On 19/04/18 13:20, Johannes Schindelin wrote:
> In the upcoming commits, we will teach the sequencer to rebase merges.
> This will be done in a very different way from the unfortunate design of
> `git rebase --preserve-merges` (which does not allow for reordering
> commits, or changing the branch topology).
>
> The main idea is to introduce new todo list commands, to support
> labeling the current revision with a given name, resetting the current
> revision to a previous state, and merging labeled revisions.
>
> This idea was developed in Git for Windows' Git garden shears (that are
> used to maintain Git for Windows' "thicket of branches" on top of
> upstream Git), and this patch is part of the effort to make it available
> to a wider audience, as well as to make the entire process more robust
> (by implementing it in a safe and portable language rather than a Unix
> shell script).
>
> This commit implements the commands to label, and to reset to, given
> revisions. The syntax is:
>
> label <name>
> reset <name>
>
> Internally, the `label <name>` command creates the ref
> `refs/rewritten/<name>`. This makes it possible to work with the labeled
> revisions interactively, or in a scripted fashion (e.g. via the todo
> list command `exec`).
>
> These temporary refs are removed upon sequencer_remove_state(), so that
> even a `git rebase --abort` cleans them up.
>
> We disallow '#' as label because that character will be used as separator
> in the upcoming `merge` command.
>
> Later in this patch series, we will mark the `refs/rewritten/` refs as
> worktree-local, to allow for interactive rebases to be run in parallel in
> worktrees linked to the same repository.
>
> As typos happen, a failed `label` or `reset` command will be rescheduled
> immediately. Note that this needs a little change in the original code to
> perform a reschedule: there is no commit from which to generate a patch
> here (and we will simply fall through to the regular `return res`). We
> keep that code path, though, because we will use it for the upcoming
> `merge` command, too.
>
> Signed-off-by: Johannes Schindelin <[email protected]>
> ---
> git-rebase--interactive.sh | 2 +
> sequencer.c | 201 +++++++++++++++++++++++++++++++++++--
> 2 files changed, 196 insertions(+), 7 deletions(-)
>
> diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
> index e1b865f43f2..e8d3a7d7588 100644
> --- a/git-rebase--interactive.sh
> +++ b/git-rebase--interactive.sh
> @@ -162,6 +162,8 @@ s, squash <commit> = use commit, but meld into previous
> commit
> f, fixup <commit> = like \"squash\", but discard this commit's log message
> x, exec <commit> = run command (the rest of the line) using shell
> d, drop <commit> = remove commit
> +l, label <label> = label current HEAD with a name
> +t, reset <label> = reset HEAD to a label
>
> These lines can be re-ordered; they are executed from top to bottom.
> " | git stripspace --comment-lines >>"$todo"
> diff --git a/sequencer.c b/sequencer.c
> index 01443e0f245..9e09026b594 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -23,6 +23,8 @@
> #include "hashmap.h"
> #include "notes-utils.h"
> #include "sigchain.h"
> +#include "unpack-trees.h"
> +#include "worktree.h"
>
> #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
>
> @@ -120,6 +122,13 @@ static GIT_PATH_FUNC(rebase_path_stopped_sha,
> "rebase-merge/stopped-sha")
> static GIT_PATH_FUNC(rebase_path_rewritten_list,
> "rebase-merge/rewritten-list")
> static GIT_PATH_FUNC(rebase_path_rewritten_pending,
> "rebase-merge/rewritten-pending")
> +
> +/*
> + * The path of the file listing refs that need to be deleted after the rebase
> + * finishes. This is used by the `label` command to record the need for
> cleanup.
> + */
> +static GIT_PATH_FUNC(rebase_path_refs_to_delete,
> "rebase-merge/refs-to-delete")
> +
> /*
> * The following files are written by git-rebase just after parsing the
> * command-line (and are only consumed, not modified, by the sequencer).
> @@ -244,18 +253,33 @@ static const char *gpg_sign_opt_quoted(struct
> replay_opts *opts)
>
> int sequencer_remove_state(struct replay_opts *opts)
> {
> - struct strbuf dir = STRBUF_INIT;
> + struct strbuf buf = STRBUF_INIT;
> int i;
>
> + if (strbuf_read_file(&buf, rebase_path_refs_to_delete(), 0) > 0) {
> + char *p = buf.buf;
> + while (*p) {
> + char *eol = strchr(p, '\n');
> + if (eol)
> + *eol = '\0';
> + if (delete_ref("(rebase -i) cleanup", p, NULL, 0) < 0)
> + warning(_("could not delete '%s'"), p);
> + if (!eol)
> + break;
> + p = eol + 1;
> + }
> + }
> +
> free(opts->gpg_sign);
> free(opts->strategy);
> for (i = 0; i < opts->xopts_nr; i++)
> free(opts->xopts[i]);
> free(opts->xopts);
>
> - strbuf_addstr(&dir, get_dir(opts));
> - remove_dir_recursively(&dir, 0);
> - strbuf_release(&dir);
> + strbuf_reset(&buf);
> + strbuf_addstr(&buf, get_dir(opts));
> + remove_dir_recursively(&buf, 0);
> + strbuf_release(&buf);
>
> return 0;
> }
> @@ -1279,6 +1303,8 @@ enum todo_command {
> TODO_SQUASH,
> /* commands that do something else than handling a single commit */
> TODO_EXEC,
> + TODO_LABEL,
> + TODO_RESET,
> /* commands that do nothing but are counted for reporting progress */
> TODO_NOOP,
> TODO_DROP,
> @@ -1297,6 +1323,8 @@ static struct {
> { 'f', "fixup" },
> { 's', "squash" },
> { 'x', "exec" },
> + { 'l', "label" },
> + { 't', "reset" },
> { 0, "noop" },
> { 'd', "drop" },
> { 0, NULL }
> @@ -1802,7 +1830,8 @@ static int parse_insn_line(struct todo_item *item,
> const char *bol, char *eol)
> return error(_("missing arguments for %s"),
> command_to_string(item->command));
>
> - if (item->command == TODO_EXEC) {
> + if (item->command == TODO_EXEC || item->command == TODO_LABEL ||
> + item->command == TODO_RESET) {
> item->commit = NULL;
> item->arg = bol;
> item->arg_len = (int)(eol - bol);
> @@ -2465,6 +2494,158 @@ static int do_exec(const char *command_line)
> return status;
> }
>
> +static int safe_append(const char *filename, const char *fmt, ...)
> +{
> + va_list ap;
> + struct lock_file lock = LOCK_INIT;
> + int fd = hold_lock_file_for_update(&lock, filename,
> + LOCK_REPORT_ON_ERROR);
> + struct strbuf buf = STRBUF_INIT;
> +
> + if (fd < 0)
> + return -1;
> +
> + if (strbuf_read_file(&buf, filename, 0) < 0 && errno != ENOENT) {
> + error_errno(_("could not read '%s'"), filename);
> + rollback_lock_file(&lock);
> + return -1;
> + }
> + strbuf_complete(&buf, '\n');
> + va_start(ap, fmt);
> + strbuf_vaddf(&buf, fmt, ap);
> + va_end(ap);
> +
> + if (write_in_full(fd, buf.buf, buf.len) < 0) {
> + error_errno(_("could not write to '%s'"), filename);
> + strbuf_release(&buf);
> + rollback_lock_file(&lock);
> + return -1;
> + }
> + if (commit_lock_file(&lock) < 0) {
> + strbuf_release(&buf);
> + rollback_lock_file(&lock);
> + return error(_("failed to finalize '%s'"), filename);
> + }
> +
> + strbuf_release(&buf);
> + return 0;
> +}
> +
> +static int do_label(const char *name, int len)
> +{
> + struct ref_store *refs = get_main_ref_store();
> + struct ref_transaction *transaction;
> + struct strbuf ref_name = STRBUF_INIT, err = STRBUF_INIT;
> + struct strbuf msg = STRBUF_INIT;
> + int ret = 0;
> + struct object_id head_oid;
> +
> + if (len == 1 && *name == '#')
> + return error("Illegal label name: '%.*s'", len, name);
> +
> + strbuf_addf(&ref_name, "refs/rewritten/%.*s", len, name);
> + strbuf_addf(&msg, "rebase -i (label) '%.*s'", len, name);
> +
> + transaction = ref_store_transaction_begin(refs, &err);
> + if (!transaction) {
> + error("%s", err.buf);
> + ret = -1;
> + } else if (get_oid("HEAD", &head_oid)) {
> + error(_("could not read HEAD"));
> + ret = -1;
> + } else if (ref_transaction_update(transaction, ref_name.buf, &head_oid,
> + NULL, 0, msg.buf, &err) < 0 ||
> + ref_transaction_commit(transaction, &err)) {
> + error("%s", err.buf);
> + ret = -1;
> + }
> + ref_transaction_free(transaction);
> + strbuf_release(&err);
> + strbuf_release(&msg);
> +
> + if (!ret)
> + ret = safe_append(rebase_path_refs_to_delete(),
> + "%s\n", ref_name.buf);
> + strbuf_release(&ref_name);
> +
> + return ret;
> +}
> +
> +static const char *reflog_message(struct replay_opts *opts,
> + const char *sub_action, const char *fmt, ...);
> +
> +static int do_reset(const char *name, int len, struct replay_opts *opts)
> +{
> + struct strbuf ref_name = STRBUF_INIT;
> + struct object_id oid;
> + struct lock_file lock = LOCK_INIT;
> + struct tree_desc desc;
> + struct tree *tree;
> + struct unpack_trees_options unpack_tree_opts;
> + int ret = 0, i;
> +
> + if (hold_locked_index(&lock, LOCK_REPORT_ON_ERROR) < 0)
> + return -1;
> +
> + /* Determine the length of the label */
> + for (i = 0; i < len; i++)
> + if (isspace(name[i]))
> + len = i;
> +
> + strbuf_addf(&ref_name, "refs/rewritten/%.*s", len, name);
> + if (get_oid(ref_name.buf, &oid) &&
> + get_oid(ref_name.buf + strlen("refs/rewritten/"), &oid)) {
> + error(_("could not read '%s'"), ref_name.buf);
> + rollback_lock_file(&lock);
> + strbuf_release(&ref_name);
> + return -1;
> + }
> +
> + memset(&unpack_tree_opts, 0, sizeof(unpack_tree_opts));
> + unpack_tree_opts.head_idx = 1;
> + unpack_tree_opts.src_index = &the_index;
> + unpack_tree_opts.dst_index = &the_index;
> + unpack_tree_opts.fn = oneway_merge;
> + unpack_tree_opts.merge = 1;
> + unpack_tree_opts.update = 1;
> +
> + if (read_cache_unmerged()) {
> + rollback_lock_file(&lock);
> + strbuf_release(&ref_name);
> + return error_resolve_conflict(_(action_name(opts)));
> + }
> +
> + if (!fill_tree_descriptor(&desc, &oid)) {
> + error(_("failed to find tree of %s"), oid_to_hex(&oid));
> + rollback_lock_file(&lock);
> + free((void *)desc.buffer);
> + strbuf_release(&ref_name);
> + return -1;
> + }
> +
> + if (unpack_trees(1, &desc, &unpack_tree_opts)) {
> + rollback_lock_file(&lock);
> + free((void *)desc.buffer);
> + strbuf_release(&ref_name);
> + return -1;
> + }
> +
> + tree = parse_tree_indirect(&oid);
> + prime_cache_tree(&the_index, tree);
> +
> + if (write_locked_index(&the_index, &lock, COMMIT_LOCK) < 0)
> + ret = error(_("could not write index"));
> + free((void *)desc.buffer);
> +
> + if (!ret)
> + ret = update_ref(reflog_message(opts, "reset", "'%.*s'",
> + len, name), "HEAD", &oid,
> + NULL, 0, UPDATE_REFS_MSG_ON_ERR);
> +
> + strbuf_release(&ref_name);
> + return ret;
> +}
> +
> static int is_final_fixup(struct todo_list *todo_list)
> {
> int i = todo_list->current;
> @@ -2610,7 +2791,7 @@ static int pick_commits(struct todo_list *todo_list,
> struct replay_opts *opts)
> res = do_pick_commit(item->command, item->commit,
> opts, is_final_fixup(todo_list));
> if (is_rebase_i(opts) && res < 0) {
> - /* Reschedule */
> +reschedule:
> advise(_(rescheduled_advice),
> get_item_line_length(todo_list,
> todo_list->current),
> @@ -2639,7 +2820,7 @@ static int pick_commits(struct todo_list *todo_list,
> struct replay_opts *opts)
> intend_to_amend();
> return error_failed_squash(item->commit, opts,
> item->arg_len, item->arg);
> - } else if (res && is_rebase_i(opts))
> + } else if (res && is_rebase_i(opts) && item->commit)
> return res | error_with_patch(item->commit,
> item->arg, item->arg_len, opts, res,
> item->command == TODO_REWORD);
> @@ -2665,6 +2846,12 @@ static int pick_commits(struct todo_list *todo_list,
> struct replay_opts *opts)
> /* `current` will be incremented below */
> todo_list->current = -1;
> }
> + } else if (item->command == TODO_LABEL) {
> + if ((res = do_label(item->arg, item->arg_len)))
> + goto reschedule;
I can see why you've implemented like this but I'm uneasy with jumping
into a block guarded with "if (item->command <= TODO_SQUASH)" when
item->command > TODO_SQUASH. I think it works OK at the moment but it's
possible that in the future someone will edit that block of code and add
something like
if (item->command == TODO_PICK)
do_something()
else
do_something_else()
assuming that item->command <= TODO_SQUASH because they haven't noticed
the goto jumping back into that block.
Best Wishes
Phillip
> + } else if (item->command == TODO_RESET) {
> + if ((res = do_reset(item->arg, item->arg_len, opts)))
> + goto reschedule;
> } else if (!is_noop(item->command))
> return error(_("unknown command %d"), item->command);
>
>
