[lldb] Fix write only file action to truncate the file

Author: kusmour

lldb/source/Host/common/FileAction.cpp

@@ -41,7 +41,7 @@ bool FileAction::Open(int fd, const FileSpec &file_spec, bool read,
     else if (read)
       m_arg = O_NOCTTY | O_RDONLY;
     else
-      m_arg = O_NOCTTY | O_CREAT | O_WRONLY;
+      m_arg = O_NOCTTY | O_CREAT | O_WRONLY | O_TRUNC;
     m_file_spec = file_spec;
     return true;
   } else {

lldb/unittests/Host/FileActionTest.cpp

@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include <fcntl.h>
+
 #include "lldb/Host/FileAction.h"
 #include "gtest/gtest.h"
 
@@ -17,3 +19,25 @@ TEST(FileActionTest, Open) {
   EXPECT_EQ(Action.GetAction(), FileAction::eFileActionOpen);
   EXPECT_EQ(Action.GetFileSpec(), FileSpec("/tmp"));
 }
+
+TEST(FileActionTest, OpenReadWrite) {
+  FileAction Action;
+  Action.Open(48, FileSpec("/tmp_0"), /*read*/ true, /*write*/ true);
+  EXPECT_TRUE(Action.GetActionArgument() & (O_NOCTTY | O_CREAT | O_RDWR));
+  EXPECT_FALSE(Action.GetActionArgument() & O_RDONLY);
+  EXPECT_FALSE(Action.GetActionArgument() & O_WRONLY);
+}
+
+TEST(FileActionTest, OpenReadOnly) {
+  FileAction Action;
+  Action.Open(49, FileSpec("/tmp_1"), /*read*/ true, /*write*/ false);
+  EXPECT_TRUE(Action.GetActionArgument() & (O_NOCTTY | O_RDONLY));
+  EXPECT_FALSE(Action.GetActionArgument() & O_WRONLY);
+}
+
+TEST(FileActionTest, OpenWriteOnly) {
+  FileAction Action;
+  Action.Open(50, FileSpec("/tmp_2"), /*read*/ false, /*write*/ true);
+  EXPECT_TRUE(Action.GetActionArgument() & (O_NOCTTY | O_CREAT | O_WRONLY | O_TRUNC));
+  EXPECT_FALSE(Action.GetActionArgument() & O_RDONLY);
+}