Add %-specifiers support.

lacme(8): for --config=, --socket=, --config-certs= (and ‘socket’/
‘config-certs’/‘challenge-directory’ configuration options *before*
privilege drop; and for the [accountd] section ‘command’/‘config’
configuration options *after* privilege drop).

lacme-accountd(1): for --config=, --socket= and --privkey= (and
‘socket’/‘privkey’ configuration options).

This also changes the default configuration file location.  lacme(8) and
lacme-accountd(1) now respectively use /etc/lacme/lacme.conf resp.
/etc/lacme/lacme-accountd.conf when running as root, and
$XDG_CONFIG_HOME/lacme/lacme.conf resp. $XDG_CONFIG_HOME/lacme/lacme-accountd.conf
when running as a normal user.  There is no fallback to /etc anymore.

1 files changed, 27 insertions, 8 deletions

diff --git a/lacme-accountd b/lacme-accountd
index b9a6e33..e170637 100755
--- a/lacme-accountd
+++ b/lacme-accountd
@@ -30,7 +30,6 @@ my $NAME = 'lacme-accountd';
 use Errno 'EINTR';
 use File::Basename 'dirname';
 use Getopt::Long qw/:config posix_default no_ignore_case gnu_getopt auto_version/;
-use List::Util 'first';
 use MIME::Base64 'encode_base64url';
 use Socket qw/PF_UNIX SOCK_STREAM SHUT_RDWR/;
 
@@ -64,11 +63,32 @@ sub usage(;$$) {
 usage(1) unless GetOptions(\%OPTS, qw/config=s privkey=s socket=s stdio quiet|q debug help|h/);
 usage(0) if $OPTS{help};
 
+sub env_fallback($$) {
+    my $v = $ENV{ shift() };
+    return (defined $v and $v ne "") ? $v : shift;
+}
+sub spec_expand($) {
+    my $str = shift;
+    $str =~ s#%(.)# my $x =
+          $1 eq "C" ? ($< == 0 ? "@@localstatedir@@/cache" : env_fallback(XDG_CACHE_HOME => "$ENV{HOME}/.cache"))
+        : $1 eq "E" ? ($< == 0 ? "@@sysconfdir@@" : env_fallback(XDG_CONFIG_HOME => "$ENV{HOME}/.config"))
+        : $1 eq "g" ? (getgrgid((split /\s/,$()[0]))[0]
+        : $1 eq "G" ? $( =~ s/\s.*//r
+        : $1 eq "h" ? (getpwuid($<))[7]
+        : $1 eq "u" ? (getpwuid($<))[0]
+        : $1 eq "U" ? $<
+        : $1 eq "t" ? ($< == 0 ? "@@runstatedir@@" : $ENV{XDG_RUNTIME_DIR})
+        : $1 eq "T" ? env_fallback(TMPDIR => "/tmp")
+        : $1 eq "%" ? "%"
+        : die "Error: \"$str\" has unknown specifier %$1\n";
+        die "Error: undefined expansion %$1 in \"$str\"\n" unless defined $x;
+        $x;
+    #ge;
+    return $str;
+}
+
 do {
-    my $conffile = $OPTS{config} // first { -f $_ }
-        ( ($ENV{XDG_CONFIG_HOME} // "$ENV{HOME}/.config") . "/lacme/$NAME.conf"
-        , "@@sysconfdir@@/lacme/$NAME.conf"
-        );
+    my $conffile = spec_expand($OPTS{config} // "%E/lacme/$NAME.conf");
 
     if (defined $OPTS{config} or -e $conffile) {
         print STDERR "Using configuration file: $conffile\n" if $OPTS{debug};
@@ -94,7 +114,7 @@ do {
 #
 my ($JWK, $SIGN);
 if ($OPTS{privkey} =~ /\A(file|gpg):(\p{Print}+)\z/) {
-    my ($method, $filename) = ($1,$2);
+    my ($method, $filename) = ($1, spec_expand($2));
     my ($fh, @command);
     if ($method eq 'file') {
         # generate with `openssl genpkey -algorithm RSA`
@@ -142,8 +162,7 @@ my $JWK_STR = JSON::->new->encode($JWK);
 # delete the file manually.
 #
 unless (defined $OPTS{stdio}) {
-    my $sockname = $OPTS{socket} // (defined $ENV{XDG_RUNTIME_DIR} ? "$ENV{XDG_RUNTIME_DIR}/S.lacme" : undef);
-    die "Missing socket option\n" unless defined $sockname;
+    my $sockname = spec_expand($OPTS{socket} // '%t/S.lacme');
     $sockname = $sockname =~ /\A(\p{Print}+)\z/ ? $1 : die "Invalid socket name\n"; # untaint $sockname
 
     # ensure we're the only user with write access to the parent dir