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

[Pavel Labath via lldb-commits]

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@@ -983,6 +1005,73 @@ llvm::Error ProcessElfCore::ParseThreadContextsFromNoteSegment(
   }
 }
 
+bool ProcessElfCore::IsElf(const 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::FindNote(const lldb::addr_t address,
+                                             const uint32_t type) {
+  if (!IsElf(address))
+    return std::nullopt;
+  const uint32_t addr_size = GetAddressByteSize();
+  const lldb::offset_t ehdr_phoff_offset = ELFOFFSETOF(Ehdr, e_phoff);
+  const lldb::offset_t ehdr_phentsize_offset = ELFOFFSETOF(Ehdr, e_phentsize);
+  const lldb::offset_t ehdr_phnum_offset = ELFOFFSETOF(Ehdr, e_phnum);
+  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);
+  DataExtractor data(buf, 4096, GetByteOrder(), addr_size);
+  lldb::offset_t offset = ehdr_phoff_offset;
+  lldb::offset_t phoff = data.GetAddress(&offset);
+
+  offset = ehdr_phentsize_offset;
+  lldb::offset_t phentsize = data.GetU16(&offset);
+  offset = ehdr_phnum_offset;
+  lldb::offset_t phnum = data.GetU16(&offset);
----------------
labath wrote:

Reuse the existing `ELFHeader` class for this. I.e., read the necessary amount of bytes (you can just always read `sizeof(Elf64_Ehdr)` as that's larger) into a DataExtractor and call `header.Parse(extractor, 0)`.

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