DosQueryThreadContext
From EDM2
Query context of a suspended thread.
Syntax
DosQueryThreadContext(tid, level, pcxt)
Parameters
- tid (TID) - input
- Thread identity.
- level (ULONG) - input
- Level of information desired:
- CONTEXT_CONTROL (0x00000001) Control registers: SS:ESP, CS:EIP, EFLAGS and EBP
- CONTEXT_INTEGER (0x00000002) EAX, EBX, ECX, EDX, ESI and EDI
- CONTEXT_SEGMENTS (0x00000004) Segment registers: DS, ES, FS, and GS
- CONTEXT_FLOATING_POINT (0x00000008) Numeric coprocessor state
- CONTEXT_FULL All of the above
- pcxt (PCONTEXTRECORD) - in/out
- Thread context record.
Return Code
- ulrc (APIRET) - returns
- DosQueryThreadContext returns one of the following values:
- 0 NO_ERROR
- 87 ERROR_INVALID_PARAMETER
- 90 ERROR_NOT_FROZEN
- 115 ERROR_PROTECTION_VIOLATION
- 309 ERROR_INVALID_THREADID
Remarks
DosQueryThreadContext returns the context record of a suspended thread. A thread may be suspended by using DosSuspendThread or DosEnterCritSec. If DosSuspendThread is used, the caller must allow some time for OS/2 to suspend the thread before querying its context.
Note: Values from the thread context should be used only when the state of the target thread is known.
Example Code
This example uses DosQueryThreadContext to query the context of a suspended thread.
#define INCL_DOSEXCEPTIONS #define INCL_DOSPROCESS #define INCL_DOSERRORS #include <os2.h> #include <stdio.h> VOID _System CntThreadProc( ULONG LoopMax ); /* Count Thread */ VOID PrintContextRecord( CONTEXTRECORD *pThread ); int main(VOID) { TID tidCntThread = 0; /* ID returned for newly created thread */ PFNTHREAD pfnCntThread = &CntThreadProc; /* Address of Thread program */ ULONG ulLoopMax = 500000; /* Parameter to thread routine */ APIRET rc = NO_ERROR; /* Return code */ /* Thread Context Record */ CONTEXTRECORD Thread_cxt= {0,{0,0,0,0,0,0,0}, {{0,0,0}, {0,0,0}, {0,0,0}, {0,0,0}, {0,0,0}, {0,0,0}, {0,0,0}, {0,0,0}}, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}; rc = DosCreateThread(&tidCntThread, /* Thread ID (return by function) */ pfnCntThread, /* Address of thread program */ ulLoopMax, /* Parameter passed to ThreadProc */ CREATE_READY | /* Thread is ready when created */ STACK_SPARSE, /* Do not pre_commit stack pages */ 8192L); /* Stack size, rounded to page bdy*/ if (rc != NO_ERROR) { printf("DosCreateThread error: return code = %u\n",rc); return 1; } rc = DosSuspendThread (tidCntThread); if (rc != NO_ERROR) printf("DosSuspendThread error: return code = %u\n",rc); else { /* Wait for thread to suspend */ printf("Waiting 5 seconds for thread to suspend...\n"); rc = DosSleep(5000); rc = DosQueryThreadContext (tidCntThread, CONTEXT_FULL, &Thread_cxt); if (rc != NO_ERROR) printf("DosQueryThreadContext error: return code = %u\n",rc); else PrintContextRecord( &Thread_cxt ); rc = DosResumeThread (tidCntThread); if (rc != NO_ERROR) { printf("DosResumeThread error: return code = %u\n",rc); return 1; } } printf("Waiting for thread to complete...\n"); rc = DosWaitThread ( &tidCntThread, DCWW_WAIT ); if (rc != NO_ERROR) { printf("DosWaitThread error: return code = %u\n",rc); return 1; } printf("Thread has completed!\n"); return NO_ERROR; } VOID _System CntThreadProc( ULONG LoopMax ) /* Count Thread */ { ULONG ulCount = 0, i = 0, j = 1, k = 1, l = 0; double w = 0.0, y = 0.0, z = 0.0; for (l=0; l < 20; l++) { for (i=0; i < LoopMax; i++) { w = 1.00 / 2.00; y = 2.00 * 2.00; z = 3.00 / 6.00; j = j + i; k = k * i; } } return; } VOID PrintContextRecord( CONTEXTRECORD *pThread ) { int i = 0; printf("\nRegisters for CONTEXT_CONTROL level:\n"); printf(" EBP= 0x%08x\t",pThread->ctx_RegEbp); printf("EIP= 0x%08x\t",pThread->ctx_RegEip); printf("CS= 0x%08x\n",pThread->ctx_SegCs); printf(" EFLAGS = 0x%08x\t",pThread->ctx_EFlags); printf("ESP= 0x%08x\t",pThread->ctx_RegEsp); printf("SS= 0x%08x\n",pThread->ctx_SegSs); printf("\nRegisters for CONTEXT_INTEGER level:\n"); printf(" EAX= 0x%08x\t",pThread->ctx_RegEax); printf("EBX= 0x%08x\t",pThread->ctx_RegEbx); printf("ECX= 0x%08x\n",pThread->ctx_RegEcx); printf(" EDX= 0x%08x\t",pThread->ctx_RegEdx); printf("ESI= 0x%08x\t",pThread->ctx_RegEsi); printf("EDI= 0x%08x\n",pThread->ctx_RegEdi); printf("\nRegisters for CONTEXT_SEGMENTS level:\n"); printf(" DS= 0x%08x\t",pThread->ctx_SegDs); printf("ES= 0x%08x\t",pThread->ctx_SegEs); printf("FS= 0x%08x\t",pThread->ctx_SegFs); printf("GS= 0x%08x\n",pThread->ctx_SegGs); printf("\nRegisters for CONTEXT_FLOATING_POINT level:\n"); printf(" - Coprocessor stack register (exponent,hisig:losig):\n"); for (i=0;i<8;i++) { printf(" ctx_stack[%d]=0x%08x ,0x%08x :0x%08x \n",i, pThread->ctx_stack[i].signexp, pThread->ctx_stack[i].hisig, pThread->ctx_stack[i].losig); } printf(" - Other element\n"); for (i=0;i<7;i++) { printf(" ctx_env[%d]=0x%08x \n",i ,pThread->ctx_env[i]); } return; }