From f0c617264aa1685bdf199d37babc1b223170d22e Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Fri, 12 Jul 2013 13:32:28 +0000
Subject: [PATCH] Don't reject an empty archive.

llvm-svn: 186159
---
 llvm/lib/Object/Archive.cpp                  | 10 ++++++----
 llvm/test/Object/Inputs/archive-test.a-empty |  1 +
 llvm/test/Object/nm-archive.test             |  3 +++
 3 files changed, 10 insertions(+), 4 deletions(-)
 create mode 100644 llvm/test/Object/Inputs/archive-test.a-empty

diff --git a/llvm/lib/Object/Archive.cpp b/llvm/lib/Object/Archive.cpp
index 60c6d21f4823..7579a9ac98dc 100644
--- a/llvm/lib/Object/Archive.cpp
+++ b/llvm/lib/Object/Archive.cpp
@@ -212,9 +212,9 @@ error_code Archive::Child::getAsBinary(OwningPtr<Binary> &Result) const {
 Archive::Archive(MemoryBuffer *source, error_code &ec)
   : Binary(Binary::ID_Archive, source), SymbolTable(end_children()) {
   // Check for sufficient magic.
-  if (!source || source->getBufferSize()
-                 < (8 + sizeof(ArchiveMemberHeader)) // Smallest archive.
-              || StringRef(source->getBufferStart(), 8) != Magic) {
+  assert(source);
+  if (source->getBufferSize() < 8 ||
+      StringRef(source->getBufferStart(), 8) != Magic) {
     ec = object_error::invalid_file_type;
     return;
   }
@@ -224,7 +224,7 @@ Archive::Archive(MemoryBuffer *source, error_code &ec)
   child_iterator e = end_children();
 
   if (i == e) {
-    ec = object_error::parse_failed;
+    ec = object_error::success;
     return;
   }
 
@@ -314,6 +314,8 @@ Archive::Archive(MemoryBuffer *source, error_code &ec)
 }
 
 Archive::child_iterator Archive::begin_children(bool skip_internal) const {
+  if (Data->getBufferSize() == 8) // empty archive.
+    return end_children();
   const char *Loc = Data->getBufferStart() + strlen(Magic);
   Child c(this, Loc);
   // Skip internals at the beginning of an archive.
diff --git a/llvm/test/Object/Inputs/archive-test.a-empty b/llvm/test/Object/Inputs/archive-test.a-empty
new file mode 100644
index 000000000000..8b277f0dd5dc
--- /dev/null
+++ b/llvm/test/Object/Inputs/archive-test.a-empty
@@ -0,0 +1 @@
+!<arch>
diff --git a/llvm/test/Object/nm-archive.test b/llvm/test/Object/nm-archive.test
index 99efc1bec67d..0d43cc701550 100644
--- a/llvm/test/Object/nm-archive.test
+++ b/llvm/test/Object/nm-archive.test
@@ -30,3 +30,6 @@ RUN: llvm-nm %p/Inputs/archive-test.a-gnu-minimal
 
 And don't crash when asked to print a non existing symtab.
 RUN: llvm-nm -s %p/Inputs/archive-test.a-gnu-minimal
+
+Don't reject an empty archive.
+RUN: llvm-nm %p/Inputs/archive-test.a-empty
-- 
2.34.1