PROCESS_HEAP_ENTRY  MB1KLO 

The PROCESS_HEAP_ENTRY structure contains information about a heap element. The HeapWalk19NUGRR function uses a PROCESS_HEAP_ENTRY structure to enumerate the elements of a heap.

typedef struct _PROCESS_HEAP_ENTRY { 

    PVOID lpData;

    DWORD cbData;

    BYTE cbOverhead;

    BYTE iRegionIndex;

    WORD wFlags;

    union { 

        struct { 

            HANDLE hMem;

            DWORD dwReserved[ 3 ];

        } Block;

        struct { 

            DWORD dwCommittedSize;

            DWORD dwUnCommittedSize;

            LPVOID lpFirstBlock;

            LPVOID lpLastBlock;

        } Region;

    };

} PROCESS_HEAP_ENTRY;

Members

lpData

Points to the data portion of the heap element.

To initiate a HeapWalk heap enumeration, set lpData to NULL.

If the PROCESS_HEAP_REGION bit flag is set in the wFlags member, lpData points to the first virtual address used by the region.

If the PROCESS_HEAP_UNCOMMITTED_RANGE bit flag is set in wFlags, lpData points to the beginning of the range of uncommitted memory.

cbData

Specifies the size, in bytes, of the data portion of the heap element.

If the PROCESS_HEAP_REGION bit flag is set in wFlags, cbData specifies the total size, in bytes, of the address space that is reserved for this region.

If the PROCESS_HEAP_UNCOMMITTED_RANGE bit flag is set in wFlags, cbData specifies the size, in bytes, of the range of uncommitted memory.

cbOverhead

Specifies the size, in bytes, of the data used by the system to maintain information about the heap element. These overhead bytes are in addition to the cbData bytes of the data portion of the heap element.

If the PROCESS_HEAP_REGION bit flag is set in wFlags, cbOverhead specifies the size, in bytes, of the heap control structures that describe the region.

If the PROCESS_HEAP_UNCOMMITTED_RANGE bit flag is set in wFlags, cbOverhead specifies the size, in bytes, of the control structures that describe this uncommitted range.

iRegionIndex

Identifies the heap region that contains the heap element. A heap consists of one or more regions of virtual memory, each with a unique region index.

In the first heap entry returned for most heap regions, HeapWalk sets the PROCESS_HEAP_REGION flag in the wFlags member. When this flag is set, the members of the Region structure contain additional information about the region.

The HeapAlloc12YJJI7 function sometimes uses the VirtualAlloc1M7V8GO function to allocate large blocks from a growable heap. The heap manager treats such a large block allocation as a separate region with a unique region index. HeapWalk does not set the PROCESS_HEAP_REGION flag in the heap entry returned for a large block region, so the members of the Region structure are not valid. You can use the VirtualQuery1MH41K0 function to get additional information about a large block region.

wFlags

A set of bit flags that specify properties of the heap element. Some of these flags affect the meaning of other members of this PROCESS_HEAP_ENTRY data structure. The following bit-flag constants are defined:

Block

This structure is valid only if both the PROCESS_HEAP_ENTRY_BUSY and PROCESS_HEAP_ENTRY_MOVEABLE flags in wFlags are set.

The members of the Block structure are as follows:

Region

This structure is valid only if the PROCESS_HEAP_REGION flag is set in the wFlags member.

The members of the Region structure are as follows:

See Also