os: make hostname and loginname functions return Result (#17414)

Author: paul-elesin

vlib/os/os_nix.c.v

@@ -235,7 +235,7 @@ pub fn uname() Uname {
 	return u
 }
 
-pub fn hostname() string {
+pub fn hostname() !string {
 	mut hstnme := ''
 	size := 256
 	mut buf := unsafe { &char(malloc_noscan(size)) }
@@ -244,15 +244,15 @@ pub fn hostname() string {
 		unsafe { free(buf) }
 		return hstnme
 	}
-	return ''
+	return error(posix_get_error_msg(C.errno))
 }
 
-pub fn loginname() string {
+pub fn loginname() !string {
 	x := C.getlogin()
 	if !isnil(x) {
 		return unsafe { cstring_to_vstring(x) }
 	}
-	return ''
+	return error(posix_get_error_msg(C.errno))
 }
 
 fn init_os_args(argc int, argv &&u8) []string {

vlib/os/os_test.v

@@ -169,6 +169,7 @@ fn test_write_and_read_string_to_file() {
 
 // test_write_and_read_bytes checks for regressions made in the functions
 // read_bytes, read_bytes_at and write_bytes.
+
 fn test_write_and_read_bytes() {
 	file_name := './byte_reader_writer.tst'
 	payload := [u8(`I`), `D`, `D`, `Q`, `D`]
@@ -457,6 +458,7 @@ fn test_realpath_absolutizes_existing_relative_paths() {
 }
 
 // TODO: think much more about whether this is desirable:
+
 fn test_realpath_does_not_absolutize_non_existing_relative_paths() {
 	relative_path := os.join_path('one', 'nonexisting_folder', '..', 'something')
 	$if !windows {
@@ -554,6 +556,7 @@ fn test_make_hardlink_check_is_link_and_remove_hardlink_with_file() {
 // println(cpid)
 // }
 // }
+
 fn test_symlink() {
 	os.mkdir('symlink') or { panic(err) }
 	os.symlink('symlink', 'symlink2') or { panic(err) }
@@ -805,9 +808,15 @@ fn test_truncate() {
 }
 
 fn test_hostname() {
-	assert os.hostname().len > 2
+	hostname := os.hostname() or { '' }
+	assert hostname.len > 2
 }
 
+// fn test_loginname() {
+// loginname := os.loginname() or { '' }
+// assert loginname.len > 2
+//}
+
 fn test_glob() {
 	os.mkdir('test_dir') or { panic(err) }
 	for i in 0 .. 4 {

vlib/os/os_windows.c.v

@@ -460,7 +460,7 @@ pub fn add_vectored_exception_handler(first bool, handler VectoredExceptionHandl
 // See: [NT Version Info](https://en.wikipedia.org/wiki/Windows_NT) @@ <https://archive.is/GnnvF>
 // and: [NT Version Info (detailed)](https://en.wikipedia.org/wiki/Comparison_of_Microsoft_Windows_versions#NT_Kernel-based_2)
 pub fn uname() Uname {
-	nodename := hostname()
+	nodename := hostname() or { '' }
 	// ToDO: environment variables have low reliability; check for another quick way
 	machine := getenv('PROCESSOR_ARCHITECTURE') // * note: 'AMD64' == 'x86_64' (not standardized, but 'x86_64' use is more common; but, python == 'AMD64')
 	version_info := execute('cmd /d/c ver').output
@@ -474,22 +474,22 @@ pub fn uname() Uname {
 	}
 }
 
-pub fn hostname() string {
+pub fn hostname() !string {
 	hostname := [255]u16{}
 	size := u32(255)
 	res := C.GetComputerNameW(&hostname[0], &size)
 	if !res {
-		return get_error_msg(int(C.GetLastError()))
+		return error(get_error_msg(int(C.GetLastError())))
 	}
 	return unsafe { string_from_wide(&hostname[0]) }
 }
 
-pub fn loginname() string {
+pub fn loginname() !string {
 	loginname := [255]u16{}
 	size := u32(255)
 	res := C.GetUserNameW(&loginname[0], &size)
 	if !res {
-		return get_error_msg(int(C.GetLastError()))
+		return error(get_error_msg(int(C.GetLastError())))
 	}
 	return unsafe { string_from_wide(&loginname[0]) }
 }