fixing the segfault

diff --git a/snapshot.cc b/snapshot.cc
index 20980015fe50d9678e67a606f37e2a3b934aa3e6..9ff0ea20b169f16f09977b65a10055d2887fe73e 100644 (file)
--- a/snapshot.cc
+++ b/snapshot.cc
@@ -36,17 +36,17 @@ struct timeval *starttime = NULL;
 #endif
 void DumpIntoLog( const char * filename, const char * message ){
 #if SSDEBUG
-       static pid_t thePID = getpid();
-       char newFn[ 1024 ] ={ 0 };
-       sprintf( newFn,"%s-%d.txt", filename, thePID );
-       FILE * myFile = fopen( newFn, "w+" );
-       struct timeval theEndTime;
-       BeginOperation( &theEndTime );
-       double elapsed = ( theEndTime.tv_sec - starttime->tv_sec ) + ( theEndTime.tv_usec - starttime->tv_usec ) / 1000000.0;
-       fprintf( myFile, "The timestamp %f:--> the message %s: the process id %d\n", elapsed, message, thePID );
-       fflush( myFile );
-       fclose( myFile );
-       myFile = NULL;
+   static pid_t thePID = getpid();
+   char newFn[ 1024 ] ={ 0 };
+   sprintf( newFn,"%s-%d.txt", filename, thePID );
+   FILE * myFile = fopen( newFn, "w+" );
+   struct timeval theEndTime;
+   BeginOperation( &theEndTime );
+   double elapsed = ( theEndTime.tv_sec - starttime->tv_sec ) + ( theEndTime.tv_usec - starttime->tv_usec ) / 1000000.0;
+   fprintf( myFile, "The timestamp %f:--> the message %s: the process id %d\n", elapsed, message, thePID );
+   fflush( myFile );
+   fclose( myFile );
+   myFile = NULL;
 #endif
 }
 #if !USE_CHECKPOINTING
@@ -57,247 +57,233 @@ static int snapshotid = 0;
 /* Initialize snapshot data structure */
 #if USE_CHECKPOINTING
 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);
-       snapshotrecord->backingStoreBasePtr= ( struct SnapShotPage * )MYMALLOC( sizeof( struct SnapShotPage ) * (numbackingpages + 1) );
-       //Page align the backingstorepages
-       snapshotrecord->backingStore=( struct SnapShotPage * )PageAlignAddressUpward(snapshotrecord->backingStoreBasePtr);
-       snapshotrecord->backingRecords=( struct BackingPageRecord * )MYMALLOC(sizeof(struct BackingPageRecord)*numbackingpages);
-       snapshotrecord->snapShots= ( struct SnapShotRecord * )MYMALLOC(sizeof(struct SnapShotRecord)*numsnapshots);
-       snapshotrecord->lastSnapShot=0;
-       snapshotrecord->lastBackingPage=0;
-       snapshotrecord->lastRegion=0;
-       snapshotrecord->maxRegions=nummemoryregions;
-       snapshotrecord->maxBackingPages=numbackingpages;
-       snapshotrecord->maxSnapShots=numsnapshots;
+  snapshotrecord=( struct SnapShot * )MYMALLOC(sizeof(struct SnapShot));
+  snapshotrecord->regionsToSnapShot=( struct MemoryRegion * )MYMALLOC(sizeof(struct MemoryRegion)*nummemoryregions);
+  snapshotrecord->backingStoreBasePtr= ( struct SnapShotPage * )MYMALLOC( sizeof( struct SnapShotPage ) * (numbackingpages + 1) );
+  //Page align the backingstorepages
+  snapshotrecord->backingStore=( struct SnapShotPage * )ReturnPageAlignedAddress((void*) ((uintptr_t)(snapshotrecord->backingStoreBasePtr)+sizeof(struct SnapShotPage)-1));
+  snapshotrecord->backingRecords=( struct BackingPageRecord * )MYMALLOC(sizeof(struct BackingPageRecord)*numbackingpages);
+  snapshotrecord->snapShots= ( struct SnapShotRecord * )MYMALLOC(sizeof(struct SnapShotRecord)*numsnapshots);
+  snapshotrecord->lastSnapShot=0;
+  snapshotrecord->lastBackingPage=0;
+  snapshotrecord->lastRegion=0;
+  snapshotrecord->maxRegions=nummemoryregions;
+  snapshotrecord->maxBackingPages=numbackingpages;
+  snapshotrecord->maxSnapShots=numsnapshots;
 }
 #endif //nothing to initialize for the fork based snapshotting.
 
 void HandlePF( int sig, siginfo_t *si, void * unused){
 #if USE_CHECKPOINTING
-       if( si->si_code == SEGV_MAPERR ){
-               printf("Real Fault at %llx\n", ( long long )si->si_addr);
-               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 %llx\n", ( long long )si->si_addr);
-               exit( EXIT_FAILURE );   
-       }
+  if( si->si_code == SEGV_MAPERR ){
+    printf("Real Fault at %llx\n", ( long long )si->si_addr);
+    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 %llx\n", ( long long )si->si_addr);
+    exit( EXIT_FAILURE );      
+  }
 
-       //copy page
-       memcpy(&(snapshotrecord->backingStore[backingpage]), addr, sizeof(struct SnapShotPage));
-       //remember where to copy page back to
-       snapshotrecord->backingRecords[backingpage].basePtrOfPage=addr;
-       //set protection to read/write
-       if (mprotect( addr, sizeof(struct SnapShotPage), PROT_READ | PROT_WRITE )) {
-               perror("mprotect");
-               // Handle error by quitting?
-       }
+  //copy page
+  memcpy(&(snapshotrecord->backingStore[backingpage]), addr, sizeof(struct SnapShotPage));
+  //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 );  
 #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.
 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.
-void * PageAlignAddressUpward(void * addr) {
-       return (void *)((((uintptr_t)addr)+PAGESIZE-1)&~(PAGESIZE-1));
+  return (void *)(((uintptr_t)addr)&~(PAGESIZE-1));
 }
 #ifdef __cplusplus
 extern "C" {
 #endif
-       void createSharedLibrary(){
+void createSharedLibrary(){
 #if !USE_CHECKPOINTING
-               //step 1. create shared memory.
-               if( sTheRecord ) return;
-               int fd = shm_open( "/ModelChecker-Snapshotter", O_RDWR | O_CREAT, 0777 ); //universal permissions.
-               if( -1 == fd ) FAILURE("shm_open");
-               if( -1 == ftruncate( fd, ( size_t )SHARED_MEMORY_DEFAULT + ( size_t )STACK_SIZE_DEFAULT ) ) FAILURE( "ftruncate" );
-               char * memMapBase = ( char * ) mmap( 0, ( size_t )SHARED_MEMORY_DEFAULT + ( size_t )STACK_SIZE_DEFAULT, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0 );
-               if( MAP_FAILED == memMapBase ) FAILURE("mmap");
-               sTheRecord = ( struct Snapshot_t * )memMapBase;
-               sTheRecord->mSharedMemoryBase = memMapBase + sizeof( struct Snapshot_t );
-               sTheRecord->mStackBase = ( char * )memMapBase + ( size_t )SHARED_MEMORY_DEFAULT;
-               sTheRecord->mStackSize = STACK_SIZE_DEFAULT;
-               sTheRecord->mIDToRollback = -1;
-               sTheRecord->currSnapShotID = 0;
+         //step 1. create shared memory.
+  if( sTheRecord ) return;
+  int fd = shm_open( "/ModelChecker-Snapshotter", O_RDWR | O_CREAT, 0777 ); //universal permissions.
+  if( -1 == fd ) FAILURE("shm_open");
+  if( -1 == ftruncate( fd, ( size_t )SHARED_MEMORY_DEFAULT + ( size_t )STACK_SIZE_DEFAULT ) ) FAILURE( "ftruncate" );
+  char * memMapBase = ( char * ) mmap( 0, ( size_t )SHARED_MEMORY_DEFAULT + ( size_t )STACK_SIZE_DEFAULT, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0 );
+  if( MAP_FAILED == memMapBase ) FAILURE("mmap");
+  sTheRecord = ( struct Snapshot_t * )memMapBase;
+  sTheRecord->mSharedMemoryBase = memMapBase + sizeof( struct Snapshot_t );
+  sTheRecord->mStackBase = ( char * )memMapBase + ( size_t )SHARED_MEMORY_DEFAULT;
+  sTheRecord->mStackSize = STACK_SIZE_DEFAULT;
+  sTheRecord->mIDToRollback = -1;
+  sTheRecord->currSnapShotID = 0;
 #endif
-       }
+}
 #ifdef __cplusplus
 }
 #endif
 void initSnapShotLibrary(unsigned int numbackingpages, unsigned int numsnapshots, unsigned int nummemoryregions, unsigned int numheappages, MyFuncPtr entryPoint){
 #if USE_CHECKPOINTING
-       struct sigaction sa;
-       sa.sa_flags = SA_SIGINFO | SA_NODEFER | SA_RESTART;
-       sigemptyset( &sa.sa_mask );
-       sa.sa_sigaction = HandlePF;
-       if( sigaction( SIGSEGV, &sa, NULL ) == -1 ){
-               printf("SIGACTION CANNOT BE INSTALLED\n");
-               exit(-1);
-       }
-       initSnapShotRecord(numbackingpages, numsnapshots, nummemoryregions);
-       
-       basemySpace=MYMALLOC((numheappages+1)*PAGESIZE);
-       void * pagealignedbase=PageAlignAddressUpward(basemySpace);
-       mySpace = create_mspace_with_base(pagealignedbase,  numheappages*PAGESIZE, 1 );
-       addMemoryRegionToSnapShot(pagealignedbase, numheappages);
-       entryPoint();
+  struct sigaction sa;
+  sa.sa_flags = SA_SIGINFO | SA_NODEFER | SA_RESTART;
+  sigemptyset( &sa.sa_mask );
+  sa.sa_sigaction = HandlePF;
+  if( sigaction( SIGSEGV, &sa, NULL ) == -1 ){
+    printf("SIGACTION CANNOT BE INSTALLED\n");
+    exit(-1);
+  }
+  mySpace = create_mspace( numheappages*PAGESIZE, 1 );
+  initSnapShotRecord(numbackingpages, numsnapshots, nummemoryregions);
+  addMemoryRegionToSnapShot(mySpace, numheappages);
+  entryPoint();
 #else
-       //add a signal to indicate that the process is going to terminate.
-       struct sigaction sa;
-       sa.sa_flags = SA_SIGINFO | SA_NODEFER | SA_RESTART;
-       sigemptyset( &sa.sa_mask );
-       sa.sa_sigaction = HandlePF;
-       if( sigaction( SIGUSR1, &sa, NULL ) == -1 ){
-               printf("SIGACTION CANNOT BE INSTALLED\n");
-               exit(-1);
-       }
-       createSharedLibrary();
-#if SSDEBUG
-       starttime = &(sTheRecord->startTimeGlobal);
-       gettimeofday( starttime, NULL );
+  //add a signal to indicate that the process is going to terminate.
+  struct sigaction sa;
+  sa.sa_flags = SA_SIGINFO | SA_NODEFER | SA_RESTART;
+  sigemptyset( &sa.sa_mask );
+  sa.sa_sigaction = HandlePF;
+  if( sigaction( SIGUSR1, &sa, NULL ) == -1 ){
+    printf("SIGACTION CANNOT BE INSTALLED\n");
+    exit(-1);
+  }
+  createSharedLibrary();
+ #if SSDEBUG
+  starttime = &(sTheRecord->startTimeGlobal);
+  gettimeofday( starttime, NULL );
 #endif
-       //step 2 setup the stack context.
+  //step 2 setup the stack context.
  
-       int alreadySwapped = 0;
-       getcontext( &savedSnapshotContext );
-       if( !alreadySwapped ){
-               alreadySwapped = 1;
-               ucontext_t currentContext, swappedContext, newContext;
-               getcontext( &newContext );
-               newContext.uc_stack.ss_sp = sTheRecord->mStackBase;
-               newContext.uc_stack.ss_size = STACK_SIZE_DEFAULT;
-               newContext.uc_link = &currentContext;
-               makecontext( &newContext, entryPoint, 0 );
-               swapcontext( &swappedContext, &newContext );
-       }
+  int alreadySwapped = 0;
+  getcontext( &savedSnapshotContext );
+  if( !alreadySwapped ){
+    alreadySwapped = 1;
+    ucontext_t currentContext, swappedContext, newContext;
+    getcontext( &newContext );
+    newContext.uc_stack.ss_sp = sTheRecord->mStackBase;
+    newContext.uc_stack.ss_size = STACK_SIZE_DEFAULT;
+    newContext.uc_link = &currentContext;
+    makecontext( &newContext, entryPoint, 0 );
+    swapcontext( &swappedContext, &newContext );
+  }
   
-       //add the code to take a snapshot here...
+   //add the code to take a snapshot here...
        //to return to user process, do a second swapcontext...
-       pid_t forkedID = 0;
-       snapshotid = sTheRecord->currSnapShotID;
-       bool swapContext = false;
-       while( !sTheRecord->mbFinalize ){
-               sTheRecord->currSnapShotID=snapshotid+1;
-               forkedID = fork();
-               if( 0 == forkedID ){ 
-                       ucontext_t currentContext;
+  pid_t forkedID = 0;
+  snapshotid = sTheRecord->currSnapShotID;
+  bool swapContext = false;
+  while( !sTheRecord->mbFinalize ){
+    sTheRecord->currSnapShotID=snapshotid+1;
+    forkedID = fork();
+    if( 0 == forkedID ){ 
+      ucontext_t currentContext;
 #if 0
-                       int dbg = 0;
-                       while( !dbg );
+      int dbg = 0;
+      while( !dbg );
 #endif
-                       if( swapContext )
-                               swapcontext( &currentContext, &( sTheRecord->mContextToRollback ) );
+      if( swapContext )
+        swapcontext( &currentContext, &( sTheRecord->mContextToRollback ) );
                        else{
                                swapcontext( &currentContext, &savedUserSnapshotContext );      
                        }
-               } else {
-                       int status;
-                       int retVal;
+    } else {
+      int status;
+      int retVal;
 #if SSDEBUG
-                       char mesg[ 1024 ] = { 0 };
-                       sprintf( mesg, "The process id of child is %d and the process id of this process is %d and snapshot id is %d", forkedID, getpid(), snapshotid );
-                       DumpIntoLog( "ModelSnapshot", mesg );
+      char mesg[ 1024 ] = { 0 };
+      sprintf( mesg, "The process id of child is %d and the process id of this process is %d and snapshot id is %d", forkedID, getpid(), snapshotid );
+      DumpIntoLog( "ModelSnapshot", mesg );
 #endif
-                       do { 
+      do { 
                                retVal=waitpid( forkedID, &status, 0 );
-                       } while( -1 == retVal && errno == EINTR );
+      } while( -1 == retVal && errno == EINTR );
 
-                       if( sTheRecord->mIDToRollback != snapshotid )
-                               exit(0);
-                       else{
-                               swapContext = true;
-                       }
-               }
-       }
+      if( sTheRecord->mIDToRollback != snapshotid )
+                         exit(0);
+      else{
+         swapContext = true;
+      }
+    }
+  }
   
 #endif
 }
 /* This function assumes that addr is page aligned */
 void addMemoryRegionToSnapShot( void * addr, unsigned int numPages) {
 #if USE_CHECKPOINTING
-       unsigned int memoryregion=snapshotrecord->lastRegion++;
-       if (memoryregion==snapshotrecord->maxRegions) {
-               printf("Exceeded supported number of memory regions!\n");
-               exit(-1);
-       }
+  unsigned int memoryregion=snapshotrecord->lastRegion++;
+  if (memoryregion==snapshotrecord->maxRegions) {
+    printf("Exceeded supported number of memory regions!\n");
+    exit(-1);
+  }
   
-       snapshotrecord->regionsToSnapShot[ memoryregion ].basePtr=addr;
-       snapshotrecord->regionsToSnapShot[ memoryregion ].sizeInPages=numPages;
+  snapshotrecord->regionsToSnapShot[ memoryregion ].basePtr=addr;
+  snapshotrecord->regionsToSnapShot[ memoryregion ].sizeInPages=numPages;
 #endif //NOT REQUIRED IN THE CASE OF FORK BASED SNAPSHOTS.
 }
 //take snapshot
 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);
-               }               
-       }
-       unsigned int snapshot=snapshotrecord->lastSnapShot++;
-       if (snapshot==snapshotrecord->maxSnapShots) {
-               printf("Out of snapshots\n");
-               exit(-1);
-       }
-       snapshotrecord->snapShots[snapshot].firstBackingPage=snapshotrecord->lastBackingPage;
+  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 ){
+      printf("Failed to mprotect inside of takeSnapShot\n");
+      exit(-1);
+    }          
+  }
+  unsigned int snapshot=snapshotrecord->lastSnapShot++;
+  if (snapshot==snapshotrecord->maxSnapShots) {
+    printf("Out of snapshots\n");
+    exit(-1);
+  }
+  snapshotrecord->snapShots[snapshot].firstBackingPage=snapshotrecord->lastBackingPage;
   
-       return snapshot;
+  return snapshot;
 #else
-       swapcontext( &savedUserSnapshotContext, &savedSnapshotContext );
-       return snapshotid;
+  swapcontext( &savedUserSnapshotContext, &savedSnapshotContext );
+  return snapshotid;
 #endif
 }
 void rollBack( snapshot_id theID ){
 #if USE_CHECKPOINTING
-       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);
-               }               
-       }
-       for(unsigned int page=snapshotrecord->snapShots[theID].firstBackingPage; page<snapshotrecord->lastBackingPage; page++) {
-               bool oldVal = false;
-               if( duplicateMap.find( snapshotrecord->backingRecords[page].basePtrOfPage ) != duplicateMap.end() ){
-                       oldVal = true;          
-               }
-               else{
-                       duplicateMap[ snapshotrecord->backingRecords[page].basePtrOfPage ] = true;    
-               }
-               if(  !oldVal ){
-                       memcpy(snapshotrecord->backingRecords[page].basePtrOfPage, &snapshotrecord->backingStore[page], sizeof(struct SnapShotPage));
-               }
-       }
-       snapshotrecord->lastSnapShot=theID;
-       snapshotrecord->lastBackingPage=snapshotrecord->snapShots[theID].firstBackingPage;
-       takeSnapshot(); //Make sure current snapshot is still good...All later ones are cleared
+  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 ){
+      printf("Failed to mprotect inside of takeSnapShot\n");
+      exit(-1);
+    }          
+  }
+  for(unsigned int page=snapshotrecord->snapShots[theID].firstBackingPage; page<snapshotrecord->lastBackingPage; page++) {
+    bool oldVal = false;
+    if( duplicateMap.find( snapshotrecord->backingRecords[page].basePtrOfPage ) != duplicateMap.end() ){
+      oldVal = true;          
+    }
+    else{
+      duplicateMap[ snapshotrecord->backingRecords[page].basePtrOfPage ] = true;    
+    }
+    if(  !oldVal ){
+      memcpy(snapshotrecord->backingRecords[page].basePtrOfPage, &snapshotrecord->backingStore[page], sizeof(struct SnapShotPage));
+    }
+  }
+  snapshotrecord->lastSnapShot=theID;
+  snapshotrecord->lastBackingPage=snapshotrecord->snapShots[theID].firstBackingPage;
+  takeSnapshot(); //Make sure current snapshot is still good...All later ones are cleared
 #else
-       sTheRecord->mIDToRollback = theID;
-       int sTemp = 0;
-       getcontext( &sTheRecord->mContextToRollback );
-       if( !sTemp ){
-               sTemp = 1;
+  sTheRecord->mIDToRollback = theID;
+  int sTemp = 0;
+  getcontext( &sTheRecord->mContextToRollback );
+  if( !sTemp ){
+    sTemp = 1;
 #if SSDEBUG
-               DumpIntoLog( "ModelSnapshot", "Invoked rollback" ); 
+       DumpIntoLog( "ModelSnapshot", "Invoked rollback" ); 
 #endif
-               exit( 0 );
-       }
+       exit( 0 );
+  }
 #endif
 }
 
 void finalize(){
 #if !USE_CHECKPOINTING
-       sTheRecord->mbFinalize = true;
+  sTheRecord->mbFinalize = true;
 #endif
 }