1 /*
2 * libgit2 "merge" example - shows how to perform merges
3 *
4 * Written by the libgit2 contributors
5 *
6 * To the extent possible under law, the author(s) have dedicated all copyright
7 * and related and neighboring rights to this software to the public domain
8 * worldwide. This software is distributed without any warranty.
9 *
10 * You should have received a copy of the CC0 Public Domain Dedication along
11 * with this software. If not, see
12 * <http://creativecommons.org/publicdomain/zero/1.0/>.
13 */
14
15 #include "common.h"
16
17 /** The following example demonstrates how to do merges with libgit2.
18 *
19 * It will merge whatever commit-ish you pass in into the current branch.
20 *
21 * Recognized options are :
22 * --no-commit: don't actually commit the merge.
23 *
24 */
25
26 struct merge_options {
27 const char **heads;
28 size_t heads_count;
29
30 git_annotated_commit **annotated;
31 size_t annotated_count;
32
33 int no_commit : 1;
34 };
35
print_usage(void)36 static void print_usage(void)
37 {
38 fprintf(stderr, "usage: merge [--no-commit] <commit...>\n");
39 exit(1);
40 }
41
merge_options_init(struct merge_options * opts)42 static void merge_options_init(struct merge_options *opts)
43 {
44 memset(opts, 0, sizeof(*opts));
45
46 opts->heads = NULL;
47 opts->heads_count = 0;
48 opts->annotated = NULL;
49 opts->annotated_count = 0;
50 }
51
opts_add_refish(struct merge_options * opts,const char * refish)52 static void opts_add_refish(struct merge_options *opts, const char *refish)
53 {
54 size_t sz;
55
56 assert(opts != NULL);
57
58 sz = ++opts->heads_count * sizeof(opts->heads[0]);
59 opts->heads = xrealloc((void *) opts->heads, sz);
60 opts->heads[opts->heads_count - 1] = refish;
61 }
62
parse_options(const char ** repo_path,struct merge_options * opts,int argc,char ** argv)63 static void parse_options(const char **repo_path, struct merge_options *opts, int argc, char **argv)
64 {
65 struct args_info args = ARGS_INFO_INIT;
66
67 if (argc <= 1)
68 print_usage();
69
70 for (args.pos = 1; args.pos < argc; ++args.pos) {
71 const char *curr = argv[args.pos];
72
73 if (curr[0] != '-') {
74 opts_add_refish(opts, curr);
75 } else if (!strcmp(curr, "--no-commit")) {
76 opts->no_commit = 1;
77 } else if (match_str_arg(repo_path, &args, "--git-dir")) {
78 continue;
79 } else {
80 print_usage();
81 }
82 }
83 }
84
resolve_heads(git_repository * repo,struct merge_options * opts)85 static int resolve_heads(git_repository *repo, struct merge_options *opts)
86 {
87 git_annotated_commit **annotated = calloc(opts->heads_count, sizeof(git_annotated_commit *));
88 size_t annotated_count = 0, i;
89 int err = 0;
90
91 for (i = 0; i < opts->heads_count; i++) {
92 err = resolve_refish(&annotated[annotated_count++], repo, opts->heads[i]);
93 if (err != 0) {
94 fprintf(stderr, "failed to resolve refish %s: %s\n", opts->heads[i], git_error_last()->message);
95 annotated_count--;
96 continue;
97 }
98 }
99
100 if (annotated_count != opts->heads_count) {
101 fprintf(stderr, "unable to parse some refish\n");
102 free(annotated);
103 return -1;
104 }
105
106 opts->annotated = annotated;
107 opts->annotated_count = annotated_count;
108 return 0;
109 }
110
perform_fastforward(git_repository * repo,const git_oid * target_oid,int is_unborn)111 static int perform_fastforward(git_repository *repo, const git_oid *target_oid, int is_unborn)
112 {
113 git_checkout_options ff_checkout_options = GIT_CHECKOUT_OPTIONS_INIT;
114 git_reference *target_ref;
115 git_reference *new_target_ref;
116 git_object *target = NULL;
117 int err = 0;
118
119 if (is_unborn) {
120 const char *symbolic_ref;
121 git_reference *head_ref;
122
123 /* HEAD reference is unborn, lookup manually so we don't try to resolve it */
124 err = git_reference_lookup(&head_ref, repo, "HEAD");
125 if (err != 0) {
126 fprintf(stderr, "failed to lookup HEAD ref\n");
127 return -1;
128 }
129
130 /* Grab the reference HEAD should be pointing to */
131 symbolic_ref = git_reference_symbolic_target(head_ref);
132
133 /* Create our master reference on the target OID */
134 err = git_reference_create(&target_ref, repo, symbolic_ref, target_oid, 0, NULL);
135 if (err != 0) {
136 fprintf(stderr, "failed to create master reference\n");
137 return -1;
138 }
139
140 git_reference_free(head_ref);
141 } else {
142 /* HEAD exists, just lookup and resolve */
143 err = git_repository_head(&target_ref, repo);
144 if (err != 0) {
145 fprintf(stderr, "failed to get HEAD reference\n");
146 return -1;
147 }
148 }
149
150 /* Lookup the target object */
151 err = git_object_lookup(&target, repo, target_oid, GIT_OBJECT_COMMIT);
152 if (err != 0) {
153 fprintf(stderr, "failed to lookup OID %s\n", git_oid_tostr_s(target_oid));
154 return -1;
155 }
156
157 /* Checkout the result so the workdir is in the expected state */
158 ff_checkout_options.checkout_strategy = GIT_CHECKOUT_SAFE;
159 err = git_checkout_tree(repo, target, &ff_checkout_options);
160 if (err != 0) {
161 fprintf(stderr, "failed to checkout HEAD reference\n");
162 return -1;
163 }
164
165 /* Move the target reference to the target OID */
166 err = git_reference_set_target(&new_target_ref, target_ref, target_oid, NULL);
167 if (err != 0) {
168 fprintf(stderr, "failed to move HEAD reference\n");
169 return -1;
170 }
171
172 git_reference_free(target_ref);
173 git_reference_free(new_target_ref);
174 git_object_free(target);
175
176 return 0;
177 }
178
output_conflicts(git_index * index)179 static void output_conflicts(git_index *index)
180 {
181 git_index_conflict_iterator *conflicts;
182 const git_index_entry *ancestor;
183 const git_index_entry *our;
184 const git_index_entry *their;
185 int err = 0;
186
187 check_lg2(git_index_conflict_iterator_new(&conflicts, index), "failed to create conflict iterator", NULL);
188
189 while ((err = git_index_conflict_next(&ancestor, &our, &their, conflicts)) == 0) {
190 fprintf(stderr, "conflict: a:%s o:%s t:%s\n",
191 ancestor ? ancestor->path : "NULL",
192 our->path ? our->path : "NULL",
193 their->path ? their->path : "NULL");
194 }
195
196 if (err != GIT_ITEROVER) {
197 fprintf(stderr, "error iterating conflicts\n");
198 }
199
200 git_index_conflict_iterator_free(conflicts);
201 }
202
create_merge_commit(git_repository * repo,git_index * index,struct merge_options * opts)203 static int create_merge_commit(git_repository *repo, git_index *index, struct merge_options *opts)
204 {
205 git_oid tree_oid, commit_oid;
206 git_tree *tree;
207 git_signature *sign;
208 git_reference *merge_ref = NULL;
209 git_annotated_commit *merge_commit;
210 git_reference *head_ref;
211 git_commit **parents = calloc(opts->annotated_count + 1, sizeof(git_commit *));
212 const char *msg_target = NULL;
213 size_t msglen = 0;
214 char *msg;
215 size_t i;
216 int err;
217
218 /* Grab our needed references */
219 check_lg2(git_repository_head(&head_ref, repo), "failed to get repo HEAD", NULL);
220 if (resolve_refish(&merge_commit, repo, opts->heads[0])) {
221 fprintf(stderr, "failed to resolve refish %s", opts->heads[0]);
222 free(parents);
223 return -1;
224 }
225
226 /* Maybe that's a ref, so DWIM it */
227 err = git_reference_dwim(&merge_ref, repo, opts->heads[0]);
228 check_lg2(err, "failed to DWIM reference", git_error_last()->message);
229
230 /* Grab a signature */
231 check_lg2(git_signature_now(&sign, "Me", "me@example.com"), "failed to create signature", NULL);
232
233 #define MERGE_COMMIT_MSG "Merge %s '%s'"
234 /* Prepare a standard merge commit message */
235 if (merge_ref != NULL) {
236 check_lg2(git_branch_name(&msg_target, merge_ref), "failed to get branch name of merged ref", NULL);
237 } else {
238 msg_target = git_oid_tostr_s(git_annotated_commit_id(merge_commit));
239 }
240
241 msglen = snprintf(NULL, 0, MERGE_COMMIT_MSG, (merge_ref ? "branch" : "commit"), msg_target);
242 if (msglen > 0) msglen++;
243 msg = malloc(msglen);
244 err = snprintf(msg, msglen, MERGE_COMMIT_MSG, (merge_ref ? "branch" : "commit"), msg_target);
245
246 /* This is only to silence the compiler */
247 if (err < 0) goto cleanup;
248
249 /* Setup our parent commits */
250 err = git_reference_peel((git_object **)&parents[0], head_ref, GIT_OBJECT_COMMIT);
251 check_lg2(err, "failed to peel head reference", NULL);
252 for (i = 0; i < opts->annotated_count; i++) {
253 git_commit_lookup(&parents[i + 1], repo, git_annotated_commit_id(opts->annotated[i]));
254 }
255
256 /* Prepare our commit tree */
257 check_lg2(git_index_write_tree(&tree_oid, index), "failed to write merged tree", NULL);
258 check_lg2(git_tree_lookup(&tree, repo, &tree_oid), "failed to lookup tree", NULL);
259
260 /* Commit time ! */
261 err = git_commit_create(&commit_oid,
262 repo, git_reference_name(head_ref),
263 sign, sign,
264 NULL, msg,
265 tree,
266 opts->annotated_count + 1, (const git_commit **)parents);
267 check_lg2(err, "failed to create commit", NULL);
268
269 /* We're done merging, cleanup the repository state */
270 git_repository_state_cleanup(repo);
271
272 cleanup:
273 free(parents);
274 return err;
275 }
276
lg2_merge(git_repository * repo,int argc,char ** argv)277 int lg2_merge(git_repository *repo, int argc, char **argv)
278 {
279 struct merge_options opts;
280 git_index *index;
281 git_repository_state_t state;
282 git_merge_analysis_t analysis;
283 git_merge_preference_t preference;
284 const char *path = ".";
285 int err = 0;
286
287 merge_options_init(&opts);
288 parse_options(&path, &opts, argc, argv);
289
290 state = git_repository_state(repo);
291 if (state != GIT_REPOSITORY_STATE_NONE) {
292 fprintf(stderr, "repository is in unexpected state %d\n", state);
293 goto cleanup;
294 }
295
296 err = resolve_heads(repo, &opts);
297 if (err != 0)
298 goto cleanup;
299
300 err = git_merge_analysis(&analysis, &preference,
301 repo,
302 (const git_annotated_commit **)opts.annotated,
303 opts.annotated_count);
304 check_lg2(err, "merge analysis failed", NULL);
305
306 if (analysis & GIT_MERGE_ANALYSIS_UP_TO_DATE) {
307 printf("Already up-to-date\n");
308 return 0;
309 } else if (analysis & GIT_MERGE_ANALYSIS_UNBORN ||
310 (analysis & GIT_MERGE_ANALYSIS_FASTFORWARD &&
311 !(preference & GIT_MERGE_PREFERENCE_NO_FASTFORWARD))) {
312 const git_oid *target_oid;
313 if (analysis & GIT_MERGE_ANALYSIS_UNBORN) {
314 printf("Unborn\n");
315 } else {
316 printf("Fast-forward\n");
317 }
318
319 /* Since this is a fast-forward, there can be only one merge head */
320 target_oid = git_annotated_commit_id(opts.annotated[0]);
321 assert(opts.annotated_count == 1);
322
323 return perform_fastforward(repo, target_oid, (analysis & GIT_MERGE_ANALYSIS_UNBORN));
324 } else if (analysis & GIT_MERGE_ANALYSIS_NORMAL) {
325 git_merge_options merge_opts = GIT_MERGE_OPTIONS_INIT;
326 git_checkout_options checkout_opts = GIT_CHECKOUT_OPTIONS_INIT;
327
328 merge_opts.flags = 0;
329 merge_opts.file_flags = GIT_MERGE_FILE_STYLE_DIFF3;
330
331 checkout_opts.checkout_strategy = GIT_CHECKOUT_FORCE|GIT_CHECKOUT_ALLOW_CONFLICTS;
332
333 if (preference & GIT_MERGE_PREFERENCE_FASTFORWARD_ONLY) {
334 printf("Fast-forward is preferred, but only a merge is possible\n");
335 return -1;
336 }
337
338 err = git_merge(repo,
339 (const git_annotated_commit **)opts.annotated, opts.annotated_count,
340 &merge_opts, &checkout_opts);
341 check_lg2(err, "merge failed", NULL);
342 }
343
344 /* If we get here, we actually performed the merge above */
345
346 check_lg2(git_repository_index(&index, repo), "failed to get repository index", NULL);
347
348 if (git_index_has_conflicts(index)) {
349 /* Handle conflicts */
350 output_conflicts(index);
351 } else if (!opts.no_commit) {
352 create_merge_commit(repo, index, &opts);
353 printf("Merge made\n");
354 }
355
356 cleanup:
357 free((char **)opts.heads);
358 free(opts.annotated);
359
360 return 0;
361 }
362