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Resolve the timing/ordering issue of a JS-to-WASM-converted xDestroy() function being uninstalled from WASM right before the underlying native call tries to call it. This has been a long-unnoticed bug which appears only when removing such functions or replacing them.

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FossilOrigin-Name: 031c9a76b6ad1572e7a88f4d2d62f206b0d37bd1170e2c8a24248c5ec628f2f5
This commit is contained in:
stephan
2023-08-04 08:45:25 +00:00
parent 444424dab8
commit a24769454e
3 changed files with 20 additions and 11 deletions
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15
ext/wasm/common/whwasmutil.js
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@ -613,8 +613,6 @@ globalThis.WhWasmUtilInstaller = function(target){
target.installFunction = (func, sig)=>__installFunction(func, sig, false);
/**
EXPERIMENTAL! DO NOT USE IN CLIENT CODE!
Works exactly like installFunction() but requires that a
scopedAllocPush() is active and uninstalls the given function
when that alloc scope is popped via scopedAllocPop().
@ -1722,7 +1720,18 @@ globalThis.WhWasmUtilInstaller = function(target){
FuncPtrAdapter.debugOut("FuncPtrAdapter uninstalling", this,
this.contextKey(argv,argIndex), '@'+pair[1], v);
}
try{target.uninstallFunction(pair[1])}
try{
/* Because the pending native call might rely on the
pointer we're replacing, e.g. as is normally the case
with sqlite3's xDestroy() methods, we don't
immediately uninstall but instead add its pointer to
the scopedAlloc stack, which will be cleared when the
xWrap() mechanism is done calling the native
function. We're relying very much here on xWrap()
having pushed an alloc scope.
*/
cache.scopedAlloc[cache.scopedAlloc.length-1].push(pair[1]);
}
catch(e){/*ignored*/}
}
pair[0] = v;