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authorSean Silva <silvas@purdue.edu>2013-06-18 23:37:23 +0000
committerSean Silva <silvas@purdue.edu>2013-06-18 23:37:23 +0000
commitc2b6adff3e94f8e299caa31947ad970096377e40 (patch)
tree333cfb1b4b16ac6afa13b589b50f329bd29169a4
parentca0170ffa1ba6d53f0008b345cb5ac777e81c3b1 (diff)
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[yaml2obj][ELF] Don't monkeypatch the YAML sections.
Previously, we would monkeypatch the vector of YAML::Section's in order to ensure that the SHT_NULL entry is present. Now we just add it unconditionally. The proliferation of small numerical adjustments is beginning to frighten me, but I can't think of a way having a single point of truth for them without introducing a whole new layer of data structures (i.e. lots of code and complexity) between the YAML and binary ELF formats. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184260 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r--tools/yaml2obj/yaml2elf.cpp31
1 files changed, 17 insertions, 14 deletions
diff --git a/tools/yaml2obj/yaml2elf.cpp b/tools/yaml2obj/yaml2elf.cpp
index a67a275bf9..3ddbe0afee 100644
--- a/tools/yaml2obj/yaml2elf.cpp
+++ b/tools/yaml2obj/yaml2elf.cpp
@@ -209,27 +209,23 @@ static int writeELF(raw_ostream &OS, const ELFYAML::Object &Doc) {
Header.e_shentsize = sizeof(Elf_Shdr);
// Immediately following the ELF header.
Header.e_shoff = sizeof(Header);
- std::vector<ELFYAML::Section> Sections = Doc.Sections;
- if (Sections.empty() || Sections.front().Type != SHT_NULL) {
- ELFYAML::Section S;
- S.Type = SHT_NULL;
- zero(S.Flags);
- zero(S.Address);
- zero(S.AddressAlign);
- Sections.insert(Sections.begin(), S);
- }
- // "+ 2" for string table and section header string table.
- Header.e_shnum = Sections.size() + 2;
+ const std::vector<ELFYAML::Section> &Sections = Doc.Sections;
+ // "+ 3" for
+ // - SHT_NULL entry (placed first, i.e. 0'th entry)
+ // - string table (.strtab) (placed second to last)
+ // - section header string table. (placed last)
+ Header.e_shnum = Sections.size() + 3;
// Place section header string table last.
- Header.e_shstrndx = Sections.size() + 1;
- const unsigned DotStrtabSecNo = Sections.size();
+ Header.e_shstrndx = Header.e_shnum - 1;
+ const unsigned DotStrtabSecNo = Header.e_shnum - 2;
SectionNameToIdxMap SN2I;
for (unsigned i = 0, e = Sections.size(); i != e; ++i) {
StringRef Name = Sections[i].Name;
if (Name.empty())
continue;
- if (SN2I.addName(Name, i)) {
+ // "+ 1" to take into account the SHT_NULL entry.
+ if (SN2I.addName(Name, i + 1)) {
errs() << "error: Repeated section name: '" << Name
<< "' at YAML section number " << i << ".\n";
return 1;
@@ -244,6 +240,13 @@ static int writeELF(raw_ostream &OS, const ELFYAML::Object &Doc) {
Header.e_ehsize + Header.e_shentsize * Header.e_shnum;
ContiguousBlobAccumulator CBA(SectionContentBeginOffset, Buf);
std::vector<Elf_Shdr> SHeaders;
+ {
+ // Ensure SHN_UNDEF entry is present. An all-zero section header is a
+ // valid SHN_UNDEF entry since SHT_NULL == 0.
+ Elf_Shdr SHdr;
+ zero(SHdr);
+ SHeaders.push_back(SHdr);
+ }
StringTableBuilder DotStrTab;
for (unsigned i = 0, e = Sections.size(); i != e; ++i) {
const ELFYAML::Section &Sec = Sections[i];