[PATCH] D77289: [Object] Fix crash caused by unhandled error.

[Xing GUO via Phabricator via llvm-commits]

Higuoxing updated this revision to Diff 254507.
Higuoxing added a comment.

Addressed comment.

- Add one more test for `.dynsym` section. `llvm-nm --dynamic`'s behavior will be fixed until D76081 <https://reviews.llvm.org/D76081> lands.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D77289/new/

https://reviews.llvm.org/D77289

Files:
  llvm/include/llvm/Object/ELFObjectFile.h
  llvm/test/Object/invalid-symtab-size.test


Index: llvm/test/Object/invalid-symtab-size.test
===================================================================
--- /dev/null
+++ llvm/test/Object/invalid-symtab-size.test
@@ -0,0 +1,36 @@
+## This test ensures llvm will not crash when dumping a symbol table
+## whose sh_size isn't a multiple of the symbol size (sh_size % sizeof(Elf_Sym) != 0).
+## TODO: It would be helpful if we could warn about this in future.
+
+# RUN: yaml2obj -DBITS=32 -DSIZE=33 %s -o %t.32-bit.o
+# RUN: llvm-nm %t.32-bit.o 2>&1 | FileCheck --implicit-check-not=warning %s
+# RUN: yaml2obj -DBITS=64 -DSIZE=49 %s -o %t.64-bit.o
+# RUN: llvm-nm %t.64-bit.o 2>&1 | FileCheck --implicit-check-not=warning %s
+
+#       CHECK: U
+# CHECK-EMPTY:
+
+## TODO: Currently, llvm-nm will print 0-index NULL symbol from .dynsym. We should correct this behavior in future.
+# RUN: llvm-nm --dynamic %t.32-bit.o 2>&1 | FileCheck --implicit-check-not=warning --check-prefix=DYN %s
+# RUN: llvm-nm --dynamic %t.64-bit.o 2>&1 | FileCheck --implicit-check-not=warning --check-prefix=DYN %s
+
+#       DYN: U
+#  DYN-NEXT: U
+# DYN-EMPTY:
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS[[BITS]]
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_386
+Sections:
+  - Name:    .dynstr
+    Type:    SHT_STRTAB
+    Content: "00"
+  - Name:    .symtab
+    Type:    SHT_SYMTAB
+    Size:    [[SIZE]]
+  - Name:    .dynsym
+    Type:    SHT_DYNSYM
+    Size:    [[SIZE]]
Index: llvm/include/llvm/Object/ELFObjectFile.h
===================================================================
--- llvm/include/llvm/Object/ELFObjectFile.h
+++ llvm/include/llvm/Object/ELFObjectFile.h
@@ -625,11 +625,17 @@
   if (ESym->getType() == ELF::STT_FILE || ESym->getType() == ELF::STT_SECTION)
     Result |= SymbolRef::SF_FormatSpecific;
 
-  auto DotSymtabSecSyms = EF.symbols(DotSymtabSec);
-  if (DotSymtabSecSyms && ESym == (*DotSymtabSecSyms).begin())
-    Result |= SymbolRef::SF_FormatSpecific;
-  auto DotDynSymSecSyms = EF.symbols(DotDynSymSec);
-  if (DotDynSymSecSyms && ESym == (*DotDynSymSecSyms).begin())
+  auto IsNULLSymbol = [this](const Elf_Sym *Sym, const Elf_Shdr *SymSec) {
+    Expected<typename ELFT::SymRange> SymbolsOrErr = EF.symbols(SymSec);
+    if (!SymbolsOrErr) {
+      // TODO: Actually report errors helpfully.
+      consumeError(SymbolsOrErr.takeError());
+      return false;
+    }
+    return Sym == SymbolsOrErr->begin();
+  };
+
+  if (IsNULLSymbol(ESym, DotSymtabSec) || IsNULLSymbol(ESym, DotDynSymSec))
     Result |= SymbolRef::SF_FormatSpecific;
 
   if (EF.getHeader()->e_machine == ELF::EM_ARM) {


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