[lldb] [Process/FreeBSDRemote] Implement GetLoadedModuleFileSpec() and GetFileLoadAddress()

[mgorny]

Summary

Copy the Linux implementation of GetLoadedModuleFileSpec()
and GetFileLoadAddress() into NativeProcessFreeBSD. This does not seem
to change anything at the moment but reducing the differences between
the plugins should help us in the long term.

[emaste]

No objection, but maybe add a comment explaining the status of this implementation? Does/will NetBSD do the same?

[labath]

These are basically workarounds for dynamic linker bugs, when we're not able to get complete information via r_debug. If your dynamic linker (loader) behaves, then it's not surprising that they make no effect.

Implementing them is fine. It might be nice to also add some explicit tests for these functions (via lldb-server tests, perhaps). We should have done something like that when we were adding these in the first place, but we weren't so big on testing then...

[mgorny]

In D92314#2422995, @emaste wrote:

No objection, but maybe add a comment explaining the status of this implementation? Does/will NetBSD do the same?

I will add the comment, and I'm planning to sync NetBSD in my free time, later on.

[mgorny]

Added an explanatory comment.

lldb/source/Plugins/Process/FreeBSDRemote/NativeProcessFreeBSD.h

public:
 
   size_t UpdateThreads() override;
 
   const ArchSpec &GetArchitecture() const override { return m_arch; }
 
   Status SetBreakpoint(lldb::addr_t addr, uint32_t size,
                        bool hardware) override;
 
+  // The two following methods are probably not necessary and probably
+  // will never be called.  Nevertheless, we implement them right now
+  // to reduce the differences between different platforms and reduce
+  // the risk of the lack of implementation actually breaking something,
+  // at least for the time being.
   Status GetLoadedModuleFileSpec(const char *module_path,
                                  FileSpec &file_spec) override;
-
   Status GetFileLoadAddress(const llvm::StringRef &file_name,
                             lldb::addr_t &load_addr) override;
 
   llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
   GetAuxvData() const override;
 
   // Interface used by NativeRegisterContext-derived classes.
   static Status PtraceWrapper(int req, lldb::pid_t pid, void *addr = nullptr,

lldb/source/Plugins/Process/FreeBSDRemote/NativeProcessFreeBSD.cpp

Status NativeProcessFreeBSD::SetBreakpoint(lldb::addr_t addr, uint32_t size,
   if (hardware)
     return Status("NativeProcessFreeBSD does not support hardware breakpoints");
   else
     return SetSoftwareBreakpoint(addr, size);
 }
 
 Status NativeProcessFreeBSD::GetLoadedModuleFileSpec(const char *module_path,
                                                      FileSpec &file_spec) {
-  return Status("Unimplemented");
+  Status error = PopulateMemoryRegionCache();
+  if (error.Fail())
+    return error;
+
+  FileSpec module_file_spec(module_path);
+  FileSystem::Instance().Resolve(module_file_spec);
+
+  file_spec.Clear();
+  for (const auto &it : m_mem_region_cache) {
+    if (it.second.GetFilename() == module_file_spec.GetFilename()) {
+      file_spec = it.second;
+      return Status();
+    }
+  }
+  return Status("Module file (%s) not found in process' memory map!",
+                module_file_spec.GetFilename().AsCString());
 }
 
 Status
 NativeProcessFreeBSD::GetFileLoadAddress(const llvm::StringRef &file_name,
                                          lldb::addr_t &load_addr) {
   load_addr = LLDB_INVALID_ADDRESS;
+  Status error = PopulateMemoryRegionCache();
+  if (error.Fail())
+    return error;
+
+  FileSpec file(file_name);
+  for (const auto &it : m_mem_region_cache) {
+    if (it.second == file) {
+      load_addr = it.first.GetRange().GetRangeBase();
       return Status();
     }
+  }
+  return Status("No load address found for file %s.", file_name.str().c_str());
+}
 
 void NativeProcessFreeBSD::SigchldHandler() {
   Log *log(ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_PROCESS));
   // Process all pending waitpid notifications.
   int status;
   ::pid_t wait_pid =
       llvm::sys::RetryAfterSignal(-1, waitpid, GetID(), &status, WNOHANG);