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[model-checker.git] / snapshot.cc

diff --git a/snapshot.cc b/snapshot.cc
index 5a25bb14efbe24bbf88ad0e4d6de8238316f884b..afe02efd851ab39062552f972b3f30e91380a6e1 100644 (file)
--- a/snapshot.cc
+++ b/snapshot.cc
@@ -44,6 +44,10 @@ static snapshot_id snapshotid = 0;
 #endif
 /* Initialize snapshot data structure */
 #if USE_MPROTECT_SNAPSHOT
+
+/** The initSnapShotRecord method initialized the snapshotting data
+ *  structures for the mprotect based snapshot. 
+ */
 void initSnapShotRecord(unsigned int numbackingpages, unsigned int numsnapshots, unsigned int nummemoryregions) {
        snapshotrecord=( struct SnapShot * )MYMALLOC(sizeof(struct SnapShot));
        snapshotrecord->regionsToSnapShot=( struct MemoryRegion * )MYMALLOC(sizeof(struct MemoryRegion)*nummemoryregions);
@@ -61,6 +65,10 @@ void initSnapShotRecord(unsigned int numbackingpages, unsigned int numsnapshots,
 }
 #endif //nothing to initialize for the fork based snapshotting.
 
+/** HandlePF is the page fault handler for mprotect based snapshotting
+ * algorithm.
+ */
+
 void HandlePF( int sig, siginfo_t *si, void * unused){
 #if USE_MPROTECT_SNAPSHOT
        if( si->si_code == SEGV_MAPERR ){
@@ -68,6 +76,7 @@ void HandlePF( int sig, siginfo_t *si, void * unused){
                exit( EXIT_FAILURE );
        }
        void* addr = ReturnPageAlignedAddress(si->si_addr);
+
        unsigned int backingpage=snapshotrecord->lastBackingPage++; //Could run out of pages...
        if (backingpage==snapshotrecord->maxBackingPages) {
                printf("Out of backing pages at %p\n", si->si_addr);
@@ -86,14 +95,18 @@ void HandlePF( int sig, siginfo_t *si, void * unused){
 #endif //nothing to handle for non snapshotting case.
 }
 
-//Return a page aligned address for the address being added
-//as a side effect the numBytes are also changed.
+/** ReturnPageAlignedAddress returns a page aligned address for the
+ * address being added as a side effect the numBytes are also changed.
+ */
+
 void * ReturnPageAlignedAddress(void * addr) {
        return (void *)(((uintptr_t)addr)&~(PAGESIZE-1));
 }
 
-//Return a page aligned address for the address being added
-//as a side effect the numBytes are also changed.
+/** PageAlignedAdressUpdate return a page aligned address for the
+ * address being added as a side effect the numBytes are also changed.
+ */
+
 void * PageAlignAddressUpward(void * addr) {
        return (void *)((((uintptr_t)addr)+PAGESIZE-1)&~(PAGESIZE-1));
 }
@@ -121,6 +134,10 @@ extern "C" {
 #ifdef __cplusplus
 }
 #endif
+
+/** The initSnapShotLibrary function initializes the Snapshot library.
+ *  @param entryPoint the function that should run the program.
+ */
 void initSnapShotLibrary(unsigned int numbackingpages,
                unsigned int numsnapshots, unsigned int nummemoryregions,
                unsigned int numheappages, VoidFuncPtr entryPoint) {
@@ -136,10 +153,17 @@ void initSnapShotLibrary(unsigned int numbackingpages,
        sa.sa_flags = SA_SIGINFO | SA_NODEFER | SA_RESTART | SA_ONSTACK;
        sigemptyset( &sa.sa_mask );
        sa.sa_sigaction = HandlePF;
+#ifdef MAC
+       if( sigaction( SIGBUS, &sa, NULL ) == -1 ){
+               printf("SIGACTION CANNOT BE INSTALLED\n");
+               exit(EXIT_FAILURE);
+       }
+#endif
        if( sigaction( SIGSEGV, &sa, NULL ) == -1 ){
                printf("SIGACTION CANNOT BE INSTALLED\n");
                exit(EXIT_FAILURE);
        }
+
        initSnapShotRecord(numbackingpages, numsnapshots, nummemoryregions);
 
        // EVIL HACK: We need to make sure that calls into the HandlePF method don't cause dynamic links
@@ -147,6 +171,7 @@ void initSnapShotLibrary(unsigned int numbackingpages,
        // Solution is to call our signal handler before we start protecting stuff...
 
        siginfo_t si;
+       memset(&si, 0, sizeof(si));
        si.si_addr=ss.ss_sp;
        HandlePF(SIGSEGV, &si, NULL);
        snapshotrecord->lastBackingPage--; //remove the fake page we copied
@@ -219,7 +244,9 @@ void initSnapShotLibrary(unsigned int numbackingpages,
 
 #endif
 }
-/* This function assumes that addr is page aligned */
+
+/** The addMemoryRegionToSnapShot function assumes that addr is page aligned. 
+ */
 void addMemoryRegionToSnapShot( void * addr, unsigned int numPages) {
 #if USE_MPROTECT_SNAPSHOT
        unsigned int memoryregion=snapshotrecord->lastRegion++;
@@ -232,7 +259,11 @@ void addMemoryRegionToSnapShot( void * addr, unsigned int numPages) {
        snapshotrecord->regionsToSnapShot[ memoryregion ].sizeInPages=numPages;
 #endif //NOT REQUIRED IN THE CASE OF FORK BASED SNAPSHOTS.
 }
-//take snapshot
+
+/** The takeSnapshot function takes a snapshot.
+ * @return The snapshot identifier.
+ */
+
 snapshot_id takeSnapshot( ){
 #if USE_MPROTECT_SNAPSHOT
        for(unsigned int region=0; region<snapshotrecord->lastRegion;region++) {
@@ -255,6 +286,11 @@ snapshot_id takeSnapshot( ){
        return snapshotid;
 #endif
 }
+
+/** The rollBack function rollback to the given snapshot identifier.
+ *  @param theID is the snapshot identifier to rollback to.
+ */
+
 void rollBack( snapshot_id theID ){
 #if USE_MPROTECT_SNAPSHOT
        std::map< void *, bool, std::less< void * >, MyAlloc< std::pair< const void *, bool > > > duplicateMap;
@@ -294,6 +330,10 @@ void rollBack( snapshot_id theID ){
 #endif
 }
 
+/** The finalize method shuts down the snapshotting system.  */
+//Subramanian -- remove this function from the external interface and
+//have us call it internally
+
 void finalize(){
 #if !USE_MPROTECT_SNAPSHOT
        sTheRecord->mbFinalize = true;