GetThreadContext function
Applies to: desktop apps only
Retrieves the context of the specified thread.
A 64-bit application can retrieve the context of a WOW64 thread using the Wow64GetThreadContext function.
Syntax
BOOL WINAPI GetThreadContext( __in HANDLE hThread, __inout LPCONTEXT lpContext );
Parameters
- hThread [in]
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A handle to the thread whose context is to be retrieved. The handle must have THREAD_GET_CONTEXT access to the thread. For more information, see Thread Security and Access Rights.
WOW64: The handle must also have THREAD_QUERY_INFORMATION access. - lpContext [in, out]
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A pointer to a CONTEXT structure that receives the appropriate context of the specified thread. The value of the ContextFlags member of this structure specifies which portions of a thread's context are retrieved. The CONTEXT structure is highly processor specific. Refer to the WinNT.h header file for processor-specific definitions of this structures and any alignment requirements.
Return value
If the function succeeds, the return value is nonzero.
If the function fails, the return value is zero. To get extended error information, call GetLastError.
Remarks
This function is used to retrieve the thread context of the specified thread. The function retrieves a selective context based on the value of the ContextFlags member of the context structure. The thread identified by the hThread parameter is typically being debugged, but the function can also operate when the thread is not being debugged.
You cannot get a valid context for a running thread. Use the SuspendThread function to suspend the thread before calling GetThreadContext.
If you call GetThreadContext for the current thread, the function returns successfully; however, the context returned is not valid.
Requirements
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Minimum supported client | Windows XP |
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Minimum supported server | Windows Server 2003 |
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Header |
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Library |
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DLL |
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See also
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Build date: 3/6/2012
#include <process.h>
#include <stdio.h>
#include <assert.h>
void mythreadfunc(void *data)
{
...
_exitthread();
}
void changeThreadState()
{
HANDLE thread = (HANDLE)_beginthread( mythreadfunc, 0, NULL );
CONTEXT context;
BOOL success;
SuspendThread(thread);
// get context
context.ContextFlags = (CONTEXT_FULL);
success = GetThreadContext(thread, &context);
assert(success);
printf( "eax=%08X, ebx=%08X, ecx=%08X\n",
context.Eax, context.Ebx, context.Ecx );
// change context (dangerous, can crash program)
context.Eax = 0x1234BBBB;
context.Ecx = 0x2468ABCD;
success = SetThreadContext(thread, &context);
assert(success);
ResumeThread(thread);
// the resumed thread should see different values of eax, and ecx
}
