builtin rebase: support --root

This option allows to rebase entire histories up to, and including, the
root commit.

The conversion from the shell script is straight-forward, apart from
the fact that we do not have to write an empty tree in C.

Signed-off-by: Pratik Karki <predatoramigo@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/rebase.c b/builtin/rebase.c
index c64d46afd53f3e17ddce2e81c53fb5cd47d159eb..b2cf779f1b42a5623d7d376b4fcc0e9bcea28e97 100644 (file)
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -76,6 +76,7 @@ struct rebase_options {
        const char *revisions;
        const char *switch_to;
        int root;
+       struct object_id *squash_onto;
        struct commit *restrict_revision;
        int dont_finish_rebase;
        enum {
@@ -375,6 +376,9 @@ static int run_specific_rebase(struct rebase_options *opts)
                opts->rebase_cousins ? "t" : "");
        add_var(&script_snippet, "strategy", opts->strategy);
        add_var(&script_snippet, "strategy_opts", opts->strategy_opts);
+       add_var(&script_snippet, "rebase_root", opts->root ? "t" : "");
+       add_var(&script_snippet, "squash_onto",
+               opts->squash_onto ? oid_to_hex(opts->squash_onto) : "");
 
        switch (opts->type) {
        case REBASE_AM:
@@ -653,6 +657,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
        const char *rebase_merges = NULL;
        int fork_point = -1;
        struct string_list strategy_options = STRING_LIST_INIT_NODUP;
+       struct object_id squash_onto;
+       char *squash_onto_name = NULL;
        struct option builtin_rebase_options[] = {
                OPT_STRING(0, "onto", &options.onto_name,
                           N_("revision"),
@@ -744,6 +750,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
                                N_("option"),
                                N_("pass the argument through to the merge "
                                   "strategy")),
+               OPT_BOOL(0, "root", &options.root,
+                        N_("rebase all reachable commits up to the root(s)")),
                OPT_END(),
        };
 
@@ -1021,6 +1029,9 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
                }
        }
 
+       if (options.root && !options.onto_name)
+               imply_interactive(&options, "--root without --onto");
+
        switch (options.type) {
        case REBASE_MERGE:
        case REBASE_INTERACTIVE:
@@ -1059,8 +1070,22 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
                if (!options.upstream)
                        die(_("invalid upstream '%s'"), options.upstream_name);
                options.upstream_arg = options.upstream_name;
-       } else
-               die("TODO: upstream for --root");
+       } else {
+               if (!options.onto_name) {
+                       if (commit_tree("", 0, the_hash_algo->empty_tree, NULL,
+                                       &squash_onto, NULL, NULL) < 0)
+                               die(_("Could not create new root commit"));
+                       options.squash_onto = &squash_onto;
+                       options.onto_name = squash_onto_name =
+                               xstrdup(oid_to_hex(&squash_onto));
+               }
+               options.upstream_name = NULL;
+               options.upstream = NULL;
+               if (argc > 1)
+                       usage_with_options(builtin_rebase_usage,
+                                          builtin_rebase_options);
+               options.upstream_arg = "--root";
+       }
 
        /* Make sure the branch to rebase onto is valid. */
        if (!options.onto_name)
@@ -1208,6 +1233,7 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
         */
        if (can_fast_forward(options.onto, &options.orig_head, &merge_base) &&
            !is_interactive(&options) && !options.restrict_revision &&
+           options.upstream &&
            !oidcmp(&options.upstream->object.oid, &options.onto->object.oid)) {
                int flag;
 
@@ -1312,5 +1338,6 @@ cleanup:
        free(options.head_name);
        free(options.gpg_sign_opt);
        free(options.cmd);
+       free(squash_onto_name);
        return ret;
 }