Add propget and ports_get method for a snapshot

1. propset are currently not supported for a snapshot
2. A method to convert a list of snapshot_ports to a
   list Tcl obj is currently underway

src/cregistry/snapshot.c

@@ -475,3 +475,84 @@ int reg_snapshot_port_variants_get(reg_registry* reg, sqlite_int64 snapshot_port
         return -1;
     }
 }
+
+/**
+ * Gets a named property of a snapshot. The property named must be one
+ * that exists in the table and must not be one with internal meaning
+ * such as `id` or `state`.
+ *
+ * @param [in] snapshot   snapshot to get property from
+ * @param [in] key        property to get
+ * @param [out] value     the value of the property
+ * @param [out] errPtr    on error, a description of the error that occurred
+ * @return                true if success; false if failure
+ */
+int reg_snapshot_propget(reg_snapshot* snapshot, char* key, char** value,
+        reg_error* errPtr) {
+    reg_registry* reg = snapshot->reg;
+    int result = 0;
+    sqlite3_stmt* stmt = NULL;
+    char* query;
+    const char *text;
+    query = sqlite3_mprintf("SELECT %q FROM registry.snapshots WHERE id=%lld", key,
+            snapshot->id);
+    if (sqlite3_prepare_v2(reg->db, query, -1, &stmt, NULL) == SQLITE_OK) {
+        int r;
+        do {
+            r = sqlite3_step(stmt);
+            switch (r) {
+                case SQLITE_ROW:
+                    text = (const char*)sqlite3_column_text(stmt, 0);
+                    if (text) {
+                        *value = strdup(text);
+                        result = 1;
+                    } else {
+                        reg_sqlite_error(reg->db, errPtr, query);
+                    }
+                    break;
+                case SQLITE_DONE:
+                    errPtr->code = REG_INVALID;
+                    errPtr->description = "an invalid snapshot was passed";
+                    errPtr->free = NULL;
+                    break;
+                case SQLITE_BUSY:
+                    continue;
+                default:
+                    reg_sqlite_error(reg->db, errPtr, query);
+                    break;
+            }
+        } while (r == SQLITE_BUSY);
+    } else {
+        reg_sqlite_error(reg->db, errPtr, query);
+    }
+    if (stmt) {
+        sqlite3_finalize(stmt);
+    }
+    sqlite3_free(query);
+    return result;
+}
+
+/**
+ * Gets all the 'ports' of a snapshot. The property named must be one
+ * that exists in the table and must not be one with internal meaning
+ * such as `id` or `state`.
+ *
+ * A 'port' here is a row in registry.snapshot_ports table and its
+ * corresponding variants in registry.snapshot_port_variants table
+ *
+ * @param [in] snapshot   snapshot to get property from
+ * @param [in] key        property to get
+ * @param [out] value     the value of the property
+ * @param [out] errPtr    on error, a description of the error that occurred
+ * @return                true if success; false if failure
+ */
+int reg_snapshot_ports_get(reg_snapshot* snapshot, port** ports,
+        reg_error* errPtr) {
+    reg_registry* reg = snapshot->reg;
+    int result = 0;
+    sqlite3_stmt* stmt = NULL;
+    char* query;
+    const char *text;
+    // TODO: get ports and their variants using snapshot->id as Fk
+    return result;
+}

src/cregistry/snapshot.h

@@ -73,4 +73,9 @@ int snapshot_store_ports(reg_registry* reg, reg_snapshot* snapshot,
 int snapshot_store_port_variants(reg_registry* reg, reg_entry* port_entry,
         int snapshot_ports_id, reg_error* errPtr);
 
+int reg_snapshot_propget(reg_snapshot* snapshot, char* key, char** value,
+        reg_error* errPtr);
+int reg_snapshot_ports_get(reg_snapshot* snapshot, port** ports,
+        reg_error* errPtr);
+
 #endif /* _CSNAPSHOT_H */

src/registry2.0/snapshotobj.c

@@ -45,7 +45,7 @@ const char* snapshot_props[] = {
     NULL
 };
 
-/* ${snapshot} prop ?value? */
+/* ${snapshot} prop */
 static int snapshot_obj_prop(Tcl_Interp* interp, reg_snapshot* snapshot, int objc,
         Tcl_Obj* CONST objv[]) {
     int index;
@@ -73,18 +73,42 @@ static int snapshot_obj_prop(Tcl_Interp* interp, reg_snapshot* snapshot, int obj
             return registry_failed(interp, &error);
         }
         return TCL_ERROR;
-    } else {
-        /* ${snapshot} prop name value; set a new value */
+    }
+}
+
+/* ${snapshot} ports */
+static int snapshot_obj_ports(Tcl_Interp* interp, reg_snapshot* snapshot, int objc,
+        Tcl_Obj* CONST objv[]) {
+    int index;
+    if (objc > 3) {
+        Tcl_WrongNumArgs(interp, 2, objv, "?value?");
+        return TCL_ERROR;
+    }
+    if (objc == 2) {
+        /* ${snapshot} prop; return the current value */
         reg_registry* reg = registry_for(interp, reg_attached);
         if (reg == NULL) {
             return TCL_ERROR;
         }
         if (Tcl_GetIndexFromObj(interp, objv[1], snapshot_props, "prop", 0, &index)
                 == TCL_OK) {
-            char* key = Tcl_GetString(objv[1]);
-            char* value = Tcl_GetString(objv[2]);
+            port** ports;
             reg_error error;
-            if (reg_snapshot_propset(snapshot, key, value, &error)) {
+            if (reg_snapshot_ports_get(snapshot, &ports, &error)) {
+
+                // TODO: correct the below for 'ports', added as a prototype for now
+                // Tcl_Obj** objs;
+                // int retval = TCL_ERROR;
+                // if (list_entry_to_obj(interp, &objs, entries, entry_count, &error)){
+                //     Tcl_Obj* result = Tcl_NewListObj(entry_count, objs);
+                //     Tcl_SetObjResult(interp, result);
+                //     free(objs);
+                //     retval = TCL_OK;
+                // } else {
+                //     retval = registry_failed(interp, &error);
+                // }
+
+                free(ports);
                 return TCL_OK;
             }
             return registry_failed(interp, &error);