure which constitutes the CWD.
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@ -3556,7 +3570,10 @@ cwdstuff::override_win32_cwd (bool init, ULONG old_dismount_count)
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fast_cwd_ptr, we can simply replace the RtlSetCurrentDirectory_U
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function entirely, just as on pre-Vista. */
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PVOID heap = peb.ProcessHeap;
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/* First allocate a new FAST_CWD strcuture on the heap. */
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/* First allocate a new FAST_CWD structure on the heap.
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The new FAST_CWD structure is 4 byte bigger than the old one,
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but we simply don't care, so we allocate always room for the
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new one. */
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PFAST_CWD f_cwd = (PFAST_CWD)
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RtlAllocateHeap (heap, 0, sizeof (FAST_CWD));
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if (!f_cwd)
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@ -3564,12 +3581,34 @@ cwdstuff::override_win32_cwd (bool init, ULONG old_dismount_count)
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debug_printf ("RtlAllocateHeap failed");
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return;
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}
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/* Fill in the values. */
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f_cwd->ReferenceCount = 1;
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f_cwd->DirectoryHandle = dir;
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f_cwd->OldDismountCount = old_dismount_count;
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/* Fill in the values. Fortunately it's simple to check for the
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new structure. Path.MaximumLength takes the same space as the
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high word of the old ReferenceCount. We know that MaximumLength
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is always MAX_PATH. For the ref count this would account for a
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pratically impossible value between 34078720 and 34079240. */
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if ((*fast_cwd_ptr)->Path.MaximumLength == MAX_PATH * sizeof (WCHAR))
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{
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/* New FAST_CWD structure. */
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IO_STATUS_BLOCK io;
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FILE_FS_DEVICE_INFORMATION ffdi;
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RtlInitEmptyUnicodeString (&f_cwd->Path, f_cwd->Buffer,
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MAX_PATH * sizeof (WCHAR));
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f_cwd->DirectoryHandle = dir;
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/* The new structure stores the device characteristics of the
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volume holding the dir. RtlGetCurrentDirectory_U checks
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if the FILE_REMOVABLE_MEDIA flag is set and, if so, checks if
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the volume is still the same as the one used when opening
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the directory handle.
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We don't call NtQueryVolumeInformationFile for the \\?\PIPE,
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though. It just returns STATUS_INVALID_HANDLE anyway. */
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f_cwd->FSCharacteristics =
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(!error
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&& NT_SUCCESS (NtQueryVolumeInformationFile (dir, &io, &ffdi,
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sizeof ffdi, FileFsDeviceInformation)))
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? ffdi.Characteristics : 0;
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f_cwd->ReferenceCount = 1;
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f_cwd->OldDismountCount = old_dismount_count;
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copy_cwd_str (&f_cwd->Path, error ? &ro_u_pipedir : &win32);
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/* Use PEB lock when switching fast_cwd_ptr to the new FAST_CWD
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structure and writing the CWD to the user process parameter
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@ -3582,19 +3621,44 @@ cwdstuff::override_win32_cwd (bool init, ULONG old_dismount_count)
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upp_cwd_str = f_cwd->Path;
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upp_cwd_hdl = dir;
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RtlLeaveCriticalSection (peb.FastPebLock);
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/* Decrement the reference count. If it's down to 0, free structure
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from heap. */
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if (old_cwd && InterlockedDecrement (&old_cwd->ReferenceCount) == 0)
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/* Decrement the reference count. If it's down to 0, free
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structure from heap. */
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if (InterlockedDecrement (&old_cwd->ReferenceCount) == 0)
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{
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/* In contrast to pre-Vista, the handle on init is always a fresh
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one and not the handle inherited from the parent process. So
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we always have to close it here. However, the handle could
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be NULL, if we cd'ed into a virtual dir. */
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/* In contrast to pre-Vista, the handle on init is always a
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fresh one and not the handle inherited from the parent
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process. So we always have to close it here. However, the
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handle could be NULL, if we cd'ed into a virtual dir. */
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if (old_cwd->DirectoryHandle)
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NtClose (old_cwd->DirectoryHandle);
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RtlFreeHeap (heap, 0, old_cwd);
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}
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}
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else
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{
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/* Old FAST_CWD structure. Otherwise same procedure as above,
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except for the non-existant FSCharacteristics member. */
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PFAST_CWD_OLD f_cwd_old = (PFAST_CWD_OLD) f_cwd;
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f_cwd_old->ReferenceCount = 1;
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f_cwd_old->DirectoryHandle = dir;
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f_cwd_old->OldDismountCount = old_dismount_count;
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RtlInitEmptyUnicodeString (&f_cwd_old->Path, f_cwd_old->Buffer,
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MAX_PATH * sizeof (WCHAR));
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copy_cwd_str (&f_cwd_old->Path, error ? &ro_u_pipedir : &win32);
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RtlEnterCriticalSection (peb.FastPebLock);
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PFAST_CWD_OLD old_cwd = (PFAST_CWD_OLD) *fast_cwd_ptr;
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*fast_cwd_ptr = (PFAST_CWD) f_cwd_old;
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upp_cwd_str = f_cwd_old->Path;
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upp_cwd_hdl = dir;
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RtlLeaveCriticalSection (peb.FastPebLock);
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if (InterlockedDecrement (&old_cwd->ReferenceCount) == 0)
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{
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if (old_cwd->DirectoryHandle)
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NtClose (old_cwd->DirectoryHandle);
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RtlFreeHeap (heap, 0, old_cwd);
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}
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}
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}
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else
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{
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/* This is more a hack, and it's only used on Vista and later if we
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@ -3636,8 +3700,12 @@ cwdstuff::override_win32_cwd (bool init, ULONG old_dismount_count)
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PFAST_CWD f_cwd = (PFAST_CWD)
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((PBYTE) upp_cwd_str.Buffer
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- __builtin_offsetof (struct _FAST_CWD, Buffer));
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if (f_cwd->Path.MaximumLength == MAX_PATH * sizeof (WCHAR))
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f_cwd->DirectoryHandle = dir;
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else
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((PFAST_CWD_OLD) f_cwd)->DirectoryHandle = dir;
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h = upp_cwd_hdl;
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f_cwd->DirectoryHandle = upp_cwd_hdl = dir;
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upp_cwd_hdl = dir;
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RtlLeaveCriticalSection (peb.FastPebLock);
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/* In contrast to pre-Vista, the handle on init is always a fresh one
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and not the handle inherited from the parent process. So we always
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