[PATCH] Readobj: If NumbersOfSections is 0xffff, it's an COFF import library.

[Rui Ueyama]

Hi rafael,

0xffff does not mean that there are 65535 sections in a COFF file but
indicated that it's a COFF import library. This patch fixes SEGV error
when an import library file is passed to llvm-readobj.

I'll check in a test for this change with
http://llvm-reviews.chandlerc.com/D2165.

http://llvm-reviews.chandlerc.com/D2182

Files:
  include/llvm/Object/COFF.h
  lib/Object/COFFObjectFile.cpp

Index: include/llvm/Object/COFF.h
===================================================================
--- include/llvm/Object/COFF.h
+++ include/llvm/Object/COFF.h
@@ -57,6 +57,8 @@
   support::ulittle32_t NumberOfSymbols;
   support::ulittle16_t SizeOfOptionalHeader;
   support::ulittle16_t Characteristics;
+
+  bool isImportLibrary() const { return NumberOfSections == 0xffff; }
 };
 
 /// The 32-bit PE header that follows the COFF header.
Index: lib/Object/COFFObjectFile.cpp
===================================================================
--- lib/Object/COFFObjectFile.cpp
+++ lib/Object/COFFObjectFile.cpp
@@ -507,9 +507,10 @@
     CurPtr += COFFHeader->SizeOfOptionalHeader;
   }
 
-  if ((ec = getObject(SectionTable, Data, base() + CurPtr,
-                      COFFHeader->NumberOfSections * sizeof(coff_section))))
-    return;
+  if (!COFFHeader->isImportLibrary())
+    if ((ec = getObject(SectionTable, Data, base() + CurPtr,
+                        COFFHeader->NumberOfSections * sizeof(coff_section))))
+      return;
 
   // Initialize the pointer to the symbol table.
   if (COFFHeader->PointerToSymbolTable != 0)
@@ -586,7 +587,9 @@
 
 section_iterator COFFObjectFile::end_sections() const {
   DataRefImpl ret;
-  ret.p = reinterpret_cast<uintptr_t>(SectionTable + COFFHeader->NumberOfSections);
+  int numSections = COFFHeader->isImportLibrary()
+      ? 0 : COFFHeader->NumberOfSections;
+  ret.p = reinterpret_cast<uintptr_t>(SectionTable + numSections);
   return section_iterator(SectionRef(ret, this));
 }
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