From a579f4400d0c9f5e8356a7b10830bc5a2caf8aa5 Mon Sep 17 00:00:00 2001
From: stephan <stephan@noemail.net>
Date: Fri, 12 Aug 2022 17:57:09 +0000
Subject: Build fiddle with WASMFS OPFS support and attempt to use it if
 available. It does not work because of an inexplicable exception in
 Emscripten-generated code and perpetually-locked db, but it's not yet clear
 why.

FossilOrigin-Name: a16f0a46ec88c560f73d5664e4bf53fb5dd1a22e99a92c11b5c8d784816c3282
---
 ext/wasm/api/sqlite3-wasm.c | 46 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

(limited to 'ext/wasm/api/sqlite3-wasm.c')

diff --git a/ext/wasm/api/sqlite3-wasm.c b/ext/wasm/api/sqlite3-wasm.c
index 6a81da3e5..30a9dafeb 100644
--- a/ext/wasm/api/sqlite3-wasm.c
+++ b/ext/wasm/api/sqlite3-wasm.c
@@ -411,3 +411,49 @@ const char * sqlite3_wasm_enum_json(void){
 #undef outf
 #undef lenCheck
 }
+
+/*
+** This function is NOT part of the sqlite3 public API. It is strictly
+** for use by the sqlite project's own JS/WASM bindings.
+**
+** This function invokes the xDelete method of the default VFS,
+** passing on the given filename. If zName is NULL, no default VFS is
+** found, or it has no xDelete method, SQLITE_MISUSE is returned, else
+** the result of the xDelete() call is returned.
+*/
+int sqlite3_wasm_vfs_unlink(const char * zName){
+  int rc = SQLITE_MISUSE /* ??? */;
+  sqlite3_vfs * const pVfs = sqlite3_vfs_find(0);
+  if( zName && pVfs && pVfs->xDelete ){
+    rc = pVfs->xDelete(pVfs, zName, 1);
+  }
+  return rc;
+}
+
+#ifdef __EMSCRIPTEN__
+#include <emscripten/wasmfs.h>
+#include <emscripten/console.h>
+/*
+** This function is NOT part of the sqlite3 public API. It is strictly
+** for use by the sqlite project's own JS/WASM bindings.
+**
+** This function should only be called if the JS side detects the
+** existence of the Origin-Private FileSystem (OPFS) APIs in the
+** client. The first time it is called, this function instantiates a
+** WASMFS backend impl for OPFS. On success, subsequent calls are
+** no-ops.
+**
+** Returns 0 on success, SQLITE_NOMEM if intantiation of the backend
+** object fails.
+*/
+int sqlite3_wasm_init_opfs(void){
+  static backend_t pOpfs = 0;
+  if( !pOpfs ){
+    pOpfs = wasmfs_create_opfs_backend();
+    if( pOpfs ){
+      emscripten_console_log("Created OPFS WASMFS backend.");
+    }
+  }
+  return pOpfs ? 0 : SQLITE_NOMEM;
+}
+#endif /* __EMSCRIPTEN__ */
-- 
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