Make sure DataBufferLLVM contents are writable

Summary:
We sometimes need to write to the object file we've mapped into memory,
generally to apply relocations to debug info sections. We've had that
ability before, but with the introduction of DataBufferLLVM, we have
lost it, as the underlying llvm class (MemoryBuffer) only supports
read-only mappings.

This switches DataBufferLLVM to use the new llvm::WritableMemoryBuffer
class as a back-end, as this one guarantees to return a writable buffer.

This removes the need for the "Private" flag to the DataBufferLLVM
creation functions, as it was really used to mean "writable". The LLVM
function also does not have the NullTerminate flag, so I've modified our
clients to not require this feature and removed that flag as well.

Reviewers: zturner, clayborg, jingham

Subscribers: emaste, aprantl, arichardson, krytarowski, lldb-commits

Differential Revision: https://reviews.llvm.org/D40079

llvm-svn: 321255

1 files changed, 13 insertions, 23 deletions

diff --git a/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp b/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
index df334f88ee3..e6941c9f6ed 100644
--- a/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
+++ b/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
@@ -38,7 +38,7 @@
 #include "lldb/Target/Thread.h"
 #include "lldb/Target/ThreadList.h"
 #include "lldb/Utility/ArchSpec.h"
-#include "lldb/Utility/DataBufferLLVM.h"
+#include "lldb/Utility/DataBuffer.h"
 #include "lldb/Utility/FileSpec.h"
 #include "lldb/Utility/Log.h"
 #include "lldb/Utility/Status.h"
@@ -862,8 +862,7 @@ ObjectFile *ObjectFileMachO::CreateInstance(const lldb::ModuleSP &module_sp,
                                             lldb::offset_t file_offset,
                                             lldb::offset_t length) {
   if (!data_sp) {
-    data_sp =
-        DataBufferLLVM::CreateSliceFromPath(file->GetPath(), length, file_offset);
+    data_sp = MapFileData(*file, length, file_offset);
     if (!data_sp)
       return nullptr;
     data_offset = 0;
@@ -874,8 +873,7 @@ ObjectFile *ObjectFileMachO::CreateInstance(const lldb::ModuleSP &module_sp,
 
   // Update the data to contain the entire file if it doesn't already
   if (data_sp->GetByteSize() < length) {
-    data_sp =
-        DataBufferLLVM::CreateSliceFromPath(file->GetPath(), length, file_offset);
+    data_sp = MapFileData(*file, length, file_offset);
     if (!data_sp)
       return nullptr;
     data_offset = 0;
@@ -914,8 +912,7 @@ size_t ObjectFileMachO::GetModuleSpecifications(
       size_t header_and_load_cmds =
           header.sizeofcmds + MachHeaderSizeFromMagic(header.magic);
       if (header_and_load_cmds >= data_sp->GetByteSize()) {
-        data_sp = DataBufferLLVM::CreateSliceFromPath(
-            file.GetPath(), header_and_load_cmds, file_offset);
+        data_sp = MapFileData(file, header_and_load_cmds, file_offset);
         data.SetData(data_sp);
         data_offset = MachHeaderSizeFromMagic(header.magic);
       }
@@ -1127,8 +1124,7 @@ bool ObjectFileMachO::ParseHeader() {
                   ReadMemory(process_sp, m_memory_addr, header_and_lc_size);
             } else {
               // Read in all only the load command data from the file on disk
-              data_sp = DataBufferLLVM::CreateSliceFromPath(
-                  m_file.GetPath(), header_and_lc_size, m_file_offset);
+              data_sp = MapFileData(m_file, header_and_lc_size, m_file_offset);
               if (data_sp->GetByteSize() != header_and_lc_size)
                 return false;
             }
@@ -2100,9 +2096,8 @@ UUID ObjectFileMachO::GetSharedCacheUUID(FileSpec dyld_shared_cache,
                                          const ByteOrder byte_order,
                                          const uint32_t addr_byte_size) {
   UUID dsc_uuid;
-  DataBufferSP DscData = DataBufferLLVM::CreateSliceFromPath(
-      dyld_shared_cache.GetPath(),
-      sizeof(struct lldb_copy_dyld_cache_header_v1), 0);
+  DataBufferSP DscData = MapFileData(
+      dyld_shared_cache, sizeof(struct lldb_copy_dyld_cache_header_v1), 0);
   if (!DscData)
     return dsc_uuid;
   DataExtractor dsc_header_data(DscData, byte_order, addr_byte_size);
@@ -2708,9 +2703,8 @@ size_t ObjectFileMachO::ParseSymtab() {
 
       // Process the dyld shared cache header to find the unmapped symbols
 
-      DataBufferSP dsc_data_sp = DataBufferLLVM::CreateSliceFromPath(
-          dsc_filespec.GetPath(), sizeof(struct lldb_copy_dyld_cache_header_v1),
-          0);
+      DataBufferSP dsc_data_sp = MapFileData(
+          dsc_filespec, sizeof(struct lldb_copy_dyld_cache_header_v1), 0);
       if (!dsc_uuid.IsValid()) {
         dsc_uuid = GetSharedCacheUUID(dsc_filespec, byte_order, addr_byte_size);
       }
@@ -2742,11 +2736,9 @@ size_t ObjectFileMachO::ParseSymtab() {
         if (uuid_match &&
             mappingOffset >= sizeof(struct lldb_copy_dyld_cache_header_v1)) {
 
-          DataBufferSP dsc_mapping_info_data_sp =
-              DataBufferLLVM::CreateSliceFromPath(
-                  dsc_filespec.GetPath(),
-                  sizeof(struct lldb_copy_dyld_cache_mapping_info),
-                  mappingOffset);
+          DataBufferSP dsc_mapping_info_data_sp = MapFileData(
+              dsc_filespec, sizeof(struct lldb_copy_dyld_cache_mapping_info),
+              mappingOffset);
 
           DataExtractor dsc_mapping_info_data(dsc_mapping_info_data_sp,
                                               byte_order, addr_byte_size);
@@ -2770,9 +2762,7 @@ size_t ObjectFileMachO::ParseSymtab() {
           if (localSymbolsOffset && localSymbolsSize) {
             // Map the local symbols
             DataBufferSP dsc_local_symbols_data_sp =
-                DataBufferLLVM::CreateSliceFromPath(dsc_filespec.GetPath(),
-                                               localSymbolsSize,
-                                               localSymbolsOffset);
+                MapFileData(dsc_filespec, localSymbolsSize, localSymbolsOffset);
 
             if (dsc_local_symbols_data_sp) {
               DataExtractor dsc_local_symbols_data(dsc_local_symbols_data_sp,