Fixed issue-979 (backup file fails with relative paths) (#980)

src/tl/tl/tlFileUtils.cc

@@ -594,6 +594,14 @@ std::string current_dir ()
 #endif
 }
 
+bool chdir (const std::string &path)
+{
+#if defined(_WIN32)
+  return _wchdir (tl::to_wstring (path).c_str ()) == 0;
+#else
+  return ::chdir (tl::to_local (path).c_str ()) == 0;
+#endif
+}
 
 static std::pair<std::string, bool> absolute_path_of_existing (const std::string &s)
 {

src/tl/tl/tlFileUtils.h

@@ -170,6 +170,11 @@ std::string TL_PUBLIC combine_path (const std::string &p1, const std::string &p2
  */
 std::string TL_PUBLIC current_dir ();
 
+/**
+ *  @brief Change the current directory and returns true if the change was successful
+ */
+bool TL_PUBLIC chdir (const std::string &path);
+
 /**
  *  @brief This function splits the path into it's components
  *  On Windows, the first component may be the drive prefix ("C:") or

src/tl/tl/tlStream.cc

@@ -938,7 +938,7 @@ OutputFileBase::OutputFileBase (const std::string &path, int keep_backups)
       }
     }
     if (! m_backup_path.empty ()) {
-      if (! tl::rename_file (path, m_backup_path)) {
+      if (! tl::rename_file (path, tl::filename (m_backup_path))) {
         tl::warn << tl::sprintf (tl::to_string (tr ("Could not create backup file: unable to rename original file '%s' to backup file")), path, m_backup_path);
         m_backup_path = std::string ();
       }

src/tl/unit_tests/tlStreamTests.cc

@@ -260,6 +260,48 @@ TEST(SafeOutput)
   }
 }
 
+TEST(SafeOutput2)
+{
+  std::string cd = tl::current_dir ();
+  tl_assert (tl::chdir (tmp_file (".")));
+
+  try {
+
+    std::string tmp_path = "x";
+    tl::rm_dir_recursive (tmp_path);
+    tl::mkpath (tmp_path);
+    std::string tp = tl::combine_path (tmp_path, "y");
+
+    {
+      tl::OutputStream os (tp);
+      os << "blabla\n";
+    }
+
+    EXPECT_EQ (tl::file_exists (tp + ".~backup"), false);
+    EXPECT_EQ (tl::file_exists (tp), true);
+
+    {
+      tl::OutputStream os (tp);
+      EXPECT_EQ (tl::file_exists (tp + ".~backup"), true);
+      EXPECT_EQ (tl::file_exists (tp), true);
+      os << "Hello, world!\n";
+    }
+
+    EXPECT_EQ (tl::file_exists (tp + ".~backup"), false);
+    EXPECT_EQ (tl::file_exists (tp), true);
+
+    {
+      tl::InputStream is (tp);
+      EXPECT_EQ (is.read_all (), "Hello, world!\n");
+    }
+
+    tl::chdir (cd);
+
+  } catch (...) {
+    tl::chdir (cd);
+    throw;
+  }
+}
 
 TEST(Backups)
 {