Commit c54980ff authored by Ian Lynagh's avatar Ian Lynagh
Browse files

Fix Windows memory freeing: add a check for fb == NULL; fixes trac #4506

Also added a few comments, and a load of code got indented 1 level deeper.
parent c50bc465
......@@ -265,57 +265,68 @@ void osReleaseFreeMemory(void)
while (a != NULL) {
a_end = a->base + a->size;
/* If a is freeable then there is a single freeblock in fb that
covers it. The end of this free block must be >= the end of
a, so skip anything in fb that ends before a. */
while (fb != NULL && fb->base + fb->size < a_end) {
prev_fb = fb;
fb = fb->next;
}
fb_end = fb->base + fb->size;
if (fb->base <= a->base) {
/* The alloc is within the free block. Now we need to know
if it sticks out at either end. */
if (fb_end == a_end) {
if (fb->base == a->base) {
/* fb and a are identical, so just free fb */
prev_fb->next = fb->next;
stgFree(fb);
fb = prev_fb->next;
if (fb == NULL) {
/* If we have nothing left in fb, then neither a nor
anything later in the list is freeable, so we are done. */
break;
}
else {
fb_end = fb->base + fb->size;
/* We have a candidate fb. But does it really cover a? */
if (fb->base <= a->base) {
/* Yes, the alloc is within the free block. Now we need
to know if it sticks out at either end. */
if (fb_end == a_end) {
if (fb->base == a->base) {
/* fb and a are identical, so just free fb */
prev_fb->next = fb->next;
stgFree(fb);
fb = prev_fb->next;
}
else {
/* fb begins earlier, so truncate it to not include a */
fb->size = a->base - fb->base;
}
}
else {
/* fb begins earlier, so truncate it to not include a */
fb->size = a->base - fb->base;
/* fb ends later, so we'll make fb just be the part
after a. First though, if it also starts earlier,
we make a new free block record for the before bit. */
if (fb->base != a->base) {
block_rec *new_fb;
new_fb = (block_rec *)stgMallocBytes(sizeof(block_rec),"osReleaseFreeMemory");
new_fb->base = fb->base;
new_fb->size = a->base - fb->base;
new_fb->next = fb;
prev_fb->next = new_fb;
}
fb->size = fb_end - a_end;
fb->base = a_end;
}
}
else {
/* fb ends later, so we'll make fb just be the part
after a. First though, if it also starts earlier,
we make a new free block record for the before bit. */
if (fb->base != a->base) {
block_rec *new_fb;
new_fb = (block_rec *)stgMallocBytes(sizeof(block_rec),"osReleaseFreeMemory");
new_fb->base = fb->base;
new_fb->size = a->base - fb->base;
new_fb->next = fb;
prev_fb->next = new_fb;
/* Now we can free the alloc */
prev_a->next = a->next;
if(!VirtualFree((void *)a->base, 0, MEM_RELEASE)) {
sysErrorBelch("freeAllMBlocks: VirtualFree MEM_RELEASE failed");
stg_exit(EXIT_FAILURE);
}
fb->size = fb_end - a_end;
fb->base = a_end;
stgFree(a);
a = prev_a->next;
}
/* Now we can free the alloc */
prev_a->next = a->next;
if(!VirtualFree((void *)a->base, 0, MEM_RELEASE)) {
sysErrorBelch("freeAllMBlocks: VirtualFree MEM_RELEASE failed");
stg_exit(EXIT_FAILURE);
else {
/* Otherwise this alloc is not freeable, so go on to the
next one */
prev_a = a;
a = a->next;
}
stgFree(a);
a = prev_a->next;
}
else {
/* Otherwise this alloc is not freeable, so go on to the
next one */
prev_a = a;
a = a->next;
}
}
......
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