am -3: do not let failed merge from completing the error codepath

When "am" was rewritten in C, the codepath for falling back to
three-way merge was mistakenly made to make an internal call to
merge-recursive, disabling the error reporting code for certain
types of errors merge-recursive detects and reports by calling
die().

This is a quick-fix for correctness.  The ideal endgame would be to
replace run_command() in run_fallback_merge_recursive() with a
direct call after making sure that internal call to merge-recursive
does not die().

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/am.c b/builtin/am.c
index 4f77e07b9549f8ff144d770fb0b66e9124ae4dc6..c869796ea6e8faab62b4c258a2a84ad3254d520f 100644 (file)
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -1589,6 +1589,38 @@ static int build_fake_ancestor(const struct am_state *state, const char *index_f
        return 0;
 }
 
+/**
+ * Do the three-way merge using fake ancestor, his tree constructed
+ * from the fake ancestor and the postimage of the patch, and our
+ * state.
+ */
+static int run_fallback_merge_recursive(const struct am_state *state,
+                                       unsigned char *orig_tree,
+                                       unsigned char *our_tree,
+                                       unsigned char *his_tree)
+{
+       struct child_process cp = CHILD_PROCESS_INIT;
+       int status;
+
+       cp.git_cmd = 1;
+
+       argv_array_pushf(&cp.env_array, "GITHEAD_%s=%.*s",
+                        sha1_to_hex(his_tree), linelen(state->msg), state->msg);
+       if (state->quiet)
+               argv_array_push(&cp.env_array, "GIT_MERGE_VERBOSITY=0");
+
+       argv_array_push(&cp.args, "merge-recursive");
+       argv_array_push(&cp.args, sha1_to_hex(orig_tree));
+       argv_array_push(&cp.args, "--");
+       argv_array_push(&cp.args, sha1_to_hex(our_tree));
+       argv_array_push(&cp.args, sha1_to_hex(his_tree));
+
+       status = run_command(&cp) ? (-1) : 0;
+       discard_cache();
+       read_cache();
+       return status;
+}
+
 /**
  * Attempt a threeway merge, using index_path as the temporary index.
  */
@@ -1596,10 +1628,6 @@ static int fall_back_threeway(const struct am_state *state, const char *index_pa
 {
        unsigned char orig_tree[GIT_SHA1_RAWSZ], his_tree[GIT_SHA1_RAWSZ],
                      our_tree[GIT_SHA1_RAWSZ];
-       const unsigned char *bases[1] = {orig_tree};
-       struct merge_options o;
-       struct commit *result;
-       char *his_tree_name;
 
        if (get_sha1("HEAD", our_tree) < 0)
                hashcpy(our_tree, EMPTY_TREE_SHA1_BIN);
@@ -1651,22 +1679,11 @@ static int fall_back_threeway(const struct am_state *state, const char *index_pa
         * changes.
         */
 
-       init_merge_options(&o);
-
-       o.branch1 = "HEAD";
-       his_tree_name = xstrfmt("%.*s", linelen(state->msg), state->msg);
-       o.branch2 = his_tree_name;
-
-       if (state->quiet)
-               o.verbosity = 0;
-
-       if (merge_recursive_generic(&o, our_tree, his_tree, 1, bases, &result)) {
+       if (run_fallback_merge_recursive(state, orig_tree, our_tree, his_tree)) {
                rerere(state->allow_rerere_autoupdate);
-               free(his_tree_name);
                return error(_("Failed to merge in the changes."));
        }
 
-       free(his_tree_name);
        return 0;
 }