From 96b7967f83ec2206a38859d908e64d09b32b1292 Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Tue, 16 Dec 2014 01:43:41 +0000
Subject: [PATCH] Start adding thin archive support.

This is just sufficient for 'ar t' to work.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224307 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Object/Archive.h |   9 ++++-----
 lib/Object/Archive.cpp        |  20 +++++++++++++++++---
 test/Object/Inputs/thin.a     | Bin 0 -> 474 bytes
 test/Object/archive-toc.test  |   8 ++++++++
 4 files changed, 29 insertions(+), 8 deletions(-)
 create mode 100644 test/Object/Inputs/thin.a

diff --git a/include/llvm/Object/Archive.h b/include/llvm/Object/Archive.h
index 7c03dcda172..da6a5419aa0 100644
--- a/include/llvm/Object/Archive.h
+++ b/include/llvm/Object/Archive.h
@@ -84,7 +84,7 @@ public:
       return getHeader()->getAccessMode();
     }
     /// \return the size of the archive member without the header or padding.
-    uint64_t getSize() const { return Data.size() - StartOfFile; }
+    uint64_t getSize() const;
 
     StringRef getBuffer() const {
       return StringRef(Data.data() + StartOfFile, getSize());
@@ -173,9 +173,7 @@ public:
     K_COFF
   };
 
-  Kind kind() const { 
-    return Format;
-  }
+  Kind kind() const { return (Kind)Format; }
 
   child_iterator child_begin(bool SkipInternal = true) const;
   child_iterator child_end() const;
@@ -201,7 +199,8 @@ private:
   child_iterator SymbolTable;
   child_iterator StringTable;
   child_iterator FirstRegular;
-  Kind Format;
+  unsigned Format : 2;
+  unsigned IsThin : 1;
 };
 
 }
diff --git a/lib/Object/Archive.cpp b/lib/Object/Archive.cpp
index d169dbee46e..5aada91ecc0 100644
--- a/lib/Object/Archive.cpp
+++ b/lib/Object/Archive.cpp
@@ -22,6 +22,7 @@ using namespace llvm;
 using namespace object;
 
 static const char *const Magic = "!<arch>\n";
+static const char *const ThinMagic = "!<thin>\n";
 
 void Archive::anchor() { }
 
@@ -86,7 +87,10 @@ Archive::Child::Child(const Archive *Parent, const char *Start)
 
   const ArchiveMemberHeader *Header =
       reinterpret_cast<const ArchiveMemberHeader *>(Start);
-  Data = StringRef(Start, sizeof(ArchiveMemberHeader) + Header->getSize());
+  uint64_t Size = sizeof(ArchiveMemberHeader);
+  if (!Parent->IsThin || Header->getName() == "/" || Header->getName() == "//")
+    Size += Header->getSize();
+  Data = StringRef(Start, Size);
 
   // Setup StartOfFile and PaddingBytes.
   StartOfFile = sizeof(ArchiveMemberHeader);
@@ -100,6 +104,12 @@ Archive::Child::Child(const Archive *Parent, const char *Start)
   }
 }
 
+uint64_t Archive::Child::getSize() const {
+  if (Parent->IsThin)
+    return getHeader()->getSize();
+  return Data.size() - StartOfFile;
+}
+
 Archive::Child Archive::Child::getNext() const {
   size_t SpaceToSkip = Data.size();
   // If it's odd, add 1 to make it even.
@@ -186,9 +196,13 @@ ErrorOr<std::unique_ptr<Archive>> Archive::create(MemoryBufferRef Source) {
 
 Archive::Archive(MemoryBufferRef Source, std::error_code &ec)
     : Binary(Binary::ID_Archive, Source), SymbolTable(child_end()) {
+  StringRef Buffer = Data.getBuffer();
   // Check for sufficient magic.
-  if (Data.getBufferSize() < 8 ||
-      StringRef(Data.getBufferStart(), 8) != Magic) {
+  if (Buffer.startswith(ThinMagic)) {
+    IsThin = true;
+  } else if (Buffer.startswith(Magic)) {
+    IsThin = false;
+  } else {
     ec = object_error::invalid_file_type;
     return;
   }
diff --git a/test/Object/Inputs/thin.a b/test/Object/Inputs/thin.a
new file mode 100644
index 0000000000000000000000000000000000000000..bb9d532a7879c7e11339b21e3bdb77ca1fe4e4ab
GIT binary patch
literal 474
zcmah_OAdlC5Unof6!iiYuoO&;i3=BQIDnfXP}HQBL=6d-@vIKz6Ce>^(l>3VZ{|%`
zyZ7yG_Q2>EE_Xw*MGh!+Y--4qa?!nyfe^AJWbvt&JV#vX^5LIe(IGnKWO9)aHf_}v
z`VmFb7_%{`QW>obgCfgpEY-7;x-eInRBx3QnUeWkD`_qdwN6q7*2cPE0IaXmG-@Z@
zggBw=IGF8Oa87C1`-y>V`-9#5(_+aMsI9+nfEjJz`{;rT<Qk~;$EIhr*0bk@tssUk
DJPBK9

literal 0
HcmV?d00001

diff --git a/test/Object/archive-toc.test b/test/Object/archive-toc.test
index 4195c400064..79a6e0e0ba8 100644
--- a/test/Object/archive-toc.test
+++ b/test/Object/archive-toc.test
@@ -26,3 +26,11 @@ CHECK:      rw-r--r-- 1002/102      8 2004-11-19 03:24:02.000000000 evenlen
 CHECK-NEXT: rw-r--r-- 1002/102      7 2004-11-19 03:24:02.000000000 oddlen
 CHECK-NEXT: rwxr-xr-x 1002/102   1465 2004-11-19 03:24:02.000000000 very_long_bytecode_file_name.bc
 CHECK-NEXT: rw-r--r-- 1002/102   2280 2004-11-19 03:24:02.000000000 IsNAN.o
+
+Test reading a thin archive created by gnu ar
+RUN: env TZ=GMT llvm-ar tv %p/Inputs/thin.a | FileCheck %s --check-prefix=THIN -strict-whitespace
+
+THIN:      rw-r--r-- 1000/1000      8 2014-12-16 00:56:27.000000000 evenlen
+THIN-NEXT: rw-r--r-- 1000/1000      7 2014-12-16 00:56:27.000000000 oddlen
+THIN-NEXT: rwxr-xr-x 1000/1000   1465 2014-12-16 00:56:27.000000000 very_long_bytecode_file_name.bc
+THIN-NEXT: rw-r--r-- 1000/1000   2280 2014-12-16 00:56:27.000000000 IsNAN.o
-- 
2.34.1