Fix not handling temp file request from sqlite

src/esp32.cpp

@@ -383,6 +383,8 @@ static int ESP32Access(
   return SQLITE_OK;
 }
 
+static char dbrootpath[MAXPATHNAME+1];
+
 /*
 ** Open a file handle.
 */
@@ -416,9 +418,6 @@ static int ESP32Open(
       //Serial.println("fn: Open");
 
 	strcpy(mode, "r");
-  if( zName==0 ){
-    return SQLITE_IOERR;
-  }
 
   if( flags&SQLITE_OPEN_MAIN_JOURNAL ){
     aBuf = (char *)sqlite3_malloc(SQLITE_ESP32VFS_BUFFERSZ);
@@ -431,7 +430,7 @@ static int ESP32Open(
           || flags&SQLITE_OPEN_MAIN_JOURNAL ) {
     struct stat st;
     memset(&st, 0, sizeof(struct stat));
-    int rc = stat( zName, &st );
+    int rc = (zName == 0 ? -1 : stat( zName, &st ));
     //Serial.println(zName);
 		if (rc < 0) {
       strcpy(mode, "w+");
@@ -446,8 +445,41 @@ static int ESP32Open(
   memset(p, 0, sizeof(ESP32File));
   //p->fd = open(zName, oflags, 0600);
   //p->fd = open(zName, oflags, S_IRUSR | S_IWUSR);
-  p->fp = fopen(zName, mode);
-  if( p->fp == (void *)NULL ) {
+  if (zName == 0) {
+    //generate a temporary file name
+    char *tName = tmpnam(NULL);
+    tName[4] = '_';
+    size_t len = strlen(dbrootpath);
+    memmove(tName + len, tName, strlen(tName) + 1);
+    memcpy(tName, dbrootpath, len);    
+    p->fp = fopen(tName, mode);
+    //https://stackoverflow.com/questions/64424287/how-to-delete-a-file-in-c-using-a-file-descriptor
+    //for temp file, then no need to handle in esp32close
+    unlink(tName);
+    //Serial.println("Temporary file name generated: " + String(tName) + " mode: " + String(mode));
+  } else {
+    //detect database root as folder for temporary files, every newly openened db will change this path
+    //this mainly fixes that vfs's have their own root name like /sd
+    char *ext = strrchr(zName, '.');
+    bool isdb = false;
+    if (ext) {
+      isdb = (strcmp(ext+1,"db") == 0);
+    }
+    if (isdb) {      
+      char zDir[MAXPATHNAME+1];
+      int i=0;
+      strcpy(zDir,zName);
+
+      for(i=1; zDir[i]!='/'; i++) {};
+      zDir[i] = '\0';
+
+      strcpy(dbrootpath, zDir);
+    }
+
+    p->fp = fopen(zName, mode);
+  }
+
+  if( p->fp<=0){
     if (aBuf)
       sqlite3_free(aBuf);
     //Serial.println("Can't open");