[Lldb-commits] [lldb] Read and store gnu build id from loaded core file (PR #92492)

[Greg Clayton via lldb-commits]

================
@@ -983,6 +1001,66 @@ llvm::Error ProcessElfCore::ParseThreadContextsFromNoteSegment(
   }
 }
 
+bool ProcessElfCore::IsElf(lldb::addr_t address) {
+  uint8_t buf[4];
+  Status error;
+  size_t byte_read = ReadMemory(address, buf, 4, error);
+  if (byte_read != 4)
+    return false;
+  return elf::ELFHeader::MagicBytesMatch(buf);
+}
+
+std::optional<UUID> ProcessElfCore::FindNoteInCoreMemory(lldb::addr_t address,
+                                                         uint32_t type) {
+  if (!IsElf(address))
+    return std::nullopt;
+  const uint32_t addr_size = GetAddressByteSize();
+  const size_t elf_header_size = addr_size == 4 ? sizeof(llvm::ELF::Elf32_Ehdr)
+                                                : sizeof(llvm::ELF::Elf64_Ehdr);
+
+  unsigned char buf[4096];
+  Status error;
+  size_t byte_read = ReadMemory(address, buf, elf_header_size, error);
+  if (byte_read != elf_header_size)
+    return std::nullopt;
+  DataExtractor data(buf, 4096, GetByteOrder(), addr_size);
+  lldb::offset_t offset = 0;
+
+  elf::ELFHeader elf_header;
+  elf_header.Parse(data, &offset);
+
+  const lldb::addr_t ph_addr = address + elf_header.e_phoff;
+
+  for (unsigned int i = 0; i < elf_header.e_phnum; ++i) {
+    byte_read = ReadMemory(ph_addr + i * elf_header.e_phentsize, buf,
+                           elf_header.e_phentsize, error);
+    if (byte_read != elf_header.e_phentsize)
+      break;
+    offset = 0;
+    elf::ELFProgramHeader program_header;
+    program_header.Parse(data, &offset);
+    if (program_header.p_type != llvm::ELF::PT_NOTE)
+      continue;
+
+    byte_read =
+        ReadMemory(program_header.p_vaddr, buf, program_header.p_memsz, error);
+    if (byte_read != program_header.p_memsz)
+      continue;
+
+    auto notes_or_error = parseSegment(data, program_header.p_memsz);
----------------
clayborg wrote:

Create a DataBuffer for only the note data, and then we won't need to pass the `program_header.p_memsz` to `parseSegment(...)`:
```
DataExtractor note_data(note_bytes.data(), note_bytes.size(), GetByteOrder(), addr_size);
auto notes_or_error = parseSegment(note_data);
```

https://github.com/llvm/llvm-project/pull/92492