+// Maximum offsets for different string table entry encodings.
+static const unsigned Max6DecimalOffset = 999999;
+static const unsigned Max7DecimalOffset = 9999999;
+static const uint64_t MaxBase64Offset = 0xFFFFFFFFFULL; // 64^6, including 0
+
+// Encode a string table entry offset in base 64, padded to 6 chars, and
+// prefixed with a double slash: '//AAAAAA', '//AAAAAB', ...
+// Buffer must be at least 8 bytes large. No terminating null appended.
+static void encodeBase64StringEntry(char *Buffer, uint64_t Value) {
+ assert(Value > Max7DecimalOffset && Value <= MaxBase64Offset &&
+ "Illegal section name encoding for value");
+
+ static const char Alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+ "abcdefghijklmnopqrstuvwxyz"
+ "0123456789+/";
+
+ Buffer[0] = '/';
+ Buffer[1] = '/';
+
+ char *Ptr = Buffer + 7;
+ for (unsigned i = 0; i < 6; ++i) {
+ unsigned Rem = Value % 64;
+ Value /= 64;
+ *(Ptr--) = Alphabet[Rem];
+ }
+}
+
+void WinCOFFObjectWriter::SetSectionName(COFFSection &S) {
+ if (S.Name.size() > COFF::NameSize) {
+ uint64_t StringTableEntry = Strings.getOffset(S.Name);
+
+ if (StringTableEntry <= Max6DecimalOffset) {
+ std::sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry));
+ } else if (StringTableEntry <= Max7DecimalOffset) {
+ // With seven digits, we have to skip the terminating null. Because
+ // sprintf always appends it, we use a larger temporary buffer.
+ char buffer[9] = {};
+ std::sprintf(buffer, "/%d", unsigned(StringTableEntry));
+ std::memcpy(S.Header.Name, buffer, 8);
+ } else if (StringTableEntry <= MaxBase64Offset) {
+ // Starting with 10,000,000, offsets are encoded as base64.
+ encodeBase64StringEntry(S.Header.Name, StringTableEntry);
+ } else {
+ report_fatal_error("COFF string table is greater than 64 GB.");
+ }
+ } else
+ std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size());