Fixing newline escapes in lineinfile

Fixes #5679

library/files/lineinfile

@@ -18,6 +18,7 @@
 # You should have received a copy of the GNU General Public License
 # along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
 
+import pipes
 import re
 import os
 import tempfile
@@ -351,9 +352,14 @@ def main():
         if ins_bef is None and ins_aft is None:
             ins_aft = 'EOF'
 
-        # Replace the newline character with an actual newline. Don't replace
-		# escaped \\n, hence sub and not str.replace.
-        line = re.sub(r'\n', os.linesep, params['line'])
+        # Replace escape sequences like '\n' while being sure 
+        # not to replace octal escape sequences (\ooo) since they
+        # match the backref syntax
+        if backrefs:
+            line = re.sub(r'(\\[0-9]{1,3})', r'\\\1', params['line'])
+        else:
+            line = params['line']
+        line = module.safe_eval(pipes.quote(line))
 
         present(module, dest, params['regexp'], line,
                 ins_aft, ins_bef, create, backup, backrefs)

test/integration/roles/test_lineinfile/tasks/main.yml

@@ -114,7 +114,7 @@
     - "result.stat.md5 == 'd5955ee042139dfef16dbe3a7334475f'"
 
 - name: replace a line with backrefs
-  lineinfile: dest={{output_dir}}/test.txt state=present line="This is line 3" backrefs=yes regexp="^(REF) .* \1$"
+  lineinfile: dest={{output_dir}}/test.txt state=present line="This is line 3" backrefs=yes regexp="^(REF) .* \\1$"
   register: result
 
 - name: assert that the line with backrefs was changed
@@ -209,3 +209,40 @@
     that:
     - "result.stat.md5 == 'fef1d487711facfd7aa2c87d788c19d9'"
 
+- name: insert a multiple lines at the end of the file
+  lineinfile: dest={{output_dir}}/test.txt state=present line="This is a line\nwith \\\n character" insertafter="EOF"
+  register: result
+
+- name: assert that the multiple lines was inserted
+  assert:
+    that:
+    - "result.changed == true"
+    - "result.msg == 'line added'"
+
+- stat: path={{output_dir}}/test.txt
+  register: result
+
+- name: assert test md5 matches after insert the multiple lines
+  assert:
+    that:
+    - "result.stat.md5 == 'c2510d5bc8fdef8e752b8f8e74c784c2'"
+
+- name: replace a line with backrefs included in the line
+  lineinfile: dest={{output_dir}}/test.txt state=present line="New \\1 created with the backref" backrefs=yes regexp="^This is (line 4)$"
+  register: result
+
+- name: assert that the line with backrefs was changed
+  assert:
+    that:
+    - "result.changed == true"
+    - "result.msg == 'line replaced'"
+
+- name: stat the test after the backref line was replaced
+  stat: path={{output_dir}}/test.txt
+  register: result
+
+- name: assert test md5 matches after backref line was replaced
+  assert:
+    that:
+    - "result.stat.md5 == '65f955c2a9722fd43d07103d7756ff9b'"
+