add skeleton of zig std command impl

lib/compiler/std-docs.zig

@@ -0,0 +1,164 @@
+const builtin = @import("builtin");
+const std = @import("std");
+const Allocator = std.mem.Allocator;
+
+pub fn main() !void {
+    var arena_instance = std.heap.ArenaAllocator.init(std.heap.page_allocator);
+    defer arena_instance.deinit();
+    const arena = arena_instance.allocator();
+
+    var general_purpose_allocator: std.heap.GeneralPurposeAllocator(.{}) = .{};
+    const gpa = general_purpose_allocator.allocator();
+
+    const args = try std.process.argsAlloc(arena);
+    const zig_lib_directory = args[1];
+    const zig_exe_path = args[2];
+    const global_cache_path = args[3];
+
+    const docs_path = try std.fs.path.join(arena, &.{ zig_lib_directory, "docs" });
+    var docs_dir = try std.fs.cwd().openDir(docs_path, .{});
+    defer docs_dir.close();
+
+    const listen_port: u16 = 0;
+    const address = std.net.Address.parseIp("127.0.0.1", listen_port) catch unreachable;
+    var http_server = try address.listen(.{});
+    const port = http_server.listen_address.in.getPort();
+    const url = try std.fmt.allocPrint(arena, "http://127.0.0.1:{d}/\n", .{port});
+    std.io.getStdOut().writeAll(url) catch {};
+    openBrowserTab(gpa, url[0 .. url.len - 1 :'\n']) catch |err| {
+        std.log.err("unable to open browser: {s}", .{@errorName(err)});
+    };
+
+    var read_buffer: [8000]u8 = undefined;
+    accept: while (true) {
+        const connection = try http_server.accept();
+        defer connection.stream.close();
+
+        var server = std.http.Server.init(connection, &read_buffer);
+        while (server.state == .ready) {
+            var request = server.receiveHead() catch |err| switch (err) {
+                error.HttpConnectionClosing => continue :accept,
+                else => {
+                    std.log.err("closing http connection: {s}", .{@errorName(err)});
+                    continue :accept;
+                },
+            };
+            serveRequest(&request, gpa, docs_dir, zig_exe_path, global_cache_path) catch |err| {
+                std.log.err("unable to serve {s}: {s}", .{ request.head.target, @errorName(err) });
+                continue :accept;
+            };
+        }
+    }
+}
+
+fn serveRequest(
+    request: *std.http.Server.Request,
+    gpa: Allocator,
+    docs_dir: std.fs.Dir,
+    zig_exe_path: []const u8,
+    global_cache_path: []const u8,
+) !void {
+    if (std.mem.eql(u8, request.head.target, "/") or
+        std.mem.eql(u8, request.head.target, "/debug/"))
+    {
+        try serveDocsFile(request, gpa, docs_dir, "index.html", "text/html");
+    } else if (std.mem.eql(u8, request.head.target, "/main.js") or
+        std.mem.eql(u8, request.head.target, "/debug/main.js"))
+    {
+        try serveDocsFile(request, gpa, docs_dir, "main.js", "application/javascript");
+    } else if (std.mem.eql(u8, request.head.target, "/main.wasm")) {
+        try serveWasm(request, gpa, zig_exe_path, global_cache_path, .ReleaseFast);
+    } else if (std.mem.eql(u8, request.head.target, "/debug/main.wasm")) {
+        try serveWasm(request, gpa, zig_exe_path, global_cache_path, .Debug);
+    } else {
+        try request.respond("not found", .{
+            .status = .not_found,
+            .extra_headers = &.{
+                .{ .name = "content-type", .value = "text/plain" },
+            },
+        });
+    }
+}
+
+fn serveDocsFile(
+    request: *std.http.Server.Request,
+    gpa: Allocator,
+    docs_dir: std.fs.Dir,
+    name: []const u8,
+    content_type: []const u8,
+) !void {
+    // The desired API is actually sendfile, which will require enhancing std.http.Server.
+    // We load the file with every request so that the user can make changes to the file
+    // and refresh the HTML page without restarting this server.
+    const file_contents = try docs_dir.readFileAlloc(gpa, name, 10 * 1024 * 1024);
+    defer gpa.free(file_contents);
+    try request.respond(file_contents, .{
+        .status = .ok,
+        .extra_headers = &.{
+            .{ .name = "content-type", .value = content_type },
+        },
+    });
+}
+
+fn serveWasm(
+    request: *std.http.Server.Request,
+    gpa: Allocator,
+    zig_exe_path: []const u8,
+    global_cache_path: []const u8,
+    optimize_mode: std.builtin.OptimizeMode,
+) !void {
+    _ = request;
+    _ = gpa;
+    _ = zig_exe_path;
+    _ = global_cache_path;
+    _ = optimize_mode;
+    @panic("TODO serve wasm");
+}
+
+const BuildWasmBinaryOptions = struct {
+    zig_exe_path: []const u8,
+    global_cache_path: []const u8,
+    main_src_path: []const u8,
+};
+
+fn buildWasmBinary(arena: Allocator, options: BuildWasmBinaryOptions) ![]const u8 {
+    var argv: std.ArrayListUnmanaged([]const u8) = .{};
+    try argv.appendSlice(arena, &.{
+        options.zig_exe_path,
+        "build-exe",
+        "-fno-entry",
+        "-OReleaseSmall",
+        "-target",
+        "wasm32-freestanding",
+        "-mcpu",
+        "baseline+atomics+bulk_memory+multivalue+mutable_globals+nontrapping_fptoint+reference_types+sign_ext",
+        "--cache-dir",
+        options.global_cache_path,
+        "--global-cache-dir",
+        options.global_cache_path,
+        "--name",
+        "autodoc",
+        "-rdynamic",
+        options.main_src_path,
+        "--listen=-",
+    });
+}
+
+fn openBrowserTab(gpa: Allocator, url: []const u8) !void {
+    // Until https://github.com/ziglang/zig/issues/19205 is implemented, we
+    // spawn a thread for this child process.
+    _ = try std.Thread.spawn(.{}, openBrowserTabThread, .{ gpa, url });
+}
+
+fn openBrowserTabThread(gpa: Allocator, url: []const u8) !void {
+    const main_exe = switch (builtin.os.tag) {
+        .windows => "explorer",
+        else => "xdg-open",
+    };
+    var child = std.ChildProcess.init(&.{ main_exe, url }, gpa);
+    child.stdin_behavior = .Ignore;
+    child.stdout_behavior = .Ignore;
+    child.stderr_behavior = .Ignore;
+    try child.spawn();
+    _ = try child.wait();
+}