[Archive] Don't throw away errors for malformed archive members

When adding an archive member with a problem, e.g. a new bitcode with an
old archiver, containing an unsupported attribute, or an ELF file with a
malformed symbol table, the archiver would throw away the error and
simply add the member to the archive without any symbol entries. This
meant that the resultant archive could be silently unusable when not
using --whole-archive, and result in unexpected undefined symbols.

This change fixes this issue by addressing two FIXMEs and only throwing
away not-an-object errors. However, this meant that some LLD tests which
didn't need symbol tables and were using invalid members deliberately to
test the linker's malformed input handling no longer worked, so this
patch also stops the archiver from looking for symbols in an object if
it doesn't require a symbol table, and updates the tests accordingly.

Differential Revision: https://reviews.llvm.org/D88288

Reviewed by: grimar, rupprecht, MaskRay

1 files changed, 23 insertions, 19 deletions

diff --git a/llvm/lib/Object/ArchiveWriter.cpp b/llvm/lib/Object/ArchiveWriter.cpp
index ca8ffa7..08f1b85 100644
--- a/llvm/lib/Object/ArchiveWriter.cpp
+++ b/llvm/lib/Object/ArchiveWriter.cpp
@@ -359,22 +359,21 @@ getSymbols(MemoryBufferRef Buf, raw_ostream &SymNames, bool &HasObject) {
   // reference to it, thus SymbolicFile should be destroyed first.
   LLVMContext Context;
   std::unique_ptr<object::SymbolicFile> Obj;
-  if (identify_magic(Buf.getBuffer()) == file_magic::bitcode) {
+
+  const file_magic Type = identify_magic(Buf.getBuffer());
+  // Treat unsupported file types as having no symbols.
+  if (!object::SymbolicFile::isSymbolicFile(Type, &Context))
+    return Ret;
+  if (Type == file_magic::bitcode) {
     auto ObjOrErr = object::SymbolicFile::createSymbolicFile(
         Buf, file_magic::bitcode, &Context);
-    if (!ObjOrErr) {
-      // FIXME: check only for "not an object file" errors.
-      consumeError(ObjOrErr.takeError());
-      return Ret;
-    }
+    if (!ObjOrErr)
+      return ObjOrErr.takeError();
     Obj = std::move(*ObjOrErr);
   } else {
     auto ObjOrErr = object::SymbolicFile::createSymbolicFile(Buf);
-    if (!ObjOrErr) {
-      // FIXME: check only for "not an object file" errors.
-      consumeError(ObjOrErr.takeError());
-      return Ret;
-    }
+    if (!ObjOrErr)
+      return ObjOrErr.takeError();
     Obj = std::move(*ObjOrErr);
   }
 
@@ -393,7 +392,7 @@ getSymbols(MemoryBufferRef Buf, raw_ostream &SymNames, bool &HasObject) {
 static Expected<std::vector<MemberData>>
 computeMemberData(raw_ostream &StringTable, raw_ostream &SymNames,
                   object::Archive::Kind Kind, bool Thin, bool Deterministic,
-                  ArrayRef<NewArchiveMember> NewMembers) {
+                  bool NeedSymbols, ArrayRef<NewArchiveMember> NewMembers) {
   static char PaddingData[8] = {'\n', '\n', '\n', '\n', '\n', '\n', '\n', '\n'};
 
   // This ignores the symbol table, but we only need the value mod 8 and the
@@ -494,13 +493,17 @@ computeMemberData(raw_ostream &StringTable, raw_ostream &SymNames,
                       ModTime, Size);
     Out.flush();
 
-    Expected<std::vector<unsigned>> Symbols =
-        getSymbols(Buf, SymNames, HasObject);
-    if (auto E = Symbols.takeError())
-      return std::move(E);
+    std::vector<unsigned> Symbols;
+    if (NeedSymbols) {
+      Expected<std::vector<unsigned>> SymbolsOrErr =
+          getSymbols(Buf, SymNames, HasObject);
+      if (auto E = SymbolsOrErr.takeError())
+        return std::move(E);
+      Symbols = std::move(*SymbolsOrErr);
+    }
 
     Pos += Header.size() + Data.size() + Padding.size();
-    Ret.push_back({std::move(*Symbols), std::move(Header), Data, Padding});
+    Ret.push_back({std::move(Symbols), std::move(Header), Data, Padding});
   }
   // If there are no symbols, emit an empty symbol table, to satisfy Solaris
   // tools, older versions of which expect a symbol table in a non-empty
@@ -564,8 +567,9 @@ static Error writeArchiveToStream(raw_ostream &Out,
   SmallString<0> StringTableBuf;
   raw_svector_ostream StringTable(StringTableBuf);
 
-  Expected<std::vector<MemberData>> DataOrErr = computeMemberData(
-      StringTable, SymNames, Kind, Thin, Deterministic, NewMembers);
+  Expected<std::vector<MemberData>> DataOrErr =
+      computeMemberData(StringTable, SymNames, Kind, Thin, Deterministic,
+                        WriteSymtab, NewMembers);
   if (Error E = DataOrErr.takeError())
     return E;
   std::vector<MemberData> &Data = *DataOrErr;