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Add JS infrastructure which enables sqlite3.capi.sqlite3_close_v2() to clean up stale JS-to-WASM collation function conversions installed on behalf of a given db handle. The same for UDF mappings is TODO.

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FossilOrigin-Name: 0e69b2c379e61893c7db8a9c9d270650f2bd63b6cea30811d41136392a2e4f04
This commit is contained in:
stephan
2022-12-26 13:00:58 +00:00
parent 20170adf14
commit 7197f0a8f2
3 changed files with 94 additions and 40 deletions
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120
ext/wasm/api/sqlite3-api-glue.js
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@ -731,43 +731,95 @@ self.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
);
};
/**
__dbCleanupMap is infrastructure for recording registration of
UDFs and collations so that sqlite3_close_v2() can clean up any
automated JS-to-WASM function conversions installed by those.
*/
const __argPDb = (pDb)=>wasm.xWrap.argAdapter('sqlite3*')(pDb);
const __argStr = (str)=>wasm.isPtr(str) ? wasm.cstrToJs(str) : str;
const __dbCleanupMap = function(
pDb, mode/*0=remove, >0=create if needed, <0=do not create if missing*/
){
pDb = __argPDb(pDb);
let m = this.dbMap.get(pDb);
if(!mode){
this.dbMap.delete(pDb);
return m;
}else if(!m && mode>0){
this.dbMap.set(pDb, (m = Object.create(null)));
}
return m;
}.bind(Object.assign(Object.create(null),{
dbMap: new Map
}));
__dbCleanupMap.addCollation = function(pDb, name){
const m = __dbCleanupMap(pDb, 1);
if(!m.collation) m.collation = new Set;
m.collation.add(__argStr(name).toLowerCase());
};
/**
Intended to be called _only_ from sqlite3_close_v2(),
passed its non-0 db argument.
This function freees up certain automatically-installed WASM
function bindings which were installed on behalf of the given db,
as those may otherwise leak.
Notable caveat: this is only ever run via
sqlite3.capi.sqlite3_close_v2(). If a client, for whatever
reason, uses sqlite3.wasm.exports.sqlite3_close_v2() (the
function directly exported from WASM), this cleanup will not
happen.
This is not a silver bullet for avoiding automation-related
leaks but represents "an honest effort."
The issue being addressed here is covered at:
https://sqlite.org/wasm/doc/trunk/api-c-style.md#convert-func-ptr
*/
__dbCleanupMap.cleanup = function(pDb){
pDb = __argPDb(pDb);
//wasm.xWrap.FuncPtrAdapter.debugFuncInstall = true;
/**
Installing NULL functions in the C API will remove those
bindings. The FuncPtrAdapter which sits between us and the C
API will also treat that as an opportunity to
wasm.uninstallFunction() any WASM function bindings it has
installed for pDb.
*/
try{capi.sqlite3_busy_handler(pDb, 0, 0)} catch(e){/*ignored*/}
try{capi.sqlite3_progress_handler(pDb, 0, 0, 0)} catch(e){/*ignored*/}
try{capi.sqlite3_trace_v2(pDb, 0, 0, 0, 0)} catch(e){/*ignored*/}
try{capi.sqlite3_set_authorizer(pDb, 0, 0)} catch(e){/*ignored*/}
const m = __dbCleanupMap(pDb, 0);
if(!m) return;
if(m.collation){
for(const name of m.collation){
try{
capi.sqlite3_create_collation_v2(
pDb, name, capi.SQLITE_UTF8, 0, 0, 0
);
}catch(e){
/*ignored*/
}
}
delete m.collation;
}
if(m.udf){
//TODO: map and clean up UDFs.
}
};
{/* Binding of sqlite3_close_v2() */
const __sqlite3CloseV2 = wasm.xWrap("sqlite3_close_v2", "int", "sqlite3*");
capi.sqlite3_close_v2 = function(pDb){
if(1!==arguments.length) return __dbArgcMismatch(pDb, 'sqlite3_close_v2', 1);
if(pDb){
/*
We do this as a basic attempt at freeing up certain
automatically-installed WASM function bindings, as those may
otherwise leak. Installing NULL functions in the C API will
remove those bindings. The FuncPtrAdapter which sits between
us and the C API will also treat that as an opportunity to
wasm.uninstallFunction() any WASM function bindings it has
installed for pDb.
This does not catch all such bindings: those which map to
both a db handle and a separate key (e.g. collation sequence
name or UDF name) cannot be unmapped here because we don't
have the other parts of the mapping key. It's also possible
for clients to call wasm.exports.sqlite3_close_v2()
directly, bypassing this cleanup altogether. i.e. this is
not a silver bullet, just an "honest effort."
Perhaps we can add some code to sqlite3-wasm.c which can
walk through the UDF and collation names to help us free up
those auto-converted functions, too. Functions are more
complicated because a given function may have multiple
mappings for different arities.
The issue being addressed here is covered at:
https://sqlite.org/wasm/doc/trunk/api-c-style.md#convert-func-ptr
*/
//wasm.xWrap.FuncPtrAdapter.debugFuncInstall = true;
try{capi.sqlite3_busy_handler(pDb, 0, 0)} catch(e){/*ignored*/}
try{capi.sqlite3_progress_handler(pDb, 0, 0, 0)} catch(e){/*ignored*/}
try{capi.sqlite3_trace_v2(pDb, 0, 0, 0, 0)} catch(e){/*ignored*/}
try{capi.sqlite3_set_authorizer(pDb, 0, 0)} catch(e){/*ignored*/}
try{__dbCleanupMap.cleanup(pDb)} catch(e){/*ignored*/}
}
return __sqlite3CloseV2(pDb);
};
@ -844,7 +896,9 @@ self.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
return __errEncoding(pDb);
}
try{
return __sqlite3CreateCollationV2(pDb, zName, eTextRep, pArg, xCompare, xDestroy);
const rc = __sqlite3CreateCollationV2(pDb, zName, eTextRep, pArg, xCompare, xDestroy);
if(xCompare) __dbCleanupMap.addCollation(pDb, zName);
return rc;
}catch(e){
return util.sqlite3_wasm_db_error(pDb, e);
}