elf-core: Document offset constants in FreeBSD prstatus parser

Also accomodate struct padding based on arch, for later i386 work.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@187040 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 20 insertions, 6 deletions

diff --git a/source/Plugins/Process/elf-core/ProcessElfCore.cpp b/source/Plugins/Process/elf-core/ProcessElfCore.cpp
index bfc68a633..a73a1d645 100644
--- a/source/Plugins/Process/elf-core/ProcessElfCore.cpp
+++ b/source/Plugins/Process/elf-core/ProcessElfCore.cpp
@@ -435,17 +435,31 @@ struct ELFNote
     }
 };
 
+// Parse a FreeBSD NT_PRSTATUS note - see FreeBSD sys/procfs.h for details.
 static void
 ParseFreeBSDPrStatus(ThreadData *thread_data, DataExtractor &data,
                      ArchSpec &arch)
 {
-    lldb::offset_t offset;
-    size_t len;
+    lldb::offset_t offset = 0;
+    bool have_padding = (arch.GetMachine() == llvm::Triple::x86_64);
+    int pr_version = data.GetU32(&offset);
+
+    Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
+    if (log)
+    {
+        if (pr_version > 1)
+            log->Printf("FreeBSD PRSTATUS unexpected version %d", pr_version);
+    }
 
-    offset = 36;
-    thread_data->signo = data.GetU32(&offset);
-    offset = 48;
-    len = data.GetByteSize() - offset;
+    if (have_padding)
+        offset += 4;
+    offset += 28;       // pr_statussz, pr_gregsetsz, pr_fpregsetsz, pr_osreldate
+    thread_data->signo = data.GetU32(&offset); // pr_cursig
+    offset += 4;        // pr_pid
+    if (have_padding)
+        offset += 4;
+    
+    size_t len = data.GetByteSize() - offset;
     thread_data->gpregset = DataExtractor(data, offset, len);
 }