encoding.iconv: Fix iconv type cstrict, add LOCAL encoding

vlib/encoding/iconv/iconv.v

@@ -16,21 +16,35 @@ fn reverse_u32(src u32) u32 {
 // vstring_to_encoding convert V string `str` to `tocode` encoding string
 // tips: use `iconv --list` check for supported encodings
 pub fn vstring_to_encoding(str string, tocode string) ![]u8 {
-	encoding_name := tocode.to_upper()
+	mut encoding_name := tocode.to_upper()
 	if encoding_name in ['UTF16', 'UTF32', 'UTF-16', 'UTF-32']! {
 		return error('please use UTF16-LE/UTF-16BE/UTF-32LE/UTF-32BE instead')
 	}
-	return conv(tocode, 'UTF-8', str.str, str.len)
+	if encoding_name == 'LOCAL' {
+		$if windows {
+			encoding_name = 'ANSI'
+		} $else {
+			encoding_name = 'UTF-8'
+		}
+	}
+	return conv(encoding_name, 'UTF-8', str.str, str.len)
 }
 
 // encoding_to_vstring converts the given `bytes` using `fromcode` encoding, to a V string (encoded with UTF-8)
 // tips: use `iconv --list` check for supported encodings
 pub fn encoding_to_vstring(bytes []u8, fromcode string) !string {
-	encoding_name := fromcode.to_upper()
+	mut encoding_name := fromcode.to_upper()
 	if encoding_name in ['UTF16', 'UTF32', 'UTF-16', 'UTF-32']! {
 		return error('please use UTF16-LE/UTF-16BE/UTF-32LE/UTF-32BE instead')
 	}
-	mut dst := conv('UTF-8', fromcode, bytes.data, bytes.len)!
+	if encoding_name == 'LOCAL' {
+		$if windows {
+			encoding_name = 'ANSI'
+		} $else {
+			encoding_name = 'UTF-8'
+		}
+	}
+	mut dst := conv('UTF-8', encoding_name, bytes.data, bytes.len)!
 	dst << 0 // add a tail zero, to build a vstring
 	return unsafe { cstring_to_vstring(dst.data) }
 }
@@ -43,7 +57,15 @@ pub fn encoding_to_vstring(bytes []u8, fromcode string) !string {
 // for utf32be, it will prepend 0x0000FEFF to the `src`
 pub fn create_utf_string_with_bom(src []u8, utf_type string) []u8 {
 	mut clone := src.clone()
-	match utf_type.to_upper() {
+	mut encoding_name := utf_type.to_upper()
+	if encoding_name == 'LOCAL' {
+		$if windows {
+			encoding_name = 'ANSI'
+		} $else {
+			encoding_name = 'UTF-8'
+		}
+	}
+	match encoding_name {
 		'UTF8', 'UTF-8' {
 			clone.prepend([u8(0xEF), 0xBB, 0xBF])
 		}
@@ -73,7 +95,15 @@ pub fn create_utf_string_with_bom(src []u8, utf_type string) []u8 {
 @[direct_array_access]
 pub fn remove_utf_string_with_bom(src []u8, utf_type string) []u8 {
 	mut clone := src.clone()
-	match utf_type.to_upper() {
+	mut encoding_name := utf_type.to_upper()
+	if encoding_name == 'LOCAL' {
+		$if windows {
+			encoding_name = 'ANSI'
+		} $else {
+			encoding_name = 'UTF-8'
+		}
+	}
+	match encoding_name {
 		'UTF8', 'UTF-8' {
 			if clone.len > 3 {
 				if clone[0] == u8(0xEF) && clone[1] == u8(0xBB) && clone[2] == u8(0xBF) {
@@ -119,10 +149,6 @@ pub fn remove_utf_string_with_bom(src []u8, utf_type string) []u8 {
 // write_file_encoding write_file convert `text` into `encoding` and writes to a file with the given `path`. If `path` already exists, it will be overwritten.
 // For `encoding` in UTF8/UTF16/UTF32, if `bom` is true, then a BOM header will write to the file.
 pub fn write_file_encoding(path string, text string, encoding string, bom bool) ! {
-	encoding_name := encoding.to_upper()
-	if encoding_name in ['UTF16', 'UTF32', 'UTF-16', 'UTF-32']! {
-		return error('please use UTF-16LE/UTF-16BE/UTF-32LE/UTF-32BE instead')
-	}
 	encoding_bytes := vstring_to_encoding(text, encoding)!
 	if bom && encoding.to_upper().starts_with('UTF') {
 		encoding_bom_bytes := create_utf_string_with_bom(encoding_bytes, encoding)
@@ -134,10 +160,6 @@ pub fn write_file_encoding(path string, text string, encoding string, bom bool)
 
 // read_file_encoding reads the file in `path` with `encoding` and returns the contents
 pub fn read_file_encoding(path string, encoding string) !string {
-	encoding_name := encoding.to_upper()
-	if encoding_name in ['UTF16', 'UTF32', 'UTF-16', 'UTF-32']! {
-		return error('please use UTF-16LE/UTF-16BE/UTF-32LE/UTF-32BE instead')
-	}
 	encoding_bytes := os.read_file_array[u8](path)
 	encoding_without_bom_bytes := remove_utf_string_with_bom(encoding_bytes, encoding)
 	return encoding_to_vstring(encoding_without_bom_bytes, encoding)!

vlib/encoding/iconv/iconv_nix.c.v

@@ -5,9 +5,9 @@ module iconv
 #include <iconv.h>
 #flag darwin -liconv
 
-fn C.iconv_open(tocode &u8, fromcode &u8) voidptr
+fn C.iconv_open(tocode charptr, fromcode charptr) voidptr
 fn C.iconv_close(cd voidptr) int
-fn C.iconv(cd voidptr, inbuf &&u8, inbytesleft &usize, outbuf &&u8, outbytesleft &usize) usize
+fn C.iconv(cd voidptr, inbuf &charptr, inbytesleft &usize, outbuf &charptr, outbytesleft &usize) usize
 
 // conv convert `fromcode` encoding string to `tocode` encoding string
 @[direct_array_access]
@@ -35,16 +35,16 @@ fn conv(tocode string, fromcode string, src &u8, src_len int) ![]u8 {
 		else {}
 	}
 
-	mut cd := C.iconv_open(dst_encoding.str, src_encoding.str)
+	mut cd := C.iconv_open(charptr(dst_encoding.str), charptr(src_encoding.str))
 	if isize(cd) == -1 {
 		return error('platform can\'t convert from ${src_encoding} to ${dst_encoding}')
 	}
 	defer { C.iconv_close(cd) }
 
 	mut dst := []u8{len: (src_len + 1) * 4} // this should be enough to hold the dst encoding string
 
-	mut src_ptr := &u8(src)
-	mut dst_ptr := &u8(dst.data)
+	mut src_ptr := charptr(src)
+	mut dst_ptr := charptr(dst.data)
 	mut src_left := usize(src_len)
 	mut dst_left := usize(dst.len)
 	res := C.iconv(cd, &src_ptr, &src_left, &dst_ptr, &dst_left)

vlib/encoding/iconv/iconv_test.v

@@ -20,6 +20,11 @@ fn test_vstring_to_encoding() {
 	abc_utf32be := iconv.vstring_to_encoding('abc', 'UTF-32BE')!
 	assert abc_utf32be == [u8(0), 0, 0, 97, 0, 0, 0, 98, 0, 0, 0, 99]
 
+	abc_local := iconv.vstring_to_encoding('abc', 'LOCAL')!
+	// Windows LOCAL: ANSI encoding
+	// Linux LOCAL: UTF-8 encoding
+	assert abc_local == [u8(97), 98, 99]
+
 	if abc_not_exist := iconv.vstring_to_encoding('abc', 'encoding_not_exist') {
 		assert false, 'encoding_not_exist'
 	}
@@ -53,6 +58,11 @@ fn test_encoding_to_vstring() {
 		'UTF-32BE')!
 	assert abc_utf32be == 'abc'
 
+	abc_local := iconv.encoding_to_vstring([u8(97), 98, 99], 'LOCAL')!
+	// Windows LOCAL: ANSI encoding
+	// Linux LOCAL: UTF-8 encoding
+	assert abc_local == 'abc'
+
 	if abc_not_exist := iconv.encoding_to_vstring([u8(97), 98, 99], 'encoding_not_exist') {
 		assert false, 'encoding_not_exist'
 	}