2 files changed, 116 insertions, 1 deletions

diff --git a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
index 084aa3886b6..841d5405e1a 100644
--- a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
+++ b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.cpp
@@ -38,7 +38,8 @@ using namespace lldb_private;
 //------------------------------------------------------------------
 PlatformDarwin::PlatformDarwin (bool is_host) :
     PlatformPOSIX(is_host),  // This is the local host platform
-    m_developer_directory ()
+    m_developer_directory (),
+    m_dispatch_queue_offsets_addr (LLDB_INVALID_ADDRESS)
 {
 }
 
@@ -847,6 +848,113 @@ PlatformDarwin::ModuleIsExcludedForNonModuleSpecificSearches (lldb_private::Targ
         return false;
 }
 
+std::string
+PlatformDarwin::GetQueueNameForThreadQAddress (Process *process, addr_t thread_dispatch_qaddr)
+{
+    std::string dispatch_queue_name;
+    if (thread_dispatch_qaddr == LLDB_INVALID_ADDRESS || thread_dispatch_qaddr == 0 || process == NULL)
+        return "";
+
+    Target &target = process->GetTarget();
+
+    // Cache the dispatch_queue_offsets_addr value so we don't always have
+    // to look it up
+    if (m_dispatch_queue_offsets_addr == LLDB_INVALID_ADDRESS)
+    {
+        static ConstString g_dispatch_queue_offsets_symbol_name ("dispatch_queue_offsets");
+        const Symbol *dispatch_queue_offsets_symbol = NULL;
+
+        // libdispatch symbols were in libSystem.B.dylib up through Mac OS X 10.6 ("Snow Leopard")
+        ModuleSpec libSystem_module_spec (FileSpec("libSystem.B.dylib", false));
+        ModuleSP module_sp(target.GetImages().FindFirstModule (libSystem_module_spec));
+        if (module_sp)
+            dispatch_queue_offsets_symbol = module_sp->FindFirstSymbolWithNameAndType (g_dispatch_queue_offsets_symbol_name, eSymbolTypeData);
+        
+        // libdispatch symbols are in their own dylib as of Mac OS X 10.7 ("Lion") and later
+        if (dispatch_queue_offsets_symbol == NULL)
+        {
+            ModuleSpec libdispatch_module_spec (FileSpec("libdispatch.dylib", false));
+            module_sp = target.GetImages().FindFirstModule (libdispatch_module_spec);
+            if (module_sp)
+                dispatch_queue_offsets_symbol = module_sp->FindFirstSymbolWithNameAndType (g_dispatch_queue_offsets_symbol_name, eSymbolTypeData);
+        }
+        if (dispatch_queue_offsets_symbol)
+            m_dispatch_queue_offsets_addr = dispatch_queue_offsets_symbol->GetAddress().GetLoadAddress(&target);
+
+        if (m_dispatch_queue_offsets_addr == LLDB_INVALID_ADDRESS)
+            return "";
+    }
+
+    uint8_t memory_buffer[8];
+    DataExtractor data (memory_buffer, 
+                        sizeof(memory_buffer), 
+                        target.GetArchitecture().GetByteOrder(), 
+                        target.GetArchitecture().GetAddressByteSize());
+
+    // Excerpt from src/queue_private.h
+    // version 4 of this struct first appears in Mac OS X 10.9 ("Mavericks") and iOS 7.
+    // TODO When version 1-3 no longer needs to be supported, the dqo_label offset should be
+    // read from the inferior one time and saved in an ivar like m_dispatch_queue_offsets_addr.
+    struct dispatch_queue_offsets_s
+    {
+        uint16_t dqo_version;
+        uint16_t dqo_label;      // in version 1-3, offset to string; in version 4+, offset to a pointer to a string
+        uint16_t dqo_label_size; // in version 1-3, length of string; in version 4+, size of a (void*) in this process
+    } dispatch_queue_offsets;
+
+    Error error;
+    if (process->ReadMemory (m_dispatch_queue_offsets_addr, memory_buffer, sizeof(dispatch_queue_offsets), error) == sizeof(dispatch_queue_offsets))
+    {
+        lldb::offset_t data_offset = 0;
+        if (data.GetU16(&data_offset, &dispatch_queue_offsets.dqo_version, sizeof(dispatch_queue_offsets)/sizeof(uint16_t)))
+        {
+            if (process->ReadMemory (thread_dispatch_qaddr, &memory_buffer, data.GetAddressByteSize(), error) == data.GetAddressByteSize())
+            {
+                data_offset = 0;
+                lldb::addr_t queue_addr = data.GetAddress(&data_offset);
+                if (dispatch_queue_offsets.dqo_version >= 4)
+                {
+                    // libdispatch versions 4+, pointer to dispatch name is in the 
+                    // queue structure.
+                    lldb::addr_t pointer_to_label_address = queue_addr + dispatch_queue_offsets.dqo_label;
+                    if (process->ReadMemory (pointer_to_label_address, &memory_buffer, data.GetAddressByteSize(), error) == data.GetAddressByteSize())
+                    {
+                        data_offset = 0;
+                        lldb::addr_t label_addr = data.GetAddress(&data_offset);
+                        process->ReadCStringFromMemory (label_addr, dispatch_queue_name, error);
+                    }
+                }
+                else
+                {
+                    // libdispatch versions 1-3, dispatch name is a fixed width char array
+                    // in the queue structure.
+                    lldb::addr_t label_addr = queue_addr + dispatch_queue_offsets.dqo_label;
+                    dispatch_queue_name.resize(dispatch_queue_offsets.dqo_label_size, '\0');
+                    size_t bytes_read = process->ReadMemory (label_addr, &dispatch_queue_name[0], dispatch_queue_offsets.dqo_label_size, error);
+                    if (bytes_read < dispatch_queue_offsets.dqo_label_size)
+                        dispatch_queue_name.erase (bytes_read);
+                }
+            }
+        }
+    }
+    return dispatch_queue_name;
+}
+
+lldb::queue_id_t
+PlatformDarwin::GetQueueIDForThreadQAddress (Process *process, lldb::addr_t dispatch_qaddr)
+{
+    if (dispatch_qaddr == LLDB_INVALID_ADDRESS || dispatch_qaddr == 0 || process == NULL)
+        return LLDB_INVALID_QUEUE_ID;
+
+    Error error;
+    uint32_t ptr_size = process->GetTarget().GetArchitecture().GetAddressByteSize();
+    uint64_t this_thread_queue_id = process->ReadUnsignedIntegerFromMemory (dispatch_qaddr, ptr_size, LLDB_INVALID_QUEUE_ID, error);
+    if (!error.Success())
+        return LLDB_INVALID_QUEUE_ID;
+
+    return this_thread_queue_id;
+}
+
 
 bool
 PlatformDarwin::x86GetSupportedArchitectureAtIndex (uint32_t idx, ArchSpec &arch)
diff --git a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.h b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.h
index 4e9b7029b51..64598c93f6b 100644
--- a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.h
+++ b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwin.h
@@ -111,6 +111,12 @@ public:
     virtual size_t
     GetEnvironment (lldb_private::StringList &environment);
 
+    std::string
+    GetQueueNameForThreadQAddress (lldb_private::Process *process, lldb::addr_t dispatch_qaddr);
+
+    lldb::queue_id_t
+    GetQueueIDForThreadQAddress (lldb_private::Process *process, lldb::addr_t dispatch_qaddr);
+
     bool
     ARMGetSupportedArchitectureAtIndex (uint32_t idx, lldb_private::ArchSpec &arch);
     
@@ -129,6 +135,7 @@ protected:
                                    bool *did_create_ptr);
 
     std::string m_developer_directory;
+    lldb::addr_t m_dispatch_queue_offsets_addr;
     
     const char *
     GetDeveloperDirectory();