cache: Don't use checksum as filename

In some cases (e.g in Pungi), the metadata is changing all the time, fus
is run multiple times a day and the cache just grows. So instead of
using checksum we use the reponame passed in the command line invocation
and the metadata type to create a filename so that only one copy exists
for that reponame. Therefore the cache layout now is:

$CACHEDIR/fus/$reponame/repodata/repomd.xml
$CACHEDIR/fus/$reponame/repodata/primary.xml.gz
$CACHEDIR/fus/$reponame/repodata/modules.xml.gz
$CACHEDIR/fus/$reponame/repodata/group_gz.x86_64.xml.xz
$CACHEDIR/fus/$reponame/repodata/filelists.xml.gz

Fixes #71

Signed-off-by: Rafael Fonseca <r4f4rfs@gmail.com>

fus.c

@@ -515,22 +515,25 @@ download_repo_metadata (SoupSession *session,
                         const char  *cachedir)
 {
   Id chksumtype;
-  const char *fpath, *fname;
   const unsigned char *chksum;
 
-  fname = repomd_find (repo, type, &chksum, &chksumtype);
-  if (!fname)
+  const char *mdname = repomd_find (repo, type, &chksum, &chksumtype);
+  if (!mdname)
     return NULL;
 
-  fpath = pool_tmpjoin (repo->pool, cachedir, "/", fname);
+  /* mdname should be "repodata/$(chksum)-$(type).xml.gz" */
+  const char *ext = strchr (mdname, '.');
+  const char *fpath = pool_tmpjoin (repo->pool, cachedir, "/", type);
+  fpath = pool_tmpappend (repo->pool, fpath, ext, 0);
+
   if (!g_file_test (fpath, G_FILE_TEST_IS_REGULAR) ||
       !checksum_matches (fpath, chksum, chksumtype))
     {
       g_autoptr(GError) error = NULL;
-      const char *furl = pool_tmpjoin (repo->pool, repo_url, "/", fname);
-      if (!download_to_path (session, furl, fpath, &error))
+      const char *mdurl = pool_tmpjoin (repo->pool, repo_url, "/", mdname);
+      if (!download_to_path (session, mdurl, fpath, &error))
         {
-          g_warning ("Could not download %s: %s", furl, error->message);
+          g_warning ("Could not download %s: %s", mdurl, error->message);
           return NULL;
         }
     }
@@ -557,7 +560,8 @@ filelist_loadcb (Pool     *pool,
     return 0;
 
   g_autofree gchar *cachedir = g_build_filename (g_get_user_cache_dir (),
-                                                 "fus", repo->name, NULL);
+                                                 "fus", repo->name, "repodata",
+                                                 NULL);
 
   fname = download_repo_metadata (session, repo, type, path, cachedir);
   fp = solv_xfopen (fname, 0);
@@ -619,17 +623,17 @@ create_repo (Pool         *pool,
   repo_add_repomdxml (repo, fp, 0);
   fclose (fp);
 
-  fname = download_repo_metadata (session, repo, "primary", path, cachedir);
+  fname = download_repo_metadata (session, repo, "primary", path, destdir);
   fp = solv_xfopen (fname, "r");
   if (fp != NULL)
     {
       repo_add_rpmmd (repo, fp, NULL, 0);
       fclose (fp);
     }
 
-  fname = download_repo_metadata (session, repo, "group_gz", path, cachedir);
+  fname = download_repo_metadata (session, repo, "group_gz", path, destdir);
   if (!fname)
-    fname = download_repo_metadata (session, repo, "group", path, cachedir);
+    fname = download_repo_metadata (session, repo, "group", path, destdir);
   fp = solv_xfopen (fname, "r");
   if (fp != NULL)
     {
@@ -656,7 +660,7 @@ create_repo (Pool         *pool,
 
   pool_createwhatprovides (pool);
 
-  fname = download_repo_metadata (session, repo, "modules", path, cachedir);
+  fname = download_repo_metadata (session, repo, "modules", path, destdir);
   fp = solv_xfopen (fname, "r");
   if (fp != NULL)
     {