[yaml2obj] - Report when unknown section is referenced from program header declaration block.

[grimar]

Summary

Previously we did not report this.
Also this removes multiple lookups in the map
what cleanups the code.

[jhenderson]

LGTM. This looks much better.

[grimar]

Sorry, during final test run I found this fix reveals a bug in one of the testcases: llvm-objcopy/ELF/no-build-id.test
I fixed it. Could you review this change please too?

[rupprecht]

llvm-objcopy test looks fine

[jhenderson]

test/tools/llvm-objcopy/ELF/no-build-id.test

13 ↗

(On Diff #197368)

If you want to leave it as is, then fine, but I'd actually prefer the section name be changed to .note.foo in both cases, not .note.gnu.foo, since the "gnu" bit implies something specific to do with GNU which isn't the case.

[grimar]

test/tools/llvm-objcopy/ELF/no-build-id.test

13 ↗

(On Diff #197368)

I changed the name as you suggested before the commit.

llvm/trunk/test/tools/llvm-objcopy/ELF/no-build-id.test

Sections:
   - Name:            .note.foo
     Type:            SHT_NOTE
     Flags:           [ SHF_ALLOC ]
     Content:         000000000000000000000000
 ProgramHeaders:
   - Type: PT_NOTE
     Flags: [ PF_R ]
     Sections:
-      - Section: .note.gnu.foo
+      - Section: .note.foo

llvm/trunk/test/tools/yaml2obj/program-header.yaml

-# RUN: yaml2obj %s -o %t
+# RUN: yaml2obj --docnum=1 %s -o %t
 # RUN: llvm-readobj -l %t | FileCheck %s
 
-!ELF
+--- !ELF
 FileHeader:
   Class:           ELFCLASS64
   Data:            ELFDATA2LSB
   Type:            ET_EXEC
   Machine:         EM_X86_64
 Sections:
   - Name:            .text
     Type:            SHT_PROGBITS

 #CHECK-NEXT:    FileSize: 4
 #CHECK-NEXT:    MemSize: 4
 #CHECK-NEXT:    Flags [
 #CHECK-NEXT:      PF_R
 #CHECK-NEXT:    ]
 #CHECK-NEXT:    Alignment: 4096
 #CHECK-NEXT:  }
 #CHECK-NEXT:]
+
+## Check we do not allow referencing sections that do not exist.
+# RUN: not yaml2obj --docnum=2 %s -o %t 2>&1 | FileCheck %s --check-prefix=ERR
+# ERR: error: Unknown section referenced: '.foo' by program header.
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_EXEC
+  Machine:         EM_X86_64
+ProgramHeaders:
+  - Type: PT_LOAD
+    Sections:
+      - Section: .foo

llvm/trunk/tools/yaml2obj/yaml2elf.cpp

void ELFState<ELFT>::initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
   }
 }
 
 template <class ELFT>
 void ELFState<ELFT>::setProgramHeaderLayout(std::vector<Elf_Phdr> &PHeaders,
                                             std::vector<Elf_Shdr> &SHeaders) {
   uint32_t PhdrIdx = 0;
   for (auto &YamlPhdr : Doc.ProgramHeaders) {
-    auto &PHeader = PHeaders[PhdrIdx++];
+    Elf_Phdr &PHeader = PHeaders[PhdrIdx++];
+
+    std::vector<Elf_Shdr *> Sections;
+    for (const ELFYAML::SectionName &SecName : YamlPhdr.Sections) {
+      unsigned Index;
+      if (SN2I.lookup(SecName.Section, Index)) {
+        WithColor::error() << "Unknown section referenced: '" << SecName.Section
+                           << "' by program header.\n";
+        exit(1);
+      }
+      Sections.push_back(&SHeaders[Index]);
+    }
 
     if (YamlPhdr.Offset) {
       PHeader.p_offset = *YamlPhdr.Offset;
     } else {
       if (YamlPhdr.Sections.size())
         PHeader.p_offset = UINT32_MAX;
       else
         PHeader.p_offset = 0;
 
       // Find the minimum offset for the program header.
-      for (auto SecName : YamlPhdr.Sections) {
-        uint32_t Index = 0;
-        SN2I.lookup(SecName.Section, Index);
-        const auto &SHeader = SHeaders[Index];
-        PHeader.p_offset = std::min(PHeader.p_offset, SHeader.sh_offset);
-      }
+      for (Elf_Shdr *SHeader : Sections)
+        PHeader.p_offset = std::min(PHeader.p_offset, SHeader->sh_offset);
     }
 
     // Find the maximum offset of the end of a section in order to set p_filesz,
     // if not set explicitly.
     if (YamlPhdr.FileSize) {
       PHeader.p_filesz = *YamlPhdr.FileSize;
     } else {
       PHeader.p_filesz = 0;
-      for (auto SecName : YamlPhdr.Sections) {
-        uint32_t Index = 0;
-        SN2I.lookup(SecName.Section, Index);
-        const auto &SHeader = SHeaders[Index];
+      for (Elf_Shdr *SHeader : Sections) {
         uint64_t EndOfSection;
-        if (SHeader.sh_type == llvm::ELF::SHT_NOBITS)
-          EndOfSection = SHeader.sh_offset;
+        if (SHeader->sh_type == llvm::ELF::SHT_NOBITS)
+          EndOfSection = SHeader->sh_offset;
         else
-          EndOfSection = SHeader.sh_offset + SHeader.sh_size;
+          EndOfSection = SHeader->sh_offset + SHeader->sh_size;
         uint64_t EndOfSegment = PHeader.p_offset + PHeader.p_filesz;
         EndOfSegment = std::max(EndOfSegment, EndOfSection);
         PHeader.p_filesz = EndOfSegment - PHeader.p_offset;
       }
     }
 
     // If not set explicitly, find the memory size by adding the size of
     // sections at the end of the segment. These should be empty (size of zero)
     // and NOBITS sections.
     if (YamlPhdr.MemSize) {
       PHeader.p_memsz = *YamlPhdr.MemSize;
     } else {
       PHeader.p_memsz = PHeader.p_filesz;
-      for (auto SecName : YamlPhdr.Sections) {
-        uint32_t Index = 0;
-        SN2I.lookup(SecName.Section, Index);
-        const auto &SHeader = SHeaders[Index];
-        if (SHeader.sh_offset == PHeader.p_offset + PHeader.p_filesz)
-          PHeader.p_memsz += SHeader.sh_size;
-      }
+      for (Elf_Shdr *SHeader : Sections)
+        if (SHeader->sh_offset == PHeader.p_offset + PHeader.p_filesz)
+          PHeader.p_memsz += SHeader->sh_size;
     }
 
     // Set the alignment of the segment to be the same as the maximum alignment
     // of the sections with the same offset so that by default the segment
     // has a valid and sensible alignment.
     if (YamlPhdr.Align) {
       PHeader.p_align = *YamlPhdr.Align;
     } else {
       PHeader.p_align = 1;
-      for (auto SecName : YamlPhdr.Sections) {
-        uint32_t Index = 0;
-        SN2I.lookup(SecName.Section, Index);
-        const auto &SHeader = SHeaders[Index];
-        if (SHeader.sh_offset == PHeader.p_offset)
-          PHeader.p_align = std::max(PHeader.p_align, SHeader.sh_addralign);
-      }
+      for (Elf_Shdr *SHeader : Sections)
+        if (SHeader->sh_offset == PHeader.p_offset)
+          PHeader.p_align = std::max(PHeader.p_align, SHeader->sh_addralign);
     }
   }
 }
 
 template <class ELFT>
 void ELFState<ELFT>::addSymbols(ArrayRef<ELFYAML::Symbol> Symbols,
                                 std::vector<Elf_Sym> &Syms,
                                 const StringTableBuilder &Strtab) {