Fix Got [ERASED] expecting X when storage compacts while executing …

…a function *in* storage on non-Bangle devices (fix #2431)

ChangeLog

@@ -30,6 +30,7 @@
             Graphics: Graphics.stringMetrics now returns 'unrenderableChars/imageCount/maxImageHeight' for much more info about rendering strings
             Graphics: wrapString now also wraps on slashes (to allow wrapping of URLs)
             nRF5x: when connecting to other devices, allow a slave latency of 2 (might increase reliability)
+            Fix `Got [ERASED] expecting X` when storage compacts while executing a function *in* storage on non-Bangle devices (fix #2431)
 
      2v19 : Fix Object.values/entries for numeric keys after 2v18 regression (fix #2375)
             nRF52: for SD>5 use static buffers for advertising and scan response data (#2367)

src/jsparse.c

@@ -406,7 +406,7 @@ NO_INLINE bool jspeFunctionDefinitionInternal(JsVar *funcVar, bool expressionOnl
   if (!expressionOnly) {
     int brackets = 0;
     JsExecFlags oldExec = execInfo.execute;
-    execInfo.execute = EXEC_NO; // set no execute so we don't parse strings    
+    execInfo.execute = EXEC_NO; // set no execute so we don't parse strings
     while (lex->tk && (brackets || lex->tk != '}')) {
       if (lex->tk == '{') brackets++;
       if (lex->tk == '}') brackets--;
@@ -932,6 +932,11 @@ NO_INLINE JsVar *jspeFunctionCall(JsVar *function, JsVar *functionName, JsVar *t
     }
 
     jsvUnLock(thisVar);
+    /* It's possible that this call or a subcall may have compacted the filesystem
+    which changed the address the var in the iterator pointed to. If so we need to
+    copy it again. This should be quick-ish so lets' just do it rather than checking
+    whether we have compacted or not. https://github.com/espruino/Espruino/issues/2431 */
+    if (lex) jsvStringIteratorUpdatePtr(&lex->it);
 
     return returnVar;
   } else if (isParsing) { // ---------------------------------- function, but not executing - just parse args and be done

src/jsvariterator.c

@@ -265,20 +265,16 @@ void jsvStringIteratorNew(JsvStringIterator *it, JsVar *str, size_t startIdx) {
     it->var = jsvLockAgain(str);
   it->varIndex = 0;
   it->charsInVar = jsvGetCharactersInVar(it->var);
-
-  if (jsvIsFlatString(it->var)) {
-    it->ptr = jsvGetFlatStringPointer(it->var);
-  } else if (jsvIsNativeString(it->var)) {
-    it->ptr = (char*)it->var->varData.nativeStr.ptr;
 #ifdef SPIFLASH_BASE
-  } else if (jsvIsFlashString(it->var)) {
+  if (jsvIsFlashString(it->var)) {
+    /* We need to handle flash strings separately as we want
+    to preload a buffer of data */
     it->charsInVar = 0;
     it->charIdx = startIdx; // if it's not UTF8 we can just load up the bit we want immediately
     return jsvStringIteratorLoadFlashString(it);
-#endif
-  } else{
-    it->ptr = &it->var->varData.str[0];
   }
+#endif
+  jsvStringIteratorUpdatePtr(it);
   it->charIdx = startIdx;
   jsvStringIteratorCatchUp(it);
 }
@@ -300,6 +296,22 @@ void jsvStringIteratorNewUTF8(JsvStringIterator *it, JsVar *str, size_t startIdx
 #endif
 }
 
+/// Update the pointer on a String iterator (should not normally be needed except when allocating a new iterator, but we may call it if we think the pointer in the var may have changed, eg during compaction)
+void jsvStringIteratorUpdatePtr(JsvStringIterator *it) {
+  if (jsvIsFlatString(it->var)) {
+    it->ptr = jsvGetFlatStringPointer(it->var);
+  } else if (jsvIsNativeString(it->var)) {
+    it->ptr = (char*)it->var->varData.nativeStr.ptr;
+#ifdef SPIFLASH_BASE
+  } else if (jsvIsFlashString(it->var)) {
+    /* don't do anything for flash strings - they are
+    handled specially in jsvStringIteratorNew */
+#endif
+  } else if (it->var)
+    it->ptr = &it->var->varData.str[0];
+  else
+    it->ptr = 0;
+}
 
 void jsvStringIteratorClone(JsvStringIterator *dstit, JsvStringIterator *it) {
   *dstit = *it;

src/jsvariterator.h

@@ -80,6 +80,9 @@ void jsvStringIteratorNew(JsvStringIterator *it, JsVar *str, size_t startIdx);
 /// Create a new String iterator from a string, starting from a specific character (ensures start character matches with actual UTF8 char number)
 void jsvStringIteratorNewUTF8(JsvStringIterator *it, JsVar *str, size_t startIdx);
 
+/// Update the pointer on a String iterator (should not normally be needed except when allocating a new iterator, but we may call it if we think the pointer in the var may have changed, eg during compaction)
+void jsvStringIteratorUpdatePtr(JsvStringIterator *it);
+
 /// Clone the string iterator
 void jsvStringIteratorClone(JsvStringIterator *dstit, JsvStringIterator *it);