[PATCH] D68249: [llvm-objdump] Don't throw error for empty dynamic section

[Yi Kong via Phabricator via llvm-commits]

kongyi created this revision.
kongyi added reviewers: rupprecht, paulsemel, MaskRay.
Herald added subscribers: llvm-commits, seiya, hiraditya.
Herald added a reviewer: alexshap.
Herald added a project: LLVM.

objcopy --only-keep-debug flag creates files with empty dynamic section. llvm-objdump should not throw error for these files.


Repository:
  rL LLVM

https://reviews.llvm.org/D68249

Files:
  llvm/lib/Object/ELF.cpp
  llvm/test/tools/llvm-objdump/elf-keep-debug-only.test


Index: llvm/test/tools/llvm-objdump/elf-keep-debug-only.test
===================================================================
--- /dev/null
+++ llvm/test/tools/llvm-objdump/elf-keep-debug-only.test
@@ -0,0 +1,27 @@
+# 'objcopy --only-keep-debug' will create objects with empty dynamic section,
+# llvm-objcopy should not crash for these files.
+# RUN: yaml2obj %s > %t
+# RUN: llvm-objdump -p %t | FileCheck %s
+
+# CHECK:      Dynamic Section:
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_EXEC
+  Machine: EM_X86_64
+Sections:
+  - Name:    .dynamic
+    Type:    SHT_DYNAMIC
+    Address: 0x1010
+ProgramHeaders:
+  - Type: PT_LOAD
+    VAddr: 0x1000
+    Sections:
+      - Section: .dynstr
+      - Section: .dynamic
+  - Type: PT_DYNAMIC
+    VAddr: 0x1010
+    Sections:
+      - Section: .dynamic
Index: llvm/lib/Object/ELF.cpp
===================================================================
--- llvm/lib/Object/ELF.cpp
+++ llvm/lib/Object/ELF.cpp
@@ -538,17 +538,15 @@
       return ArrayRef<Elf_Dyn>();
   }
 
-  if (Dyn.empty())
-    // TODO: this error is untested.
-    return createError("invalid empty dynamic section");
-
-  if (DynSecSize % sizeof(Elf_Dyn) != 0)
-    // TODO: this error is untested.
-    return createError("malformed dynamic section");
-
-  if (Dyn.back().d_tag != ELF::DT_NULL)
-    // TODO: this error is untested.
-    return createError("dynamic sections must be DT_NULL terminated");
+  if (!Dyn.empty()) {
+    if (DynSecSize % sizeof(Elf_Dyn) != 0)
+      // TODO: this error is untested.
+      return createError("malformed dynamic section");
+
+    if (Dyn.back().d_tag != ELF::DT_NULL)
+      // TODO: this error is untested.
+      return createError("dynamic sections must be DT_NULL terminated");
+  }
 
   return Dyn;
 }


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