From a4145bf4ffd7b69919f100683cbb2ce580087d0c Mon Sep 17 00:00:00 2001
From: steve-chavez <stevechavezast@gmail.com>
Date: Wed, 13 Aug 2025 16:30:27 -0500
Subject: [PATCH] refactor: use curl_global_init_mem with pg allocators

Uses `curl_global_init_mem(CURL_GLOBAL_DEFAULT, net_malloc, net_free, net_realloc, net_strdup, net_calloc)`
to keep better track of memory allocation by curl.

The aim is to fix https://github.com/supabase/pg_net/issues/216.

Unfortunately this currently segfaults when reaching 2 iterations:

```sql
-- do twice
select net.http_get('http://localhost:8080/pathological?status=200') from generate_series(1,10);
select net.http_get('http://localhost:8080/pathological?status=200') from generate_series(1,10);

-- or once (this will do two iterations since the batch size defaults to 200)
select net.http_get('http://localhost:8080/pathological?status=200') from generate_series(1,300);
```

The logs:

```
2025-08-14 17:55:08.571 -05 [643019] DEBUG:  net_realloc(palloc): a((nil)), sz(32)
2025-08-14 17:55:08.571 -05 [643019] DEBUG:  net_malloc: sz(32)
2025-08-14 17:55:08.665 -05 [643013] LOG:  background worker "pg_net 0.19.5 worker" (PID 643019) was terminated by signal 11: Segmentation fault
```

Using `gdb` (via convenience `sudo xpg gdb`) will show that this will
always fail when hitting curl functions:

```
Curl_attach_connection
Curl_llist_count
Curl_conn_is_alive
```

Which are called when using `curl_multi_socket_action` in our codebase
in https://github.com/supabase/pg_net/blob/a7792bfd913c7859e14025d606624982706c2a7f/src/worker.c#L320-L336

Unfortunately this is quite hard to debug, it might be a bug in curl itself.
---
 src/worker.c | 44 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 43 insertions(+), 1 deletion(-)

diff --git a/src/worker.c b/src/worker.c
index cec0b5e..c41e496 100644
--- a/src/worker.c
+++ b/src/worker.c
@@ -232,6 +232,48 @@ static void unlock_extension(Oid ext_table_oids[static total_extension_tables]){
   UnlockRelationOid(ext_table_oids[1], AccessShareLock);
 }
 
+static void *
+net_calloc(size_t a, size_t b)
+{
+  elog(DEBUG1, "net_calloc: a(%zu), b(%zu)", a, b);
+  return palloc0(mul_size(a, b));
+}
+
+static void
+net_free(void *a)
+{
+  elog(DEBUG1, "net_free");
+  if (a)
+    pfree(a);
+}
+
+static void *
+net_malloc(size_t sz)
+{
+  elog(DEBUG1, "net_malloc: sz(%zu)", sz);
+  return sz ? palloc(sz) : NULL;
+}
+
+static void *
+net_realloc(void *a, size_t sz)
+{
+  elog(DEBUG1, "net_realloc(%s): a(%p), sz(%zu)", (sz>0?(a?"repalloc":"palloc"):"return"), a, sz);
+  if (sz > 0){
+    if (a)
+      return repalloc(a, sz);
+    else
+      return net_malloc(sz);
+  }
+  else
+    return a;
+}
+
+static char *
+net_strdup(const char *in)
+{
+  return pstrdup(in);
+}
+
 void pg_net_worker(__attribute__ ((unused)) Datum main_arg) {
   worker_state->shared_latch = &MyProc->procLatch;
   on_proc_exit(net_on_exit, 0);
@@ -246,7 +288,7 @@ void pg_net_worker(__attribute__ ((unused)) Datum main_arg) {
 
   elog(INFO, "pg_net worker started with a config of: pg_net.ttl=%s, pg_net.batch_size=%d, pg_net.username=%s, pg_net.database_name=%s", guc_ttl, guc_batch_size, guc_username, guc_database_name);
 
-  int curl_ret = curl_global_init(CURL_GLOBAL_ALL);
+  int curl_ret = curl_global_init_mem(CURL_GLOBAL_DEFAULT, net_malloc, net_free, net_realloc, net_strdup, net_calloc);
   if(curl_ret != CURLE_OK)
     ereport(ERROR, errmsg("curl_global_init() returned %s\n", curl_easy_strerror(curl_ret)));