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Initial build of kvvfs in wasm. It loads but cannot find the VFS for as-yet-unknown reasons (sqlite3 shell works fine), and most APIs throw "null function or function signature mismatch" from deep within wasm, presumably as a side effect of the "missing" VFS.
FossilOrigin-Name: 1a2f24a0bdfc6eaae478916b8f4f9c6b63ead9964534fc2951fb4e995ffe61f1
This commit is contained in:
stephan
206
src/os_kv.c
206
src/os_kv.c
@@ -166,10 +166,6 @@ static sqlite3_io_methods kvvfs_jrnl_io_methods = {
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/* Forward declarations for the low-level storage engine
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*/
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#define KVSTORAGE_KEY_SZ 32
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static int kvstorageWrite(const char*, const char *zKey, const char *zData);
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static int kvstorageDelete(const char*, const char *zKey);
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static int kvstorageRead(const char*, const char *zKey, char *zBuf, int nBuf);
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/* Expand the key name with an appropriate prefix and put the result
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** zKeyOut[]. The zKeyOut[] buffer is assumed to hold at least
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@@ -183,6 +179,207 @@ static void kvstorageMakeKey(
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sqlite3_snprintf(KVSTORAGE_KEY_SZ, zKeyOut, "kvvfs-%s-%s", zClass, zKeyIn);
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}
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#ifdef __EMSCRIPTEN__
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/* Provide Emscripten-based impls of kvstorageWrite/Read/Delete()... */
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#include <emscripten.h>
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#include <emscripten/console.h>
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/*
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** WASM_KEEP is identical to EMSCRIPTEN_KEEPALIVE but is not
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** Emscripten-specific. It explicitly includes marked functions for
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** export into the target wasm file without requiring explicit listing
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** of those functions in Emscripten's -sEXPORTED_FUNCTIONS=... list
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** (or equivalent in other build platforms). Any function with neither
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** this attribute nor which is listed as an explicit export will not
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** be exported from the wasm file (but may still be used internally
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** within the wasm file).
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**
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** The functions in this file (sqlite3-wasm.c) which require exporting
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** are marked with this flag. They may also be added to any explicit
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** build-time export list but need not be. All of these APIs are
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** intended for use only within the project's own JS/WASM code, and
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** not by client code, so an argument can be made for reducing their
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** visibility by not including them in any build-time export lists.
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**
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** 2022-09-11: it's not yet _proven_ that this approach works in
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** non-Emscripten builds. If not, such builds will need to export
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** those using the --export=... wasm-ld flag (or equivalent). As of
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** this writing we are tied to Emscripten for various reasons
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** and cannot test the library with other build environments.
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*/
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#define WASM_KEEP __attribute__((used,visibility("default")))
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/*
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** An internal level of indirection for accessing the static
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** kvstorageMakeKey() from EM_JS()-generated functions. This must be
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** made available for export via Emscripten but is not intended to be
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** used from client code. If called with a NULL zKeyOut it is a no-op.
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** It returns KVSTORAGE_KEY_SZ, so JS code (which cannot see that
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** constant) may call it with NULL arguments to get the size of the
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** allocation they'll need for a kvvfs key.
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**
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** Maintenance reminder: Emscripten will install this in the Module
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** init scope and will prefix its name with "_".
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*/
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WASM_KEEP
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int sqlite3_wasm__kvvfsMakeKey(const char *zClass, const char *zKeyIn,
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char *zKeyOut){
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if( 0!=zKeyOut ) kvstorageMakeKey(zClass, zKeyIn, zKeyOut);
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return KVSTORAGE_KEY_SZ;
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}
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/*
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** Internal helper for kvstorageWrite/Read/Delete() which creates a
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** storage key for the given zClass/zKeyIn combination. Returns a
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** pointer to the key: a C string allocated on the WASM stack, or 0 if
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** allocation fails. It is up to the caller to save/restore the stack
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** before/after this operation.
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*/
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EM_JS(const char *, kvstorageMakeKeyOnJSStack,
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(const char *zClass, const char *zKeyIn),{
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if( 0==zClass || 0==zKeyIn) return 0;
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const zXKey = stackAlloc(_sqlite3_wasm__kvvfsMakeKey(0,0,0));
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if(zXKey) _sqlite3_wasm__kvvfsMakeKey(zClass, zKeyIn, zXKey);
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return zXKey;
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});
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/*
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** JS impl of kvstorageWrite(). Main docs are in the C impl. This impl
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** writes zData to the global sessionStorage (if zClass starts with
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** 's') or localStorage, using a storage key derived from zClass and
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** zKey.
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*/
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EM_JS(int, kvstorageWrite,
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(const char *zClass, const char *zKey, const char *zData),{
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const stack = stackSave();
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try {
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const zXKey = kvstorageMakeKeyOnJSStack(zClass,zKey);
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if(!zXKey) return 1/*OOM*/;
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const jKey = UTF8ToString(zXKey);
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/**
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We could simplify this function and eliminate the
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kvstorageMakeKey() symbol acrobatics if we'd simply hard-code
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the key algo into the 3 functions which need it:
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const jKey = "kvvfs-"+UTF8ToString(zClass)+"-"+UTF8ToString(zKey);
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*/
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((115/*=='s'*/===getValue(zClass))
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? sessionStorage : localStorage).setItem(jKey, UTF8ToString(zData));
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}catch(e){
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console.error("kvstorageWrite()",e);
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return 1; // Can't access SQLITE_xxx from here
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}finally{
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stackRestore(stack);
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}
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return 0;
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});
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/*
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** JS impl of kvstorageDelete(). Main docs are in the C impl. This
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** impl generates a key derived from zClass and zKey, and removes the
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** matching entry (if any) from global sessionStorage (if zClass
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** starts with 's') or localStorage.
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*/
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EM_JS(int, kvstorageDelete,
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(const char *zClass, const char *zKey),{
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const stack = stackSave();
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try {
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const zXKey = kvstorageMakeKeyOnJSStack(zClass,zKey);
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if(!zXKey) return 1/*OOM*/;
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_sqlite3_wasm__kvvfsMakeKey(zClass, zKey, zXKey);
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const jKey = UTF8ToString(zXKey);
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((115/*=='s'*/===getValue(zClass))
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? sessionStorage : localStorage).removeItem(jKey);
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}catch(e){
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console.error("kvstorageDelete()",e);
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return 1;
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}finally{
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stackRestore(stack);
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}
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return 0;
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});
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/*
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** JS impl of kvstorageRead(). Main docs are in the C impl. This impl
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** reads its data from the global sessionStorage (if zClass starts
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** with 's') or localStorage, using a storage key derived from zClass
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** and zKey.
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*/
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EM_JS(int, kvstorageRead,
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(const char *zClass, const char *zKey, char *zBuf, int nBuf),{
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const stack = stackSave();
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try {
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const zXKey = kvstorageMakeKeyOnJSStack(zClass,zKey);
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if(!zXKey) return -3/*OOM*/;
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const jKey = UTF8ToString(zXKey);
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const jV = ((115/*=='s'*/===getValue(zClass))
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? sessionStorage : localStorage).getItem(jKey);
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if(!jV) return -1;
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const nV = jV.length /* Note that we are relying 100% on v being
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ASCII so that jV.length is equal to the
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C-string's byte length. */;
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if(nBuf<=0) return nV;
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else if(1===nBuf){
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setValue(zBuf, 0);
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return nV;
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}
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const zV = allocateUTF8OnStack(jV);
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if(nBuf > nV + 1) nBuf = nV + 1;
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HEAPU8.copyWithin(zBuf, zV, zV + nBuf - 1);
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setValue( zBuf + nBuf - 1, 0 );
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return nBuf - 1;
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}catch(e){
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console.error("kvstorageRead()",e);
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return -2;
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}finally{
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stackRestore(stack);
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}
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});
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/*
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** This function exists for (1) WASM testing purposes and (2) as a
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** hook to get Emscripten to export several EM_JS()-generated
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** functions (if we don't reference them from exported C functions
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** then they get stripped away at build time). It is not part of the
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** public API and its signature and semantics may change at any time.
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** It's not even part of the private API, for that matter - it's part
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** of the Emscripten C/JS/WASM glue.
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*/
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WASM_KEEP
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int sqlite3__wasm_emjs_kvvfs(int whichOp){
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int rc = 0;
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const char * zClass =
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"sezzion" /*don't collide with "session" records!*/;
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const char * zKey = "hello";
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switch( whichOp ){
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case 0: break;
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case 1:
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kvstorageWrite(zClass, zKey, "world");
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break;
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case 2: {
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char buffer[128] = {0};
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char * zBuf = &buffer[0];
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rc = kvstorageRead(zClass, zKey, zBuf, (int)sizeof(buffer));
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emscripten_console_logf("kvstorageRead()=%d %s\n", rc, zBuf);
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break;
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}
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case 3:
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kvstorageDelete(zClass, zKey);
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break;
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case 4:
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kvstorageMakeKeyOnJSStack(0,0);
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break;
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default: break;
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}
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return rc;
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}
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#undef WASM_KEEP
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#else /* end ifdef __EMSCRIPTEN__ */
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/* Forward declarations for the low-level storage engine
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*/
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static int kvstorageWrite(const char*, const char *zKey, const char *zData);
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static int kvstorageDelete(const char*, const char *zKey);
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static int kvstorageRead(const char*, const char *zKey, char *zBuf, int nBuf);
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/* Write content into a key. zClass is the particular namespace of the
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** underlying key/value store to use - either "local" or "session".
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**
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@@ -277,6 +474,7 @@ static int kvstorageRead(
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return (int)n;
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}
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}
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#endif /* ifdef __EMSCRIPTEN__ */
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/****** Utility subroutines ************************************************/
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