DosSetRelMaxFH
Description
Adjusts the maximum number of file handles for the calling process.
Syntax
#define INCL_DOSFILEMGR #include <os2.h> PLONG pcbReqCount; /* Address of the number to be added to the maximum number of file handles for the calling process. */ PULONG pcbCurMaxFH; /* Address of the variable to receive the new total number of allocated file handles. */ APIRET ulrc; /* Return Code. */ ulrc = DosSetRelMaxFH(pcbReqCount, pcbCurMaxFH);
Parameters
- pcbReqCount (PLONG) - input
- Address of the number to be added to the maximum number of file handles for the calling process.
If pcbReqCount is positive, the maximum number of file handles is increased. If pcbReqCount is negative, the maximum number of file handles is decreased.
The system treats a decrease in the maximum number of file handles as an advisory request that may or may not be granted; the system may track and defer such a request.
- pcbCurMaxFH (PULONG) - output
- Address of the variable to receive the new total number of allocated file handles.
Return Code
ulrc (APIRET) - returns
DosSetRelMaxFH returns one of the following values:
- 0 NO_ERROR
Remarks
All file handles that are currently open are preserved. The system may defer or disregard a request to decrease the maximum number of file handles for the current process. The return code is set to NO_ERROR even if the system defers or disregards a request for a decrease.
You should examine the value of pcbCurMaxFH to determine the result of DosSetRelMaxFH.
Example Code
This example shows how to define and adjust the maximum number of file handles.
#define INCL_DOSFILEMGR /* File Manager values */
#define INCL_DOSERRORS /* DOS Error values */
#include <os2.h>
#include <stdio.h>
int main(VOID){
ULONG CurMaxFH = 0; /* Current count of handles */
LONG ReqCount = 0; /* Number to adjust file handles */
APIRET rc = NO_ERROR; /* Return code */
rc = DosSetRelMaxFH(&ReqCount, /* Using 0 here will return the */
&CurMaxFH); /* current number of file handles */
if (rc != NO_ERROR) {
printf("DosSetRelMaxFH error: return code = %u\n", rc);
return 1;
} else {
printf("Maximum number of file handles is %u.\n", CurMaxFH);
}
rc = DosSetMaxFH(110L); /* Set maximum file handles to 110 */
if (rc != NO_ERROR) {
printf("DosSetMaxFH error: return code = %u\n", rc);
return 1;
}
ReqCount = -5L; /* Want 5 less file handles */
rc = DosSetRelMaxFH(&ReqCount,&CurMaxFH); /* Change handle maximum */
if (rc != NO_ERROR) {
printf("DosSetRelMaxFH error: return code = %u\n", rc);
return 1;
} else {
printf("Maximum number of file handles is now %u.\n", CurMaxFH);
}
return NO_ERROR;
}