Check size of path buffer before writing into it

[git.git] / builtin-checkout.c

diff --git a/builtin-checkout.c b/builtin-checkout.c
index 8a9a474218c128b7878647045ba471df9902636a..e2dd0cd0c05f13e4e07e1eff1e31e88731e1ee5a 100644 (file)
--- a/builtin-checkout.c
+++ b/builtin-checkout.c
@@ -396,13 +396,15 @@ static int merge_working_tree(struct checkout_opts *opts,
                topts.initial_checkout = is_cache_unborn();
                topts.update = 1;
                topts.merge = 1;
-               topts.gently = opts->merge;
+               topts.gently = opts->merge && old->commit;
                topts.verbose_update = !opts->quiet;
                topts.fn = twoway_merge;
                topts.dir = xcalloc(1, sizeof(*topts.dir));
                topts.dir->flags |= DIR_SHOW_IGNORED;
                topts.dir->exclude_per_dir = ".gitignore";
-               tree = parse_tree_indirect(old->commit->object.sha1);
+               tree = parse_tree_indirect(old->commit ?
+                                          old->commit->object.sha1 :
+                                          (unsigned char *)EMPTY_TREE_SHA1_BIN);
                init_tree_desc(&trees[0], tree->buffer, tree->size);
                tree = parse_tree_indirect(new->commit->object.sha1);
                init_tree_desc(&trees[1], tree->buffer, tree->size);
@@ -419,7 +421,13 @@ static int merge_working_tree(struct checkout_opts *opts,
                        struct merge_options o;
                        if (!opts->merge)
                                return 1;
-                       parse_commit(old->commit);
+
+                       /*
+                        * Without old->commit, the below is the same as
+                        * the two-tree unpack we already tried and failed.
+                        */
+                       if (!old->commit)
+                               return 1;
 
                        /* Do more real merge */
 
@@ -541,14 +549,6 @@ static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
                parse_commit(new->commit);
        }
 
-       if (!old.commit && !opts->force) {
-               if (!opts->quiet) {
-                       warning("You appear to be on a branch yet to be born.");
-                       warning("Forcing checkout of %s.", new->name);
-               }
-               opts->force = 1;
-       }
-
        ret = merge_working_tree(opts, &old, new);
        if (ret)
                return ret;