Support for truncate/append on log files

Summary:
Presently, if a log file already exists, lldb simply starts overwriting bits of it, without
truncating or anything. This patch makes it use eFileOptionFileTruncate by default. It also adds
an --append option, which will append to the file without truncating. A test is included.

Reviewers: clayborg

Subscribers: lldb-commits

Differential Revision: http://reviews.llvm.org/D8450

llvm-svn: 232801

1 files changed, 6 insertions, 1 deletions

diff --git a/lldb/source/Core/Debugger.cpp b/lldb/source/Core/Debugger.cpp
index f93da0eb5cd..7134d418ead 100644
--- a/lldb/source/Core/Debugger.cpp
+++ b/lldb/source/Core/Debugger.cpp
@@ -1331,7 +1331,12 @@ Debugger::EnableLog (const char *channel, const char **categories, const char *l
             log_stream_sp = pos->second.lock();
         if (!log_stream_sp)
         {
-            log_stream_sp.reset (new StreamFile (log_file));
+            uint32_t options = File::eOpenOptionWrite | File::eOpenOptionCanCreate
+                                | File::eOpenOptionCloseOnExec | File::eOpenOptionAppend;
+            if (! (log_options & LLDB_LOG_OPTION_APPEND))
+                options |= File::eOpenOptionTruncate;
+
+            log_stream_sp.reset (new StreamFile (log_file, options));
             m_log_streams[log_file] = log_stream_sp;
         }
     }