[Object][COFF] Improve section name parsing

[pzheng]

Summary

Inspired by discussions on D127369, we probably can further improve LLVM's COFF
section name parsing. Hopefully, this makes the logic simpler and handles some
edge cases more elegantly.

[rnk]

Thanks, this is a good idea.

llvm/lib/Object/COFFObjectFile.cpp

1159

This can now be getAsInteger, right?

[pzheng]

llvm/lib/Object/COFFObjectFile.cpp

1159

Compared to getAsInteger, consumeInteger is a little more error tolerant and can handle inputs like "/4abcdef". However, I haven't actually seen any input like that in the wild yet, so it's probably fine if we use getAsInteger. Thoughts?

[rnk]

lgtm

llvm/lib/Object/COFFObjectFile.cpp

1159

I think it would be reasonable to report an error for such a section name, so I support that change, but either way, the split code is simpler than what we currently have.

[pzheng]

llvm/lib/Object/COFFObjectFile.cpp

1159

Agreed, will change to getAsInteger.

[pzheng]

Use getAsInteger

llvm/lib/Object/COFFObjectFile.cpp

assert(Offset % getSymbolTableEntrySize() == 0 &&
          "Symbol did not point to the beginning of a symbol");
   size_t Index = Offset / getSymbolTableEntrySize();
   assert(Index < getNumberOfSymbols());
   return Index;
 }
 
 Expected<StringRef>
 COFFObjectFile::getSectionName(const coff_section *Sec) const {
-  StringRef Name;
-  if (Sec->Name[COFF::NameSize - 1] == 0)
-    // Null terminated, let ::strlen figure out the length.
-    Name = Sec->Name;
-  else
-    // Not null terminated, use all 8 bytes.
-    Name = StringRef(Sec->Name, COFF::NameSize);
+  StringRef Name = StringRef(Sec->Name, COFF::NameSize).split('\0').first;
 
   // Check for string table entry. First byte is '/'.
   if (Name.startswith("/")) {
     uint32_t Offset;
     if (Name.startswith("//")) {
       if (decodeBase64StringEntry(Name.substr(2), Offset))
         return createStringError(object_error::parse_failed,
                                  "invalid section name");
     } else {
-      if (Name.substr(1).consumeInteger(10, Offset))
+      if (Name.substr(1).getAsInteger(10, Offset))
         return createStringError(object_error::parse_failed,
                                  "invalid section name");
     }
     return getString(Offset);
   }
 
   return Name;
 }