summaryrefslogtreecommitdiff
path: root/examples/merge.c
blob: a275ecbeb5f2418c1988911cb8178d38b1ff5009 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
/*
 * libgit2 "merge" example - shows how to perform merges
 *
 * Written by the libgit2 contributors
 *
 * To the extent possible under law, the author(s) have dedicated all copyright
 * and related and neighboring rights to this software to the public domain
 * worldwide. This software is distributed without any warranty.
 *
 * You should have received a copy of the CC0 Public Domain Dedication along
 * with this software. If not, see
 * <http://creativecommons.org/publicdomain/zero/1.0/>.
 */

#include "common.h"
#include <assert.h>

#ifdef _MSC_VER
#define snprintf sprintf_s
#endif

/** The following example demonstrates how to do merges with libgit2.
 *
 * It will merge whatever commit-ish you pass in into the current branch.
 *
 * Recognized options are :
 *  --no-commit: don't actually commit the merge.
 *
 */

typedef struct {
	const char **heads;
	size_t heads_count;

	git_annotated_commit **annotated;
	size_t annotated_count;

	int no_commit : 1;
} merge_options;

static void print_usage(void)
{
	fprintf(stderr, "usage: merge [--no-commit] <commit...>\n");
	exit(1);
}

static void merge_options_init(merge_options *opts)
{
	memset(opts, 0, sizeof(*opts));

	opts->heads = NULL;
	opts->heads_count = 0;
	opts->annotated = NULL;
	opts->annotated_count = 0;
}

static void opts_add_refish(merge_options *opts, const char *refish)
{
	size_t sz;

	assert(opts != NULL);

	sz = ++opts->heads_count * sizeof(opts->heads[0]);
	opts->heads = xrealloc(opts->heads, sz);
	opts->heads[opts->heads_count - 1] = refish;
}

static void parse_options(const char **repo_path, merge_options *opts, int argc, char **argv)
{
	struct args_info args = ARGS_INFO_INIT;

	if (argc <= 1)
		print_usage();

	for (args.pos = 1; args.pos < argc; ++args.pos) {
		const char *curr = argv[args.pos];

		if (curr[0] != '-') {
			opts_add_refish(opts, curr);
		} else if (!strcmp(curr, "--no-commit")) {
			opts->no_commit = 1;
		} else if (match_str_arg(repo_path, &args, "--git-dir")) {
			continue;
		} else {
			print_usage();
		}
	}
}

static int resolve_heads(git_repository *repo, merge_options *opts)
{
	git_annotated_commit **annotated = calloc(opts->heads_count, sizeof(git_annotated_commit *));
	size_t annotated_count = 0, i;
	int err = 0;

	for (i = 0; i < opts->heads_count; i++) {
		err = resolve_refish(&annotated[annotated_count++], repo, opts->heads[i]);
		if (err != 0) {
			fprintf(stderr, "failed to resolve refish %s: %s\n", opts->heads[i], git_error_last()->message);
			annotated_count--;
			continue;
		}
	}

	if (annotated_count != opts->heads_count) {
		fprintf(stderr, "unable to parse some refish\n");
		free(annotated);
		return -1;
	}

	opts->annotated = annotated;
	opts->annotated_count = annotated_count;
	return 0;
}

static int perform_fastforward(git_repository *repo, const git_oid *target_oid, int is_unborn)
{
	git_checkout_options ff_checkout_options = GIT_CHECKOUT_OPTIONS_INIT;
	git_reference *target_ref;
	git_reference *new_target_ref;
	git_object *target = NULL;
	int err = 0;

	if (is_unborn) {
		const char *symbolic_ref;
		git_reference *head_ref;

		/* HEAD reference is unborn, lookup manually so we don't try to resolve it */
		err = git_reference_lookup(&head_ref, repo, "HEAD");
		if (err != 0) {
			fprintf(stderr, "failed to lookup HEAD ref\n");
			return -1;
		}

		/* Grab the reference HEAD should be pointing to */
		symbolic_ref = git_reference_symbolic_target(head_ref);

		/* Create our master reference on the target OID */
		err = git_reference_create(&target_ref, repo, symbolic_ref, target_oid, 0, NULL);
		if (err != 0) {
			fprintf(stderr, "failed to create master reference\n");
			return -1;
		}

		git_reference_free(head_ref);
	} else {
		/* HEAD exists, just lookup and resolve */
		err = git_repository_head(&target_ref, repo);
		if (err != 0) {
			fprintf(stderr, "failed to get HEAD reference\n");
			return -1;
		}
	}

	/* Lookup the target object */
	err = git_object_lookup(&target, repo, target_oid, GIT_OBJECT_COMMIT);
	if (err != 0) {
		fprintf(stderr, "failed to lookup OID %s\n", git_oid_tostr_s(target_oid));
		return -1;
	}

	/* Checkout the result so the workdir is in the expected state */
	ff_checkout_options.checkout_strategy = GIT_CHECKOUT_SAFE;
	err = git_checkout_tree(repo, target, &ff_checkout_options);
	if (err != 0) {
		fprintf(stderr, "failed to checkout HEAD reference\n");
		return -1;
	}

	/* Move the target reference to the target OID */
	err = git_reference_set_target(&new_target_ref, target_ref, target_oid, NULL);
	if (err != 0) {
		fprintf(stderr, "failed to move HEAD reference\n");
		return -1;
	}

	git_reference_free(target_ref);
	git_reference_free(new_target_ref);
	git_object_free(target);

	return 0;
}

static void output_conflicts(git_index *index)
{
	git_index_conflict_iterator *conflicts;
	const git_index_entry *ancestor;
	const git_index_entry *our;
	const git_index_entry *their;
	int err = 0;

	check_lg2(git_index_conflict_iterator_new(&conflicts, index), "failed to create conflict iterator", NULL);

	while ((err = git_index_conflict_next(&ancestor, &our, &their, conflicts)) == 0) {
		fprintf(stderr, "conflict: a:%s o:%s t:%s\n",
		        ancestor ? ancestor->path : "NULL",
		        our->path ? our->path : "NULL",
		        their->path ? their->path : "NULL");
	}

	if (err != GIT_ITEROVER) {
		fprintf(stderr, "error iterating conflicts\n");
	}

	git_index_conflict_iterator_free(conflicts);
}

static int create_merge_commit(git_repository *repo, git_index *index, merge_options *opts)
{
	git_oid tree_oid, commit_oid;
	git_tree *tree;
	git_signature *sign;
	git_reference *merge_ref = NULL;
	git_annotated_commit *merge_commit;
	git_reference *head_ref;
	git_commit **parents = calloc(opts->annotated_count + 1, sizeof(git_commit *));
	const char *msg_target = NULL;
	size_t msglen = 0;
	char *msg;
	size_t i;
	int err;

	/* Grab our needed references */
	check_lg2(git_repository_head(&head_ref, repo), "failed to get repo HEAD", NULL);
	if (resolve_refish(&merge_commit, repo, opts->heads[0])) {
		fprintf(stderr, "failed to resolve refish %s", opts->heads[0]);
		return -1;
	}

	/* Maybe that's a ref, so DWIM it */
	err = git_reference_dwim(&merge_ref, repo, opts->heads[0]);
	check_lg2(err, "failed to DWIM reference", git_error_last()->message);

	/* Grab a signature */
	check_lg2(git_signature_now(&sign, "Me", "me@example.com"), "failed to create signature", NULL);

#define MERGE_COMMIT_MSG "Merge %s '%s'"
	/* Prepare a standard merge commit message */
	if (merge_ref != NULL) {
		check_lg2(git_branch_name(&msg_target, merge_ref), "failed to get branch name of merged ref", NULL);
	} else {
		msg_target = git_oid_tostr_s(git_annotated_commit_id(merge_commit));
	}

	msglen = snprintf(NULL, 0, MERGE_COMMIT_MSG, (merge_ref ? "branch" : "commit"), msg_target);
	if (msglen > 0) msglen++;
	msg = malloc(msglen);
	err = snprintf(msg, msglen, MERGE_COMMIT_MSG, (merge_ref ? "branch" : "commit"), msg_target);

	/* This is only to silence the compiler */
	if (err < 0) goto cleanup;

	/* Setup our parent commits */
	err = git_reference_peel((git_object **)&parents[0], head_ref, GIT_OBJECT_COMMIT);
	check_lg2(err, "failed to peel head reference", NULL);
	for (i = 0; i < opts->annotated_count; i++) {
		git_commit_lookup(&parents[i + 1], repo, git_annotated_commit_id(opts->annotated[i]));
	}

	/* Prepare our commit tree */
	check_lg2(git_index_write_tree(&tree_oid, index), "failed to write merged tree", NULL);
	check_lg2(git_tree_lookup(&tree, repo, &tree_oid), "failed to lookup tree", NULL);

	/* Commit time ! */
	err = git_commit_create(&commit_oid,
	                        repo, git_reference_name(head_ref),
	                        sign, sign,
	                        NULL, msg,
	                        tree,
	                        opts->annotated_count + 1, (const git_commit **)parents);
	check_lg2(err, "failed to create commit", NULL);

	/* We're done merging, cleanup the repository state */
	git_repository_state_cleanup(repo);

cleanup:
	free(parents);
	return err;
}

int lg2_merge(git_repository *repo, int argc, char **argv)
{
	merge_options opts;
	git_index *index;
	git_repository_state_t state;
	git_merge_analysis_t analysis;
	git_merge_preference_t preference;
	const char *path = ".";
	int err = 0;

	merge_options_init(&opts);
	parse_options(&path, &opts, argc, argv);

	state = git_repository_state(repo);
	if (state != GIT_REPOSITORY_STATE_NONE) {
		fprintf(stderr, "repository is in unexpected state %d\n", state);
		goto cleanup;
	}

	err = resolve_heads(repo, &opts);
	if (err != 0)
		goto cleanup;

	err = git_merge_analysis(&analysis, &preference,
	                         repo,
	                         (const git_annotated_commit **)opts.annotated,
	                         opts.annotated_count);
	check_lg2(err, "merge analysis failed", NULL);

	if (analysis & GIT_MERGE_ANALYSIS_UP_TO_DATE) {
		printf("Already up-to-date\n");
		return 0;
	} else if (analysis & GIT_MERGE_ANALYSIS_UNBORN ||
	          (analysis & GIT_MERGE_ANALYSIS_FASTFORWARD &&
	          !(preference & GIT_MERGE_PREFERENCE_NO_FASTFORWARD))) {
		const git_oid *target_oid;
		if (analysis & GIT_MERGE_ANALYSIS_UNBORN) {
			printf("Unborn\n");
		} else {
			printf("Fast-forward\n");
		}

		/* Since this is a fast-forward, there can be only one merge head */
		target_oid = git_annotated_commit_id(opts.annotated[0]);
		assert(opts.annotated_count == 1);

		return perform_fastforward(repo, target_oid, (analysis & GIT_MERGE_ANALYSIS_UNBORN));
	} else if (analysis & GIT_MERGE_ANALYSIS_NORMAL) {
		git_merge_options merge_opts = GIT_MERGE_OPTIONS_INIT;
		git_checkout_options checkout_opts = GIT_CHECKOUT_OPTIONS_INIT;

		merge_opts.flags = 0;
		merge_opts.file_flags = GIT_MERGE_FILE_STYLE_DIFF3;

		checkout_opts.checkout_strategy = GIT_CHECKOUT_FORCE|GIT_CHECKOUT_ALLOW_CONFLICTS;

		if (preference & GIT_MERGE_PREFERENCE_FASTFORWARD_ONLY) {
			printf("Fast-forward is preferred, but only a merge is possible\n");
			return -1;
		}

		err = git_merge(repo,
		                (const git_annotated_commit **)opts.annotated, opts.annotated_count,
		                &merge_opts, &checkout_opts);
		check_lg2(err, "merge failed", NULL);
	}

	/* If we get here, we actually performed the merge above */

	check_lg2(git_repository_index(&index, repo), "failed to get repository index", NULL);

	if (git_index_has_conflicts(index)) {
		/* Handle conflicts */
		output_conflicts(index);
	} else if (!opts.no_commit) {
		create_merge_commit(repo, index, &opts);
		printf("Merge made\n");
	}

cleanup:
	free(opts.heads);
	free(opts.annotated);

	return 0;
}