[PATCH] D41657: Do not look up symbol names when n_strx == 0

[Michael Trent via Phabricator via llvm-commits]

mtrent updated this revision to Diff 128573.
mtrent marked an inline comment as done.
mtrent added a comment.

Updating comment based upon review feedback.


https://reviews.llvm.org/D41657

Files:
  lib/Object/MachOObjectFile.cpp
  test/tools/llvm-nm/X86/Inputs/macho-dwarf-x86_64
  test/tools/llvm-nm/X86/macho-dwarf.test


Index: test/tools/llvm-nm/X86/macho-dwarf.test
===================================================================
--- /dev/null
+++ test/tools/llvm-nm/X86/macho-dwarf.test
@@ -0,0 +1,15 @@
+# This file was constructed from 3 trivial source files and linked with macOS's
+# ld64 linker. 
+#
+#   cc -gdwarf-2 -o foo.o -c foo.c
+#   cc -gdwarf-2 -o bar.o -c bar.c
+#   ld -r foo.o bar.o -o foobar.o
+#   cc -gdwarf-2 -o baz foobar.o baz.c
+
+# RUN: llvm-nm -ap %p/Inputs/macho-dwarf-x86_64 | FileCheck -match-full-lines -strict-whitespace %s
+
+# CHECK:000000000000002a - 01 0000 ENSYM 
+# CHECK:0000000000000010 - 01 0000 ENSYM 
+# CHECK:000000000000000b - 01 0000 ENSYM 
+
+
Index: lib/Object/MachOObjectFile.cpp
===================================================================
--- lib/Object/MachOObjectFile.cpp
+++ lib/Object/MachOObjectFile.cpp
@@ -1659,6 +1659,10 @@
 Expected<StringRef> MachOObjectFile::getSymbolName(DataRefImpl Symb) const {
   StringRef StringTable = getStringTableData();
   MachO::nlist_base Entry = getSymbolTableEntryBase(*this, Symb);
+  if (Entry.n_strx == 0)
+    // A n_strx value of 0 indicates that no name is associated with a
+    // particular symbol table entry.
+    return StringRef();
   const char *Start = &StringTable.data()[Entry.n_strx];
   if (Start < getData().begin() || Start >= getData().end()) {
     return malformedError("bad string index: " + Twine(Entry.n_strx) +


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