Add sqlite3.wasm.alloc.impl() as a "public back door" into the low-level non-throwing allocator. Correct sqlite3.WasmAllocError constructor to behave like its usages expect it to and add tests for that.

FossilOrigin-Name: cea8bf9a144d842c4755c3130273524926e8c4831d7f21c4e34d4e8c74109c8c

ext/wasm/api/sqlite3-api-prologue.js

@@ -399,8 +399,22 @@ self.sqlite3ApiBootstrap = function sqlite3ApiBootstrap(
      exceptions.
   */
   class WasmAllocError extends Error {
+    /**
+       If called with 2 arguments and the 2nd one is an object, it
+       behaves like the Error constructor, else it concatenates all
+       arguments together with a single space between each to
+       construct an error message string. As a special case, if
+       called with no arguments then it uses a default error
+       message.
+    */
     constructor(...args){
-      super(...args);
+      if(2===args.length && 'object'===typeof args){
+        super(...args);
+      }else if(args.length){
+        super(args.join(' '));
+      }else{
+        super("Allocation failed.");
+      }
       this.name = 'WasmAllocError';
     }
   };
@@ -710,21 +724,33 @@ self.sqlite3ApiBootstrap = function sqlite3ApiBootstrap(
        API NOT throw and must instead return SQLITE_NOMEM (or
        equivalent, depending on the context).
 
-       That said, very few cases in the API can result in
+       Very few cases in the sqlite3 JS APIs can result in
        client-defined functions propagating exceptions via the C-style
-       API. Most notably, this applies ot User-defined SQL Functions
-       (UDFs) registered via sqlite3_create_function_v2(). For that
-       specific case it is recommended that all UDF creation be
-       funneled through a utility function and that a wrapper function
-       be added around the UDF which catches any exception and sets
-       the error state to OOM. (The overall complexity of registering
-       UDFs essentially requires a helper for doing so!)
+       API. Most notably, this applies to WASM-bound JS functions
+       which are created directly by clients and passed on _as WASM
+       function pointers_ to functions such as
+       sqlite3_create_function_v2(). Such bindings created
+       transparently by this API will automatically use wrappers which
+       catch exceptions and convert them to appropriate error codes.
+
+       For cases where non-throwing allocation is required, use
+       sqlite3.wasm.alloc.impl(), which is direct binding of the
+       underlying C-level allocator.
+
+       Design note: this function is not named "malloc" primarily
+       because Emscripten uses that name and we wanted to avoid any
+       confusion early on in this code's development, when it still
+       had close ties to Emscripten's glue code.
     */
     alloc: undefined/*installed later*/,
+
     /**
        The API's one single point of access to the WASM-side memory
        deallocator. Works like free(3) (and is likely bound to
        free()).
+
+       Design note: this function is not named "free" for the same
+       reason that this.alloc() is not called this.malloc().
     */
     dealloc: undefined/*installed later*/
 
@@ -752,7 +778,9 @@ self.sqlite3ApiBootstrap = function sqlite3ApiBootstrap(
   wasm.allocFromTypedArray = function(srcTypedArray){
     affirmBindableTypedArray(srcTypedArray);
     const pRet = wasm.alloc(srcTypedArray.byteLength || 1);
-    wasm.heapForSize(srcTypedArray.constructor).set(srcTypedArray.byteLength ? srcTypedArray : [0], pRet);
+    wasm.heapForSize(srcTypedArray.constructor).set(
+      srcTypedArray.byteLength ? srcTypedArray : [0], pRet
+    );
     return pRet;
   };
 
@@ -763,13 +791,13 @@ self.sqlite3ApiBootstrap = function sqlite3ApiBootstrap(
     if(!(f instanceof Function)) toss3("Missing required exports[",key,"] function.");
   }
 
-  wasm.alloc = function(n){
-    const m = wasm.exports[keyAlloc](n);
-    if(!m) throw new WasmAllocError("Failed to allocate "+n+" bytes.");
+  wasm.alloc = function f(n){
+    const m = f.impl(n);
+    if(!m) throw new WasmAllocError("Failed to allocate",n," bytes.");
     return m;
   };
-
-  wasm.dealloc = (m)=>wasm.exports[keyDealloc](m);
+  wasm.alloc.impl = wasm.exports[keyAlloc];
+  wasm.dealloc = wasm.exports[keyDealloc];
 
   /**
      Reports info about compile-time options using

ext/wasm/tester1.js

@@ -342,8 +342,20 @@
         throw new sqlite3.WasmAllocError;
       }catch(e){
         T.assert(e instanceof Error)
-          .assert(e instanceof sqlite3.WasmAllocError);
+          .assert(e instanceof sqlite3.WasmAllocError)
+          .assert("Allocation failed." === e.message);
       }
+      try {
+        throw new sqlite3.WasmAllocError("test",{
+          cause: 3
+        });
+      }catch(e){
+        T.assert(3 === e.cause)
+          .assert("test" === e.message);
+      }
+      try {throw new sqlite3.WasmAllocError("test","ing",".")}
+      catch(e){T.assert("test ing ." === e.message)}
+
       try{ throw new sqlite3.SQLite3Error(capi.SQLITE_SCHEMA) }
       catch(e){ T.assert('SQLITE_SCHEMA' === e.message) }
       try{ sqlite3.SQLite3Error.toss(capi.SQLITE_CORRUPT,{cause: true}) }

manifest

@@ -1,5 +1,5 @@
-C Fix\srequirements\smarks\sso\sthat\sthey\smatch\sdocumentation\scorrections.
-D 2022-11-07T12:21:06.865
+C Add\ssqlite3.wasm.alloc.impl()\sas\sa\s"public\sback\sdoor"\sinto\sthe\slow-level\snon-throwing\sallocator.\sCorrect\ssqlite3.WasmAllocError\sconstructor\sto\sbehave\slike\sits\susages\sexpect\sit\sto\sand\sadd\stests\sfor\sthat.
+D 2022-11-07T13:06:20.227
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -502,7 +502,7 @@ F ext/wasm/api/sqlite3-api-cleanup.js ecdc69dbfccfe26146f04799fcfd4a6f5790d46e7e
 F ext/wasm/api/sqlite3-api-glue.js 056f44b82c126358a0175e08a892d56fadfce177b0d7a0012502a6acf67ea6d5
 F ext/wasm/api/sqlite3-api-oo1.js e9a83489bbb4838ce0aee46eaaa9350e0e25a5b926b565e4f5ae8e840e4fbaed
 F ext/wasm/api/sqlite3-api-opfs.js cdcbb57acc66f4569ac9e18f9d13d5a3657d8aae195725c6324943da56c1005d
-F ext/wasm/api/sqlite3-api-prologue.js 80ec5c035b0fd06ae6fbb4fb9de4cada005d044e4bd9bb60cfa7c0f313e927ba
+F ext/wasm/api/sqlite3-api-prologue.js fd526fa017fa2578673ca18158354515c719e719a5d93f2f6d0e43f39170430e
 F ext/wasm/api/sqlite3-api-worker1.js e94ba98e44afccfa482874cd9acb325883ade50ed1f9f9526beb9de1711f182f
 F ext/wasm/api/sqlite3-license-version-header.js a661182fc93fc2cf212dfd0b987f8e138a3ac98f850b1112e29b5fbdaecc87c3
 F ext/wasm/api/sqlite3-opfs-async-proxy.js ab7d2888ad9b3dd24bb782bd882fcada2a20cb88eb78c8f36e7bfe708857dbd1
@@ -549,7 +549,7 @@ F ext/wasm/test-opfs-vfs.html 1f2d672f3f3fce810dfd48a8d56914aba22e45c6834e262555
 F ext/wasm/test-opfs-vfs.js 44363db07b2a20e73b0eb1808de4400ca71b703af718d0fa6d962f15e73bf2ac
 F ext/wasm/tester1-worker.html 51bf39e2b87f974ae3d5bc3086e2fb36d258f3698c54f6e21ba4b3b99636fa27
 F ext/wasm/tester1.html 624ec41cd9f78a1f2b6d7df70aaa7a6394396b1f2455ecbd6de5775c1275b121
-F ext/wasm/tester1.js 3a5558201359ff8a1c3051ab24fcc8bed5a4e99ae5e086e5184cbfc915d08724
+F ext/wasm/tester1.js bff806de454de115922d78c056f11d523ec7ed9ed3839d4e21433a9f72558b88
 F ext/wasm/version-info.c 3b36468a90faf1bbd59c65fd0eb66522d9f941eedd364fabccd72273503ae7d5
 F ext/wasm/wasmfs.make edfd60691d10fd19ada4c061280fd7fbe4cf5f6bf6b913268e8ebedfccea6ab5
 F install-sh 9d4de14ab9fb0facae2f48780b874848cbf2f895 x
@@ -2054,8 +2054,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
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 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 2c448368913a844bdb5e69f8fa3bad91a2b6612ba3b7f3f650dd07b81db25a77
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-U drh
-Z beb5dbfff782217ad4460048cb127dcb
+P 10d6189d23133006b39ea230045a918483721dd48f5558f77e57e23693097d16
+R dbbc6e5147410c1ff1f5e52d341a107c
+U stephan
+Z 38b0ee956ab9968f2c2619fa1c2e4c41
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-10d6189d23133006b39ea230045a918483721dd48f5558f77e57e23693097d16
+cea8bf9a144d842c4755c3130273524926e8c4831d7f21c4e34d4e8c74109c8c