4 files changed, 39 insertions, 7 deletions
diff --git a/llvm/include/llvm/Object/Archive.h b/llvm/include/llvm/Object/Archive.h
index e461564ace8..597f0d48c11 100644
--- a/llvm/include/llvm/Object/Archive.h
+++ b/llvm/include/llvm/Object/Archive.h
@@ -94,9 +94,7 @@ public:
     /// \return the size in the archive header for this member.
     uint64_t getRawSize() const;
 
-    StringRef getBuffer() const {
-      return StringRef(Data.data() + StartOfFile, getSize());
-    }
+    ErrorOr<StringRef> getBuffer() const;
     uint64_t getChildOffset() const;
 
     ErrorOr<MemoryBufferRef> getMemoryBufferRef() const;
@@ -208,7 +206,11 @@ public:
 
   bool hasSymbolTable() const;
   child_iterator getSymbolTableChild() const { return SymbolTable; }
-  StringRef getSymbolTable() const { return SymbolTable->getBuffer(); }
+  StringRef getSymbolTable() const {
+    // We know that the symbol table is not an external file,
+    // so we just assert there is no error.
+    return *SymbolTable->getBuffer();
+  }
   uint32_t getNumberOfSymbols() const;
 
 private:
@@ -217,6 +219,7 @@ private:
   child_iterator FirstRegular;
   unsigned Format : 2;
   unsigned IsThin : 1;
+  mutable std::vector<std::unique_ptr<MemoryBuffer>> ThinBuffers;
 };
 
 }
diff --git a/llvm/lib/Object/Archive.cpp b/llvm/lib/Object/Archive.cpp
index c29e63941f2..d4821196a6c 100644
--- a/llvm/lib/Object/Archive.cpp
+++ b/llvm/lib/Object/Archive.cpp
@@ -17,6 +17,7 @@
 #include "llvm/ADT/Twine.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Path.h"
 
 using namespace llvm;
 using namespace object;
@@ -115,6 +116,23 @@ uint64_t Archive::Child::getRawSize() const {
   return getHeader()->getSize();
 }
 
+ErrorOr<StringRef> Archive::Child::getBuffer() const {
+  if (!Parent->IsThin)
+    return StringRef(Data.data() + StartOfFile, getSize());
+  ErrorOr<StringRef> Name = getName();
+  if (std::error_code EC = Name.getError())
+    return EC;
+  SmallString<128> FullName =
+      Parent->getMemoryBufferRef().getBufferIdentifier();
+  sys::path::remove_filename(FullName);
+  sys::path::append(FullName, *Name);
+  ErrorOr<std::unique_ptr<MemoryBuffer>> Buf = MemoryBuffer::getFile(FullName);
+  if (std::error_code EC = Buf.getError())
+    return EC;
+  Parent->ThinBuffers.push_back(std::move(*Buf));
+  return Parent->ThinBuffers.back()->getBuffer();
+}
+
 Archive::Child Archive::Child::getNext() const {
   size_t SpaceToSkip = Data.size();
   // If it's odd, add 1 to make it even.
@@ -186,7 +204,10 @@ ErrorOr<MemoryBufferRef> Archive::Child::getMemoryBufferRef() const {
   if (std::error_code EC = NameOrErr.getError())
     return EC;
   StringRef Name = NameOrErr.get();
-  return MemoryBufferRef(getBuffer(), Name);
+  ErrorOr<StringRef> Buf = getBuffer();
+  if (std::error_code EC = Buf.getError())
+    return EC;
+  return MemoryBufferRef(*Buf, Name);
 }
 
 ErrorOr<std::unique_ptr<Binary>>
diff --git a/llvm/test/Object/archive-extract.test b/llvm/test/Object/archive-extract.test
index c1ddcf71725..a77adf2cabb 100644
--- a/llvm/test/Object/archive-extract.test
+++ b/llvm/test/Object/archive-extract.test
@@ -48,3 +48,9 @@ NOTFOUND: foo.o was not found
 
 RUN: not llvm-ar x %p/Inputs/thin.a foo.o 2>&1 | FileCheck %s --check-prefix=THINEXTRACT
 THINEXTRACT: extracting from a thin archive is not supported
+
+RUN: llvm-ar p %p/Inputs/thin.a evenlen | FileCheck %s --check-prefix=EVENLEN
+EVENLEN: evenlen
+
+RUN: not llvm-ar p %p/Inputs/thin-path.a t/test2.o | FileCheck %s --check-prefix=MISSING
+MISSING: No such file or directory.
diff --git a/llvm/tools/llvm-ar/llvm-ar.cpp b/llvm/tools/llvm-ar/llvm-ar.cpp
index c87606d7826..2c9668c63b8 100644
--- a/llvm/tools/llvm-ar/llvm-ar.cpp
+++ b/llvm/tools/llvm-ar/llvm-ar.cpp
@@ -299,7 +299,9 @@ static void doPrint(StringRef Name, const object::Archive::Child &C) {
   if (Verbose)
     outs() << "Printing " << Name << "\n";
 
-  StringRef Data = C.getBuffer();
+  ErrorOr<StringRef> DataOrErr = C.getBuffer();
+  failIfError(DataOrErr.getError());
+  StringRef Data = *DataOrErr;
   outs().write(Data.data(), Data.size());
 }
 
@@ -355,7 +357,7 @@ static void doExtract(StringRef Name, const object::Archive::Child &C) {
     raw_fd_ostream file(FD, false);
 
     // Get the data and its length
-    StringRef Data = C.getBuffer();
+    StringRef Data = *C.getBuffer();
 
     // Write the data.
     file.write(Data.data(), Data.size());