openfam::fam::fam_change_permissions

Change permissions associated with a data item or region in FAM.

Synopsis

void fam_change_permissions(Fam_Descriptor *descriptor, mode_t accessPermissions);
void fam_change_permissions(Fam_Region_Descriptor *descriptor, mode_t accessPermissions);

Description

This method changes read/write permissions for a data item or region.

Input Arguments

Name	Description
descriptor	Descriptor associated with the data item or region.
accessPermissions	New access permissions to be associated with the item.

Return Values

None. Throws Fam_Exception on error.

Fam error numbers

Error	Description
FAM_ERR_NOPERM	Caller does not have access rights
FAM_ERR_NOTFOUND	Data item name not found in FAM
FAM_ERR_RPC	Communication error from grpc layer.
FAM_ERR_RPC_CLIENT_NOTFOUND	RPC service not available.
FAM_ERR_METADATA	Metadata service error.
FAM_ERR_MEMORY	Memory service error.
FAM_ERR_RESOURCE	Resource not available.

Notes

Permissions are checked on first descriptor use in a running program. Changed permissions are only applied the next time the program is run, not immediately on next access.

Example

#include <string.h>
#include <fam/fam.h>
#include <fam/fam_exception.h>
using namespace std;
using namespace openfam;

int main(void) {
	fam *myFam = new fam();

	// ... Initialization code here
	try {
		Fam_Region_Descriptor *region = myFam->fam_lookup_region("myRegion");
		// create 50 element named integer array in FAM with 0600
		// (read/write by owner) permissions in myRegion
		Fam_Descriptor *descriptor = myFam->fam_allocate("myItem", 50*sizeof(int), 0600, region);
			
		printf("Successfully allocated 50 unnamed integer elements\n");
		// initialize the allocated space here with meaningful values
			
		// make the item read-only (0400) to prevent further change by
		// subsequent programs
		myFam->fam_change_permissions(descriptor, 0400);
		printf("Successfully changed permission from 0600 to 0400\n");	
	} catch (Fam_Exception &e) {
		printf("fam API failed: %d: %s\n", e.fam_error(), e.fam_error_msg());
	}
	
	// ... Finalization code here
}