From 216aed2f87555453db815033e840835f9c7cc859 Mon Sep 17 00:00:00 2001
From: Tim Byrne <sultan@locehilios.com>
Date: Sun, 28 Feb 2021 10:55:37 -0600
Subject: [PATCH] Adjust special handling of existing read-only output files

Instead of duplicating the permissions on the temp file, the permissions
are duplicated on the output file directly. If the output file exists as
read-only, it is made writeable first.

There are some environments which don't allow the mv to work if the file
itself is read-only.
---
 test/test_unit_template_default.py |  6 ++++++
 test/test_unit_template_esh.py     |  6 ++++++
 test/test_unit_template_j2.py      |  6 ++++++
 yadm                               | 19 +++++++------------
 4 files changed, 25 insertions(+), 12 deletions(-)

diff --git a/test/test_unit_template_default.py b/test/test_unit_template_default.py
index 639cb29..ea2f904 100644
--- a/test/test_unit_template_default.py
+++ b/test/test_unit_template_default.py
@@ -127,6 +127,12 @@ def test_template_default(runner, yadm, tmpdir):
     input_file.chmod(FILE_MODE)
     output_file = tmpdir.join('output')
 
+    # ensure overwrite works when file exists as read-only (there is some
+    # special processing when this is encountered because some environments do
+    # not properly overwrite read-only files)
+    output_file.write('existing')
+    output_file.chmod(0o400)
+
     script = f"""
         YADM_TEST=1 source {yadm}
         set_awk
diff --git a/test/test_unit_template_esh.py b/test/test_unit_template_esh.py
index e975152..23766c4 100644
--- a/test/test_unit_template_esh.py
+++ b/test/test_unit_template_esh.py
@@ -86,6 +86,12 @@ def test_template_esh(runner, yadm, tmpdir):
     input_file.chmod(FILE_MODE)
     output_file = tmpdir.join('output')
 
+    # ensure overwrite works when file exists as read-only (there is some
+    # special processing when this is encountered because some environments do
+    # not properly overwrite read-only files)
+    output_file.write('existing')
+    output_file.chmod(0o400)
+
     script = f"""
         YADM_TEST=1 source {yadm}
         local_class="{LOCAL_CLASS}"
diff --git a/test/test_unit_template_j2.py b/test/test_unit_template_j2.py
index f81f4c6..981112b 100644
--- a/test/test_unit_template_j2.py
+++ b/test/test_unit_template_j2.py
@@ -88,6 +88,12 @@ def test_template_j2(runner, yadm, tmpdir, processor):
     input_file.chmod(FILE_MODE)
     output_file = tmpdir.join('output')
 
+    # ensure overwrite works when file exists as read-only (there is some
+    # special processing when this is encountered because some environments do
+    # not properly overwrite read-only files)
+    output_file.write('existing')
+    output_file.chmod(0o400)
+
     script = f"""
         YADM_TEST=1 source {yadm}
         local_class="{LOCAL_CLASS}"
diff --git a/yadm b/yadm
index 7ba9f2f..52aab3f 100755
--- a/yadm
+++ b/yadm
@@ -489,20 +489,15 @@ function move_file() {
   local output=$2
   local temp_file=$3
 
-  if [ ! -f "$temp_file" ] ; then
-    return 0
-  fi
+  [ ! -f "$temp_file" ] && return
+
+  # if the output files already exists as read-only, change it to be writable.
+  # there are some environments in which a read-only file will prevent the move
+  # from being successful.
+  [[ -e "$output" && ! -w "$output" ]] && chmod u+w "$output"
 
-  local read_only
-  copy_perms "$input" "$temp_file"
-  if [[ -e "$output" && ! -w "$output" ]]; then
-    read_only=1
-    chmod u+w "$output"
-  fi
   mv -f "$temp_file" "$output"
-  if [ -n "$read_only" ]; then
-    chmod u-w "$output"
-  fi
+  copy_perms "$input" "$output"
 }
 
 # ****** yadm Commands ******