diff options
| -rw-r--r-- | Objects/obmalloc.c | 76 |
1 files changed, 57 insertions, 19 deletions
diff --git a/Objects/obmalloc.c b/Objects/obmalloc.c index b92116c..7f5306f 100644 --- a/Objects/obmalloc.c +++ b/Objects/obmalloc.c @@ -1418,7 +1418,7 @@ static void * _PyMem_DebugRawAlloc(int use_calloc, void *ctx, size_t nbytes) { debug_alloc_api_t *api = (debug_alloc_api_t *)ctx; - uint8_t *p; /* base address of malloc'epad d block */ + uint8_t *p; /* base address of malloc'ed pad block */ uint8_t *data; /* p + 2*SST == pointer to data bytes */ uint8_t *tail; /* data + nbytes == pointer to tail pad bytes */ size_t total; /* 2 * SST + nbytes + 2 * SST */ @@ -1516,45 +1516,83 @@ _PyMem_DebugRawRealloc(void *ctx, void *p, size_t nbytes) } debug_alloc_api_t *api = (debug_alloc_api_t *)ctx; - uint8_t *q; /* base address of malloc'epad d block */ - uint8_t *data; /* p + 2*SST == pointer to data bytes */ + uint8_t *head; /* base address of malloc'ed pad block */ + uint8_t *data; /* pointer to data bytes */ + uint8_t *r; uint8_t *tail; /* data + nbytes == pointer to tail pad bytes */ size_t total; /* 2 * SST + nbytes + 2 * SST */ size_t original_nbytes; - int i; + size_t serialno; +#define ERASED_SIZE 64 + uint8_t save[2*ERASED_SIZE]; /* A copy of erased bytes. */ _PyMem_DebugCheckAddress(api->api_id, p); - q = (uint8_t *)p; - original_nbytes = read_size_t(q - 2*SST); + data = (uint8_t *)p; + head = data - 2*SST; + original_nbytes = read_size_t(head); if (nbytes > (size_t)PY_SSIZE_T_MAX - 4*SST) { /* integer overflow: can't represent total as a Py_ssize_t */ return NULL; } total = nbytes + 4*SST; - /* Resize and add decorations. */ - q = (uint8_t *)api->alloc.realloc(api->alloc.ctx, q - 2*SST, total); - if (q == NULL) { - return NULL; + tail = data + original_nbytes; + serialno = read_size_t(tail + SST); + /* Mark the header, the trailer, ERASED_SIZE bytes at the begin and + ERASED_SIZE bytes at the end as dead and save the copy of erased bytes. + */ + if (original_nbytes <= sizeof(save)) { + memcpy(save, data, original_nbytes); + memset(data - 2*SST, DEADBYTE, original_nbytes + 4*SST); + } + else { + memcpy(save, data, ERASED_SIZE); + memset(head, DEADBYTE, ERASED_SIZE + 2*SST); + memcpy(&save[ERASED_SIZE], tail - ERASED_SIZE, ERASED_SIZE); + memset(tail - ERASED_SIZE, DEADBYTE, ERASED_SIZE + 2*SST); } - bumpserialno(); - write_size_t(q, nbytes); - assert(q[SST] == (uint8_t)api->api_id); - for (i = 1; i < SST; ++i) { - assert(q[SST + i] == FORBIDDENBYTE); + /* Resize and add decorations. */ + r = (uint8_t *)api->alloc.realloc(api->alloc.ctx, head, total); + if (r == NULL) { + nbytes = original_nbytes; + } + else { + head = r; + bumpserialno(); + serialno = _PyRuntime.mem.serialno; } - data = q + 2*SST; + + write_size_t(head, nbytes); + head[SST] = (uint8_t)api->api_id; + memset(head + SST + 1, FORBIDDENBYTE, SST-1); + data = head + 2*SST; tail = data + nbytes; memset(tail, FORBIDDENBYTE, SST); - write_size_t(tail + SST, _PyRuntime.mem.serialno); + write_size_t(tail + SST, serialno); + + /* Restore saved bytes. */ + if (original_nbytes <= sizeof(save)) { + memcpy(data, save, Py_MIN(nbytes, original_nbytes)); + } + else { + size_t i = original_nbytes - ERASED_SIZE; + memcpy(data, save, Py_MIN(nbytes, ERASED_SIZE)); + if (nbytes > i) { + memcpy(data + i, &save[ERASED_SIZE], + Py_MIN(nbytes - i, ERASED_SIZE)); + } + } + + if (r == NULL) { + return NULL; + } if (nbytes > original_nbytes) { /* growing: mark new extra memory clean */ - memset(data + original_nbytes, CLEANBYTE, - nbytes - original_nbytes); + memset(data + original_nbytes, CLEANBYTE, nbytes - original_nbytes); } return data; |