lyrics: Remove French prefix which lyrics.ovh embeds into lyrics

[radioactiveman]

https://lyrics.ovh embeds a French prefix for Lyrics of the song {title} by {artist} to all lyrics,
regardless of the lyrics language or user country (verified with proxies).

Examples:

• https://api.lyrics.ovh/v1/R.E.M./Shiny%20Happy%20People
• https://api.lyrics.ovh/v1/R.E.M./At%20My%20Most%20Beautiful

Questions:

• Is it safe to return the char pointer like this or should it be wrapped into a String or StringBuf?
• Is there a way to trim also non-breaking-space characters? g_strchug() does not remove them.
  The 2nd example shows therefore unnecessary newlines below the header.

[jlindgren90]

* Is it safe to return the char pointer like this or should it be wrapped into a String or StringBuf?

No, it's not safe because the char pointer points inside the temporary StringBuf.

* Is there a way to trim also non-breaking-space characters? `g_strchug()` does not remove them.
  The 2nd example shows therefore unnecessary newlines below the header.

g_strchug() handles ASCII only, but GLib has some UTF-8 functions that should work for this. I think this should work:

static String truncate_prefix (const String & lyrics, const char * prefix)
{
    if (! str_has_prefix_nocase (lyrics, prefix))
        return lyrics;

    const char * truncated = strstr (lyrics, "\r\n");
    if (! truncated || ! g_utf8_validate (truncated, -1, NULL))
        return lyrics;

    while ((* truncated) && g_unichar_isspace (g_utf8_get_char (truncated)))
        truncated = g_utf8_next_char (truncated);

    return String (truncated);
}

[radioactiveman]

Works perfectly, thanks John.