From c1e2d8d3195ebce3d42cf5b771e4f85f16d5288d Mon Sep 17 00:00:00 2001
From: Konstantin Demin <rockdrilla@gmail.com>
Date: Tue, 16 Jul 2024 11:33:20 +0300
Subject: [PATCH] improve template expansion

---
 image-entry.d/53-expand-templates.sh | 19 +++++++++++---
 jinja2/j2common.py                   | 39 +++++++++++++++-------------
 scripts/j2-multi                     |  4 ++-
 scripts/j2-single                    |  4 ++-
 4 files changed, 43 insertions(+), 23 deletions(-)

diff --git a/image-entry.d/53-expand-templates.sh b/image-entry.d/53-expand-templates.sh
index df7acd3..2489088 100755
--- a/image-entry.d/53-expand-templates.sh
+++ b/image-entry.d/53-expand-templates.sh
@@ -1,8 +1,21 @@
 #!/bin/sh
-set -ef
+set -f
 
 . /image-entry.d/00-common.envsh
 
+[ "${NGX_STRICT_LOAD}" = 0 ] || set -e
+
+expand_error() {
+	[ "${expand_error_seen:-}" = 1 ] || log_always 'template expansion has failed'
+	expand_error_seen=1
+	if [ "${NGX_STRICT_LOAD}" = 1 ] ; then
+		t=10
+		log_always "injecting delay for $t seconds"
+		sleep $t
+		exit 1
+	fi
+}
+
 dirs='conf mod modules njs site snip'
 [ "${NGX_PROCESS_STATIC}" = 0 ] || dirs="${dirs} static"
 
@@ -10,8 +23,8 @@ for n in ${dirs} ; do
 	merged_dir="${merged_root}/$n"
 	[ -d "${merged_dir}" ] || continue
 
-	expand_dir_envsubst "${merged_dir}/"
-	expand_dir_jinja    "${merged_dir}/"
+	expand_dir_envsubst "${merged_dir}/" || expand_error
+	expand_dir_jinja    "${merged_dir}/" || expand_error
 done
 
 exit 0
diff --git a/jinja2/j2common.py b/jinja2/j2common.py
index 5a05177..09fd2d0 100755
--- a/jinja2/j2common.py
+++ b/jinja2/j2common.py
@@ -40,7 +40,7 @@ J2_KWARGS = {}
 
 
 def merge_dict_from_file(filename):
-    if (not filename) or (filename == ''):
+    if (not filename) or (str(filename) == ''):
         return False
     if not os.path.exists(filename):
         return False
@@ -81,7 +81,7 @@ def render_error(msg, fail=True) -> bool:
 
 
 def render_file(file_in, file_out=None, fail=True):
-    if (not file_in) or (file_in == ''):
+    if (not file_in) or (str(file_in) == ''):
         return render_error(
             'argument "file_in" is empty',
             fail)
@@ -94,24 +94,14 @@ def render_file(file_in, file_out=None, fail=True):
             f'not a file: {file_in}',
             fail)
 
-    if file_out:
-        if str(file_in) == str(file_out):
-            return render_error(
-                f'unable to process template inplace: {file_in}',
-                fail)
-        f_out = file_out
-    else:
+    f_out = file_out
+    if not f_out:
         if not file_in.endswith(J2_SUFFIX):
             return render_error(
                 f'input file name extension mismatch: {file_in}',
                 fail)
         f_out = os.path.splitext(file_in)[0]
 
-    if os.path.exists(f_out):
-        return render_error(
-            f'output file already exists: {f_out}',
-            fail)
-
     dirs = J2_SEARCH_PATH.copy()
     for d in [os.path.dirname(file_in), os.getcwd()]:
         if d not in dirs:
@@ -132,16 +122,29 @@ def render_file(file_in, file_out=None, fail=True):
     j2_template = j2_environ.get_template(file_in)
     j2_stream = j2_template.stream(**J2_KWARGS)
     j2_stream.disable_buffering()
+
+    if os.path.lexists(f_out):
+        if os.path.islink(f_out) or (not os.path.isfile(f_out)):
+            return render_error(
+                f'output file is not safely writable: {f_out}',
+                fail)
+    if os.path.exists(f_out):
+        if os.path.samefile(file_in, f_out):
+            return render_error(
+                f'unable to process template inplace: {file_in}',
+                fail)
     j2_stream.dump(f_out, encoding='utf-8')
     return True
 
 
 def init():
-    global J2_KWARGS
+    kwa = {}
     for m in J2_MODULES:
-        J2_KWARGS[m] = importlib.import_module(m)
-    J2_KWARGS['env'] = os.environ
-    J2_KWARGS['cfg'] = {}
+        kwa[m] = importlib.import_module(m)
+    kwa['env'] = os.environ
+    kwa['cfg'] = {}
+    global J2_KWARGS
+    J2_KWARGS = kwa
 
     if J2_CONFIG != '':
         if os.path.isfile(J2_CONFIG):
diff --git a/scripts/j2-multi b/scripts/j2-multi
index 4970288..4bfcbb8 100755
--- a/scripts/j2-multi
+++ b/scripts/j2-multi
@@ -1,6 +1,8 @@
 #!/bin/sh
 [ "${IEP_VERBOSE}" = 0 ] || {
-	echo "Running ${0##*/}:" >&2
+	pfx=
+	[ "${IEP_TRACE}" = 0 ] || pfx="$(date +'%Y-%m-%d %H:%M:%S.%03N %z'): "
+	echo "# ${pfx}${0##*/}:" >&2
 	printf ' - %s\n' "$@" >&2
 }
 exec python3 "/usr/local/lib/jinja2/${0##*/}.py" "$@"
\ No newline at end of file
diff --git a/scripts/j2-single b/scripts/j2-single
index 45907e2..076b5a7 100755
--- a/scripts/j2-single
+++ b/scripts/j2-single
@@ -1,5 +1,7 @@
 #!/bin/sh
 [ "${IEP_VERBOSE}" = 0 ] || {
-	echo "Running ${0##*/}: $*" >&2
+	pfx=
+	[ "${IEP_TRACE}" = 0 ] || pfx="$(date +'%Y-%m-%d %H:%M:%S.%03N %z'): "
+	echo "# ${pfx}${0##*/}:${*:+ $*}" >&2
 }
 exec python3 "/usr/local/lib/jinja2/${0##*/}.py" "$@"
\ No newline at end of file