snapshot: use perror() on failed library calls

This will print more informative messages when we fail.

diff --git a/snapshot.cc b/snapshot.cc
index 9a92aac259d644a62c3fef5b672b621d55d4d888..f5cefe685f2b2eef8c738ecb895c3b2624c8c018 100644 (file)
--- a/snapshot.cc
+++ b/snapshot.cc
@@ -91,7 +91,10 @@ void HandlePF( int sig, siginfo_t *si, void * unused){
        //remember where to copy page back to
        snapshotrecord->backingRecords[backingpage].basePtrOfPage=addr;
        //set protection to read/write
-       mprotect( addr, sizeof(struct SnapShotPage), PROT_READ | PROT_WRITE );  
+       if (mprotect( addr, sizeof(struct SnapShotPage), PROT_READ | PROT_WRITE )) {
+               perror("mprotect");
+               // Handle error by quitting?
+       }
 #endif //nothing to handle for non snapshotting case.
 }
 
@@ -226,6 +229,7 @@ snapshot_id takeSnapshot( ){
 #if USE_CHECKPOINTING
        for(unsigned int region=0; region<snapshotrecord->lastRegion;region++) {
                if( mprotect(snapshotrecord->regionsToSnapShot[region].basePtr, snapshotrecord->regionsToSnapShot[region].sizeInPages*sizeof(struct SnapShotPage), PROT_READ ) == -1 ){
+                       perror("mprotect");
                        printf("Failed to mprotect inside of takeSnapShot\n");
                        exit(-1);
                }               
@@ -248,6 +252,7 @@ void rollBack( snapshot_id theID ){
        std::map< void *, bool, std::less< void * >, MyAlloc< std::pair< const void *, bool > > > duplicateMap;
        for(unsigned int region=0; region<snapshotrecord->lastRegion;region++) {
                if( mprotect(snapshotrecord->regionsToSnapShot[region].basePtr, snapshotrecord->regionsToSnapShot[region].sizeInPages*sizeof(struct SnapShotPage), PROT_READ | PROT_WRITE ) == -1 ){
+                       perror("mprotect");
                        printf("Failed to mprotect inside of takeSnapShot\n");
                        exit(-1);
                }