Recommit r354328, r354329 "[obj2yaml][yaml2obj] - Add support of parsing/dumping of the .gnu.version_r section."

Fix:
Replace
assert(!IO.getContext() && "The IO context is initialized already");
with
assert(IO.getContext() && "The IO context is not initialized");
(this was introduced in r354329, where I tried to quickfix the darwin BB
and seems copypasted the assert from the wrong place).

Original commit message:

The section is described here:
https://refspecs.linuxfoundation.org/LSB_1.3.0/gLSB/gLSB/symverrqmts.html

Patch just teaches obj2yaml/yaml2obj to dump and parse such sections.

We did the finalization of string tables very late,
and I had to move the logic to make it a bit earlier.
That was needed in this patch since .gnu.version_r adds strings to .dynstr.
This might also be useful for implementing other special sections.

Everything else changed in this patch seems to be straightforward.

Differential revision: https://reviews.llvm.org/D58119

llvm-svn: 354335

1 files changed, 65 insertions, 0 deletions

diff --git a/llvm/tools/obj2yaml/elf2yaml.cpp b/llvm/tools/obj2yaml/elf2yaml.cpp
index a3fe811b9d5..cb18e1820df 100644
--- a/llvm/tools/obj2yaml/elf2yaml.cpp
+++ b/llvm/tools/obj2yaml/elf2yaml.cpp
@@ -57,6 +57,7 @@ class ELFDumper {
   ErrorOr<ELFYAML::RawContentSection *>
   dumpContentSection(const Elf_Shdr *Shdr);
   ErrorOr<ELFYAML::NoBitsSection *> dumpNoBitsSection(const Elf_Shdr *Shdr);
+  ErrorOr<ELFYAML::VerneedSection *> dumpVerneedSection(const Elf_Shdr *Shdr);
   ErrorOr<ELFYAML::Group *> dumpGroup(const Elf_Shdr *Shdr);
   ErrorOr<ELFYAML::MipsABIFlags *> dumpMipsABIFlags(const Elf_Shdr *Shdr);
 
@@ -184,6 +185,13 @@ template <class ELFT> ErrorOr<ELFYAML::Object *> ELFDumper<ELFT>::dump() {
       Y->Sections.push_back(std::unique_ptr<ELFYAML::Section>(S.get()));
       break;
     }
+    case ELF::SHT_GNU_verneed: {
+      ErrorOr<ELFYAML::VerneedSection *> S = dumpVerneedSection(&Sec);
+      if (std::error_code EC = S.getError())
+        return EC;
+      Y->Sections.push_back(std::unique_ptr<ELFYAML::Section>(S.get()));
+      break;
+    }
     default: {
       ErrorOr<ELFYAML::RawContentSection *> S = dumpContentSection(&Sec);
       if (std::error_code EC = S.getError())
@@ -444,6 +452,63 @@ ELFDumper<ELFT>::dumpNoBitsSection(const Elf_Shdr *Shdr) {
 }
 
 template <class ELFT>
+ErrorOr<ELFYAML::VerneedSection *>
+ELFDumper<ELFT>::dumpVerneedSection(const Elf_Shdr *Shdr) {
+  typedef typename ELFT::Verneed Elf_Verneed;
+  typedef typename ELFT::Vernaux Elf_Vernaux;
+
+  auto S = make_unique<ELFYAML::VerneedSection>();
+  if (std::error_code EC = dumpCommonSection(Shdr, *S))
+    return EC;
+
+  S->Info = Shdr->sh_info;
+
+  auto Contents = Obj.getSectionContents(Shdr);
+  if (!Contents)
+    return errorToErrorCode(Contents.takeError());
+
+  auto StringTableShdrOrErr = Obj.getSection(Shdr->sh_link);
+  if (!StringTableShdrOrErr)
+    return errorToErrorCode(StringTableShdrOrErr.takeError());
+
+  auto StringTableOrErr = Obj.getStringTable(*StringTableShdrOrErr);
+  if (!StringTableOrErr)
+    return errorToErrorCode(StringTableOrErr.takeError());
+
+  llvm::ArrayRef<uint8_t> Data = *Contents;
+  const uint8_t *Buf = Data.data();
+  while (Buf) {
+    const Elf_Verneed *Verneed = reinterpret_cast<const Elf_Verneed *>(Buf);
+
+    ELFYAML::VerneedEntry Entry;
+    Entry.Version = Verneed->vn_version;
+    Entry.File =
+        StringRef(StringTableOrErr->drop_front(Verneed->vn_file).data());
+
+    const uint8_t *BufAux = Buf + Verneed->vn_aux;
+    while (BufAux) {
+      const Elf_Vernaux *Vernaux =
+          reinterpret_cast<const Elf_Vernaux *>(BufAux);
+
+      ELFYAML::VernauxEntry Aux;
+      Aux.Hash = Vernaux->vna_hash;
+      Aux.Flags = Vernaux->vna_flags;
+      Aux.Other = Vernaux->vna_other;
+      Aux.Name =
+          StringRef(StringTableOrErr->drop_front(Vernaux->vna_name).data());
+
+      Entry.AuxV.push_back(Aux);
+      BufAux = Vernaux->vna_next ? BufAux + Vernaux->vna_next : nullptr;
+    }
+
+    S->VerneedV.push_back(Entry);
+    Buf = Verneed->vn_next ? Buf + Verneed->vn_next : nullptr;
+  }
+
+  return S.release();
+}
+
+template <class ELFT>
 ErrorOr<ELFYAML::Group *> ELFDumper<ELFT>::dumpGroup(const Elf_Shdr *Shdr) {
   auto S = make_unique<ELFYAML::Group>();