MC: Support COFF string tables larger than 10MB
Offsets past the range of single-slash encoding are encoded as base64,
padded to 6 characters, and prefixed with two slashes. This encoding is
undocumented but used by MSVC.
llvm-svn: 201940
diff --git a/llvm/lib/Object/COFFObjectFile.cpp b/llvm/lib/Object/COFFObjectFile.cpp
index ed5494d..415b4cb 100644
--- a/llvm/lib/Object/COFFObjectFile.cpp
+++ b/llvm/lib/Object/COFFObjectFile.cpp
@@ -19,6 +19,7 @@
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include <cctype>
+#include <limits>
using namespace llvm;
using namespace object;
@@ -52,6 +53,40 @@
return object_error::success;
}
+// Decode a string table entry in base 64 (//AAAAAA). Expects \arg Str without
+// prefixed slashes.
+static bool decodeBase64StringEntry(StringRef Str, uint32_t &Result) {
+ assert(Str.size() <= 6 && "String too long, possible overflow.");
+ if (Str.size() > 6)
+ return true;
+
+ uint64_t Value = 0;
+ while (!Str.empty()) {
+ unsigned CharVal;
+ if (Str[0] >= 'A' && Str[0] <= 'Z') // 0..25
+ CharVal = Str[0] - 'A';
+ else if (Str[0] >= 'a' && Str[0] <= 'z') // 26..51
+ CharVal = Str[0] - 'a' + 26;
+ else if (Str[0] >= '0' && Str[0] <= '9') // 52..61
+ CharVal = Str[0] - '0' + 52;
+ else if (Str[0] == '+') // 62
+ CharVal = Str[0] - '+' + 62;
+ else if (Str[0] == '/') // 63
+ CharVal = Str[0] - '/' + 63;
+ else
+ return true;
+
+ Value = (Value * 64) + CharVal;
+ Str = Str.substr(1);
+ }
+
+ if (Value > std::numeric_limits<uint32_t>::max())
+ return true;
+
+ Result = static_cast<uint32_t>(Value);
+ return false;
+}
+
const coff_symbol *COFFObjectFile::toSymb(DataRefImpl Ref) const {
const coff_symbol *Addr = reinterpret_cast<const coff_symbol*>(Ref.p);
@@ -766,8 +801,13 @@
// Check for string table entry. First byte is '/'.
if (Name[0] == '/') {
uint32_t Offset;
- if (Name.substr(1).getAsInteger(10, Offset))
- return object_error::parse_failed;
+ if (Name[1] == '/') {
+ if (decodeBase64StringEntry(Name.substr(2), Offset))
+ return object_error::parse_failed;
+ } else {
+ if (Name.substr(1).getAsInteger(10, Offset))
+ return object_error::parse_failed;
+ }
if (error_code EC = getString(Offset, Name))
return EC;
}