builder: declare Darwin socket and process symbols

builder/darwin-libsystem.go

@@ -1,13 +1,50 @@
 package builder
 
 import (
+	"os"
 	"path/filepath"
 	"strings"
 
 	"github.com/tinygo-org/tinygo/compileopts"
 	"github.com/tinygo-org/tinygo/goenv"
 )
 
+// Extra declarations for libSystem exports absent from macos-minimal-sdk.
+// See https://github.com/tinygo-org/macos-minimal-sdk for the SDK sources.
+var darwinExtraLibSystemSymbols = []string{
+	// The BSD socket API, which the host netdev in src/net reaches through
+	// the standard library syscall package.
+	"accept",
+	"bind",
+	"connect",
+	"getpeername",
+	"getsockname",
+	"getsockopt",
+	"listen",
+	"recvfrom",
+	"recvmsg",
+	"sendmsg",
+	"sendto",
+	"setsockopt",
+	"shutdown",
+	"socket",
+	"socketpair",
+
+	// addchdir_np requires macOS 10.15 or later.
+	"posix_spawn",
+	"posix_spawn_file_actions_addchdir_np",
+	"posix_spawn_file_actions_addclose",
+	"posix_spawn_file_actions_adddup2",
+	"posix_spawn_file_actions_addopen",
+	"posix_spawn_file_actions_destroy",
+	"posix_spawn_file_actions_init",
+	"posix_spawnattr_destroy",
+	"posix_spawnattr_init",
+	"posix_spawnattr_setflags",
+	"posix_spawnattr_setpgroup",
+	"posix_spawnattr_setsigmask",
+}
+
 // Create a job that builds a Darwin libSystem.dylib stub library. This library
 // contains all the symbols needed so that we can link against it, but it
 // doesn't contain any real symbol implementations.
@@ -36,7 +73,34 @@ func makeDarwinLibSystemJob(config *compileopts.Config, tmpdir string) *compileJ
 				return err
 			}
 
-			// Link object file to dynamic library.
+			// Compile the extra stubs into a second object file, so that the
+			// generated one stays as it is.
+			extrapath := filepath.Join(tmpdir, "libSystem-extra.s")
+			extraobjpath := filepath.Join(tmpdir, "libSystem-extra.o")
+			var extra strings.Builder
+			extra.WriteString("// Stubs for symbols exported by libSystem but not declared in lib/macos-minimal-sdk.\n")
+			for _, symbol := range darwinExtraLibSystemSymbols {
+				extra.WriteString("\n.global _" + symbol + "\n_" + symbol + ":\n")
+			}
+			if err := os.WriteFile(extrapath, []byte(extra.String()), 0o666); err != nil {
+				return err
+			}
+			flags = []string{
+				"-nostdlib",
+				"--target=" + config.Triple(),
+				"-c",
+				"-o", extraobjpath,
+				extrapath,
+			}
+			if config.Options.PrintCommands != nil {
+				config.Options.PrintCommands("clang", flags...)
+			}
+			err = runCCompiler(flags...)
+			if err != nil {
+				return err
+			}
+
+			// Link object files to dynamic library.
 			platformVersion := strings.TrimPrefix(strings.Split(config.Triple(), "-")[2], "macosx")
 			flags = []string{
 				"-flavor", "darwin",
@@ -48,6 +112,7 @@ func makeDarwinLibSystemJob(config *compileopts.Config, tmpdir string) *compileJ
 				"-install_name", "/usr/lib/libSystem.B.dylib",
 				"-o", job.result,
 				objpath,
+				extraobjpath,
 			}
 			if config.Options.PrintCommands != nil {
 				config.Options.PrintCommands("ld.lld", flags...)

main_test.go

@@ -122,6 +122,9 @@ func TestBuild(t *testing.T) {
 		t.Parallel()
 		hostOptions := optionsFromTarget("", sema)
 		runPlatTests(hostOptions, tests, t)
+		if runtime.GOOS == "darwin" {
+			runPlatTests(hostOptions, []string{"darwinsockets.go"}, t)
+		}
 
 		// scheduler.threads needs threadID, which exists only on Linux and Darwin.
 		// scheduler.none does not link on Windows.

testdata/darwinsockets.go

@@ -0,0 +1,34 @@
+package main
+
+import "syscall"
+
+func main() {
+	fd, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_STREAM, 0)
+	check(err)
+	defer syscall.Close(fd)
+	check(syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1))
+	check(syscall.Bind(fd, &syscall.SockaddrInet4{Addr: [4]byte{127, 0, 0, 1}}))
+	check(syscall.Listen(fd, 1))
+	addr, err := syscall.Getsockname(fd)
+	check(err)
+	if addr.(*syscall.SockaddrInet4).Port == 0 {
+		panic("the listener has no port")
+	}
+	client, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_STREAM, 0)
+	check(err)
+	defer syscall.Close(client)
+	check(syscall.Connect(client, addr))
+	peer, _, err := syscall.Accept(fd)
+	check(err)
+	defer syscall.Close(peer)
+	_, err = syscall.Getpeername(peer)
+	check(err)
+	check(syscall.Shutdown(client, syscall.SHUT_RDWR))
+	println("Darwin socket symbols linked and ran")
+}
+
+func check(err error) {
+	if err != nil {
+		panic(err)
+	}
+}

testdata/darwinsockets.txt

@@ -0,0 +1 @@
+Darwin socket symbols linked and ran