delme: syscall_unix workaround wip

src/syscall/syscall_libc.go

@@ -203,6 +203,15 @@ func Execve(pathname string, argv []string, envv []string) (err error) {
 	return
 }
 
+func Truncate(path string, length int64) (err error) {
+	data := cstring(path)
+	fail := int(libc_truncate(&data[0], length))
+	if fail < 0 {
+		err = getErrno()
+	}
+	return
+}
+
 func Faccessat(dirfd int, path string, mode uint32, flags int) (err error)
 
 func Kill(pid int, sig Signal) (err error) {
@@ -451,3 +460,8 @@ func libc_fork() int32
 //
 //export execve
 func libc_execve(filename *byte, argv **byte, envp **byte) int
+
+// int truncate(const char *path, off_t length);
+//
+//export truncate
+func libc_truncate(path *byte, length int64) int32

src/syscall/syscall_unix.go

@@ -1,9 +1,10 @@
+//go: build !darwin && !nintendoswitch && !wasip1 && !wasip2
+
 package syscall
 
-func Exec(argv0 string, argv []string, envv []string) (err error)
+import "errors"
 
 // The two SockaddrInet* structs have been copied from the Go source tree.
-
 type SockaddrInet4 struct {
 	Port int
 	Addr [4]byte
@@ -16,3 +17,54 @@ type SockaddrInet6 struct {
 	Addr   [16]byte
 	raw    RawSockaddrInet6
 }
+
+func Fork() (err error) {
+	fail := int(libc_fork())
+	if fail < 0 {
+		// TODO: parse the syscall return codes
+		return errors.New("fork failed")
+	}
+	return
+}
+
+// the golang standard library does not expose interfaces for execve and fork, so we define them here the same way via the libc wrapper
+func Execve(pathname string, argv []string, envv []string) (err error) {
+	argv0 := cstring(pathname)
+
+	// transform argv and envv into the format expected by execve
+	argv1 := make([]*byte, len(argv)+1)
+	for i, arg := range argv {
+		argv1[i] = &cstring(arg)[0]
+	}
+	argv1[len(argv)] = nil
+
+	env1 := make([]*byte, len(envv)+1)
+	for i, env := range envv {
+		env1[i] = &cstring(env)[0]
+	}
+	env1[len(envv)] = nil
+
+	fail := int(libc_execve(&argv0[0], &argv1[0], &env1[0]))
+	if fail < 0 {
+		// TODO: parse the syscall return codes
+		return errors.New("fork failed")
+	}
+	return
+}
+
+func cstring(s string) []byte {
+	data := make([]byte, len(s)+1)
+	copy(data, s)
+	// final byte should be zero from the initial allocation
+	return data
+}
+
+// pid_t fork(void);
+//
+//export fork
+func libc_fork() int32
+
+// int execve(const char *filename, char *const argv[], char *const envp[]);
+//
+//export execve
+func libc_execve(filename *byte, argv **byte, envp **byte) int