dpkg: Add restrictions for configuration of a Multi-Arch: same package

A “Multi-Arch: same” package can only be configured if all the other
instances of the same package are synchronized (i.e. have the same
unpacked version) and if they are in state where they can be configured.

Sponsored-by: Linaro Limited

[guillem@debian.org:
 - Rework error strings.
 - Fix coding-style.
 - Check against <= stat_configfiles instead of < stat_halfinstalled.
 - Split unrelated check into different conditionals. ]

Signed-off-by: Guillem Jover <guillem@debian.org>

src/configure.c

@@ -5,6 +5,8 @@
  * Copyright © 1995 Ian Jackson <ian@chiark.greenend.org.uk>
  * Copyright © 1999, 2002 Wichert Akkerman <wichert@deephackmode.org>
  * Copyright © 2007-2012 Guillem Jover <guillem@debian.org>
+ * Copyright © 2011 Linaro Limited
+ * Copyright © 2011 Raphaël Hertzog <hertzog@debian.org>
  *
  * This is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -258,6 +260,7 @@ deferred_configure(struct pkginfo *pkg)
 {
 	struct varbuf aemsgs = VARBUF_INIT;
 	struct conffile *conff;
+	struct pkginfo *otherpkg;
 	int ok;
 
 	if (pkg->status == stat_notinstalled)
@@ -272,6 +275,31 @@ deferred_configure(struct pkginfo *pkg)
 		       pkg_name(pkg, pnaw_nonambig),
 		       statusinfos[pkg->status].name);
 
+	for (otherpkg = &pkg->set->pkg; otherpkg; otherpkg = otherpkg->arch_next) {
+		if (otherpkg == pkg)
+			continue;
+		if (otherpkg->status <= stat_configfiles)
+			continue;
+
+		if (otherpkg->status < stat_unpacked)
+			ohshit(_("package %s cannot be configured because "
+			         "%s is not ready (current status '%s')"),
+			       pkg_name(pkg, pnaw_always),
+			       pkg_name(otherpkg, pnaw_always),
+			       statusinfos[otherpkg->status].name);
+
+		if (versioncompare(&pkg->installed.version,
+		                   &otherpkg->installed.version))
+			ohshit(_("package %s %s cannot be configured because "
+			         "%s is at a different version (%s)"),
+			       pkg_name(pkg, pnaw_always),
+			       versiondescribe(&pkg->installed.version,
+			                       vdew_nonambig),
+			       pkg_name(otherpkg, pnaw_always),
+			       versiondescribe(&otherpkg->installed.version,
+			                       vdew_nonambig));
+	}
+
 	if (dependtry > 1)
 		if (findbreakcycle(pkg))
 			sincenothing = 0;