conf.sh: Allow load_conf to take an absolute filepath

This is useful in dbscripts.

This also has a couple of happy side-effects in the implementation
details
 - list_files and list_envvars are now only called once each
 - we now do save readarray-based splitting of list_files and list_envvars
   output

2 files changed, 32 insertions, 20 deletions

diff --git a/src/lib/conf.sh.3.ronn b/src/lib/conf.sh.3.ronn
index c17a3ee..fee0529 100644
--- a/src/lib/conf.sh.3.ronn
+++ b/src/lib/conf.sh.3.ronn
@@ -47,14 +47,18 @@ configuration files; that is the basename of the files.  For example,
 
 The routines you will likely actually use are:
 
-   * `load_conf` <SLUG>.conf <VARS>...:
+   * `load_conf` {<SLUG>.conf|<ABSPATH>} <VARS>...:
      Loads the configuration files for <SLUG>, loading the files in
      the correct order, and checking the appropriate environmental
-     variables.  If any <VARS> are listed, check to make sure that
-     each of them are defined.  If any of them are not defined, it
-     prints a message telling the user to configure them in the
-     configuration files for <SLUG>, and returns with a non-zero
-     status.
+     variables.  Alternatively, instead of giving a <SLUG>, you may
+     give an absolute filepath to a configuration file (bypassing
+     `list_files`, see below) which will be loaded with no
+     environmental overrides (bypassing `list_envvars`, see below).
+
+     If any <VARS> are listed, check to make sure that each of them
+     are defined.  If any of them are not defined, it prints a message
+     telling the user to configure them in the appropriate files, and
+     returns with a non-zero status.
    * `get_var` <SLUG> <VAR> <DEFAULT>:
      If <VAR> is set in the configuration for <SLUG>, print its
      value, considering environmental variables.  If it is not set,
diff --git a/src/lib/conf.sh.in b/src/lib/conf.sh.in
index 15666a6..0ff88f9 100644
--- a/src/lib/conf.sh.in
+++ b/src/lib/conf.sh.in
@@ -107,43 +107,51 @@ list_envvars() {
 
 # High-level generic functions #################################################
 
-# Usage: load_conf $slug.conf [VAR1 VAR2...]
+# Usage: load_conf {$slug.conf|$abspath} [VAR1 VAR2...]
 #
 # Loads the configuration files for $slug in the proper order, and
 # optionally verify that certain variables are set.
 load_conf() {
-	[[ "$1" = *.conf ]] || libremessages panic || exit 1 # $EXIT_FAILURE
-	local slug=${1%.conf}
-	shift
-
+	[[ $1 = /* || $1 = *.conf ]] || libremessages panic || exit 1 # $EXIT_FAILURE
+	local files envvars
+	if [[ $1 = /* ]]; then
+		files=("$1")
+		envvars=()
+		shift
+	else
+		local slug=${1%.conf}
+		shift
+		readarray -t files   < <(list_files   "$slug")
+		readarray -t envvars < <(list_envvars "$slug")
+	fi
 	local var file
 
 	# Save the existing versions at _VARNAME
-	while read -r var; do
+	for var in "${envvars[@]}"; do
 		[[ -n ${!var:-} ]] && eval "local _$var=\${$var}"
-	done < <(list_envvars "$slug")
+	done
 
 	# Load the files
-	while read -r file; do
+	for file in "${files[@]}"; do
 		if [[ -r $file ]]; then
 			. "$file" || return 6 # $EXIT_NOTCONFIGURED
 		fi
-	done < <(list_files "$slug")
+	done
 
 	# Restore the _SAVED versions
-	while read -r var; do
+	for var in "${envvars[@]}"; do
 		eval "$var=\${_$var:-\${$var:-}}"
-	done < <(list_envvars "$slug")
+	done
 
 	# Verify that the variables we need were set
 	declare -i ret=0 # $EXIT_SUCCESS
 	for var in "$@"; do
 		if [[ -z ${!var:-} ]]; then
-			if [[ $(list_files "$slug"|wc -l) -gt 1 ]]; then
+			if [[ ${#files[@]} -gt 1 ]]; then
 				libremessages _l print "Configure '%s' in one of:" "$var"
-				list_files "$slug" | sed 's/./  -> &/'
+				printf '  -> %s\n' "${files[@]}"
 			else
-				libremessages _l print "Configure '%s' in '%s'" "$var" "$(list_files "$slug")"
+				libremessages _l print "Configure '%s' in '%s'" "$var" "${files[0]}"
 			fi
 			ret=6 # $EXIT_NOTCONFIGURED
 		fi