create more zig-friendly request interface

src/interface.zig

@@ -1,5 +1,6 @@
 const std = @import("std");
 
+// C interfaces between main and libraries
 pub const Header = extern struct {
     name_ptr: [*]u8,
     name_len: usize,
@@ -26,6 +27,13 @@ pub const Request = extern struct {
     headers_len: usize,
 };
 
+// If the library is Zig, we can use these helpers
+pub const ZigRequest = struct {
+    method: [:0]u8,
+    content: []u8,
+    headers: []Header,
+};
+
 pub fn toHeaders(alloc: std.mem.Allocator, headers: std.StringHashMap([]const u8)) ![*]Header {
     var header_array = try std.ArrayList(Header).initCapacity(alloc, headers.count());
     var iterator = headers.iterator();
@@ -56,7 +64,7 @@ pub fn zigInit(parent_allocator: *anyopaque) callconv(.C) void {
     allocator = @ptrCast(*std.mem.Allocator, @alignCast(@alignOf(*std.mem.Allocator), parent_allocator));
 }
 
-pub const ZigRequestHandler = *const fn (std.mem.Allocator, Request, ZigResponse) anyerror!void;
+pub const ZigRequestHandler = *const fn (std.mem.Allocator, ZigRequest, ZigResponse) anyerror!void;
 
 const log = std.log.scoped(.interface);
 pub fn handleRequest(request: *Request, zigRequestHandler: ZigRequestHandler) ?*Response {
@@ -69,10 +77,18 @@ pub fn handleRequest(request: *Request, zigRequestHandler: ZigRequestHandler) ?*
 
     // setup headers
     var headers = std.StringHashMap([]const u8).init(alloc);
-    zigRequestHandler(alloc, request.*, .{
+    zigRequestHandler(
+        alloc,
+        .{
+            .method = request.method[0..request.method_len :0],
+            .content = request.content[0..request.content_len],
+            .headers = request.headers[0..request.headers_len],
+        },
+        .{
             .body = &response,
             .headers = &headers,
-    }) catch |e| {
+        },
+    ) catch |e| {
         log.err("Unexpected error processing request: {any}", .{e});
         if (@errorReturnTrace()) |trace| {
             std.debug.dumpStackTrace(trace.*);

src/main-lib.zig

@@ -8,10 +8,20 @@ const log = std.log.scoped(.@"main-lib");
 // request. Useful for deallocating memory
 // export fn request_deinit() void {
 // }
+
+/// handle_request will be called on a single request, but due to the preservation
+/// of restrictions imposed by the calling interface, it should generally be more
+/// useful to call into the interface library to let it do the conversion work
+/// on your behalf
 export fn handle_request(request: *interface.Request) callconv(.C) ?*interface.Response {
     return interface.handleRequest(request, handleRequest);
 }
 
+// zigInit is an optional export called at the beginning of a request. It will
+// be passed an allocator (which...shh...is an arena allocator). Since the
+// interface library provides a request handler that requires a built-in allocator,
+// if you are using the interface library, you will need to also include this
+// export
 comptime {
     @export(
         interface.zigInit,
@@ -25,12 +35,12 @@ comptime {
 //
 // handleRequest function here is the last line of boilerplate and the
 // entry to a request
-fn handleRequest(allocator: std.mem.Allocator, request: interface.Request, response: interface.ZigResponse) !void {
+fn handleRequest(allocator: std.mem.Allocator, request: interface.ZigRequest, response: interface.ZigResponse) !void {
     _ = allocator;
     // setup
     var response_writer = response.body.writer();
     // real work
-    response_writer.print(" {d}", .{request.headers_len}) catch unreachable;
+    response_writer.print(" {d}", .{request.headers.len}) catch unreachable;
     try response.headers.put("X-custom-foo", "bar");
     log.info("handlerequest header count {d}", .{response.headers.count()});
 }