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Bulletproof leak dump against null hash entries

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Previously, the malloc leak checking code would crash in qsort()
if null entries existed in its bookkeeping table.  This change
makes the comparison function detect null entries and sort them
to the end safely.

Change-Id: I88244a7df1e289dd9d7992ce29606d505bd63079
This commit is contained in:
Christopher Tate 2010-08-09 13:43:46 -07:00
parent 18c5bcc66a
commit 52e7d3d91a
1 changed files with 29 additions and 20 deletions
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49
libc/bionic/malloc_debug_common.c
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@ -60,34 +60,43 @@ HashTable gHashTable;
static int hash_entry_compare(const void* arg1, const void* arg2)
{
int result;
HashEntry* e1 = *(HashEntry**)arg1;
HashEntry* e2 = *(HashEntry**)arg2;
size_t nbAlloc1 = e1->allocations;
size_t nbAlloc2 = e2->allocations;
size_t size1 = e1->size & ~SIZE_FLAG_MASK;
size_t size2 = e2->size & ~SIZE_FLAG_MASK;
size_t alloc1 = nbAlloc1 * size1;
size_t alloc2 = nbAlloc2 * size2;
// sort in descending order by:
// 1) total size
// 2) number of allocations
//
// This is used for sorting, not determination of equality, so we don't
// need to compare the bit flags.
int result;
if (alloc1 > alloc2) {
// if one or both arg pointers are null, deal gracefully
if (e1 == NULL) {
result = (e2 == NULL) ? 0 : 1;
} else if (e2 == NULL) {
result = -1;
} else if (alloc1 < alloc2) {
result = 1;
} else {
if (nbAlloc1 > nbAlloc2) {
size_t nbAlloc1 = e1->allocations;
size_t nbAlloc2 = e2->allocations;
size_t size1 = e1->size & ~SIZE_FLAG_MASK;
size_t size2 = e2->size & ~SIZE_FLAG_MASK;
size_t alloc1 = nbAlloc1 * size1;
size_t alloc2 = nbAlloc2 * size2;
// sort in descending order by:
// 1) total size
// 2) number of allocations
//
// This is used for sorting, not determination of equality, so we don't
// need to compare the bit flags.
int result;
if (alloc1 > alloc2) {
result = -1;
} else if (nbAlloc1 < nbAlloc2) {
} else if (alloc1 < alloc2) {
result = 1;
} else {
result = 0;
if (nbAlloc1 > nbAlloc2) {
result = -1;
} else if (nbAlloc1 < nbAlloc2) {
result = 1;
} else {
result = 0;
}
}
}
return result;