Avoid crashing by not mmap'ing files on network mounted file systems.

This is implemented by making a new FileSystem function:

bool
FileSystem::IsLocal(const FileSpec &spec)

Then using this in a new function:

DataBufferSP
FileSpec::MemoryMapFileContentsIfLocal(off_t file_offset, size_t file_size) const;

This function only mmaps data if the file is a local file since that means we can reliably page in data. We were experiencing crashes where people would use debug info files on network mounted file systems and that mount would go away and cause the next access to a page that wasn't paged in to crash LLDB. 

We now avoid this by just copying the data into a heap buffer and keeping a permanent copy to avoid the crash. Updated all previous users of FileSpec::MemoryMapFileContentsIfLocal() in ObjectFile subclasses over to use the new FileSpec::MemoryMapFileContentsIfLocal() function.

<rdar://problem/19470249>

llvm-svn: 230283

1 files changed, 5 insertions, 5 deletions

diff --git a/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp b/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
index ec14450c4b8..7b49daa59ab 100644
--- a/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
+++ b/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
@@ -931,7 +931,7 @@ ObjectFileMachO::CreateInstance (const lldb::ModuleSP &module_sp,
 {
     if (!data_sp)
     {
-        data_sp = file->MemoryMapFileContents(file_offset, length);
+        data_sp = file->MemoryMapFileContentsIfLocal(file_offset, length);
         data_offset = 0;
     }
 
@@ -940,7 +940,7 @@ 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 = file->MemoryMapFileContents(file_offset, length);
+            data_sp = file->MemoryMapFileContentsIfLocal(file_offset, length);
             data_offset = 0;
         }
         std::unique_ptr<ObjectFile> objfile_ap(new ObjectFileMachO (module_sp, data_sp, data_offset, file, file_offset, length));
@@ -2650,7 +2650,7 @@ ObjectFileMachO::ParseSymtab ()
             // Save some VM space, do not map the entire cache in one shot.
 
             DataBufferSP dsc_data_sp;
-            dsc_data_sp = dsc_filespec.MemoryMapFileContents(0, sizeof(struct lldb_copy_dyld_cache_header_v1));
+            dsc_data_sp = dsc_filespec.MemoryMapFileContentsIfLocal(0, sizeof(struct lldb_copy_dyld_cache_header_v1));
 
             if (dsc_data_sp)
             {
@@ -2704,7 +2704,7 @@ ObjectFileMachO::ParseSymtab ()
                 if (uuid_match && mappingOffset >= sizeof(struct lldb_copy_dyld_cache_header_v0))
                 {
 
-                    DataBufferSP dsc_mapping_info_data_sp = dsc_filespec.MemoryMapFileContents(mappingOffset, sizeof (struct lldb_copy_dyld_cache_mapping_info));
+                    DataBufferSP dsc_mapping_info_data_sp = dsc_filespec.MemoryMapFileContentsIfLocal(mappingOffset, sizeof (struct lldb_copy_dyld_cache_mapping_info));
                     DataExtractor dsc_mapping_info_data(dsc_mapping_info_data_sp, byte_order, addr_byte_size);
                     offset = 0;
 
@@ -2721,7 +2721,7 @@ ObjectFileMachO::ParseSymtab ()
                     if (localSymbolsOffset && localSymbolsSize)
                     {
                         // Map the local symbols
-                        if (DataBufferSP dsc_local_symbols_data_sp = dsc_filespec.MemoryMapFileContents(localSymbolsOffset, localSymbolsSize))
+                        if (DataBufferSP dsc_local_symbols_data_sp = dsc_filespec.MemoryMapFileContentsIfLocal(localSymbolsOffset, localSymbolsSize))
                         {
                             DataExtractor dsc_local_symbols_data(dsc_local_symbols_data_sp, byte_order, addr_byte_size);