Incremental PR analysis: Implement the hashing

[pavel-mikula-sonarsource]

Fixes #1369

It works with this Java counterpart:

  @Test
  public void fixme() throws Throwable {
    assertThat(contentHash("EmptyWithBom.cs")).isEqualTo("f1945cd6c19e56b3c1c78943ef5ec18116907a4ca1efc40a57d48ab1db7adfc5");
    assertThat(contentHash("EmptyNoBom.cs")).isEqualTo("e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855");
    assertThat(contentHash("CodeWithBom.cs")).isEqualTo("b98aaf2ce5a3f9cdf8ab785563951f2309d577baa6351098f78908300fdc610a");
    assertThat(contentHash("CodeNoBom.cs")).isEqualTo("8c7535a8e3679bf8cc241b5749cef5fc38243401556f2b7869495c7b48ee4980");
    assertThat(contentHash("Utf8.cs")).isEqualTo("13aa54e315a806270810f3a91501f980a095a2ef1bcc53167d4c750a1b78684d");
    assertThat(contentHash("Utf16.cs")).isEqualTo("a9b3c4402770855d090ba4b49adeb5ad601cb3bbd6de18495302f45f242ef932");
    assertThat(contentHash("Ansi.cs")).isEqualTo("b965073262109da4f106cd90a5eeea025e2441c244af272537afa2cfb03c3ab8");
  }

  private String contentHash(String fileName) throws Throwable {
    MessageDigest sha256 = MessageDigest.getInstance("SHA-256");
    byte[] content = Files.readAllBytes(Path.of("d:\\_Temp\\HashFiles\\", fileName));
    byte[] hash = sha256.digest(content);
    return bytesToHex(hash);
  }

  private static final byte[] HEX_ARRAY = "0123456789abcdef".getBytes(StandardCharsets.US_ASCII);

  private static String bytesToHex(byte[] bytes) {
    byte[] hexChars = new byte[bytes.length * 2];
    for (int i = 0; i < bytes.length; i++) {
      int v = bytes[i] & 0xFF; // FIXME: WTF?
      hexChars[i * 2] = HEX_ARRAY[v >>> 4];
      hexChars[i * 2 + 1] = HEX_ARRAY[v & 0x0F];
    }
    return new String(hexChars, StandardCharsets.UTF_8);
  }

The biggest pain is bytesToHex part 🤦‍♂️ 🤦‍♂️ 🤦‍♂️

[costin-zaharia-sonarsource]

I think it would be better to use the async operations. Since here we target net46, we can use the FileStream class (using var stream = File.Open(path, FileMode.Open);).

[pavel-mikula-sonarsource]

We don't have any other work to do meanwhile, so async will not help.

[sonarqubecloud]

SonarCloud Quality Gate failed.   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
2 Code Smells

100.0% Coverage
0.0% Duplication

[costin-zaharia-sonarsource]

LGTM!