[PATCH] D69192: llvm-objdump can error out with an unexpected EOF error if .bss is larger than the file being dumped.

[Sid Manning via Phabricator via llvm-commits]

sidneym created this revision.
sidneym added reviewers: grimar, MaskRay, rupprecht, bcain.
Herald added subscribers: llvm-commits, seiya.
Herald added a project: LLVM.

llvm-objdump -D  this file:

  int a[100000];
  
  int
  main() {
    return 0;
  }

Will produce an error, "The end of the file was unexpectedly encountered"

This happens because of a check in Binary.h checkOffset.  (Addr + Size > M.getBufferEnd()).

Since the .bss section doesn't occupy space in the file this check fails when the above program is dumped with -D.

This change avoids the reading .bss sections.

I added a test for X86_64 but this isn't target specific.


Repository:
  rL LLVM

https://reviews.llvm.org/D69192

Files:
  llvm/test/tools/llvm-objdump/X86/Inputs/bss.c
  llvm/test/tools/llvm-objdump/X86/Inputs/bss.exe.elf-x86_64
  llvm/test/tools/llvm-objdump/X86/bss.test
  llvm/tools/llvm-objdump/llvm-objdump.cpp


Index: llvm/tools/llvm-objdump/llvm-objdump.cpp
===================================================================
--- llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -1223,8 +1223,10 @@
     SmallString<40> Comments;
     raw_svector_ostream CommentStream(Comments);
 
-    ArrayRef<uint8_t> Bytes = arrayRefFromStringRef(
-        unwrapOrError(Section.getContents(), Obj->getFileName()));
+    ArrayRef<uint8_t> Bytes =
+        Section.isBSS() ? 0
+                        : arrayRefFromStringRef(unwrapOrError(
+                              Section.getContents(), Obj->getFileName()));
 
     uint64_t VMAAdjustment = 0;
     if (shouldAdjustVA(Section))
Index: llvm/test/tools/llvm-objdump/X86/bss.test
===================================================================
--- /dev/null
+++ llvm/test/tools/llvm-objdump/X86/bss.test
@@ -0,0 +1,8 @@
+# Check that when BSS is larger than the file llvm-objdump doesn't
+# assert with an unexpected end of file error.
+
+# To rebuild the input: clang bss.c -o bss.exe.elf-x86_64
+
+# RUN: llvm-objdump -D %p/Inputs/bss.exe.elf-x86_64 | FileCheck %s
+
+# CHECK-NOT: The end of the file was unexpectedly encountered
Index: llvm/test/tools/llvm-objdump/X86/Inputs/bss.c
===================================================================
--- /dev/null
+++ llvm/test/tools/llvm-objdump/X86/Inputs/bss.c
@@ -0,0 +1,8 @@
+
+int a[100000];
+
+int
+main() {
+  return 0;
+}
+


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