improve error reporting

1 files changed, 28 insertions, 25 deletions

diff --git a/wordpress/export-json.bash b/wordpress/export-json.bash
index f146c19..714946e 100644
--- a/wordpress/export-json.bash
+++ b/wordpress/export-json.bash
@@ -65,34 +65,33 @@
 arg1_to_env0()
 {
         case "$1" in
-                *[^a-zA-Z0-9_=]* | *=*=* )
-                        echo "Error: invalid variable: '$1'" >&2
+                *=*=* )
+                        set -- "${1#*=}"
+                        echo "Error: invalid variable: ${1@Q}" >&2
+                        return 30
+                        ;;
+                *[^a-zA-Z0-9_=]* )
+                        echo "Error: invalid variable: ${1@Q}" >&2
                         return 10
                         ;;
                 [a-zA-Z_]* )
-                        set -- "${1#*=}" "${1%%=*}"
                         ;;
                 * )
-                        echo "Error: invalid variable: '$1'" >&2
+                        echo "Error: invalid variable: ${1@Q}" >&2
                         return 20
                         ;;
         esac
+        set -- "${1##*=}" "${1%%=*}"
         if [ -v "$2" ]
         then
                 printf '%s=%s\0' "$1" "${!2}"
         else
-                echo "Warning: ignoring unset variable: '$2'" >&2
+                echo "Warning: ignoring unset variable: ${2@Q}" >&2
         fi
 }
 
-# for_each - environmentally-hygienic loop
-#
-# The first argument is de-quoted as a command
-# evaluated once against each of the other
-# supplied arguments, in order, aborting if the
-# command returns an error.
-#
-# Doesn't touch the bash environment.
+# Hygienic loop.  Doesn't touch the shell
+# environment.
 for_each()
 {
         while [ $# -ge 2 ]
@@ -102,11 +101,6 @@ for_each()
         done
 }
 
-export_to_env0()
-{
-        for_each arg1_to_env0 "$@"
-}
-
 to_JSON_all()
 {
         jq -s 'add' < \
@@ -190,11 +184,20 @@ json_encode_string()
 
 to_JSON()
 {
-        case $# in
-                0)
-                        to_JSON_all -a
+        case "$#$1" in
+                0 )
+                        printf \
+                                '%s\n' \
+                                'usage: to_JSON -a' \
+                                '       to_JSON -A' \
+                                '       to_JSON <variable name> [...]' \
+                                >&2
+                        return -1
                         ;;
-                *)
+                1-a | 1-A )
+                        to_JSON_all $1
+                        ;;
+                * )
                         for_each to_JSON1 "$@"
                         ;;
         esac
@@ -229,7 +232,7 @@ export_JSON_unsafe()
 {
         (
                 set -o pipefail
-                export_to_env0 "$@" | env0_to_JSON
+                for_each arg1_to_env0 "$@" | env0_to_JSON
         )
 }
 
@@ -237,7 +240,7 @@ safety_pipe()
 {
         [ $# -ge 2 ] || return
         set -- "$(mktemp)" "$@" || return
-        if (shift 2; "$@") > "$1"
+        if "${@:3}" > "$1"
         then
                 "$2" < "$1"
         else
@@ -247,7 +250,7 @@ safety_pipe()
 
 export_JSON()
 {
-        safety_pipe env0_to_JSON export_to_env0 "$@"
+        safety_pipe env0_to_JSON for_each arg1_to_env0 "$@"
 }
 
 filter_vars()