builtin rebase: try to fast forward when possible
[git/git.git] / builtin / rebase.c
CommitLineData
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1/*
2 * "git rebase" builtin command
3 *
4 * Copyright (c) 2018 Pratik Karki
5 */
6
7#include "builtin.h"
8#include "run-command.h"
9#include "exec-cmd.h"
10#include "argv-array.h"
11#include "dir.h"
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12#include "packfile.h"
13#include "refs.h"
14#include "quote.h"
15#include "config.h"
16#include "cache-tree.h"
17#include "unpack-trees.h"
18#include "lockfile.h"
f28d40d3 19#include "parse-options.h"
075bc852 20#include "commit.h"
bff014da 21#include "diff.h"
e0333e5c 22#include "wt-status.h"
9a48a615 23#include "revision.h"
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24
25static char const * const builtin_rebase_usage[] = {
26 N_("git rebase [-i] [options] [--exec <cmd>] [--onto <newbase>] "
27 "[<upstream>] [<branch>]"),
28 N_("git rebase [-i] [options] [--exec <cmd>] [--onto <newbase>] "
29 "--root [<branch>]"),
30 N_("git rebase --continue | --abort | --skip | --edit-todo"),
31 NULL
32};
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33
34static GIT_PATH_FUNC(apply_dir, "rebase-apply")
35static GIT_PATH_FUNC(merge_dir, "rebase-merge")
36
37enum rebase_type {
38 REBASE_UNSPECIFIED = -1,
39 REBASE_AM,
40 REBASE_MERGE,
41 REBASE_INTERACTIVE,
42 REBASE_PRESERVE_MERGES
43};
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44
45static int use_builtin_rebase(void)
46{
47 struct child_process cp = CHILD_PROCESS_INIT;
48 struct strbuf out = STRBUF_INIT;
49 int ret;
50
51 argv_array_pushl(&cp.args,
52 "config", "--bool", "rebase.usebuiltin", NULL);
53 cp.git_cmd = 1;
54 if (capture_command(&cp, &out, 6)) {
55 strbuf_release(&out);
56 return 0;
57 }
58
59 strbuf_trim(&out);
60 ret = !strcmp("true", out.buf);
61 strbuf_release(&out);
62 return ret;
63}
64
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65static int apply_autostash(void)
66{
67 warning("TODO");
68 return 0;
69}
70
71struct rebase_options {
72 enum rebase_type type;
73 const char *state_dir;
74 struct commit *upstream;
75 const char *upstream_name;
06e4775a 76 const char *upstream_arg;
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77 char *head_name;
78 struct object_id orig_head;
79 struct commit *onto;
80 const char *onto_name;
81 const char *revisions;
82 int root;
83 struct commit *restrict_revision;
84 int dont_finish_rebase;
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85 enum {
86 REBASE_NO_QUIET = 1<<0,
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87 REBASE_VERBOSE = 1<<1,
88 REBASE_DIFFSTAT = 1<<2,
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89 } flags;
90 struct strbuf git_am_opt;
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91};
92
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93static int is_interactive(struct rebase_options *opts)
94{
95 return opts->type == REBASE_INTERACTIVE ||
96 opts->type == REBASE_PRESERVE_MERGES;
97}
98
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99/* Returns the filename prefixed by the state_dir */
100static const char *state_dir_path(const char *filename, struct rebase_options *opts)
101{
102 static struct strbuf path = STRBUF_INIT;
103 static size_t prefix_len;
104
105 if (!prefix_len) {
106 strbuf_addf(&path, "%s/", opts->state_dir);
107 prefix_len = path.len;
108 }
109
110 strbuf_setlen(&path, prefix_len);
111 strbuf_addstr(&path, filename);
112 return path.buf;
113}
114
115static int finish_rebase(struct rebase_options *opts)
116{
117 struct strbuf dir = STRBUF_INIT;
118 const char *argv_gc_auto[] = { "gc", "--auto", NULL };
119
120 delete_ref(NULL, "REBASE_HEAD", NULL, REF_NO_DEREF);
121 apply_autostash();
122 close_all_packs(the_repository->objects);
123 /*
124 * We ignore errors in 'gc --auto', since the
125 * user should see them.
126 */
127 run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
128 strbuf_addstr(&dir, opts->state_dir);
129 remove_dir_recursively(&dir, 0);
130 strbuf_release(&dir);
131
132 return 0;
133}
134
135static struct commit *peel_committish(const char *name)
136{
137 struct object *obj;
138 struct object_id oid;
139
140 if (get_oid(name, &oid))
141 return NULL;
142 obj = parse_object(the_repository, &oid);
143 return (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
144}
145
146static void add_var(struct strbuf *buf, const char *name, const char *value)
147{
148 if (!value)
149 strbuf_addf(buf, "unset %s; ", name);
150 else {
151 strbuf_addf(buf, "%s=", name);
152 sq_quote_buf(buf, value);
153 strbuf_addstr(buf, "; ");
154 }
155}
156
157static int run_specific_rebase(struct rebase_options *opts)
158{
159 const char *argv[] = { NULL, NULL };
160 struct strbuf script_snippet = STRBUF_INIT;
161 int status;
162 const char *backend, *backend_func;
163
164 add_var(&script_snippet, "GIT_DIR", absolute_path(get_git_dir()));
165 add_var(&script_snippet, "state_dir", opts->state_dir);
166
167 add_var(&script_snippet, "upstream_name", opts->upstream_name);
168 add_var(&script_snippet, "upstream",
169 oid_to_hex(&opts->upstream->object.oid));
170 add_var(&script_snippet, "head_name", opts->head_name);
171 add_var(&script_snippet, "orig_head", oid_to_hex(&opts->orig_head));
172 add_var(&script_snippet, "onto", oid_to_hex(&opts->onto->object.oid));
173 add_var(&script_snippet, "onto_name", opts->onto_name);
174 add_var(&script_snippet, "revisions", opts->revisions);
175 add_var(&script_snippet, "restrict_revision", opts->restrict_revision ?
176 oid_to_hex(&opts->restrict_revision->object.oid) : NULL);
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177 add_var(&script_snippet, "GIT_QUIET",
178 opts->flags & REBASE_NO_QUIET ? "" : "t");
179 add_var(&script_snippet, "git_am_opt", opts->git_am_opt.buf);
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180 add_var(&script_snippet, "verbose",
181 opts->flags & REBASE_VERBOSE ? "t" : "");
182 add_var(&script_snippet, "diffstat",
183 opts->flags & REBASE_DIFFSTAT ? "t" : "");
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184
185 switch (opts->type) {
186 case REBASE_AM:
187 backend = "git-rebase--am";
188 backend_func = "git_rebase__am";
189 break;
190 case REBASE_INTERACTIVE:
191 backend = "git-rebase--interactive";
192 backend_func = "git_rebase__interactive";
193 break;
194 case REBASE_MERGE:
195 backend = "git-rebase--merge";
196 backend_func = "git_rebase__merge";
197 break;
198 case REBASE_PRESERVE_MERGES:
199 backend = "git-rebase--preserve-merges";
200 backend_func = "git_rebase__preserve_merges";
201 break;
202 default:
203 BUG("Unhandled rebase type %d", opts->type);
204 break;
205 }
206
207 strbuf_addf(&script_snippet,
208 ". git-sh-setup && . git-rebase--common &&"
209 " . %s && %s", backend, backend_func);
210 argv[0] = script_snippet.buf;
211
212 status = run_command_v_opt(argv, RUN_USING_SHELL);
213 if (opts->dont_finish_rebase)
214 ; /* do nothing */
215 else if (status == 0) {
216 if (!file_exists(state_dir_path("stopped-sha", opts)))
217 finish_rebase(opts);
218 } else if (status == 2) {
219 struct strbuf dir = STRBUF_INIT;
220
221 apply_autostash();
222 strbuf_addstr(&dir, opts->state_dir);
223 remove_dir_recursively(&dir, 0);
224 strbuf_release(&dir);
225 die("Nothing to do");
226 }
227
228 strbuf_release(&script_snippet);
229
230 return status ? -1 : 0;
231}
232
233#define GIT_REFLOG_ACTION_ENVIRONMENT "GIT_REFLOG_ACTION"
234
235static int reset_head(struct object_id *oid, const char *action,
236 const char *switch_to_branch, int detach_head)
237{
238 struct object_id head_oid;
239 struct tree_desc desc;
240 struct lock_file lock = LOCK_INIT;
241 struct unpack_trees_options unpack_tree_opts;
242 struct tree *tree;
243 const char *reflog_action;
244 struct strbuf msg = STRBUF_INIT;
245 size_t prefix_len;
246 struct object_id *orig = NULL, oid_orig,
247 *old_orig = NULL, oid_old_orig;
248 int ret = 0;
249
250 if (hold_locked_index(&lock, LOCK_REPORT_ON_ERROR) < 0)
251 return -1;
252
253 if (!oid) {
254 if (get_oid("HEAD", &head_oid)) {
255 rollback_lock_file(&lock);
256 return error(_("could not determine HEAD revision"));
257 }
258 oid = &head_oid;
259 }
260
261 memset(&unpack_tree_opts, 0, sizeof(unpack_tree_opts));
262 setup_unpack_trees_porcelain(&unpack_tree_opts, action);
263 unpack_tree_opts.head_idx = 1;
264 unpack_tree_opts.src_index = the_repository->index;
265 unpack_tree_opts.dst_index = the_repository->index;
266 unpack_tree_opts.fn = oneway_merge;
267 unpack_tree_opts.update = 1;
268 unpack_tree_opts.merge = 1;
269 if (!detach_head)
270 unpack_tree_opts.reset = 1;
271
272 if (read_index_unmerged(the_repository->index) < 0) {
273 rollback_lock_file(&lock);
274 return error(_("could not read index"));
275 }
276
277 if (!fill_tree_descriptor(&desc, oid)) {
278 error(_("failed to find tree of %s"), oid_to_hex(oid));
279 rollback_lock_file(&lock);
280 free((void *)desc.buffer);
281 return -1;
282 }
283
284 if (unpack_trees(1, &desc, &unpack_tree_opts)) {
285 rollback_lock_file(&lock);
286 free((void *)desc.buffer);
287 return -1;
288 }
289
290 tree = parse_tree_indirect(oid);
291 prime_cache_tree(the_repository->index, tree);
292
293 if (write_locked_index(the_repository->index, &lock, COMMIT_LOCK) < 0)
294 ret = error(_("could not write index"));
295 free((void *)desc.buffer);
296
297 if (ret)
298 return ret;
299
300 reflog_action = getenv(GIT_REFLOG_ACTION_ENVIRONMENT);
301 strbuf_addf(&msg, "%s: ", reflog_action ? reflog_action : "rebase");
302 prefix_len = msg.len;
303
304 if (!get_oid("ORIG_HEAD", &oid_old_orig))
305 old_orig = &oid_old_orig;
306 if (!get_oid("HEAD", &oid_orig)) {
307 orig = &oid_orig;
308 strbuf_addstr(&msg, "updating ORIG_HEAD");
309 update_ref(msg.buf, "ORIG_HEAD", orig, old_orig, 0,
310 UPDATE_REFS_MSG_ON_ERR);
311 } else if (old_orig)
312 delete_ref(NULL, "ORIG_HEAD", old_orig, 0);
313 strbuf_setlen(&msg, prefix_len);
314 strbuf_addstr(&msg, "updating HEAD");
315 if (!switch_to_branch)
316 ret = update_ref(msg.buf, "HEAD", oid, orig, REF_NO_DEREF,
317 UPDATE_REFS_MSG_ON_ERR);
318 else {
319 ret = create_symref("HEAD", switch_to_branch, msg.buf);
320 if (!ret)
321 ret = update_ref(msg.buf, "HEAD", oid, NULL, 0,
322 UPDATE_REFS_MSG_ON_ERR);
323 }
324
325 strbuf_release(&msg);
326 return ret;
327}
328
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329static int rebase_config(const char *var, const char *value, void *data)
330{
331 struct rebase_options *opts = data;
332
333 if (!strcmp(var, "rebase.stat")) {
334 if (git_config_bool(var, value))
335 opts->flags |= REBASE_DIFFSTAT;
336 else
337 opts->flags &= !REBASE_DIFFSTAT;
338 return 0;
339 }
340
341 return git_default_config(var, value, data);
342}
343
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344/*
345 * Determines whether the commits in from..to are linear, i.e. contain
346 * no merge commits. This function *expects* `from` to be an ancestor of
347 * `to`.
348 */
349static int is_linear_history(struct commit *from, struct commit *to)
350{
351 while (to && to != from) {
352 parse_commit(to);
353 if (!to->parents)
354 return 1;
355 if (to->parents->next)
356 return 0;
357 to = to->parents->item;
358 }
359 return 1;
360}
361
362static int can_fast_forward(struct commit *onto, struct object_id *head_oid,
363 struct object_id *merge_base)
364{
365 struct commit *head = lookup_commit(the_repository, head_oid);
366 struct commit_list *merge_bases;
367 int res;
368
369 if (!head)
370 return 0;
371
372 merge_bases = get_merge_bases(onto, head);
373 if (merge_bases && !merge_bases->next) {
374 oidcpy(merge_base, &merge_bases->item->object.oid);
375 res = !oidcmp(merge_base, &onto->object.oid);
376 } else {
377 oidcpy(merge_base, &null_oid);
378 res = 0;
379 }
380 free_commit_list(merge_bases);
381 return res && is_linear_history(onto, head);
382}
383
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384int cmd_rebase(int argc, const char **argv, const char *prefix)
385{
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386 struct rebase_options options = {
387 .type = REBASE_UNSPECIFIED,
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388 .flags = REBASE_NO_QUIET,
389 .git_am_opt = STRBUF_INIT,
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390 };
391 const char *branch_name;
392 int ret, flags;
06e4775a 393 int ok_to_skip_pre_rebase = 0;
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394 struct strbuf msg = STRBUF_INIT;
395 struct strbuf revisions = STRBUF_INIT;
075bc852 396 struct object_id merge_base;
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397 struct option builtin_rebase_options[] = {
398 OPT_STRING(0, "onto", &options.onto_name,
399 N_("revision"),
400 N_("rebase onto given branch instead of upstream")),
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401 OPT_BOOL(0, "no-verify", &ok_to_skip_pre_rebase,
402 N_("allow pre-rebase hook to run")),
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403 OPT_NEGBIT('q', "quiet", &options.flags,
404 N_("be quiet. implies --no-stat"),
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405 REBASE_NO_QUIET| REBASE_VERBOSE | REBASE_DIFFSTAT),
406 OPT_BIT('v', "verbose", &options.flags,
407 N_("display a diffstat of what changed upstream"),
408 REBASE_NO_QUIET | REBASE_VERBOSE | REBASE_DIFFSTAT),
409 {OPTION_NEGBIT, 'n', "no-stat", &options.flags, NULL,
410 N_("do not show diffstat of what changed upstream"),
411 PARSE_OPT_NOARG, NULL, REBASE_DIFFSTAT },
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412 OPT_END(),
413 };
ac7f467f 414
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415 /*
416 * NEEDSWORK: Once the builtin rebase has been tested enough
417 * and git-legacy-rebase.sh is retired to contrib/, this preamble
418 * can be removed.
419 */
420
421 if (!use_builtin_rebase()) {
422 const char *path = mkpath("%s/git-legacy-rebase",
423 git_exec_path());
424
425 if (sane_execvp(path, (char **)argv) < 0)
426 die_errno(_("could not exec %s"), path);
427 else
428 BUG("sane_execvp() returned???");
429 }
430
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431 if (argc == 2 && !strcmp(argv[1], "-h"))
432 usage_with_options(builtin_rebase_usage,
433 builtin_rebase_options);
434
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435 prefix = setup_git_directory();
436 trace_repo_setup(prefix);
437 setup_work_tree();
438
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439 git_config(rebase_config, &options);
440
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441 argc = parse_options(argc, argv, prefix,
442 builtin_rebase_options,
443 builtin_rebase_usage, 0);
444
445 if (argc > 2)
446 usage_with_options(builtin_rebase_usage,
447 builtin_rebase_options);
ac7f467f 448
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449 if (!(options.flags & REBASE_NO_QUIET))
450 strbuf_addstr(&options.git_am_opt, " -q");
451
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452 switch (options.type) {
453 case REBASE_MERGE:
454 case REBASE_INTERACTIVE:
455 case REBASE_PRESERVE_MERGES:
456 options.state_dir = merge_dir();
457 break;
458 case REBASE_AM:
459 options.state_dir = apply_dir();
460 break;
461 default:
462 /* the default rebase backend is `--am` */
463 options.type = REBASE_AM;
464 options.state_dir = apply_dir();
465 break;
466 }
467
468 if (!options.root) {
f28d40d3 469 if (argc < 1)
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470 die("TODO: handle @{upstream}");
471 else {
f28d40d3 472 options.upstream_name = argv[0];
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473 argc--;
474 argv++;
475 if (!strcmp(options.upstream_name, "-"))
476 options.upstream_name = "@{-1}";
477 }
478 options.upstream = peel_committish(options.upstream_name);
479 if (!options.upstream)
480 die(_("invalid upstream '%s'"), options.upstream_name);
06e4775a 481 options.upstream_arg = options.upstream_name;
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482 } else
483 die("TODO: upstream for --root");
484
485 /* Make sure the branch to rebase onto is valid. */
486 if (!options.onto_name)
487 options.onto_name = options.upstream_name;
488 if (strstr(options.onto_name, "...")) {
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489 if (get_oid_mb(options.onto_name, &merge_base) < 0)
490 die(_("'%s': need exactly one merge base"),
491 options.onto_name);
492 options.onto = lookup_commit_or_die(&merge_base,
493 options.onto_name);
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494 } else {
495 options.onto = peel_committish(options.onto_name);
496 if (!options.onto)
497 die(_("Does not point to a valid commit '%s'"),
498 options.onto_name);
499 }
500
501 /*
502 * If the branch to rebase is given, that is the branch we will rebase
503 * branch_name -- branch/commit being rebased, or
504 * HEAD (already detached)
505 * orig_head -- commit object name of tip of the branch before rebasing
506 * head_name -- refs/heads/<that-branch> or "detached HEAD"
507 */
f28d40d3 508 if (argc > 0)
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509 die("TODO: handle switch_to");
510 else {
511 /* Do not need to switch branches, we are already on it. */
512 options.head_name =
513 xstrdup_or_null(resolve_ref_unsafe("HEAD", 0, NULL,
514 &flags));
515 if (!options.head_name)
516 die(_("No such ref: %s"), "HEAD");
517 if (flags & REF_ISSYMREF) {
518 if (!skip_prefix(options.head_name,
519 "refs/heads/", &branch_name))
520 branch_name = options.head_name;
521
522 } else {
523 options.head_name = xstrdup("detached HEAD");
524 branch_name = "HEAD";
525 }
526 if (get_oid("HEAD", &options.orig_head))
527 die(_("Could not resolve HEAD to a revision"));
528 }
529
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530 if (read_index(the_repository->index) < 0)
531 die(_("could not read index"));
532
533 if (require_clean_work_tree("rebase",
534 _("Please commit or stash them."), 1, 1)) {
535 ret = 1;
536 goto cleanup;
537 }
538
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539 /*
540 * Now we are rebasing commits upstream..orig_head (or with --root,
541 * everything leading up to orig_head) on top of onto.
542 */
543
544 /*
545 * Check if we are already based on onto with linear history,
546 * but this should be done only when upstream and onto are the same
547 * and if this is not an interactive rebase.
548 */
549 if (can_fast_forward(options.onto, &options.orig_head, &merge_base) &&
550 !is_interactive(&options) && !options.restrict_revision &&
551 !oidcmp(&options.upstream->object.oid, &options.onto->object.oid)) {
552 int flag;
553
554 if (!(options.flags & REBASE_NO_QUIET))
555 ; /* be quiet */
556 else if (!strcmp(branch_name, "HEAD") &&
557 resolve_ref_unsafe("HEAD", 0, NULL, &flag))
558 puts(_("HEAD is up to date, rebase forced."));
559 else
560 printf(_("Current branch %s is up to date, rebase "
561 "forced.\n"), branch_name);
562 }
563
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564 /* If a hook exists, give it a chance to interrupt*/
565 if (!ok_to_skip_pre_rebase &&
566 run_hook_le(NULL, "pre-rebase", options.upstream_arg,
567 argc ? argv[0] : NULL, NULL))
568 die(_("The pre-rebase hook refused to rebase."));
569
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570 if (options.flags & REBASE_DIFFSTAT) {
571 struct diff_options opts;
572
573 if (options.flags & REBASE_VERBOSE)
574 printf(_("Changes from %s to %s:\n"),
575 oid_to_hex(&merge_base),
576 oid_to_hex(&options.onto->object.oid));
577
578 /* We want color (if set), but no pager */
579 diff_setup(&opts);
580 opts.stat_width = -1; /* use full terminal width */
581 opts.stat_graph_width = -1; /* respect statGraphWidth config */
582 opts.output_format |=
583 DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
584 opts.detect_rename = DIFF_DETECT_RENAME;
585 diff_setup_done(&opts);
586 diff_tree_oid(&merge_base, &options.onto->object.oid,
587 "", &opts);
588 diffcore_std(&opts);
589 diff_flush(&opts);
590 }
591
592 /* Detach HEAD and reset the tree */
593 if (options.flags & REBASE_NO_QUIET)
594 printf(_("First, rewinding head to replay your work on top of "
595 "it...\n"));
596
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597 strbuf_addf(&msg, "rebase: checkout %s", options.onto_name);
598 if (reset_head(&options.onto->object.oid, "checkout", NULL, 1))
599 die(_("Could not detach HEAD"));
600 strbuf_release(&msg);
601
602 strbuf_addf(&revisions, "%s..%s",
603 options.root ? oid_to_hex(&options.onto->object.oid) :
604 (options.restrict_revision ?
605 oid_to_hex(&options.restrict_revision->object.oid) :
606 oid_to_hex(&options.upstream->object.oid)),
607 oid_to_hex(&options.orig_head));
608
609 options.revisions = revisions.buf;
610
611 ret = !!run_specific_rebase(&options);
612
e0333e5c 613cleanup:
ac7f467f
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614 strbuf_release(&revisions);
615 free(options.head_name);
616 return ret;
55071ea2 617}