feat: support extism_current_plugin_host_context (#17)

Author: zshipko

src/current_plugin.zig

@@ -39,3 +39,7 @@ pub fn returnBytes(self: *Self, val: *c.ExtismVal, data: []const u8) void {
 pub fn inputBytes(self: *Self, val: *const c.ExtismVal) []const u8 {
     return self.getMemory(@intCast(val.v.i64));
 }
+
+pub fn hostContext(self: *Self) ?*anyopaque {
+    return c.extism_current_plugin_host_context(self.c_currplugin);
+}

src/plugin.zig

@@ -58,9 +58,7 @@ pub fn cancelHandle(self: *Self) CancelHandle {
     return .{ .handle = ptr };
 }
 
-/// Call a function with the given input
-pub fn call(self: *Self, function_name: []const u8, input: []const u8) ![]const u8 {
-    const res = c.extism_plugin_call(self.ptr, function_name.ptr, input.ptr, @as(u64, input.len));
+fn handleCall(self: *Self, res: i32) ![]const u8 {
     if (res != 0) {
         const err_c = c.extism_plugin_error(self.ptr);
         const err = std.mem.span(err_c);
@@ -80,6 +78,19 @@ pub fn call(self: *Self, function_name: []const u8, input: []const u8) ![]const
     }
     return "";
 }
+
+/// Call a function with the given input
+pub fn call(self: *Self, function_name: []const u8, input: []const u8) ![]const u8 {
+    const res = c.extism_plugin_call(self.ptr, function_name.ptr, input.ptr, @as(u64, input.len));
+    return self.handleCall(res);
+}
+
+/// Call a function with the given input and host context
+pub fn callWithContext(self: *Self, function_name: []const u8, input: []const u8, host_context: *anyopaque) ![]const u8 {
+    const res = c.extism_plugin_call_with_host_context(self.ptr, function_name.ptr, input.ptr, @as(u64, input.len), host_context);
+    return self.handleCall(res);
+}
+
 /// Set configuration values
 pub fn setConfig(self: *Self, allocator: std.mem.Allocator, config: std.json.ArrayHashMap([]const u8)) !void {
     const config_json = try std.json.stringifyAlloc(allocator, config, .{ .emit_null_optional_fields = false });

test.zig

@@ -15,6 +15,10 @@ export fn hello_world(plugin_ptr: ?*sdk.c.ExtismCurrentPlugin, inputs: [*c]const
     var curr_plugin = CurrentPlugin.getCurrentPlugin(plugin_ptr orelse unreachable);
     const input = curr_plugin.inputBytes(&input_slice[0]);
     std.debug.print("input: {s}\n", .{input});
+    if (curr_plugin.hostContext()) |ctx_ptr| {
+        const ctx: *u64 = @alignCast(@ptrCast(ctx_ptr));
+        std.debug.print("Host context={}\n", .{ctx.*});
+    }
     output_slice[0] = input_slice[0];
 }
 
@@ -40,9 +44,12 @@ test "Single threaded tests" {
     std.debug.print("\nregister loaded plugin: {}\n", .{std.fmt.fmtDuration(wasm_start.read())});
     const repeat = 1182;
     const input = "aeiouAEIOU____________________________________&smtms_y?" ** repeat;
-    const data = try plugin.call("count_vowels", input);
+    var data = try plugin.call("count_vowels", input);
     try testing.expectEqualStrings("{\"count\": 11820}", data);
     std.debug.print("register plugin + function call: {}, sent input size: {} bytes\n", .{ std.fmt.fmtDuration(wasm_start.read()), input.len });
+    var ctx: u64 = 12345;
+    data = try plugin.callWithContext("count_vowels", input, @ptrCast(&ctx));
+    try testing.expectEqualStrings("{\"count\": 11820}", data);
     std.debug.print("--------------\n", .{});
     var i: usize = 0;
     var wasm_elapsed: u64 = 0;