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Merge pull request #628 from pietern/unstable-zip

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Fix ziplist edge case
This commit is contained in:
Salvatore Sanfilippo 2012-08-22 02:32:27 -07:00
commit 724371d748
1 changed files with 61 additions and 7 deletions
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68
src/ziplist.c
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@ -500,12 +500,13 @@ static unsigned char *__ziplistDelete(unsigned char *zl, unsigned char *p, unsig
totlen = p-first.p;
if (totlen > 0) {
if (p[0] != ZIP_END) {
/* Tricky: storing the prevlen in this entry might reduce or
* increase the number of bytes needed, compared to the current
* prevlen. Note that we can always store this length because
* it was previously stored by an entry that is being deleted. */
/* Storing `prevrawlen` in this entry may increase or decrease the
* number of bytes required compare to the current `prevrawlen`.
* There always is room to store this, because it was previously
* stored by an entry that is now being deleted. */
nextdiff = zipPrevLenByteDiff(p,first.prevrawlen);
zipPrevEncodeLength(p-nextdiff,first.prevrawlen);
p -= nextdiff;
zipPrevEncodeLength(p,first.prevrawlen);
/* Update offset for tail */
ZIPLIST_TAIL_OFFSET(zl) =
@ -521,8 +522,8 @@ static unsigned char *__ziplistDelete(unsigned char *zl, unsigned char *p, unsig
}
/* Move tail to the front of the ziplist */
memmove(first.p,p-nextdiff,
intrev32ifbe(ZIPLIST_BYTES(zl))-(p-zl)-1+nextdiff);
memmove(first.p,p,
intrev32ifbe(ZIPLIST_BYTES(zl))-(p-zl)-1);
} else {
/* The entire tail was deleted. No need to move memory. */
ZIPLIST_TAIL_OFFSET(zl) =
@ -1034,6 +1035,22 @@ int randstring(char *target, unsigned int min, unsigned int max) {
return len;
}
void verify(unsigned char *zl, zlentry *e) {
int i;
int len = ziplistLen(zl);
zlentry _e;
for (i = 0; i < len; i++) {
memset(&e[i], 0, sizeof(zlentry));
e[i] = zipEntry(ziplistIndex(zl, i));
memset(&_e, 0, sizeof(zlentry));
_e = zipEntry(ziplistIndex(zl, -len+i));
assert(memcmp(&e[i], &_e, sizeof(zlentry)) == 0);
}
}
int main(int argc, char **argv) {
unsigned char *zl, *p;
unsigned char *entry;
@ -1315,6 +1332,43 @@ int main(int argc, char **argv) {
printf("SUCCESS\n\n");
}
printf("Regression test deleting next to last entries:\n");
{
char v[3][257];
zlentry e[3];
int i;
for (i = 0; i < (sizeof(v)/sizeof(v[0])); i++) {
memset(v[i], 'a' + i, sizeof(v[0]));
}
v[0][256] = '\0';
v[1][ 1] = '\0';
v[2][256] = '\0';
zl = ziplistNew();
for (i = 0; i < (sizeof(v)/sizeof(v[0])); i++) {
zl = ziplistPush(zl, (unsigned char *) v[i], strlen(v[i]), ZIPLIST_TAIL);
}
verify(zl, e);
assert(e[0].prevrawlensize == 1);
assert(e[1].prevrawlensize == 5);
assert(e[2].prevrawlensize == 1);
/* Deleting entry 1 will increase `prevrawlensize` for entry 2 */
unsigned char *p = e[1].p;
zl = ziplistDelete(zl, &p);
verify(zl, e);
assert(e[0].prevrawlensize == 1);
assert(e[1].prevrawlensize == 5);
printf("SUCCESS\n\n");
}
printf("Create long list and check indices:\n");
{
zl = ziplistNew();