feat: add the cloudsync_logout function

also add a test for this function

Author: andinux

src/cloudsync.c

@@ -3150,6 +3150,90 @@ void cloudsync_commit_alter (sqlite3_context *context, int argc, sqlite3_value *
     }
 }
 
+/**
+ * Cleanup all local data from cloudsync-enabled tables, so the database can be safely reused
+ * by another user without exposing any data from the previous session.
+ *
+ * Warning: this function deletes all data from the tables. Use with caution.
+ */
+void cloudsync_logout (sqlite3_context *context, int argc, sqlite3_value **argv) {
+    bool completed = false;
+    char *errmsg = NULL;
+    sqlite3 *db = sqlite3_context_db_handle(context);
+
+    // if the network layer is enabled, remove the token or apikey
+    #ifndef CLOUDSYNC_OMIT_NETWORK
+    sqlite3_exec(db, "SELECT cloudsync_network_set_token('');", NULL, NULL, NULL);
+    #endif
+    
+    // get the list of cloudsync-enabled tables
+    char *sql = "SELECT tbl_name, key, value FROM cloudsync_table_settings;";
+    char **result = NULL;
+    int nrows, ncols;
+    int rc = sqlite3_get_table(db, sql, &result, &nrows, &ncols, NULL);
+    if (rc != SQLITE_OK) {
+        errmsg = cloudsync_memory_mprintf("Unable to get current cloudsync configuration. %s", sqlite3_errmsg(db));
+        goto finalize;
+    }
+    
+    // run everything in a savepoint
+    rc = sqlite3_exec(db, "SAVEPOINT cloudsync_logout_sp;", NULL, NULL, NULL);
+    if (rc != SQLITE_OK) {
+        errmsg = cloudsync_memory_mprintf("Unable to create cloudsync_logout savepoint. %s", sqlite3_errmsg(db));
+        return;
+    }
+
+    // disable cloudsync for all the previously enabled tables: cloudsync_cleanup('*')
+    rc = sqlite3_exec(db, "SELECT cloudsync_cleanup('*')", NULL, NULL, NULL);
+    if (rc != SQLITE_OK) {
+        errmsg = cloudsync_memory_mprintf("Unable to cleanup current cloudsync configuration. %s", sqlite3_errmsg(db));
+        goto finalize;
+    }
+    
+    // delete all the local data for each previously enabled table
+    // re-enable cloudsync on previously enabled tables
+    for (int i = 1; i <= nrows; i++) {
+        char *tbl_name  = result[i * ncols + 0];
+        char *key       = result[i * ncols + 1];
+        char *value     = result[i * ncols + 2];
+        
+        if (strcmp(key, "algo") != 0) continue;
+        
+        sql = cloudsync_memory_mprintf("DELETE FROM \"%w\";", tbl_name);
+        rc = sqlite3_exec(db, sql, NULL, NULL, NULL);
+        cloudsync_memory_free(sql);
+        if (rc != SQLITE_OK) {
+            errmsg = cloudsync_memory_mprintf("Unable to delete data from table %s. %s", tbl_name, sqlite3_errmsg(db));
+            goto finalize;
+        }
+        
+        sql = cloudsync_memory_mprintf("SELECT cloudsync_init(\"%w\", \"%w\", 1);", tbl_name, value);
+        rc = sqlite3_exec(db, sql, NULL, NULL, NULL);
+        cloudsync_memory_free(sql);
+        if (rc != SQLITE_OK) {
+            errmsg = cloudsync_memory_mprintf("Unable to enable cloudsync on table %s. %s", tbl_name, sqlite3_errmsg(db));
+            goto finalize;
+        }
+    }
+    
+    completed = true;
+        
+finalize:
+    if (completed) {
+        sqlite3_exec(db, "RELEASE cloudsync_logout_sp;", NULL, NULL, NULL);
+    } else {
+        // cleanup:
+        // ROLLBACK TO command reverts the state of the database back to what it was just after the corresponding SAVEPOINT
+        // then RELEASE to remove the SAVEPOINT from the transaction stack
+        sqlite3_exec(db, "ROLLBACK TO cloudsync_logout_sp;", NULL, NULL, NULL);
+        sqlite3_exec(db, "RELEASE cloudsync_logout_sp;", NULL, NULL, NULL);
+        sqlite3_result_error(context, errmsg, -1);
+        sqlite3_result_error_code(context, rc);
+    }
+    sqlite3_free_table(result);
+    cloudsync_memory_free(errmsg);
+}
+    
 // MARK: - Main Entrypoint -
 
 APIEXPORT int sqlite3_cloudsync_init (sqlite3 *db, char **pzErrMsg, const sqlite3_api_routines *pApi) {
@@ -3268,6 +3352,9 @@ APIEXPORT int sqlite3_cloudsync_init (sqlite3 *db, char **pzErrMsg, const sqlite
     rc = dbutils_register_function(db, "cloudsync_seq", cloudsync_seq, 0, pzErrMsg, ctx, NULL);
     if (rc != SQLITE_OK) return rc;
 
+    rc = dbutils_register_function(db, "cloudsync_logout", cloudsync_logout, 0, pzErrMsg, ctx, NULL);
+    if (rc != SQLITE_OK) return rc;
+
     // NETWORK LAYER
     #ifndef CLOUDSYNC_OMIT_NETWORK
     rc = cloudsync_network_register(db, pzErrMsg, ctx);

test/unit.c

@@ -994,6 +994,25 @@ bool do_test_functions (sqlite3 *db, bool print_results) {
     if (print_results) printf("New uuid: %s\n", uuid);
     cloudsync_memory_free(uuid);
 
+    rc = sqlite3_exec(db, "SELECT cloudsync_init('*');", NULL, NULL, NULL);
+    if (rc != SQLITE_OK) goto abort_test_functions;
+    rc = sqlite3_exec(db, "INSERT INTO tbl1 (col1, col2) VALUES ('abc123', 'qwe321');", NULL, NULL, NULL);
+    sqlite3_int64 nrows1 = dbutils_int_select(db, "SELECT count(*) FROM tbl1;");
+    if (nrows1 != 1) goto abort_test_functions;
+    char *siteid1 = dbutils_text_select(db, "SELECT hex(cloudsync_siteid());");
+    sqlite3_int64 nmaster1 = dbutils_int_select(db, "SELECT count(*) FROM sqlite_master;");
+    rc = sqlite3_exec(db, "SELECT cloudsync_logout();", NULL, NULL, NULL);
+    char *siteid2 = dbutils_text_select(db, "SELECT hex(cloudsync_siteid());");
+    sqlite3_int64 nmaster2 = dbutils_int_select(db, "SELECT count(*) FROM sqlite_master;");
+    sqlite3_int64 nrows2 = dbutils_int_select(db, "SELECT count(*) FROM tbl1;");
+    int siteidcmp = strcmp(siteid1, siteid2);
+    cloudsync_memory_free(siteid1);
+    cloudsync_memory_free(siteid2);
+    if (rc != SQLITE_OK) goto abort_test_functions;
+    if (siteidcmp == 0) goto abort_test_functions;
+    if (nmaster1 != nmaster2) goto abort_test_functions;
+    if (nrows2 != 0) goto abort_test_functions;
+    
     return true;
 
 abort_test_functions: