0629c87b19d59d7003f50fa9524953515b409909
[git/git.git] / builtin / merge-tree.c
1 #define USE_THE_INDEX_COMPATIBILITY_MACROS
2 #include "builtin.h"
3 #include "tree-walk.h"
4 #include "xdiff-interface.h"
5 #include "object-store.h"
6 #include "repository.h"
7 #include "blob.h"
8 #include "exec-cmd.h"
9 #include "merge-blobs.h"
10
11 static const char merge_tree_usage[] = "git merge-tree <base-tree> <branch1> <branch2>";
12
13 struct merge_list {
14 struct merge_list *next;
15 struct merge_list *link; /* other stages for this object */
16
17 unsigned int stage : 2;
18 unsigned int mode;
19 const char *path;
20 struct blob *blob;
21 };
22
23 static struct merge_list *merge_result, **merge_result_end = &merge_result;
24
25 static void add_merge_entry(struct merge_list *entry)
26 {
27 *merge_result_end = entry;
28 merge_result_end = &entry->next;
29 }
30
31 static void merge_trees(struct tree_desc t[3], const char *base);
32
33 static const char *explanation(struct merge_list *entry)
34 {
35 switch (entry->stage) {
36 case 0:
37 return "merged";
38 case 3:
39 return "added in remote";
40 case 2:
41 if (entry->link)
42 return "added in both";
43 return "added in local";
44 }
45
46 /* Existed in base */
47 entry = entry->link;
48 if (!entry)
49 return "removed in both";
50
51 if (entry->link)
52 return "changed in both";
53
54 if (entry->stage == 3)
55 return "removed in local";
56 return "removed in remote";
57 }
58
59 static void *result(struct merge_list *entry, unsigned long *size)
60 {
61 enum object_type type;
62 struct blob *base, *our, *their;
63 const char *path = entry->path;
64
65 if (!entry->stage)
66 return read_object_file(&entry->blob->object.oid, &type, size);
67 base = NULL;
68 if (entry->stage == 1) {
69 base = entry->blob;
70 entry = entry->link;
71 }
72 our = NULL;
73 if (entry && entry->stage == 2) {
74 our = entry->blob;
75 entry = entry->link;
76 }
77 their = NULL;
78 if (entry)
79 their = entry->blob;
80 return merge_blobs(the_repository->index, path,
81 base, our, their, size);
82 }
83
84 static void *origin(struct merge_list *entry, unsigned long *size)
85 {
86 enum object_type type;
87 while (entry) {
88 if (entry->stage == 2)
89 return read_object_file(&entry->blob->object.oid,
90 &type, size);
91 entry = entry->link;
92 }
93 return NULL;
94 }
95
96 static int show_outf(void *priv_, mmbuffer_t *mb, int nbuf)
97 {
98 int i;
99 for (i = 0; i < nbuf; i++)
100 printf("%.*s", (int) mb[i].size, mb[i].ptr);
101 return 0;
102 }
103
104 static void show_diff(struct merge_list *entry)
105 {
106 unsigned long size;
107 mmfile_t src, dst;
108 xpparam_t xpp;
109 xdemitconf_t xecfg;
110 xdemitcb_t ecb;
111
112 xpp.flags = 0;
113 memset(&xecfg, 0, sizeof(xecfg));
114 xecfg.ctxlen = 3;
115 ecb.out_hunk = NULL;
116 ecb.out_line = show_outf;
117 ecb.priv = NULL;
118
119 src.ptr = origin(entry, &size);
120 if (!src.ptr)
121 size = 0;
122 src.size = size;
123 dst.ptr = result(entry, &size);
124 if (!dst.ptr)
125 size = 0;
126 dst.size = size;
127 if (xdi_diff(&src, &dst, &xpp, &xecfg, &ecb))
128 die("unable to generate diff");
129 free(src.ptr);
130 free(dst.ptr);
131 }
132
133 static void show_result_list(struct merge_list *entry)
134 {
135 printf("%s\n", explanation(entry));
136 do {
137 struct merge_list *link = entry->link;
138 static const char *desc[4] = { "result", "base", "our", "their" };
139 printf(" %-6s %o %s %s\n", desc[entry->stage], entry->mode, oid_to_hex(&entry->blob->object.oid), entry->path);
140 entry = link;
141 } while (entry);
142 }
143
144 static void show_result(void)
145 {
146 struct merge_list *walk;
147
148 walk = merge_result;
149 while (walk) {
150 show_result_list(walk);
151 show_diff(walk);
152 walk = walk->next;
153 }
154 }
155
156 /* An empty entry never compares same, not even to another empty entry */
157 static int same_entry(struct name_entry *a, struct name_entry *b)
158 {
159 return !is_null_oid(&a->oid) &&
160 !is_null_oid(&b->oid) &&
161 oideq(&a->oid, &b->oid) &&
162 a->mode == b->mode;
163 }
164
165 static int both_empty(struct name_entry *a, struct name_entry *b)
166 {
167 return is_null_oid(&a->oid) && is_null_oid(&b->oid);
168 }
169
170 static struct merge_list *create_entry(unsigned stage, unsigned mode, const struct object_id *oid, const char *path)
171 {
172 struct merge_list *res = xcalloc(1, sizeof(*res));
173
174 res->stage = stage;
175 res->path = path;
176 res->mode = mode;
177 res->blob = lookup_blob(the_repository, oid);
178 return res;
179 }
180
181 static char *traverse_path(const struct traverse_info *info, const struct name_entry *n)
182 {
183 char *path = xmallocz(traverse_path_len(info, tree_entry_len(n)));
184 return make_traverse_path(path, info, n->path, n->pathlen);
185 }
186
187 static void resolve(const struct traverse_info *info, struct name_entry *ours, struct name_entry *result)
188 {
189 struct merge_list *orig, *final;
190 const char *path;
191
192 /* If it's already ours, don't bother showing it */
193 if (!ours)
194 return;
195
196 path = traverse_path(info, result);
197 orig = create_entry(2, ours->mode, &ours->oid, path);
198 final = create_entry(0, result->mode, &result->oid, path);
199
200 final->link = orig;
201
202 add_merge_entry(final);
203 }
204
205 static void unresolved_directory(const struct traverse_info *info,
206 struct name_entry n[3])
207 {
208 char *newbase;
209 struct name_entry *p;
210 struct tree_desc t[3];
211 void *buf0, *buf1, *buf2;
212
213 for (p = n; p < n + 3; p++) {
214 if (p->mode && S_ISDIR(p->mode))
215 break;
216 }
217 if (n + 3 <= p)
218 return; /* there is no tree here */
219
220 newbase = traverse_path(info, p);
221
222 #define ENTRY_OID(e) (((e)->mode && S_ISDIR((e)->mode)) ? &(e)->oid : NULL)
223 buf0 = fill_tree_descriptor(t + 0, ENTRY_OID(n + 0));
224 buf1 = fill_tree_descriptor(t + 1, ENTRY_OID(n + 1));
225 buf2 = fill_tree_descriptor(t + 2, ENTRY_OID(n + 2));
226 #undef ENTRY_OID
227
228 merge_trees(t, newbase);
229
230 free(buf0);
231 free(buf1);
232 free(buf2);
233 free(newbase);
234 }
235
236
237 static struct merge_list *link_entry(unsigned stage, const struct traverse_info *info, struct name_entry *n, struct merge_list *entry)
238 {
239 const char *path;
240 struct merge_list *link;
241
242 if (!n->mode)
243 return entry;
244 if (entry)
245 path = entry->path;
246 else
247 path = traverse_path(info, n);
248 link = create_entry(stage, n->mode, &n->oid, path);
249 link->link = entry;
250 return link;
251 }
252
253 static void unresolved(const struct traverse_info *info, struct name_entry n[3])
254 {
255 struct merge_list *entry = NULL;
256 int i;
257 unsigned dirmask = 0, mask = 0;
258
259 for (i = 0; i < 3; i++) {
260 mask |= (1 << i);
261 /*
262 * Treat missing entries as directories so that we return
263 * after unresolved_directory has handled this.
264 */
265 if (!n[i].mode || S_ISDIR(n[i].mode))
266 dirmask |= (1 << i);
267 }
268
269 unresolved_directory(info, n);
270
271 if (dirmask == mask)
272 return;
273
274 if (n[2].mode && !S_ISDIR(n[2].mode))
275 entry = link_entry(3, info, n + 2, entry);
276 if (n[1].mode && !S_ISDIR(n[1].mode))
277 entry = link_entry(2, info, n + 1, entry);
278 if (n[0].mode && !S_ISDIR(n[0].mode))
279 entry = link_entry(1, info, n + 0, entry);
280
281 add_merge_entry(entry);
282 }
283
284 /*
285 * Merge two trees together (t[1] and t[2]), using a common base (t[0])
286 * as the origin.
287 *
288 * This walks the (sorted) trees in lock-step, checking every possible
289 * name. Note that directories automatically sort differently from other
290 * files (see "base_name_compare"), so you'll never see file/directory
291 * conflicts, because they won't ever compare the same.
292 *
293 * IOW, if a directory changes to a filename, it will automatically be
294 * seen as the directory going away, and the filename being created.
295 *
296 * Think of this as a three-way diff.
297 *
298 * The output will be either:
299 * - successful merge
300 * "0 mode sha1 filename"
301 * NOTE NOTE NOTE! FIXME! We really really need to walk the index
302 * in parallel with this too!
303 *
304 * - conflict:
305 * "1 mode sha1 filename"
306 * "2 mode sha1 filename"
307 * "3 mode sha1 filename"
308 * where not all of the 1/2/3 lines may exist, of course.
309 *
310 * The successful merge rules are the same as for the three-way merge
311 * in git-read-tree.
312 */
313 static int threeway_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *entry, struct traverse_info *info)
314 {
315 /* Same in both? */
316 if (same_entry(entry+1, entry+2) || both_empty(entry+1, entry+2)) {
317 /* Modified, added or removed identically */
318 resolve(info, NULL, entry+1);
319 return mask;
320 }
321
322 if (same_entry(entry+0, entry+1)) {
323 if (!is_null_oid(&entry[2].oid) && !S_ISDIR(entry[2].mode)) {
324 /* We did not touch, they modified -- take theirs */
325 resolve(info, entry+1, entry+2);
326 return mask;
327 }
328 /*
329 * If we did not touch a directory but they made it
330 * into a file, we fall through and unresolved()
331 * recurses down. Likewise for the opposite case.
332 */
333 }
334
335 if (same_entry(entry+0, entry+2) || both_empty(entry+0, entry+2)) {
336 /* We added, modified or removed, they did not touch -- take ours */
337 resolve(info, NULL, entry+1);
338 return mask;
339 }
340
341 unresolved(info, entry);
342 return mask;
343 }
344
345 static void merge_trees(struct tree_desc t[3], const char *base)
346 {
347 struct traverse_info info;
348
349 setup_traverse_info(&info, base);
350 info.fn = threeway_callback;
351 traverse_trees(&the_index, 3, t, &info);
352 }
353
354 static void *get_tree_descriptor(struct tree_desc *desc, const char *rev)
355 {
356 struct object_id oid;
357 void *buf;
358
359 if (get_oid(rev, &oid))
360 die("unknown rev %s", rev);
361 buf = fill_tree_descriptor(desc, &oid);
362 if (!buf)
363 die("%s is not a tree", rev);
364 return buf;
365 }
366
367 int cmd_merge_tree(int argc, const char **argv, const char *prefix)
368 {
369 struct tree_desc t[3];
370 void *buf1, *buf2, *buf3;
371
372 if (argc != 4)
373 usage(merge_tree_usage);
374
375 buf1 = get_tree_descriptor(t+0, argv[1]);
376 buf2 = get_tree_descriptor(t+1, argv[2]);
377 buf3 = get_tree_descriptor(t+2, argv[3]);
378 merge_trees(t, "");
379 free(buf1);
380 free(buf2);
381 free(buf3);
382
383 show_result();
384 return 0;
385 }