Fiddle: replace db export routine with a C-side one which works for both Emscripten FS-hosted and OPFS-hosted db files. Minor code-adjacent cleanups.

FossilOrigin-Name: 3579a8d6f1f6cd3cd8aad9949536870c5fe7bae8c1778f700dd85d763e266b94

ext/wasm/EXPORTED_FUNCTIONS.fiddle.in

@@ -6,4 +6,5 @@ _fiddle_interrupt
 _fiddle_main
 _fiddle_reset_db
 _fiddle_db_handle
-_fiddle_db_is_opfs
+_fiddle_db_vfs
+_fiddle_export_db

ext/wasm/api/sqlite3-api-oo1.js

@@ -1025,51 +1025,6 @@ self.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
         this.exec("ROLLBACK to SAVEPOINT oo1; RELEASE SAVEPOINT oo1");
         throw e;
       }
-    },
-    
-    /**
-       This function currently does nothing and always throws.  It
-       WILL BE REMOVED pending other refactoring, to eliminate a hard
-       dependency on Emscripten. This feature will be moved into a
-       higher-level API or a runtime-configurable feature.
-
-       That said, what its replacement should eventually do is...
-
-       Exports a copy of this db's file as a Uint8Array and
-       returns it. It is technically not legal to call this while
-       any prepared statement are currently active because,
-       depending on the platform, it might not be legal to read
-       the db while a statement is locking it. Throws if this db
-       is not open or has any opened statements.
-
-       The resulting buffer can be passed to this class's
-       constructor to restore the DB.
-
-       Maintenance reminder: the corresponding sql.js impl of this
-       feature closes the current db, finalizing any active
-       statements and (seemingly unnecessarily) destroys any UDFs,
-       copies the file, and then re-opens it (without restoring
-       the UDFs). Those gymnastics are not necessary on the tested
-       platform but might be necessary on others. Because of that
-       eventuality, this interface currently enforces that no
-       statements are active when this is run. It will throw if
-       any are.
-    */
-    exportBinaryImage: function(){
-      toss3("exportBinaryImage() is slated for removal for portability reasons.");
-      /***********************
-         The following is currently kept only for reference when
-         porting to some other layer, noting that we may well not be
-         able to implement this, at this level, when using the OPFS
-         VFS because of its exclusive locking policy.
-
-         affirmDbOpen(this);
-         if(this.openStatementCount()>0){
-           toss3("Cannot export with prepared statements active!",
-                 "finalize() all statements and try again.");
-         }
-         return MODCFG.FS.readFile(this.filename, {encoding:"binary"});
-      ***********************/
     }
   }/*DB.prototype*/;
 

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

@@ -637,7 +637,7 @@ sqlite3.installOpfsVfs = function callee(asyncProxyUri = callee.defaultProxyUri)
         const rc = opRun('xFileSize', pFile);
         if(0==rc){
           const sz = state.s11n.deserialize()[0];
-          wasm.setMemValue(pSz64, BigInt(sz), 'i64');
+          wasm.setMemValue(pSz64, sz, 'i64');
         }
         mTimeEnd();
         return rc;
@@ -820,10 +820,12 @@ sqlite3.installOpfsVfs = function callee(asyncProxyUri = callee.defaultProxyUri)
     }
 
     /* Install the vfs/io_methods into their C-level shared instances... */
-    let inst = installMethod(opfsIoMethods);
+    for(let k of Object.keys(ioSyncWrappers)){
-    for(let k of Object.keys(ioSyncWrappers)) inst(k, ioSyncWrappers[k]);
+      installMethod(opfsIoMethods, k, ioSyncWrappers[k]);
-    inst = installMethod(opfsVfs);
+    }
-    for(let k of Object.keys(vfsSyncWrappers)) inst(k, vfsSyncWrappers[k]);
+    for(let k of Object.keys(vfsSyncWrappers)){
+      installMethod(opfsVfs, k, vfsSyncWrappers[k]);
+    }
 
     /**
        Syncronously deletes the given OPFS filesystem entry, ignoring
@@ -831,7 +833,7 @@ sqlite3.installOpfsVfs = function callee(asyncProxyUri = callee.defaultProxyUri)
        directory", the given name must be an absolute path. If the 2nd
        argument is truthy, deletion is recursive (use with caution!).
 
-       Returns true if the deletion succeeded and fails if it fails,
+       Returns true if the deletion succeeded and false if it fails,
        but cannot report the nature of the failure.
     */
     opfsUtil.deleteEntry = function(fsEntryName,recursive=false){

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

@@ -784,13 +784,16 @@ self.sqlite3ApiBootstrap = function sqlite3ApiBootstrap(
   }
 
   /**
-     Given an `sqlite3*` and an sqlite3_vfs name, returns a truthy
+     Given an `sqlite3*`, an sqlite3_vfs name, and an optional db
-     value (see below) if that db handle uses that VFS, else returns
+     name, returns a truthy value (see below) if that db handle uses
-     false. If pDb is falsy then this function returns a truthy value
+     that VFS, else returns false. If pDb is falsy then the 3rd
-     if the default VFS is that VFS. Results are undefined if pDb is
+     argument is ignored and this function returns a truthy value if
-     truthy but refers to an invalid pointer.
+     the default VFS name matches that of the 2nd argument. Results
+     are undefined if pDb is truthy but refers to an invalid
+     pointer. The 3rd argument specifies the database name of the
+     given database connection to check, defaulting to the main db.
 
-     The 2nd argument may either be a JS string or a C-string
+     The 2nd and 3rd arguments may either be a JS string or a C-string
      allocated from the wasm environment.
 
      The truthy value it returns is a pointer to the `sqlite3_vfs`
@@ -801,11 +804,9 @@ self.sqlite3ApiBootstrap = function sqlite3ApiBootstrap(
      bad arguments cause a conversion error when passing into
      wasm-space, false is returned.
   */
-  capi.sqlite3_web_db_uses_vfs = function(pDb,vfsName){
+  capi.sqlite3_web_db_uses_vfs = function(pDb,vfsName,dbName="main"){
     try{
-      const pK = ('number'===vfsName)
+      const pK = capi.sqlite3_vfs_find(vfsName);
-            ? capi.wasm.exports.sqlite3_vfs_find(vfsName)
-            : capi.sqlite3_vfs_find(vfsName);
       if(!pK) return false;
       else if(!pDb){
         return capi.sqlite3_vfs_find(0)===pK ? pK : false;
@@ -814,7 +815,7 @@ self.sqlite3ApiBootstrap = function sqlite3ApiBootstrap(
       try{
         return (
           (0===capi.sqlite3_file_control(
-            pDb, "main", capi.SQLITE_FCNTL_VFS_POINTER, ppVfs
+            pDb, dbName, capi.SQLITE_FCNTL_VFS_POINTER, ppVfs
           )) && (capi.wasm.getPtrValue(ppVfs) === pK)
         ) ? pK : false;
       }finally{

ext/wasm/common/whwasmutil.js

@@ -63,7 +63,7 @@
    - WASM-exported "indirect function table" access and
      manipulation. e.g.  creating new WASM-side functions using JS
      functions, analog to Emscripten's addFunction() and
-     removeFunction() but slightly different.
+     uninstallFunction() but slightly different.
 
    - Get/set specific heap memory values, analog to Emscripten's
      getValue() and setValue().
@@ -483,9 +483,12 @@ self.WhWasmUtilInstaller = function(target){
      available slot of this.functionTable(), and returns the
      function's index in that table (which acts as a pointer to that
      function). The returned pointer can be passed to
-     removeFunction() to uninstall it and free up the table slot for
+     uninstallFunction() to uninstall it and free up the table slot for
      reuse.
 
+     If passed (string,function) arguments then it treats the first
+     argument as the signature and second as the function.
+
      As a special case, if the passed-in function is a WASM-exported
      function then the signature argument is ignored and func is
      installed as-is, without requiring re-compilation/re-wrapping.
@@ -499,12 +502,20 @@ self.WhWasmUtilInstaller = function(target){
      Sidebar: this function differs from Emscripten's addFunction()
      _primarily_ in that it does not share that function's
      undocumented behavior of reusing a function if it's passed to
-     addFunction() more than once, which leads to removeFunction()
+     addFunction() more than once, which leads to uninstallFunction()
      breaking clients which do not take care to avoid that case:
 
      https://github.com/emscripten-core/emscripten/issues/17323
   */
   target.installFunction = function f(func, sig){
+    if(2!==arguments.length){
+      toss("installFunction() requires exactly 2 arguments");
+    }
+    if('string'===typeof func && sig instanceof Function){
+      const x = sig;
+      sig = func;
+      func = x;
+    }
     const ft = target.functionTable();
     const oldLen = ft.length;
     let ptr;

ext/wasm/fiddle/fiddle-worker.js

@@ -103,6 +103,7 @@
     throw new Error(args.join(' '));
   };
   const fixmeOPFS = "(FIXME: won't work with vanilla OPFS.)";
+  let sqlite3 /* gets assigned when the wasm module is loaded */;
 
   self.onerror = function(/*message, source, lineno, colno, error*/) {
     const err = arguments[4];
@@ -121,9 +122,18 @@
   const Sqlite3Shell = {
     /** Returns the name of the currently-opened db. */
     dbFilename: function f(){
-      if(!f._) f._ = fiddleModule.cwrap('fiddle_db_filename', "string", ['string']);
+      if(!f._) f._ = sqlite3.capi.wasm.xWrap('fiddle_db_filename', "string", ['string']);
+      return f._(0);
+    },
+    dbHandle: function f(){
+      if(!f._) f._ = sqlite3.capi.wasm.xWrap("fiddle_db_handle", "sqlite3*");
       return f._();
     },
+    dbIsOpfs: function f(){
+      return sqlite3.opfs && sqlite3.capi.sqlite3_web_db_uses_vfs(
+        this.dbHandle(), "opfs"
+      );
+    },
     runMain: function f(){
       if(f.argv) return 0===f.argv.rc;
       const dbName = "/fiddle.sqlite3";
@@ -141,7 +151,8 @@
          after sqlite3_initialize() has been called. This means,
          however, that any initialization done by the JS code may need
          to be re-done (e.g.  re-registration of dynamically-loaded
-         VFSes). */
+         VFSes). We need a more generic approach to running such
+         init-level code. */
       S.capi.sqlite3_shutdown();
       f.argv.pArgv = S.capi.wasm.allocMainArgv(f.argv);
       f.argv.rc = S.capi.wasm.exports.fiddle_main(
@@ -196,6 +207,12 @@
       }
     },
     resetDb: function f(){
+      if(Sqlite3Shell.dbIsOpfs()){
+        /* The problem is that fiddle_reset_db() uses the POSIX APIs
+           for file removal, which cannot see OPFS-hosted files. */
+        stderr("TODO: cannot currently reset an OPFS-hosted db.");
+        return;
+      }
       if(!f._) f._ = fiddleModule.cwrap('fiddle_reset_db', null);
       stdout("Resetting database.",fixmeOPFS);
       f._();
@@ -216,29 +233,30 @@
      (and, hypothetically, kvvfs). Throws on error. On success returns
      a Blob containing the whole db contents.
 
-     Bug: xFileSize() is returning garbage for the default VFS but
+     Bug/to investigate: xFileSize() is returning garbage for the
-     works in OPFS. Thus for exporting that impl we'll use the
+     default VFS but works in OPFS. Thus for exporting that impl we'll
-     fiddleModule.FS API for the time being.
+     use the fiddleModule.FS API for the time being. The equivalent
+     native impl, fiddle_export_db(), works okay with both VFSes, so
+     the bug is apparently in (or via) this code.
   */
-  const exportDbFileToBlob = function(){
+  const brokenExportDbFileToBlob = function(){
     const S = fiddleModule.sqlite3, capi = S.capi, wasm = capi.wasm;
-    const pDb = wasm.xCall("fiddle_db_handle");
+    const pDb = Sqlite3Shell.dbHandle();
     if(!pDb) toss("No db is opened.");
     const scope = wasm.scopedAllocPush();
     try{
       const ppFile = wasm.scopedAlloc(12/*sizeof(i32 + i64)*/);
       const pFileSize = ppFile + 4;
-      wasm.setMemValue(ppFile, 0, 'i32');
+      wasm.setMemValue(ppFile, 0, '*');
       let rc = capi.sqlite3_file_control(
         pDb, "main", capi.SQLITE_FCNTL_FILE_POINTER, ppFile
       );
       if(rc) toss("Cannot get sqlite3_file handle.");
       const jFile = new capi.sqlite3_file(wasm.getPtrValue(ppFile));
       const jIom = new capi.sqlite3_io_methods(jFile.$pMethods);
-      console.warn("jIom =",jIom);
       const xFileSize = wasm.functionEntry(jIom.$xFileSize);
       const xRead = wasm.functionEntry(jIom.$xRead);
-      wasm.setMemValue(pFileSize, 0n, 'i64');
+      wasm.setMemValue(pFileSize, 0, 'i64');
       //stderr("nFileSize =",wasm.getMemValue(pFileSize,'i64'),"pFileSize =",pFileSize);
       rc = xFileSize( jFile.pointer, pFileSize );
       if(rc) toss("Cannot get db file size.");
@@ -273,6 +291,30 @@
     }
   }/*exportDbFileToBlob()*/;
 
+  const exportDbFileToBlob = function f(){
+    if(!f._){
+      f._ = sqlite3.capi.wasm.xWrap('fiddle_export_db', 'int', '*');
+    }
+    const capi = sqlite3.capi;
+    const wasm = capi.wasm;
+    const blobList = [];
+    const heap = wasm.heap8u();
+    const callback = wasm.installFunction('ipi', function(buf, n){
+      blobList.push(heap.slice(buf, buf+n));
+      return 0;
+    });
+    try {
+      const rc = wasm.exports.fiddle_export_db( callback );
+      if(rc) toss("DB export failed with code", capi.sqlite3_wasm_rc_str(rc));
+      return new Blob(blobList);
+    }catch(e){
+      console.error("exportDbFileToBlob():",e.message);
+      throw(e);
+    }finally{
+      wasm.uninstallFunction(callback);
+    }
+  }/*exportDbFileToBlob()*/;
+  
   self.onmessage = function f(ev){
     ev = ev.data;
     if(!f.cache){
@@ -302,18 +344,9 @@
           const fn2 = fn ? fn.split(/[/\\]/).pop() : null;
           try{
             if(!fn2) throw new Error("DB appears to be closed.");
-            if(fiddleModule.sqlite3.capi.wasm.xCall(
-              'fiddle_db_is_opfs'
-            )){
             exportDbFileToBlob().arrayBuffer().then((buffer)=>{
               wMsg('db-export',{filename: fn2, buffer}, [buffer]);
             });
-            }else{
-              const buffer = fiddleModule.FS.readFile(
-                fn, {encoding:"binary"}
-              ).buffer;
-              wMsg('db-export',{filename: fn2, buffer}, [buffer]);
-            }
           }catch(e){
             /* Post a failure message so that UI elements disabled
                during the export can be re-enabled. */
@@ -427,15 +460,15 @@
      emcc ... -sMODULARIZE=1 -sEXPORT_NAME=initFiddleModule
   */
   initFiddleModule(fiddleModule).then(function(thisModule){
-    const S = thisModule.sqlite3;
+    sqlite3 = thisModule.sqlite3;
     const atEnd = ()=>{
       thisModule.fsUnlink = (fn)=>{
         stderr("unlink:",fixmeOPFS);
-        return S.capi.wasm.sqlite3_wasm_vfs_unlink(fn);
+        return sqlite3.capi.wasm.sqlite3_wasm_vfs_unlink(fn);
       };
       wMsg('fiddle-ready');
     };
-    if(S.installOpfsVfs) S.installOpfsVfs().finally(atEnd);
+    if(sqlite3.installOpfsVfs) sqlite3.installOpfsVfs().finally(atEnd);
     else atEnd();
   })/*then()*/;
 })();

manifest

@@ -1,5 +1,5 @@
-C Get\sfiddle\sdb\sexport\sworking\sfor\sOPFS\sVFS.\sAdd\sroot\sdir\shandle\sto\sthe\smain\sOPFS\sVFS\sworker\sto\senable\screation\sof\scertain\sutility\sfunctions\swithout\sdelegating\sto\sthe\sasync\sworker.\sAdd\ssqlite3.capi.sqlite3_wasm_rc_str()\sto\smap\sinteger\sresult\scodes\sback\sto\stheir\sSQLITE_xxx\scounterparts.\sMinor\sdoc\stouchups.
+C Fiddle:\sreplace\sdb\sexport\sroutine\swith\sa\sC-side\sone\swhich\sworks\sfor\sboth\sEmscripten\sFS-hosted\sand\sOPFS-hosted\sdb\sfiles.\sMinor\scode-adjacent\scleanups.
-D 2022-09-26T11:38:58.930
+D 2022-09-26T13:55:10.137
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -472,7 +472,7 @@ F ext/session/test_session.c f433f68a8a8c64b0f5bc74dc725078f12483301ad4ae8375205
 F ext/userauth/sqlite3userauth.h 7f3ea8c4686db8e40b0a0e7a8e0b00fac13aa7a3
 F ext/userauth/user-auth.txt e6641021a9210364665fe625d067617d03f27b04
 F ext/userauth/userauth.c 7f00cded7dcaa5d47f54539b290a43d2e59f4b1eb5f447545fa865f002fc80cb
-F ext/wasm/EXPORTED_FUNCTIONS.fiddle.in 48af0d812e2e1099798ae0e27f1d4836d572d0d068c83b3e2088ef4d97c45c2f
+F ext/wasm/EXPORTED_FUNCTIONS.fiddle.in 27450c8b8c70875a260aca55435ec927068b34cef801a96205adb81bdcefc65c
 F ext/wasm/EXPORTED_RUNTIME_METHODS.fiddle 0e88c8cfc3719e4b7e74980d9da664c709e68acf863e48386cda376edfd3bfb0
 F ext/wasm/GNUmakefile 34a84e30e6b25e24959a8264e9dec020dffa82d96879dc55ad65d3c31c95d3b1
 F ext/wasm/README.md e1ee1e7c321c6a250bf78a84ca6f5882890a237a450ba5a0649c7a8399194c52
@@ -483,9 +483,9 @@ F ext/wasm/api/post-js-footer.js b64319261d920211b8700004d08b956a6c285f3b0bba814
 F ext/wasm/api/post-js-header.js 2e5c886398013ba2af88028ecbced1e4b22dc96a86467f1ecc5ba9e64ef90a8b
 F ext/wasm/api/sqlite3-api-cleanup.js 8564a6077cdcaea9a9f428a019af8a05887f0131e6a2a1e72a7ff1145fadfe77
 F ext/wasm/api/sqlite3-api-glue.js fe5ca21ac519e6411f5e7a6403d06fe92c51ef81cca8e07ea8895df8ec9c2e4e
-F ext/wasm/api/sqlite3-api-oo1.js f974e79d9af8f26bf33928c5730b0988cc706d14f59a5fe36394739b92249841
+F ext/wasm/api/sqlite3-api-oo1.js 455fcb28dd77b9781e087aac77392fb78f8ee8e5b125a99c1488604de27a5bb1
-F ext/wasm/api/sqlite3-api-opfs.js 151f8bab445915dd4fa8fe3329accc5250351e7bf0af1518cb5cc49886c123d2
+F ext/wasm/api/sqlite3-api-opfs.js e0dfae09aedc6fe414d8d350e7228a6a88de030a0cb19a748ac8269aef9b11db
-F ext/wasm/api/sqlite3-api-prologue.js 76db12cce58ec6724ec01a977dfbedabfd4916e915a6e7679ffc24dd52eef64e
+F ext/wasm/api/sqlite3-api-prologue.js d39bda7d83aaeb8e15574afe8308221ed11c6f24865ccff06cf0424b665e681e
 F ext/wasm/api/sqlite3-api-worker1.js 2eeb2a24e1a90322d84a9b88a99919b806623de62792436446099c0988f2030b
 F ext/wasm/api/sqlite3-wasi.h 25356084cfe0d40458a902afb465df8c21fc4152c1d0a59b563a3fba59a068f9
 F ext/wasm/api/sqlite3-wasm.c 7010405f1981cd5929568403a618f80398f7acbf76b3eb11c4f23789206eb164
@@ -494,7 +494,7 @@ F ext/wasm/batch-runner.js 6f5b86e0b5519a9a941d9f17ee9c5ecdc63f452f157602fe7fdf8
 F ext/wasm/common/SqliteTestUtil.js 529161a624265ba84271a52db58da022649832fa1c71309fb1e02cc037327a2b
 F ext/wasm/common/emscripten.css 3d253a6fdb8983a2ac983855bfbdd4b6fa1ff267c28d69513dd6ef1f289ada3f
 F ext/wasm/common/testing.css 3a5143699c2b73a85b962271e1a9b3241b30d90e30d895e4f55665e648572962
-F ext/wasm/common/whwasmutil.js 2a8cd8b0c936da5812971aa39c8d989306c2ad8fc841dcd037c3be62737dc652
+F ext/wasm/common/whwasmutil.js 20291bbf4955358d0b5ead58db4c575be269b4976e39c43a93331547e3b86363
 F ext/wasm/demo-123-worker.html e419b66495d209b5211ec64903b4cfb3ca7df20d652b41fcd28bf018a773234f
 F ext/wasm/demo-123.html aa281d33b7eefa755f3122b7b5a18f39a42dc5fb69c8879171bf14b4c37c4ec4
 F ext/wasm/demo-123.js 234655683e35a4543a23de7b10800d76b0369947b33e089e5613171fa7795afb
@@ -502,7 +502,7 @@ F ext/wasm/demo-kvvfs1.html 7d4f28873de67f51ac18c584b7d920825139866a96049a49c424
 F ext/wasm/demo-kvvfs1.js e884ea35022d772c0d1dd884b40011413696438394f605c6cd4808cfb1642a4a
 F ext/wasm/fiddle.make fd56fa21bada6ecbf860686a9a789ebda7cc3d9b60835927000fcb00246ea50f
 F ext/wasm/fiddle/emscripten.css 3d253a6fdb8983a2ac983855bfbdd4b6fa1ff267c28d69513dd6ef1f289ada3f
-F ext/wasm/fiddle/fiddle-worker.js 42c31065660e57844afa796bcf120666348c060fc4c656c335151b62da7fc60d
+F ext/wasm/fiddle/fiddle-worker.js 1fe173ba963314df99df9eb8f0f45f1c3a72c056f16510e47787eb1790cb5531
 F ext/wasm/fiddle/fiddle.html 5daf54e8f3d7777cbb1ca4f93affe28858dbfff25841cb4ab81d694efed28ec2
 F ext/wasm/fiddle/fiddle.js aa44051be6e48c53fd23c829177d43f557dcc6f0998ccfcbae7c473ff405f0c6
 F ext/wasm/index.html a39d14f6de6bd1294d39522fcf40eca3c9f0b6da44bb8df6948378e9f30468f5
@@ -615,7 +615,7 @@ F src/random.c 546d6feb15ec69c1aafe9bb351a277cbb498fd5410e646add673acb805714960
 F src/resolve.c efea4e5fbecfd6d0a9071b0be0d952620991673391b6ffaaf4c277b0bb674633
 F src/rowset.c ba9515a922af32abe1f7d39406b9d35730ed65efab9443dc5702693b60854c92
 F src/select.c d69dfb5b082f9a25e6700e152ddb3d942359b847b1df504eb09f9b4531844f8d
-F src/shell.c.in 00a72221c8b2df823f3a9d712457ae8bebe627b5989fefa1ccfe099eafab5139
+F src/shell.c.in 2980312ab57fc5ccf298d1f0682588ec3832f52a878bea8abe34647d2cf31d05
 F src/sqlite.h.in b9b7fd73239d94db20332bb6e504688001e5564b655e1318a4427a1caef4b99e
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h a988810c9b21c0dc36dc7a62735012339dc76fc7ab448fb0792721d30eacb69d
@@ -2026,8 +2026,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 85f2e877e53899860af4dc6630044b471a9c7c82faba1f4e1e60ae991460b943
+P 9b2244e1c8a40efe6547094a1b57acc8f2173145a8731abb0e36268ce0a8ef41
-R 021d11845b25e048635a4d675c2c9f1f
+R ee45c68d4b4cfbf2a729d26cea95ac0e
 U stephan
-Z 684fe82520a24a3caf4c9fdd7b640f27
+Z a7778a8aaef90b52f5b829e56bd6cae3
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-9b2244e1c8a40efe6547094a1b57acc8f2173145a8731abb0e36268ce0a8ef41
+3579a8d6f1f6cd3cd8aad9949536870c5fe7bae8c1778f700dd85d763e266b94

src/shell.c.in

@@ -12639,6 +12639,20 @@ sqlite3 * fiddle_db_handle(){
   return globalDb;
 }
 
+/*
+** Returns a pointer to the given DB name's VFS. If zDbName is 0 then
+** "main" is assumed. Returns 0 if no db with the given name is
+** open.
+*/
+sqlite3_vfs * fiddle_db_vfs(const char *zDbName){
+  sqlite3_vfs * pVfs = 0;
+  if(globalDb){
+    sqlite3_file_control(globalDb, zDbName ? zDbName : "main",
+                         SQLITE_FCNTL_VFS_POINTER, &pVfs);
+  }
+  return pVfs;
+}
+
 /* Only for emcc experimentation purposes. */
 sqlite3 * fiddle_db_arg(sqlite3 *arg){
     printf("fiddle_db_arg(%p)\n", (const void*)arg);
@@ -12689,53 +12703,46 @@ void fiddle_reset_db(void){
 }
 
 /*
-** This is a bit of a workaround: returns true if the current db uses
+** Uses the current database's VFS xRead to stream the db file's
-** the "opfs" VFS, else false.
+** contents out to the given callback. The callback gets a single
+** chunk of size n (its 2nd argument) on each call and must return 0
+** on success, non-0 on error. This function returns 0 on success,
+** SQLITE_NOTFOUND if no db is open, or propagates any other non-0
+** code from the callback. Note that this is not thread-friendly: it
+** expects that it will be the only thread reading the db file and
+** takes no measures to ensure that is the case.
 */
-int fiddle_db_is_opfs(void){
+int fiddle_export_db( int (*xCallback)(unsigned const char *zOut, int n) ){
-  sqlite3_vfs * pVfs = 0;
-  if( 0!=shellState.db ){
-    sqlite3_file_control( shellState.db, "main",
-                          SQLITE_FCNTL_VFS_POINTER, &pVfs );
-  }
-  return pVfs ? 0==strcmp("opfs", pVfs->zName) : 0;
-}
-
-#if 0
-/* TODO: test whether this impl works properly wrt xSize() in the
-** unix-none VFS. The JS impl works fine for OPFS but not unix-none
-** because xSize() is returning a garbage size.
-*/
-int fiddle_export_db( int (*callback)(unsigned const char *zOut, int n) ){
   sqlite3_int64 nSize = 0;
   sqlite3_int64 nPos = 0;
-  sqlite3_vfs * pVfs = 0;
   sqlite3_file * pFile = 0;
-  unsigned char buf[1024 * 4];
+  unsigned char buf[1024 * 8];
-  const int nBuf = (int)sizeof(buf);
+  int nBuf = (int)sizeof(buf);
   int rc = shellState.db
     ? sqlite3_file_control(shellState.db, "main",
-                           SQLITE_FCNTL_VFS_POINTER, &pVfs)
+                           SQLITE_FCNTL_FILE_POINTER, &pFile)
-    : 0;
+    : SQLITE_NOTFOUND;
-  if( rc ) return rc;
-  else if( 0==pVfs ) return SQLITE_NOTFOUND;
-  rc = sqlite3_file_control(shellState.db, "main",
-                            SQLITE_FCNTL_FILE_POINTER, &pFile);
   if( rc ) return rc;
   rc = pFile->pMethods->xFileSize(pFile, &nSize);
   if( rc ) return rc;
+  if(nSize % nBuf){
+    /* DB size is not an even multiple of the buffer size. Reduce
+    ** buffer size so that we do not unduly inflate the db size when
+    ** exporting. */
+    if(0 == nSize % 4096) nBuf = 4096;
+    else if(0 == nSize % 2048) nBuf = 2048;
+    else if(0 == nSize % 1024) nBuf = 1024;
+    else nBuf = 512;
+  }
   for( ; 0==rc && nPos<nSize; nPos += nBuf ){
     rc = pFile->pMethods->xRead(pFile, buf, nBuf, nPos);
     if(SQLITE_IOERR_SHORT_READ == rc){
       rc = (nPos + nBuf) < nSize ? rc : 0/*assume EOF*/;
     }
-    if(rc) return rc;
+    if( 0==rc ) rc = xCallback(buf, nBuf);
-    nPos += nBuf;
-    rc = callback(buf, nBuf);
   }
   return rc;
 }
-#endif
 
 /*
 ** Trivial exportable function for emscripten. It processes zSql as if