git-update-cache refuses to add a file where a directory is registed.

And vice versa.  The next commit will introduce an option
--replace to allow replacing existing entries.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/read-cache.c b/read-cache.c
index a6fbf08..327888b 100644 (file)
--- a/read-cache.c
+++ b/read-cache.c
@@ -123,6 +123,88 @@ int same_name(struct cache_entry *a, struct cache_entry *b)
        return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
 }
 
+/* We may be in a situation where we already have path/file and path
+ * is being added, or we already have path and path/file is being
+ * added.  Either one would result in a nonsense tree that has path
+ * twice when git-write-tree tries to write it out.  Prevent it.
+ */
+static int check_file_directory_conflict(const struct cache_entry *ce)
+{
+       int pos;
+       const char *path = ce->name;
+       int namelen = strlen(path);
+       int stage = ce_stage(ce);
+       char *pathbuf = xmalloc(namelen + 1);
+       char *cp;
+
+       memcpy(pathbuf, path, namelen + 1);
+
+       /*
+        * We are inserting path/file.  Do they have path registered at
+        * the same stage?  We need to do this for all the levels of our
+        * subpath.
+        */
+       cp = pathbuf;
+       while (1) {
+               char *ep = strchr(cp, '/');
+               if (ep == 0)
+                       break;
+               *ep = 0;    /* first cut it at slash */
+               pos = cache_name_pos(pathbuf,
+                                    htons(create_ce_flags(ep-cp, stage)));
+               if (0 <= pos) {
+                       /* Our leading path component is registered as a file,
+                        * and we are trying to make it a directory.  This is
+                        * bad.
+                        */
+                       free(pathbuf);
+                       return -1;
+               }
+               *ep = '/';  /* then restore it and go downwards */
+               cp = ep + 1;
+       }
+       free(pathbuf);
+
+       /* Do we have an entry in the cache that makes our path a prefix
+        * of it?  That is, are we creating a file where they already expect
+        * a directory there?
+        */
+       pos = cache_name_pos(path,
+                            htons(create_ce_flags(namelen, stage)));
+
+       /* (0 <= pos) cannot happen because add_cache_entry()
+        * should have taken care of that case.
+        */
+       pos = -pos-1;
+
+       /* pos would point at an existing entry that would come immediately
+        * after our path.  It could be the same as our path in higher stage,
+        * or different path but in a lower stage.
+        *
+        * E.g. when we are inserting path at stage 2,
+        *
+        *        1 path
+        * pos->  3 path
+        *        2 path/file
+        *        3 path/file
+        *
+        * We need to examine pos, ignore it because it is at different
+        * stage, examine next to find the path/file at stage 2, and
+        * complain.
+        */
+
+       while (pos < active_nr) {
+               struct cache_entry *other = active_cache[pos];
+               if (strncmp(other->name, path, namelen))
+                       break; /* it is not our "subdirectory" anymore */
+               if ((ce_stage(other) == stage) && other->name[namelen] == '/')
+                       return -1;
+               pos++;
+       }
+
+       return 0;
+}
+
 int add_cache_entry(struct cache_entry *ce, int ok_to_add)
 {
        int pos;
@@ -152,6 +234,9 @@ int add_cache_entry(struct cache_entry *ce, int ok_to_add)
        if (!ok_to_add)
                return -1;
 
+       if (check_file_directory_conflict(ce))
+               return -1;
+
        /* Make sure the array is big enough .. */
        if (active_nr == active_alloc) {
                active_alloc = alloc_nr(active_alloc);