FsRtlLookupLargeMcbEntry function (ntifs.h)
Given a virtual block number (VBN) and a map control block (MCB), the FsRtlLookupLargeMcbEntry routine searches the MCB for mapping information corresponding to the specified VBN.
Syntax
BOOLEAN FsRtlLookupLargeMcbEntry(
PLARGE_MCB Mcb,
LONGLONG Vbn,
PLONGLONG Lbn,
PLONGLONG SectorCountFromLbn,
PLONGLONG StartingLbn,
PLONGLONG SectorCountFromStartingLbn,
[out, optional] PULONG Index
);
Parameters
Mcb
Pointer to an initialized MCB structure.
Vbn
Pointer to the requested VBN.
Lbn
Pointer to a variable that receives the LBN that is mapped to LargeVbn in the mapping entry, or -1 if no such LBN exists. This parameter is optional and can be NULL.
SectorCountFromLbn
Pointer to a variable that receives the number of sectors that follow LargeVbn in the mapping run. This parameter is optional and can be NULL.
StartingLbn
Pointer to a variable that receives the LBN corresponding to the start of the mapping run, or -1 if no such LBN exists. This parameter is optional and can be NULL.
SectorCountFromStartingLbn
Pointer to a variable that receives the number of sectors in the mapping run. This parameter is optional and can be NULL.
[out, optional] Index
Pointer to a variable that receives the index of the mapping run that contains the VBN. This parameter is optional and can be NULL.
Return value
FsRtlLookupLargeMcbEntry returns TRUE if the specified VBN is within the range of VBNs that are mapped by the MCB, FALSE otherwise.
Remarks
FsRtlLookupLargeMcbEntry searches for a mapping entry in the MCB whose run includes the specified VBN.
If such a mapping exists, the lookup operation yields positive values for the corresponding LBN and sector count, and FsRtlLookupLargeMcbEntry returns TRUE.
If no such mapping exists, but the specified VBN is lower than the highest VBN mapped by the MCB, this is referred to as a hole in the mapping. In this case, FsRtlLookupLargeMcbEntry still returns TRUE, but the lookup operation yields a value of -1 for the LBN.
If the specified VBN is higher than the highest VBN mapped by the MCB, or if the MCB contains no mappings, FsRtlLookupLargeMcbEntry returns FALSE.
The upper 32 bits of the LBN are ignored. Only the lower 32 bits are used.
Requirements
| Requirement | Value |
|---|---|
| Target Platform | Universal |
| Header | ntifs.h (include Ntifs.h) |
| Library | NtosKrnl.lib |
| DLL | NtosKrnl.exe |
| IRQL | <= APC_LEVEL |