Rework [76c8435a] to eliminate automatic JS-to-WASM function conversions of sqlite3_set_auxdata() destructors because it can leads to leaks on every call of a UDF. This feature never worked before [76c8435a] but fixing it was ill-conceived because of the memory leakage it introduces. WASM function pointers can still be used as destructors in this context.

FossilOrigin-Name: 3fb993af0caf041da934cea29c039b27c468be0b75bce1537a6425767cf9bf8d

1 files changed, 24 insertions, 13 deletions

diff --git a/ext/wasm/api/sqlite3-api-glue.c-pp.js b/ext/wasm/api/sqlite3-api-glue.c-pp.js
index bcaff7243..a40b83282 100644
--- a/ext/wasm/api/sqlite3-api-glue.c-pp.js
+++ b/ext/wasm/api/sqlite3-api-glue.c-pp.js
@@ -229,14 +229,15 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
       '*'
     ]],
     /**
-       2025-02-03: We do not have a way to automatically clean up
-       destructors which are automatically converted from JS functions
-       via the final argument to sqlite3_set_auxdata(). Because of
-       that, it is strongly recommended that clients use
-       wasm.installFunction() to create such callbacks, then pass that
-       pointer to sqlite3_set_auxdata(). Relying on automated
-       conversions here will lead to leaks of JS/WASM proxy functions
-       because sqlite3_set_auxdata() is frequently called in UDFs.
+       We do not have a way to automatically clean up destructors
+       which are automatically converted from JS functions via the
+       final argument to sqlite3_set_auxdata(). Because of that,
+       automatic function conversion is not supported for this
+       function.  Clients should use wasm.installFunction() to create
+       such callbacks, then pass that pointer to
+       sqlite3_set_auxdata(). Relying on automated conversions here
+       would lead to leaks of JS/WASM proxy functions because
+       sqlite3_set_auxdata() is frequently called in UDFs.
 
        The sqlite3.oo1.DB class's onclose handlers can be used for this
        purpose. For example:
@@ -252,14 +253,24 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
 
        Then pass pAuxDtor as the final argument to appropriate
        sqlite3_set_auxdata() calls.
+
+       Note that versions prior to 3.49.0 ostensibly had automatic
+       function conversion here but a typo prevented it from
+       working.  Rather than fix it, it was removed because testing the
+       fix brought the huge potential for memory leaks to the
+       forefront.
     */
     ["sqlite3_set_auxdata", undefined, [
       "sqlite3_context*", "int", "*",
-      new wasm.xWrap.FuncPtrAdapter({
-        name: 'xDestroyAuxData',
-        signature: 'v(p)',
-        contextKey: (argv, argIndex)=>argv[0/* sqlite3_context* */]
-      })
+      true
+        ? "*"
+        : new wasm.xWrap.FuncPtrAdapter({
+          /* If we can find a way to automate their cleanup, JS functions can
+             be auto-converted with this. */
+          name: 'xDestroyAuxData',
+          signature: 'v(p)',
+          contextKey: (argv, argIndex)=>argv[0/* sqlite3_context* */]
+        })
     ]],
     ["sqlite3_shutdown", undefined],
     ["sqlite3_sourceid", "string"],