[Process/elf-core] Read PID from FreeBSD prpsinfo

[mgorny]

Summary

Add a function to read NT_PRPSINFO note from FreeBSD core dumps. This
is necessary to get the process ID (NT_PRSTATUS has only thread ID).
Move the lp64 check from NT_PRSTATUS parsing to the parseFreeBSDNotes()
to avoid repeating it.

[emaste]

LGTM

lldb/source/Plugins/Process/elf-core/ProcessElfCore.cpp

lldb::addr_t ProcessElfCore::GetImageInfoAddress() {
   if (addr.IsValid())
     return addr.GetLoadAddress(&GetTarget());
   return LLDB_INVALID_ADDRESS;
 }
 
 // Parse a FreeBSD NT_PRSTATUS note - see FreeBSD sys/procfs.h for details.
 static void ParseFreeBSDPrStatus(ThreadData &thread_data,
                                  const DataExtractor &data,
-                                 const ArchSpec &arch) {
+                                 bool lp64) {
   lldb::offset_t offset = 0;
-  bool lp64 = (arch.GetMachine() == llvm::Triple::aarch64 ||
-               arch.GetMachine() == llvm::Triple::mips64 ||
-               arch.GetMachine() == llvm::Triple::ppc64 ||
-               arch.GetMachine() == llvm::Triple::x86_64);
   int pr_version = data.GetU32(&offset);
 
   Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_PROCESS));
   if (log) {
     if (pr_version > 1)
       LLDB_LOGF(log, "FreeBSD PRSTATUS unexpected version %d", pr_version);
   }
 
   // Skip padding, pr_statussz, pr_gregsetsz, pr_fpregsetsz, pr_osreldate
   if (lp64)
     offset += 32;
   else
     offset += 16;
 
   thread_data.signo = data.GetU32(&offset); // pr_cursig
   thread_data.tid = data.GetU32(&offset);   // pr_pid
   if (lp64)
     offset += 4;
 
   size_t len = data.GetByteSize() - offset;
   thread_data.gpregset = DataExtractor(data, offset, len);
 }
 
+// Parse a FreeBSD NT_PRPSINFO note - see FreeBSD sys/procfs.h for details.
+static void ParseFreeBSDPrPsInfo(ProcessElfCore &process,
+                                 const DataExtractor &data,
+                                 bool lp64) {
+  lldb::offset_t offset = 0;
+  int pr_version = data.GetU32(&offset);
+
+  Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_PROCESS));
+  if (log) {
+    if (pr_version > 1)
+      LLDB_LOGF(log, "FreeBSD PRPSINFO unexpected version %d", pr_version);
+  }
+
+  // Skip pr_psinfosz, pr_fname, pr_psargs
+  offset += 108;
+  if (lp64)
+    offset += 4;
+
+  process.SetID(data.GetU32(&offset)); // pr_pid
+}
+
 static llvm::Error ParseNetBSDProcInfo(const DataExtractor &data,
                                        uint32_t &cpi_nlwps,
                                        uint32_t &cpi_signo,
                                        uint32_t &cpi_siglwp,
                                        uint32_t &cpi_pid) {
   lldb::offset_t offset = 0;
 
   uint32_t version = data.GetU32(&offset);
while (offset < segment.GetByteSize()) {
     result.push_back({note, note_data});
     offset += note_size;
   }
 
   return std::move(result);
 }
 
 llvm::Error ProcessElfCore::parseFreeBSDNotes(llvm::ArrayRef<CoreNote> notes) {
+  ArchSpec arch = GetArchitecture();
+  bool lp64 = (arch.GetMachine() == llvm::Triple::aarch64 ||
+               arch.GetMachine() == llvm::Triple::mips64 ||
+               arch.GetMachine() == llvm::Triple::ppc64 ||
+               arch.GetMachine() == llvm::Triple::x86_64);
   bool have_prstatus = false;
   bool have_prpsinfo = false;
   ThreadData thread_data;
   for (const auto &note : notes) {
     if (note.info.n_name != "FreeBSD")
       continue;
 
     if ((note.info.n_type == ELF::NT_PRSTATUS && have_prstatus) ||
         (note.info.n_type == ELF::NT_PRPSINFO && have_prpsinfo)) {
       assert(thread_data.gpregset.GetByteSize() > 0);
       // Add the new thread to thread list
       m_thread_data.push_back(thread_data);
       thread_data = ThreadData();
       have_prstatus = false;
       have_prpsinfo = false;
     }
 
     switch (note.info.n_type) {
     case ELF::NT_PRSTATUS:
       have_prstatus = true;
-      ParseFreeBSDPrStatus(thread_data, note.data, GetArchitecture());
+      ParseFreeBSDPrStatus(thread_data, note.data, lp64);
       break;
     case ELF::NT_PRPSINFO:
       have_prpsinfo = true;
+      ParseFreeBSDPrPsInfo(*this, note.data, lp64);
       break;
     case ELF::NT_FREEBSD_THRMISC: {
       lldb::offset_t offset = 0;
       thread_data.name = note.data.GetCStr(&offset, 20);
       break;
     }
     case ELF::NT_FREEBSD_PROCSTAT_AUXV:
       // FIXME: FreeBSD sticks an int at the beginning of the note