From 240fa2a2e33ddeba7b13f051157b05889ffa6e19 Mon Sep 17 00:00:00 2001
From: Martin Storsjo <martin@martin.st>
Date: Fri, 11 Jan 2019 13:47:37 +0000
Subject: [PATCH] [llvm-objcopy] [COFF] Fix writing object files without
 symbols/string table

Previously, this was broken - by setting PointerToSymbolTable to zero
but still actually writing the string table length, the object file
header was corrupted.

Differential Revision: https://reviews.llvm.org/D56584

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@350926 91177308-0d34-0410-b5e6-96231b3b80d8
---
 test/tools/llvm-objcopy/COFF/Inputs/no-symbols.yaml | 11 +++++++++++
 test/tools/llvm-objcopy/COFF/basic-copy.test        |  6 ++++++
 tools/llvm-objcopy/COFF/Writer.cpp                  |  9 ++++-----
 3 files changed, 21 insertions(+), 5 deletions(-)
 create mode 100644 test/tools/llvm-objcopy/COFF/Inputs/no-symbols.yaml

diff --git a/test/tools/llvm-objcopy/COFF/Inputs/no-symbols.yaml b/test/tools/llvm-objcopy/COFF/Inputs/no-symbols.yaml
new file mode 100644
index 00000000000..db8aeb63d5e
--- /dev/null
+++ b/test/tools/llvm-objcopy/COFF/Inputs/no-symbols.yaml
@@ -0,0 +1,11 @@
+--- !COFF
+header:          
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: [  ]
+sections:        
+  - Name:            .text
+    Characteristics: [  ]
+    Alignment:       4
+    SectionData:     E800000000C3C3C3
+symbols:         
+...
diff --git a/test/tools/llvm-objcopy/COFF/basic-copy.test b/test/tools/llvm-objcopy/COFF/basic-copy.test
index ddd12dcaf2f..ecdf430faf1 100644
--- a/test/tools/llvm-objcopy/COFF/basic-copy.test
+++ b/test/tools/llvm-objcopy/COFF/basic-copy.test
@@ -40,3 +40,9 @@ RUN: llvm-objcopy %t.x86_64.exe %t.x86_64-copy.exe
 RUN: obj2yaml %t.x86_64.exe > %t.x86_64.exe.yaml
 RUN: obj2yaml %t.x86_64-copy.exe > %t.x86_64-copy.exe.yaml
 RUN: cmp %t.x86_64.exe.yaml %t.x86_64-copy.exe.yaml
+
+RUN: yaml2obj %p/Inputs/no-symbols.yaml > %t.no-symbols.o
+RUN: llvm-objcopy %t.no-symbols.o %t.no-symbols-copy.o
+RUN: obj2yaml %t.no-symbols.o > %t.no-symbols.o.yaml
+RUN: obj2yaml %t.no-symbols-copy.o > %t.no-symbols-copy.o.yaml
+RUN: cmp %t.no-symbols.o.yaml %t.no-symbols-copy.o.yaml
diff --git a/tools/llvm-objcopy/COFF/Writer.cpp b/tools/llvm-objcopy/COFF/Writer.cpp
index d7a5224b5ef..213cb11b788 100644
--- a/tools/llvm-objcopy/COFF/Writer.cpp
+++ b/tools/llvm-objcopy/COFF/Writer.cpp
@@ -154,12 +154,11 @@ Error COFFWriter::finalize(bool IsBigObj) {
   size_t PointerToSymbolTable = FileSize;
   // StrTabSize <= 4 is the size of an empty string table, only consisting
   // of the length field.
-  if (SymTabSize == 0 && StrTabSize <= 4) {
-    // Don't point to the symbol table if empty.
+  if (SymTabSize == 0 && StrTabSize <= 4 && Obj.IsPE) {
+    // For executables, don't point to the symbol table and skip writing
+    // the length field, if both the symbol and string tables are empty.
     PointerToSymbolTable = 0;
-    // For executables, skip the length field of an empty string table.
-    if (Obj.IsPE)
-      StrTabSize = 0;
+    StrTabSize = 0;
   }
 
   size_t NumRawSymbols = SymTabSize / SymbolSize;
-- 
2.11.4.GIT