Add connectivity tracking to fsck.

This shows that I've lost track of one commit already. Most likely
because I forgot to update the .dircache/HEAD file when doing a
commit, so that the next commit referenced not the top-of-tree, but
the one older commit.

Having dangling commits is fine (in fact, you should always have
at least _one_ dangling commit in the top-of-tree). But it's
good to know about them.

diff --git a/fsck-cache.c b/fsck-cache.c
index c35acaa..5dca6db 100644 (file)
--- a/fsck-cache.c
+++ b/fsck-cache.c
@@ -3,18 +3,113 @@
 #include <sys/types.h>
 #include <dirent.h>
 
+struct needs {
+       unsigned char parent[20];
+       unsigned char needs[20];
+       char tag[10];
+};
+
+struct seen {
+       unsigned char sha1[20];
+       char tag[10];
+       unsigned needed;
+};
+
+static struct needs *needs;
+static struct seen *seen;
+
+static int nr_seen, alloc_seen, nr_needs, alloc_needs;
+
 /*
- * These two functions should build up a graph in memory about
+ * These two functions build up a graph in memory about
  * what objects we've referenced, and found, and types..
- *
- * Right now we don't do that kind of reachability checking. Yet.
  */
-static void mark_needs_sha1(unsigned char *parent, const char * type, unsigned char *child)
+static int compare_seen(const void *s1, const void *s2)
+{
+       return memcmp(s1, s2, 20);
+}
+
+static int lookup_seen(unsigned char *sha1, char *tag)
+{
+       int first = 0, last = nr_seen;
+
+       while (last > first) {
+               int next = (last + first) / 2;
+               struct seen *s = seen + next;
+               int cmp = memcmp(sha1, s->sha1, 20);
+
+               if (cmp < 0) {
+                       last = next;
+                       continue;
+               }
+               if (cmp > 0) {
+                       first = next+1;
+                       continue;
+               }
+               if (strcmp(tag, s->tag))
+                       break;
+               s->needed++;
+               return 1;
+       }
+       return 0;
+}
+
+static void check_connectivity(void)
+{
+       int i;
+
+       /* Sort the "seen" tags for quicker lookup */
+       qsort(seen, nr_seen, sizeof(struct seen), compare_seen);
+
+       /* Look up all the requirements, warn about missing objects.. */
+       for (i = 0; i < nr_needs; i++) {
+               struct needs *n = needs + i;
+               char hex[60];
+
+               if (lookup_seen(n->needs, n->tag))
+                       continue;
+               strcpy(hex, sha1_to_hex(n->parent));
+       }
+
+       /* Tell the user about things not referenced.. */
+       for (i = 0; i < nr_seen; i++) {
+               struct seen *s = seen + i;
+
+               if (s->needed)
+                       continue;
+               printf("unreferenced %s: %s\n", s->tag, sha1_to_hex(s->sha1));
+       }
+}
+
+static void mark_needs_sha1(unsigned char *parent, const char * tag, unsigned char *child)
 {
+       struct needs *n;
+
+       if (nr_needs == alloc_needs) {
+               alloc_needs = alloc_nr(alloc_needs);
+               needs = realloc(needs, alloc_needs*sizeof(struct needs));
+       }
+       n = needs + nr_needs;
+       nr_needs++;
+       memcpy(n->parent, parent, 20);
+       memcpy(n->needs, child, 20);
+       strncpy(n->tag, tag, sizeof(n->tag));
 }
 
 static int mark_sha1_seen(unsigned char *sha1, char *tag)
 {
+       struct seen *s;
+
+       if (nr_seen == alloc_seen) {
+               alloc_seen = alloc_nr(alloc_seen);
+               seen = realloc(seen, alloc_seen*sizeof(struct seen));
+       }
+       s = seen + nr_seen;
+       memset(s, 0, sizeof(s));
+       nr_seen++;
+       memcpy(s->sha1, sha1, 20);
+       strncpy(s->tag, tag, sizeof(s->tag));
+       
        return 0;
 }
 
@@ -150,5 +245,6 @@ int main(int argc, char **argv)
                sprintf(dir, "%s/%02x", sha1_dir, i);
                fsck_dir(i, dir);
        }
+       check_connectivity();
        return 0;
 }