diff -r 296eac3183bc -r 691fae7db8fe update/update.c
--- a/update/update.c	Fri Jul 08 08:26:29 2016 +0100
+++ b/update/update.c	Fri Mar 22 11:53:00 2019 +0000
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2009, 2011  J. Ali Harlow <ali@juiblex.co.uk>
+ * Copyright (C) 2009, 2011, 2016  J. Ali Harlow <ali@juiblex.co.uk>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -18,6 +18,7 @@
 
 #include <stdlib.h>
 #include <stdio.h>
+#include <errno.h>
 #include <lua.h>
 #include "config.h"
 #include "plover/plover.h"
@@ -27,22 +28,85 @@
 
 void update(const char *argv0)
 {
-    char *path;
-    gchar *s,*prefix;
+    char *yum_uri,*local_database,*active_database,*alternate_database;
+    gchar *s,*prefix,*distribution,*vendor_prefix;
     int ch;
     struct comps *comps;
     GError *error=NULL;
-    path=plover_get_program_directory(argv0);
-    s=g_strconcat(path,"/repodata/comps.xml",NULL);
-    comps=plover_comps_new_from_file(s);
+    s=plover_get_program(argv0);
+    yum_uri=razor_path_to_uri(s);
+    g_free(s);
+    s=g_strconcat(yum_uri,"/repodata/comps.xml",NULL);
+    comps=plover_comps_new_from_uri(s,&error);
+    g_free(s);
+    if (g_error_matches(error,PLOVER_RAZOR_ERROR,
+      RAZOR_GENERAL_ERROR_UNSUPPORTED_ARCHIVE))
+    {
+	g_clear_error(&error);
+	free(yum_uri);
+	s=plover_get_program_directory(argv0);
+	yum_uri=razor_path_to_uri(s);
+	g_free(s);
+	s=g_strconcat(yum_uri,"/repodata/comps.xml",NULL);
+	comps=plover_comps_new_from_uri(s,&error);
+    }
     if (!comps)
     {
-	perror(s);
+	fprintf(stderr,"%s\n",error->message);
+	g_error_free(error);
 	exit(1);
     }
-    g_free(s);
-    prefix=plover_default_prefix_for_vendor(comps->vendor);
-    if (!plover_installed_files_match_prefix(prefix))
+    prefix=plover_comps_get_default_prefix(comps);
+    if (prefix)
+    {
+	s=g_strconcat(prefix,"/var/lib/razor",NULL);
+	local_database=razor_path_to_uri(s);
+	g_free(s);
+    }
+    else
+	local_database=NULL;
+    switch(comps->database)
+    {
+	case COMPS_DATABASE_DISTRIBUTION_LOCAL:
+	    active_database=local_database;
+	    alternate_database=NULL;
+	    break;
+	case COMPS_DATABASE_GLOBAL:
+	    active_database=NULL;
+	    alternate_database=local_database;
+	    break;
+    }
+    if (prefix)
+    {
+	distribution=g_strdup(comps->distribution);
+	plover_comps_set_distribution(comps,NULL);
+	vendor_prefix=plover_comps_get_default_prefix(comps);
+	plover_comps_set_distribution(comps,distribution);
+	g_free(distribution);
+	razor_set_database_uri(alternate_database);
+	if (plover_installed_files_match_prefix(vendor_prefix)==1)
+	{
+	    printf("There is an existing installation under %s\n"
+	      "which is not compatible with this distribution. In order\n"
+	      "to continue, the existing installation must be uninstalled.\n"
+	      "Do you want to remove all packages in the existing installion? ",
+	      prefix);
+	    ch=getchar();
+	    if (ch!='y' && ch!='Y' && ch!=EOF && ch!='\n')
+		exit(1);
+	    while(ch!='\n' && ch!=EOF)
+		ch=getchar();
+	    if (plover_remove(NULL,&error))
+	    {
+		fprintf(stderr,"%s\n",error->message);
+		g_error_free(error);
+		exit(1);
+	    }
+	}
+	g_free(vendor_prefix);
+    }
+    razor_set_database_uri(active_database);
+    if (prefix && !plover_installed_files_match_prefix(prefix))
     {
 	printf("The existing installation is not under %s\n"
 	  "In order to continue, all the existing packages must be removed.\n"
@@ -59,15 +123,16 @@
 	    exit(1);
 	}
     }
+    free(local_database);
     plover_comps_free(comps);
-    if (!plover_update(path,prefix,NULL,&error))
+    if (!plover_update_uri(yum_uri,prefix,NULL,&error))
     {
 	fprintf(stderr,"%s\n",error->message);
 	g_error_free(error);
 	exit(1);
     }
     g_free(prefix);
-    free(path);
+    free(yum_uri);
 }
 
 int main(int argc,char **argv)