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Posted to commits@cloudberry.apache.org by "Smyatkin-Maxim (via GitHub)" <gi...@apache.org> on 2026/05/16 18:32:56 UTC
[PR] Fix infinite loop in replaceStringInfoString [cloudberry]
Smyatkin-Maxim opened a new pull request, #1750:
URL: https://github.com/apache/cloudberry/pull/1750
The function had a few problems:
- replace ="a" and replacement="ab" would give an infinite loop leading to OOM. We have a similar case in pg_dump: replace="range", replacement="multirange"
- Copying the whole string each time there is a match
- Empty replace pattern also leads to infinite loop
We can still do better: for example count number of matches and do a single allocation, or even run the replacement inplace. But it's probably not worth it.
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Re: [PR] Fix infinite loop in replaceStringInfoString [cloudberry]
Posted by "reshke (via GitHub)" <gi...@apache.org>.
reshke commented on code in PR #1750:
URL: https://github.com/apache/cloudberry/pull/1750#discussion_r3264056798
##########
src/common/stringinfo.c:
##########
@@ -364,16 +364,32 @@ enlargeStringInfo(StringInfo str, int needed)
void
replaceStringInfoString(StringInfo str, char *replace, char *replacement)
{
- char *ptr;
+ char *match_ptr = NULL;
+ char *start_ptr = str->data;
+ char *dup = NULL;
+ size_t replace_len = strlen(replace);
- while ((ptr = strstr(str->data, replace)) != NULL)
- {
- char *dup = pstrdup(str->data);
+ // prevent empty loop, cuz strstr will always return start_ptr
Review Comment:
cuz -> because
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Re: [PR] Fix infinite loop in replaceStringInfoString [cloudberry]
Posted by "tuhaihe (via GitHub)" <gi...@apache.org>.
tuhaihe merged PR #1750:
URL: https://github.com/apache/cloudberry/pull/1750
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Re: [PR] Fix infinite loop in replaceStringInfoString [cloudberry]
Posted by "tuhaihe (via GitHub)" <gi...@apache.org>.
tuhaihe commented on code in PR #1750:
URL: https://github.com/apache/cloudberry/pull/1750#discussion_r3575612971
##########
src/common/stringinfo.c:
##########
@@ -361,16 +361,32 @@ enlargeStringInfo(StringInfo str, int needed)
void
replaceStringInfoString(StringInfo str, char *replace, char *replacement)
{
- char *ptr;
+ char *match_ptr = NULL;
+ char *start_ptr = str->data;
+ char *dup = NULL;
+ size_t replace_len = strlen(replace);
- while ((ptr = strstr(str->data, replace)) != NULL)
- {
- char *dup = pstrdup(str->data);
+ // prevent empty loop, cuz strstr will always return start_ptr
Review Comment:
```suggestion
// prevent empty loop, because strstr will always return start_ptr
```
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