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106 lines
2.9 KiB
Rust
106 lines
2.9 KiB
Rust
// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
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use encoding_rs::*;
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use std::{
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borrow::Cow,
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io::{Error, ErrorKind},
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};
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pub const BOM_CHAR: char = '\u{FEFF}';
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/// Attempts to detect the character encoding of the provided bytes.
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///
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/// Supports UTF-8, UTF-16 Little Endian and UTF-16 Big Endian.
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pub fn detect_charset(bytes: &'_ [u8]) -> &'static str {
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const UTF16_LE_BOM: &[u8] = b"\xFF\xFE";
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const UTF16_BE_BOM: &[u8] = b"\xFE\xFF";
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if bytes.starts_with(UTF16_LE_BOM) {
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"utf-16le"
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} else if bytes.starts_with(UTF16_BE_BOM) {
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"utf-16be"
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} else {
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// Assume everything else is utf-8
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"utf-8"
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}
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}
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/// Attempts to convert the provided bytes to a UTF-8 string.
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///
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/// Supports all encodings supported by the encoding_rs crate, which includes
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/// all encodings specified in the WHATWG Encoding Standard, and only those
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/// encodings (see: <https://encoding.spec.whatwg.org/>).
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pub fn convert_to_utf8<'a>(
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bytes: &'a [u8],
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charset: &'_ str,
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) -> Result<Cow<'a, str>, Error> {
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match Encoding::for_label(charset.as_bytes()) {
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Some(encoding) => encoding
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.decode_without_bom_handling_and_without_replacement(bytes)
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.ok_or_else(|| ErrorKind::InvalidData.into()),
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None => Err(Error::new(
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ErrorKind::InvalidInput,
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format!("Unsupported charset: {}", charset),
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)),
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}
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}
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/// Strips the byte order mark from the provided text if it exists.
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pub fn strip_bom(text: &str) -> &str {
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if text.starts_with(BOM_CHAR) {
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&text[BOM_CHAR.len_utf8()..]
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} else {
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text
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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fn test_detection(test_data: &[u8], expected_charset: &str) {
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let detected_charset = detect_charset(test_data);
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assert_eq!(
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expected_charset.to_lowercase(),
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detected_charset.to_lowercase()
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);
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}
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#[test]
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fn test_detection_utf8_no_bom() {
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let test_data = "Hello UTF-8 it is \u{23F0} for Deno!"
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.to_owned()
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.into_bytes();
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test_detection(&test_data, "utf-8");
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}
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#[test]
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fn test_detection_utf16_little_endian() {
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let test_data = b"\xFF\xFEHello UTF-16LE".to_owned().to_vec();
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test_detection(&test_data, "utf-16le");
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}
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#[test]
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fn test_detection_utf16_big_endian() {
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let test_data = b"\xFE\xFFHello UTF-16BE".to_owned().to_vec();
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test_detection(&test_data, "utf-16be");
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}
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#[test]
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fn test_decoding_unsupported_charset() {
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let test_data = Vec::new();
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let result = convert_to_utf8(&test_data, "utf-32le");
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assert!(result.is_err());
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let err = result.expect_err("Err expected");
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assert!(err.kind() == ErrorKind::InvalidInput);
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}
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#[test]
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fn test_decoding_invalid_utf8() {
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let test_data = b"\xFE\xFE\xFF\xFF".to_vec();
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let result = convert_to_utf8(&test_data, "utf-8");
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assert!(result.is_err());
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let err = result.expect_err("Err expected");
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assert!(err.kind() == ErrorKind::InvalidData);
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}
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}
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