RtlDecompressFragment - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers 
#ifndef _NTRTL_H

NTSYSAPI
NTSTATUS
NTAPI
RtlDecompressFragment(
    _In_ USHORT CompressionFormat,
    _Out_writes_bytes_to_(UncompressedFragmentSize, *FinalUncompressedSize) PUCHAR UncompressedFragment,
    _In_ ULONG UncompressedFragmentSize,
    _In_reads_bytes_(CompressedBufferSize) PUCHAR CompressedBuffer,
    _In_ ULONG CompressedBufferSize,
    _In_range_(<, CompressedBufferSize) ULONG FragmentOffset,
    _Out_ PULONG FinalUncompressedSize,
    _In_ PVOID WorkSpace
    );

#endif

View code on GitHub
// ntifs.h

NT_RTL_COMPRESS_API NTSTATUS RtlDecompressFragment(
  [in]  USHORT CompressionFormat,
  [out] PUCHAR UncompressedFragment,
  [in]  ULONG  UncompressedFragmentSize,
  [in]  PUCHAR CompressedBuffer,
  [in]  ULONG  CompressedBufferSize,
  [in]  ULONG  FragmentOffset,
  [out] PULONG FinalUncompressedSize,
  [in]  PVOID  WorkSpace
);
View the official Windows Driver Kit DDI reference

NtDoc

This function is documented in Windows Driver Kit.

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Windows Driver Kit DDI reference (nf-ntifs-rtldecompressfragment)

RtlDecompressFragment function

Description

The RtlDecompressFragment function is used to decompress part of a compressed buffer (that is, a buffer "fragment").

Parameters

CompressionFormat [in]

Bitmask specifying the compression format of the compressed buffer. This parameter must be set to COMPRESSION_FORMAT_LZNT1. The meaning of this and other related compression format values are as follows:

Value Meaning
COMPRESSION_FORMAT_NONE Not supported by this function.
COMPRESSION_FORMAT_DEFAULT Not supported by this function.
COMPRESSION_FORMAT_LZNT1 Specifies that compression should be performed. This value is required.

UncompressedFragment [out]

Pointer to a caller-allocated buffer (allocated from paged or non-paged pool) receiving the decompressed data from CompressedBuffer. This parameter is required and cannot be NULL.

UncompressedFragmentSize [in]

The size, in bytes, of the UncompressedFragment buffer.

CompressedBuffer [in]

A pointer to the buffer containing the data to decompress. This parameter is required and cannot be NULL.

CompressedBufferSize [in]

The size, in bytes, of the CompressedBuffer buffer.

FragmentOffset [in]

The zero-based offset, in bytes, where the uncompressed fragment is being extract from. This offset value is the position within the original uncompressed buffer.

FinalUncompressedSize [out]

A pointer to a caller-allocated variable which receives the size, in bytes, of the decompressed data stored in UncompressedFragment. This parameter is required and cannot be NULL.

WorkSpace [in]

A pointer to a caller-allocated work space buffer used by the RtlDecompressFragment function during decompression. Use the RtlGetCompressionWorkSpaceSize function to determine the correct work space buffer size.

Return value

RtlDecompressFragmentreturns an appropriate NTSTATUS code, such as one of the following:

Return code Description
STATUS_SUCCESS The CompressedBuffer buffer was successfully decompressed into UncompressedFragment.
STATUS_INVALID_PARAMETER An invalid compression format was specified via the CompressionFormat parameter. If CompressionFormat is either COMPRESSION_FORMAT_NONE or COMPRESSION_FORMAT_DEFAULT (but not both), this value is returned.
STATUS_UNSUPPORTED_COMPRESSION An invalid compression format was specified via the CompressionFormat parameter. If CompressionFormat is not one of the following, STATUS_UNSUPPORTED_COMPRESSION is returned: COMPRESSION_FORMAT_LZNT1
STATUS_BAD_COMPRESSION_BUFFER UncompressedFragment is not large enough to contain the uncompressed data.

Remarks

Relative to the RtlDecompressBuffer function, RtlDecompressFragment is used for decompressing a portion of the data from a compressed buffer (as opposed to the entire buffer).

To determine the correct buffer size for the WorkSpace parameter, use the RtlGetCompressionWorkSpaceSize function (that is, the value returned by the RtlGetCompressionWorkSpaceSize parameter).

To compress an uncompressed buffer, use the RtlCompressBuffer function.

To decompress an entire compressed buffer, use the RtlDecompressBuffer function.

See also

FILE_COMPRESSION_INFORMATION

RtlCompressBuffer

RtlDecompressBuffer

RtlDecompressBufferEx

RtlDecompressBufferEx2

RtlDecompressFragmentEx

View the official Windows Driver Kit DDI reference

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