[lldb] Don't persist the LINKEDIT slide in the indirect symbol offset

[JDevlieghere]

Summary

The current code increment the indirect symbol offset with the LINKEDIT slide every time ObjectFileMachO::ParseSymtab is called. This resulted in a crash when calling add-dsym which causes us to potentially re-parse the original binary's symbol table (see ObjectFileMachO::ProcessSegmentCommand).

rdar://72337717

[JDevlieghere]

PS: I don't think we should ever parse the symbol table more than onceafter D114288, but this patch is still the right thing to do imho.

[jasonmolenda]

Ah, good catch. Yes this looks correct to me.

lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp

void ObjectFileMachO::ParseSymtab(Symtab &symtab) {
   const char *file_name = file.GetFilename().AsCString("<Unknown>");
   LLDB_SCOPED_TIMERF("ObjectFileMachO::ParseSymtab () module = %s", file_name);
   Progress progress(llvm::formatv("Parsing symbol table for {0}", file_name));
 
   llvm::MachO::symtab_command symtab_load_command = {0, 0, 0, 0, 0, 0};
   llvm::MachO::linkedit_data_command function_starts_load_command = {0, 0, 0, 0};
   llvm::MachO::linkedit_data_command exports_trie_load_command = {0, 0, 0, 0};
   llvm::MachO::dyld_info_command dyld_info = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+  llvm::MachO::dysymtab_command dysymtab = m_dysymtab;
   // The data element of type bool indicates that this entry is thumb
   // code.
   typedef AddressDataArray<lldb::addr_t, bool, 100> FunctionStarts;
 
   // Record the address of every function/data that we add to the symtab.
   // We add symbols to the table in the order of most information (nlist
   // records) to least (function starts), and avoid duplicating symbols
   // via this set.
if (linkedit_section_sp) {
         // symbols, we force dyld to load from memory despite the user's
         // target.memory-module-load-level setting.
         if (memory_module_load_level == eMemoryModuleLoadLevelComplete ||
             m_header.filetype == llvm::MachO::MH_DYLINKER) {
           DataBufferSP nlist_data_sp(
               ReadMemory(process_sp, symoff_addr, nlist_data_byte_size));
           if (nlist_data_sp)
             nlist_data.SetData(nlist_data_sp, 0, nlist_data_sp->GetByteSize());
-          if (m_dysymtab.nindirectsyms != 0) {
+          if (dysymtab.nindirectsyms != 0) {
             const addr_t indirect_syms_addr = linkedit_load_addr +
-                                              m_dysymtab.indirectsymoff -
+                                              dysymtab.indirectsymoff -
                                               linkedit_file_offset;
             DataBufferSP indirect_syms_data_sp(ReadMemory(
-                process_sp, indirect_syms_addr, m_dysymtab.nindirectsyms * 4));
+                process_sp, indirect_syms_addr, dysymtab.nindirectsyms * 4));
             if (indirect_syms_data_sp)
               indirect_symbol_index_data.SetData(
                   indirect_syms_data_sp, 0,
                   indirect_syms_data_sp->GetByteSize());
             // If this binary is outside the shared cache,
             // cache the string table.
             // Binaries in the shared cache all share a giant string table,
             // and we can't share the string tables across multiple
if (is_local_shared_cache_image) {
       // segments. We need to convert the load command offsets to be
       // relative to the beginning of our specific image.
       lldb::addr_t linkedit_offset = linkedit_section_sp->GetFileOffset();
       lldb::offset_t linkedit_slide =
           linkedit_offset - m_linkedit_original_offset;
       symtab_load_command.symoff += linkedit_slide;
       symtab_load_command.stroff += linkedit_slide;
       dyld_info.export_off += linkedit_slide;
-      m_dysymtab.indirectsymoff += linkedit_slide;
+      dysymtab.indirectsymoff += linkedit_slide;
       function_starts_load_command.dataoff += linkedit_slide;
       exports_trie_load_command.dataoff += linkedit_slide;
     }
 
     nlist_data.SetData(m_data, symtab_load_command.symoff,
                        nlist_data_byte_size);
     strtab_data.SetData(m_data, symtab_load_command.stroff,
                         strtab_data_byte_size);
 
     // We shouldn't have exports data from both the LC_DYLD_INFO command
     // AND the LC_DYLD_EXPORTS_TRIE command in the same binary:
     lldbassert(!((dyld_info.export_size > 0)
                  && (exports_trie_load_command.datasize > 0)));
     if (dyld_info.export_size > 0) {
       dyld_trie_data.SetData(m_data, dyld_info.export_off,
                              dyld_info.export_size);
     } else if (exports_trie_load_command.datasize > 0) {
       dyld_trie_data.SetData(m_data, exports_trie_load_command.dataoff,
                              exports_trie_load_command.datasize);
     }
 
-    if (m_dysymtab.nindirectsyms != 0) {
-      indirect_symbol_index_data.SetData(m_data, m_dysymtab.indirectsymoff,
-                                         m_dysymtab.nindirectsyms * 4);
+    if (dysymtab.nindirectsyms != 0) {
+      indirect_symbol_index_data.SetData(m_data, dysymtab.indirectsymoff,
+                                         dysymtab.nindirectsyms * 4);
     }
     if (function_starts_load_command.cmd) {
       function_starts_data.SetData(m_data, function_starts_load_command.dataoff,
                                    function_starts_load_command.datasize);
     }
   }
 
   const bool have_strtab_data = strtab_data.GetByteSize() > 0;