dgit: Enforce a syntax for nominal distros

These appear in various interchange output like tags.  They should be
sane.  They're going to appear in Dgit: too where people will need to
use them.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

2 files changed, 6 insertions, 1 deletions

diff --git a/Debian/Dgit.pm b/Debian/Dgit.pm
index 314bd8c..5a7b59d 100644
--- a/Debian/Dgit.pm
+++ b/Debian/Dgit.pm
@@ -50,6 +50,7 @@ BEGIN {
 		      git_get_ref git_for_each_ref
                       git_for_each_tag_referring is_fast_fwd
                       $package_re $component_re $deliberately_re
+		      $distro_re
                       $branchprefix
                       initdebug enabledebug enabledebuglevel
                       printdebug debugcmd
@@ -65,6 +66,7 @@ our @EXPORT_OK;
 our $package_re = '[0-9a-z][-+.0-9a-z]*';
 our $component_re = '[0-9a-zA-Z][-+.0-9a-zA-Z]*';
 our $deliberately_re = "(?:TEST-)?$package_re";
+our $distro_re = $component_re;
 our $branchprefix = 'dgit';
 
 # policy hook exit status bits
diff --git a/dgit b/dgit
index 54b0e6f..de7b4de 100755
--- a/dgit
+++ b/dgit
@@ -727,7 +727,10 @@ sub access_basedistro () {
 
 sub access_nomdistro () {
     my $base = access_basedistro();
-    return cfg("dgit-distro.$base.nominal-distro",'RETURN-UNDEF') // $base;
+    my $r = cfg("dgit-distro.$base.nominal-distro",'RETURN-UNDEF') // $base;
+    $r =~ m/^$distro_re$/ or badcfg
+ "bad syntax for (nominal) distro \`$r' (does not match /^$distro_re$/)";
+    return $r;
 }
 
 sub access_quirk () {