From b74279d14c10a19431bbac7a559678f070a732e6 Mon Sep 17 00:00:00 2001
From: Sam Doran <sdoran@redhat.com>
Date: Wed, 3 Oct 2018 17:27:34 -0400
Subject: [PATCH] Use proper index value with insertbefore on a one line file
 (#46071)

Add tests and changelog
---
 ...nfile-insertbefore-index-out-of-range.yaml |  2 ++
 lib/ansible/modules/files/lineinfile.py       |  2 +-
 .../targets/lineinfile/tasks/main.yml         | 31 +++++++++++++++++++
 3 files changed, 34 insertions(+), 1 deletion(-)
 create mode 100644 changelogs/fragments/lineinfile-insertbefore-index-out-of-range.yaml

diff --git a/changelogs/fragments/lineinfile-insertbefore-index-out-of-range.yaml b/changelogs/fragments/lineinfile-insertbefore-index-out-of-range.yaml
new file mode 100644
index 0000000000..52d4565fea
--- /dev/null
+++ b/changelogs/fragments/lineinfile-insertbefore-index-out-of-range.yaml
@@ -0,0 +1,2 @@
+bugfixes:
+  - lineinfile - fix index out of range error when using insertbefore on a file with only one line (https://github.com/ansible/ansible/issues/46043)
diff --git a/lib/ansible/modules/files/lineinfile.py b/lib/ansible/modules/files/lineinfile.py
index 8469b76df0..00c45eb70a 100644
--- a/lib/ansible/modules/files/lineinfile.py
+++ b/lib/ansible/modules/files/lineinfile.py
@@ -333,7 +333,7 @@ def present(module, dest, regexp, line, insertafter, insertbefore, create,
             elif insertbefore and insertbefore != 'BOF':
                 # If the line to insert before is at the beginning of the file
                 # use the appropriate index value.
-                if index[1] == 0:
+                if index[1] <= 0:
                     if b_lines[index[1]].rstrip(b('\r\n')) != b_line:
                         b_lines.insert(index[1], b_line + b_linesep)
                         msg = 'line replaced'
diff --git a/test/integration/targets/lineinfile/tasks/main.yml b/test/integration/targets/lineinfile/tasks/main.yml
index e9c76c4aef..680394f426 100644
--- a/test/integration/targets/lineinfile/tasks/main.yml
+++ b/test/integration/targets/lineinfile/tasks/main.yml
@@ -718,6 +718,37 @@
     that:
       - result.stat.checksum == 'eca8d8ea089d4ea57a3b87d4091599ca8b60dfd2'
 
+- name: Copy empty file to test with insertbefore
+  copy:
+    src: testempty.txt
+    dest: "{{ output_dir }}/testempty.txt"
+
+- name: Add a line to empty file with insertbefore
+  lineinfile:
+    path: "{{ output_dir }}/testempty.txt"
+    line: top
+    insertbefore: '^not in the file$'
+  register: oneline_insbefore_test1
+
+- name: Add a line to file with only one line using insertbefore
+  lineinfile:
+    path: "{{ output_dir }}/testempty.txt"
+    line: top
+    insertbefore: '^not in the file$'
+  register: oneline_insbefore_test2
+
+- name: Stat the file
+  stat:
+    path:  "{{ output_dir }}/testempty.txt"
+  register: oneline_insbefore_file
+
+- name: Assert that insertebefore worked properly with a one line file
+  assert:
+    that:
+      - oneline_insbefore_test1 is changed
+      - oneline_insbefore_test2 is not changed
+      - oneline_insbefore_file.stat.checksum == '4dca56d05a21f0d018cd311f43e134e4501cf6d9'
+
 ###################################################################
 # Issue 29443
 # When using an empty regexp, replace the last line (since it matches every line)