shell/caucase.sh: Split file-or-folder detection from updateCACertificate.

So it can be reused elsewhere.

shell/caucase.sh

@@ -271,6 +271,28 @@ alias foreachCRL='_forEachPEM _matchCRLBoundary'
 # Iterate over CRLs of a PEM file, piping each to <command>
 # Usage: <command> [<arg> ...] < pem
 
+foreachCACertificate () {
+  # Iterate over CA certificates in given file or directory, piping each to
+  # <command>.
+  # Usage: <ca> <command> [<arg> ...]
+  # shellcheck disable=SC2039
+  local ca="$1" ca_file ca_is_file
+  shift
+  ca_is_file="$(_isFile "$ca")" || return
+  if [ "$ca_is_file" -eq 0 ]; then
+    for ca_file in "$ca"/*; do
+      # double use:
+      # - skips non-files
+      # - skips the one iteration when there is nothing in "$ca"/
+      if [ -f "$ca_file" ] && [ ! -h "$ca_file" ]; then
+        forEachCertificate "$@" < "$ca_file" || return
+      fi
+    done
+  elif [ -e "$ca" ]; then
+    forEachCertificate "$@" < "$ca" || return
+  fi
+}
+
 alias pem2fingerprint='openssl x509 -fingerprint -noout'
 
 pemFingerprintIs () {
@@ -300,6 +322,30 @@ printIfExpiresAfter () {
   printf '%s\n' "$crt" | expiresBefore "$1" || printf '%s\n' "$crt"
 }
 
+_isFile () {
+  # Prints 1 if given path either points at an existing file, or its basename
+  # contains a non-empty filename, followed by a "." and a non-empty extension.
+  # Otherwise, prints 0 and create given path as a directory (if it does not
+  # already exists).
+  # Returns 0 on success, anything else on error.
+  # Usage: <path>
+  if [ -e "$1" ]; then
+    if [ -f "$1" ]; then
+      echo 1
+    elif [ -d "$1" ]; then
+      echo 0
+    else
+      printf '%s exists and is neither a directory nor a file\n' "$1" 1>&2
+      return 1
+    fi
+  elif printf '%s\n' "$1" | grep -q '\(^\|/\)[^/]\+\.[^/]\+$'; then
+    echo 1
+  else
+    mkdir -p "$1" || return 1
+    echo 0
+  fi
+}
+
 storeCertBySerial () {
   # Store certificate in a file named after its serial, in given directory
   # and using given printf format string.
@@ -468,49 +514,15 @@ updateCACertificate () {
   local url="$1" \
     ca="$2" \
     future_ca \
-    status \
-    orig_ca="" \
+    orig_ca \
     ca_is_file \
     ca_file \
     valid_ca
-  if [ -e "$ca" ]; then
-    if [ -f "$ca" ]; then
-      ca_is_file=1
-      orig_ca="$(cat "$ca")"
-    elif [ -d "$ca" ]; then
-      ca_is_file=0
-    else
-      printf "%s exists and is neither a directory nor a file\n" "$ca"
-      return 1
-    fi
-  else
-    case "$ca" in
-      *.*)
-        ca_is_file=1
-        ;;
-      *)
-        mkdir "$ca"
-        ca_is_file=0
-        ;;
-    esac
-  fi
-  if [ $ca_is_file -eq 0 ]; then
-    for ca_file in "$ca"/*; do
-      # double use:
-      # - skips non-files
-      # - skips the one iteration when there is nothing in "$ca"/
-      if [ -f "$ca_file" ] && [ ! -h "$ca_file" ]; then
-        orig_ca="$( \
-          printf "%s\n%s" "$orig_ca" "$(cat "$ca_file")" \
-        )"
-      fi
-    done
-  fi
+  ca_is_file="$(_isFile "$ca")" || return
+  orig_ca="$(foreachCACertificate "$ca" cat)" || return
   if [ -z "$orig_ca" ]; then
-    orig_ca="$(_curlInsecure "$url/crt/ca.crt.pem")"
+    orig_ca="$(_curlInsecure "$url/crt/ca.crt.pem")" || return
   fi
-  status=$?
-  test $status -ne 0 && return 1
   valid_ca="$(
     printf '%s\n' "$orig_ca" \
     | forEachCertificate printIfExpiresAfter "$(date +%s)"