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When escaping characters for XML, don't escape valid surrogate pairs on platforms where wchar_t (and, by extension, wxUChar) is 2 bytes. Also, ignore invalid surrogates and the noncharacters U+FFFE and U+FFFF.

This commit is contained in:
Yarn366 2017-06-08 18:33:27 -04:00 committed by Steve Daulton
parent 25a65c34e7
commit f667b9f269
1 changed files with 31 additions and 3 deletions
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34
src/xml/XMLWriter.cpp
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@ -50,6 +50,16 @@ static int charXMLCompatiblity[] =
/* 0x1C */ 0, 0, 0, 0,
};
// These are used by XMLEsc to handle surrogate pairs and filter invalid characters outside the ASCII range.
#define MIN_HIGH_SURROGATE static_cast<wxUChar>(0xD800)
#define MAX_HIGH_SURROGATE static_cast<wxUChar>(0xDCFF)
#define MIN_LOW_SURROGATE static_cast<wxUChar>(0xDC00)
#define MAX_LOW_SURROGATE static_cast<wxUChar>(0xDFFF)
// Unicode defines other noncharacters, but only these two are invalid in XML.
#define NONCHARACTER_FFFE static_cast<wxUChar>(0xFFFE)
#define NONCHARACTER_FFFF static_cast<wxUChar>(0xFFFF)
///
/// XMLWriter base class
@ -243,13 +253,31 @@ wxString XMLWriter::XMLEsc(const wxString & s)
break;
default:
if (!wxIsprint(c)) {
if (sizeof(c) == 2 && c >= MIN_HIGH_SURROGATE && c <= MAX_HIGH_SURROGATE && i < len - 1) {
// If wxUChar is 2 bytes, then supplementary characters (those greater than U+FFFF) are represented
// with a high surrogate (U+D800..U+DBFF) followed by a low surrogate (U+DC00..U+DFFF).
// Handle those here.
wxUChar c2 = s.GetChar(++i);
if (c2 >= MIN_LOW_SURROGATE && c2 <= MAX_LOW_SURROGATE) {
// Surrogate pair found; simply add it to the output string.
result += c;
result += c2;
}
else {
// That high surrogate isn't paired, so ignore it.
i--;
}
}
else if (!wxIsprint(c)) {
//ignore several characters such ase eot (0x04) and stx (0x02) because it makes expat parser bail
//see xmltok.c in expat checkCharRefNumber() to see how expat bails on these chars.
//also see wxWidgets-2.8.12/src/expat/lib/asciitab.h to see which characters are nonxml compatible
//post decode (we can still encode '&' and '<' with this table, but it prevents us from encoding eot)
//everything is compatible past ascii 0x20, so we don't check higher than this.
if(c> 0x1F || charXMLCompatiblity[c]!=0)
//everything is compatible past ascii 0x20 except for surrogates and the noncharacters U+FFFE and U+FFFF,
//so we don't check the compatibility table higher than this.
if((c> 0x1F || charXMLCompatiblity[c]!=0) &&
(c < MIN_HIGH_SURROGATE || c > MAX_LOW_SURROGATE) &&
c != NONCHARACTER_FFFE && c != NONCHARACTER_FFFF)
result += wxString::Format(wxT("&#x%04x;"), c);
}
else {