Skip to content

Commit

Permalink
[ALL] fix some bugs in efence and format the source code
Browse files Browse the repository at this point in the history
  • Loading branch information
@Donald-Zhuang
Donald-Zhuang committed Nov 24, 2018
1 parent 05b2a84 commit 915636f
Showing 1 changed file with 43 additions and 39 deletions.
82 changes: 43 additions & 39 deletions efence.c
View file
Original file line number Original file line Diff line number Diff line change
@@ -1,7 +1,7 @@
/* /*
* Electric Fence - Red-Zone memory allocator. * Electric Fence - Red-Zone memory allocator.
* Bruce Perens, 1988, 1993 * Bruce Perens, 1988, 1993
* *
* For email below, drop spaces and <spam-buster> tag. * For email below, drop spaces and <spam-buster> tag.
* MODIFIED: March 20, 2014 (jric<spam-buster> @ <spam-buster> chegg DOT com) * MODIFIED: March 20, 2014 (jric<spam-buster> @ <spam-buster> chegg DOT com)
* *
Expand Down Expand Up @@ -206,7 +206,7 @@ static void lock() {
} else { } else {
pthread_mutex_lock(&mutex); pthread_mutex_lock(&mutex);
} }
} }
mutexpid=getpid(); mutexpid=getpid();
locknr=1; locknr=1;
} }
Expand Down Expand Up @@ -377,6 +377,7 @@ allocateMoreSlots(void)
size_t newSize = allocationListSize + bytesPerPage; size_t newSize = allocationListSize + bytesPerPage;
void * newAllocation; void * newAllocation;
void * oldAllocation = allocationList; void * oldAllocation = allocationList;
Slot* slot = NULL;


Page_AllowAccess(allocationList, allocationListSize); Page_AllowAccess(allocationList, allocationListSize);
noAllocationListProtection = 1; noAllocationListProtection = 1;
Expand All @@ -391,6 +392,12 @@ allocateMoreSlots(void)
slotCount += slotsPerPage; slotCount += slotsPerPage;
unUsedSlots += slotsPerPage; unUsedSlots += slotsPerPage;


/* Update the allocator's checklist in slot[0] */
slot = allocationList;
slot[0].internalSize = slot[0].userSize = allocationListSize;
slot[0].internalAddress = slot[0].userAddress = allocationList;
slot[0].mode = INTERNAL_USE;

free(oldAllocation); free(oldAllocation);


/* /*
Expand All @@ -417,11 +424,11 @@ allocateMoreSlots(void)
* functions on Sun systems, which do word references to the string memory * functions on Sun systems, which do word references to the string memory
* and may refer to memory up to three bytes beyond the end of the string. * and may refer to memory up to three bytes beyond the end of the string.
* For this reason, I take the alignment requests to memalign() and valloc() * For this reason, I take the alignment requests to memalign() and valloc()
* seriously, and * seriously, and
* *
* Electric Fence wastes lots of memory. I do a best-fit allocator here * Electric Fence wastes lots of memory. I do a best-fit allocator here
* so that it won't waste even more. It's slow, but thrashing because your * so that it won't waste even more. It's slow, but thrashing because your
* working set is too big for a system's RAM is even slower. * working set is too big for a system's RAM is even slower.
*/ */
extern C_LINKAGE void * extern C_LINKAGE void *
memalign(size_t alignment, size_t userSize) memalign(size_t alignment, size_t userSize)
Expand Down Expand Up @@ -482,7 +489,7 @@ memalign(size_t alignment, size_t userSize)
if ( !internalUse && unUsedSlots < 7 ) { if ( !internalUse && unUsedSlots < 7 ) {
allocateMoreSlots(); allocateMoreSlots();
} }

/* /*
* Iterate through all of the slot structures. Attempt to find a slot * Iterate through all of the slot structures. Attempt to find a slot
* containing free memory of the exact right size. Accept a slot with * containing free memory of the exact right size. Accept a slot with
Expand All @@ -492,7 +499,7 @@ memalign(size_t alignment, size_t userSize)
* we have to create new memory and mark it as free. * we have to create new memory and mark it as free.
* *
*/ */

for ( slot = allocationList, count = slotCount ; count > 0; count-- ) { for ( slot = allocationList, count = slotCount ; count > 0; count-- ) {
if ( slot->mode == FREE if ( slot->mode == FREE
&& slot->internalSize >= internalSize ) { && slot->internalSize >= internalSize ) {
Expand Down Expand Up @@ -583,7 +590,7 @@ memalign(size_t alignment, size_t userSize)
Page_AllowAccess( Page_AllowAccess(
fullSlot->internalAddress fullSlot->internalAddress
,internalSize - bytesPerPage); ,internalSize - bytesPerPage);

address += internalSize - bytesPerPage; address += internalSize - bytesPerPage;


/* Set up the "dead" page. */ /* Set up the "dead" page. */
Expand All @@ -602,7 +609,7 @@ memalign(size_t alignment, size_t userSize)


/* Set up the "dead" page. */ /* Set up the "dead" page. */
Page_DenyAccess(address, bytesPerPage); Page_DenyAccess(address, bytesPerPage);

address += bytesPerPage; address += bytesPerPage;


/* Set up the "live" page. */ /* Set up the "live" page. */
Expand Down Expand Up @@ -631,7 +638,7 @@ slotForUserAddress(void * address)
{ {
register Slot * slot = allocationList; register Slot * slot = allocationList;
register size_t count = slotCount; register size_t count = slotCount;

for ( ; count > 0; count-- ) { for ( ; count > 0; count-- ) {
if ( slot->userAddress == address ) if ( slot->userAddress == address )
return slot; return slot;
Expand All @@ -649,7 +656,7 @@ slotForInternalAddress(void * address)
{ {
register Slot * slot = allocationList; register Slot * slot = allocationList;
register size_t count = slotCount; register size_t count = slotCount;

for ( ; count > 0; count-- ) { for ( ; count > 0; count-- ) {
if ( slot->internalAddress == address ) if ( slot->internalAddress == address )
return slot; return slot;
Expand All @@ -668,7 +675,7 @@ slotForInternalAddressPreviousTo(void * address)
{ {
register Slot * slot = allocationList; register Slot * slot = allocationList;
register size_t count = slotCount; register size_t count = slotCount;

for ( ; count > 0; count-- ) { for ( ; count > 0; count-- ) {
if ( ((char *)slot->internalAddress) if ( ((char *)slot->internalAddress)
+ slot->internalSize == address ) + slot->internalSize == address )
Expand Down Expand Up @@ -713,21 +720,17 @@ free(void * address)
} }
} }


if ( EF_PROTECT_FREE ) slot->mode = EF_PROTECT_FREE ? PROTECTED : FREE;
slot->mode = PROTECTED;
else
slot->mode = FREE;


if ( EF_FREE_WIPES ) if ( EF_FREE_WIPES )
memset(slot->userAddress, 0xbd, slot->userSize); {
memset(slot->userAddress, 0xbd, slot->userSize);
}


/* Only coalesces the same mode of previous/next slot with this one. */
previousSlot = slotForInternalAddressPreviousTo(slot->internalAddress); previousSlot = slotForInternalAddressPreviousTo(slot->internalAddress);
nextSlot = slotForInternalAddress( if ( previousSlot && (previousSlot->mode == slot->mode) )
((char *)slot->internalAddress) + slot->internalSize); {

if ( previousSlot
&& (previousSlot->mode == FREE || previousSlot->mode == PROTECTED) ) {
/* Coalesce previous slot with this one. */
previousSlot->internalSize += slot->internalSize; previousSlot->internalSize += slot->internalSize;
if ( EF_PROTECT_FREE ) if ( EF_PROTECT_FREE )
previousSlot->mode = PROTECTED; previousSlot->mode = PROTECTED;
Expand All @@ -738,9 +741,10 @@ free(void * address)
slot = previousSlot; slot = previousSlot;
unUsedSlots++; unUsedSlots++;
} }
if ( nextSlot
&& (nextSlot->mode == FREE || nextSlot->mode == PROTECTED) ) { nextSlot = slotForInternalAddress(((char *)slot->internalAddress) + slot->internalSize);
/* Coalesce next slot with this one. */ if ( nextSlot && (nextSlot->mode == slot->mode) )
{
slot->internalSize += nextSlot->internalSize; slot->internalSize += nextSlot->internalSize;
nextSlot->internalAddress = nextSlot->userAddress = 0; nextSlot->internalAddress = nextSlot->userAddress = 0;
nextSlot->internalSize = nextSlot->userSize = 0; nextSlot->internalSize = nextSlot->userSize = 0;
Expand All @@ -754,7 +758,7 @@ free(void * address)
/* /*
* Free memory is _always_ set to deny access. When EF_PROTECT_FREE * Free memory is _always_ set to deny access. When EF_PROTECT_FREE
* is true, free memory is never reallocated, so it remains access * is true, free memory is never reallocated, so it remains access
* denied for the life of the process. When EF_PROTECT_FREE is false, * denied for the life of the process. When EF_PROTECT_FREE is false,
* the memory may be re-allocated, at which time access to it will be * the memory may be re-allocated, at which time access to it will be
* allowed again. * allowed again.
*/ */
Expand All @@ -779,7 +783,7 @@ realloc(void * oldBuffer, size_t newSize)


Page_AllowAccess(allocationList, allocationListSize); Page_AllowAccess(allocationList, allocationListSize);
noAllocationListProtection = 1; noAllocationListProtection = 1;

slot = slotForUserAddress(oldBuffer); slot = slotForUserAddress(oldBuffer);


if ( slot == 0 ) if ( slot == 0 )
Expand All @@ -800,7 +804,7 @@ realloc(void * oldBuffer, size_t newSize)


if ( size < newSize ) if ( size < newSize )
memset(&(((char *)newBuffer)[size]), 0, newSize - size); memset(&(((char *)newBuffer)[size]), 0, newSize - size);

/* Internal memory was re-protected in free() */ /* Internal memory was re-protected in free() */
} }
unlock(); unlock();
Expand All @@ -811,14 +815,14 @@ realloc(void * oldBuffer, size_t newSize)
extern C_LINKAGE void * extern C_LINKAGE void *
malloc(size_t size) malloc(size_t size)
{ {
void *allocation; void *allocation;

if ( allocationList == 0 ) { if ( allocationList == 0 ) {
pthread_mutex_init(&mutex, NULL); pthread_mutex_init(&mutex, NULL);
initialize(); /* This sets EF_ALIGNMENT */ initialize(); /* This sets EF_ALIGNMENT */
} }
lock(); lock();
allocation=memalign(EF_ALIGNMENT, size); allocation=memalign(EF_ALIGNMENT, size);


unlock(); unlock();


Expand Down Expand Up @@ -868,9 +872,9 @@ calloc(size_t nelem, size_t elsize)
{ {
size_t size = nelem * elsize; size_t size = nelem * elsize;
void * allocation; void * allocation;

lock(); lock();

allocation = malloc(size); allocation = malloc(size);
memset(allocation, 0, size); memset(allocation, 0, size);
unlock(); unlock();
Expand All @@ -886,10 +890,10 @@ extern C_LINKAGE void *
valloc (size_t size) valloc (size_t size)
{ {
void * allocation; void * allocation;

lock(); lock();
allocation= memalign(bytesPerPage, size); allocation= memalign(bytesPerPage, size);
unlock(); unlock();

return allocation; return allocation;
} }

0 comments on commit 915636f

Please sign in to comment.