Geoff Chappell, Software Analyst
The SYSTEM_OBJECT_INFORMATION structure is an irregularly recurring element in what a successful call to ZwQuerySystemInformation or NtQuerySystemInformation produces in its output buffer when given the information class SystemObjectInformation (0x11). The output begins with a SYSTEM_OBJECTTYPE_INFORMATION. There can be, and typically are, more of these throughout the buffer, but irregularly because each can be followed by any number of SYSTEM_OBJECT_INFORMATION structures. These too are irregularly spaced because although each is fixed in size, each has a pointer to a variable-size name.
The SYSTEM_OBJECT_INFORMATION structure is not documented.
Microsoft does publish the practical equivalent of a C-language definition as type information in public symbol files, though not for the kernel, where the structure is prepared, nor even for low-level user-mode DLLs that interpret the structure, but for various higher-level user-mode DLLs such as URLMON.DLL and only then starting with version 6.2.
Two earlier disclosures of type information are known, though not in symbol files but in statically linked libraries: GDISRVL.LIB from the Device Driver Kit (DDK) for Windows NT 3.51; and SHELL32.LIB from the DDK for Windows NT 4.0.
The SYSTEM_OBJECT_INFORMATION is 0x30 or 0x50 bytes in 32-bit and 64-bit Windows, respectively.
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