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The MmCanFileBeTruncated routine checks whether a file can be truncated.
Syntax
BOOLEAN MmCanFileBeTruncated(
[in] PSECTION_OBJECT_POINTERS SectionPointer,
[in, optional] PLARGE_INTEGER NewFileSize
);
Parameters
[in] SectionPointer
Pointer to a structure that contains the file object's section object pointers.
[in, optional] NewFileSize
Pointer to a variable that specifies the size in bytes to which the file is to be truncated. If this parameter is NULL, then a length of zero is assumed and MmCanFileBeTruncated checks whether the entire file can be truncated.
Return value
MmCanFileBeTruncated returns TRUE if the file can be truncated; FALSE otherwise.
Remarks
MmCanFileBeTruncated must always be called before a file is truncated.
A file cannot be truncated (and MmCanFileBeTruncated will return FALSE) if any of the following are true:
An image section exists for the file.
There are one or more outstanding write probes on the file's data section.
There is a mapped view of file's data section within the truncation range determined by NewFileSize.
One or more users hold references to the data section for the file, and NewFileSize <= the current file size.
Requirements
| Requirement | Value |
|---|---|
| Target Platform | Universal |
| Header | ntifs.h (include Ntifs.h) |
| Library | NtosKrnl.lib |
| DLL | NtosKrnl.exe |
| IRQL | < DISPATCH_LEVEL |