tree-walk: add a strbuf wrapper for make_traverse_path()
[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 struct strbuf buf = STRBUF_INIT;
184 strbuf_make_traverse_path(&buf, info, n->path, n->pathlen);
185 return strbuf_detach(&buf, NULL);
186 }
187
188 static void resolve(const struct traverse_info *info, struct name_entry *ours, struct name_entry *result)
189 {
190 struct merge_list *orig, *final;
191 const char *path;
192
193 /* If it's already ours, don't bother showing it */
194 if (!ours)
195 return;
196
197 path = traverse_path(info, result);
198 orig = create_entry(2, ours->mode, &ours->oid, path);
199 final = create_entry(0, result->mode, &result->oid, path);
200
201 final->link = orig;
202
203 add_merge_entry(final);
204 }
205
206 static void unresolved_directory(const struct traverse_info *info,
207 struct name_entry n[3])
208 {
209 char *newbase;
210 struct name_entry *p;
211 struct tree_desc t[3];
212 void *buf0, *buf1, *buf2;
213
214 for (p = n; p < n + 3; p++) {
215 if (p->mode && S_ISDIR(p->mode))
216 break;
217 }
218 if (n + 3 <= p)
219 return; /* there is no tree here */
220
221 newbase = traverse_path(info, p);
222
223 #define ENTRY_OID(e) (((e)->mode && S_ISDIR((e)->mode)) ? &(e)->oid : NULL)
224 buf0 = fill_tree_descriptor(t + 0, ENTRY_OID(n + 0));
225 buf1 = fill_tree_descriptor(t + 1, ENTRY_OID(n + 1));
226 buf2 = fill_tree_descriptor(t + 2, ENTRY_OID(n + 2));
227 #undef ENTRY_OID
228
229 merge_trees(t, newbase);
230
231 free(buf0);
232 free(buf1);
233 free(buf2);
234 free(newbase);
235 }
236
237
238 static struct merge_list *link_entry(unsigned stage, const struct traverse_info *info, struct name_entry *n, struct merge_list *entry)
239 {
240 const char *path;
241 struct merge_list *link;
242
243 if (!n->mode)
244 return entry;
245 if (entry)
246 path = entry->path;
247 else
248 path = traverse_path(info, n);
249 link = create_entry(stage, n->mode, &n->oid, path);
250 link->link = entry;
251 return link;
252 }
253
254 static void unresolved(const struct traverse_info *info, struct name_entry n[3])
255 {
256 struct merge_list *entry = NULL;
257 int i;
258 unsigned dirmask = 0, mask = 0;
259
260 for (i = 0; i < 3; i++) {
261 mask |= (1 << i);
262 /*
263 * Treat missing entries as directories so that we return
264 * after unresolved_directory has handled this.
265 */
266 if (!n[i].mode || S_ISDIR(n[i].mode))
267 dirmask |= (1 << i);
268 }
269
270 unresolved_directory(info, n);
271
272 if (dirmask == mask)
273 return;
274
275 if (n[2].mode && !S_ISDIR(n[2].mode))
276 entry = link_entry(3, info, n + 2, entry);
277 if (n[1].mode && !S_ISDIR(n[1].mode))
278 entry = link_entry(2, info, n + 1, entry);
279 if (n[0].mode && !S_ISDIR(n[0].mode))
280 entry = link_entry(1, info, n + 0, entry);
281
282 add_merge_entry(entry);
283 }
284
285 /*
286 * Merge two trees together (t[1] and t[2]), using a common base (t[0])
287 * as the origin.
288 *
289 * This walks the (sorted) trees in lock-step, checking every possible
290 * name. Note that directories automatically sort differently from other
291 * files (see "base_name_compare"), so you'll never see file/directory
292 * conflicts, because they won't ever compare the same.
293 *
294 * IOW, if a directory changes to a filename, it will automatically be
295 * seen as the directory going away, and the filename being created.
296 *
297 * Think of this as a three-way diff.
298 *
299 * The output will be either:
300 * - successful merge
301 * "0 mode sha1 filename"
302 * NOTE NOTE NOTE! FIXME! We really really need to walk the index
303 * in parallel with this too!
304 *
305 * - conflict:
306 * "1 mode sha1 filename"
307 * "2 mode sha1 filename"
308 * "3 mode sha1 filename"
309 * where not all of the 1/2/3 lines may exist, of course.
310 *
311 * The successful merge rules are the same as for the three-way merge
312 * in git-read-tree.
313 */
314 static int threeway_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *entry, struct traverse_info *info)
315 {
316 /* Same in both? */
317 if (same_entry(entry+1, entry+2) || both_empty(entry+1, entry+2)) {
318 /* Modified, added or removed identically */
319 resolve(info, NULL, entry+1);
320 return mask;
321 }
322
323 if (same_entry(entry+0, entry+1)) {
324 if (!is_null_oid(&entry[2].oid) && !S_ISDIR(entry[2].mode)) {
325 /* We did not touch, they modified -- take theirs */
326 resolve(info, entry+1, entry+2);
327 return mask;
328 }
329 /*
330 * If we did not touch a directory but they made it
331 * into a file, we fall through and unresolved()
332 * recurses down. Likewise for the opposite case.
333 */
334 }
335
336 if (same_entry(entry+0, entry+2) || both_empty(entry+0, entry+2)) {
337 /* We added, modified or removed, they did not touch -- take ours */
338 resolve(info, NULL, entry+1);
339 return mask;
340 }
341
342 unresolved(info, entry);
343 return mask;
344 }
345
346 static void merge_trees(struct tree_desc t[3], const char *base)
347 {
348 struct traverse_info info;
349
350 setup_traverse_info(&info, base);
351 info.fn = threeway_callback;
352 traverse_trees(&the_index, 3, t, &info);
353 }
354
355 static void *get_tree_descriptor(struct tree_desc *desc, const char *rev)
356 {
357 struct object_id oid;
358 void *buf;
359
360 if (get_oid(rev, &oid))
361 die("unknown rev %s", rev);
362 buf = fill_tree_descriptor(desc, &oid);
363 if (!buf)
364 die("%s is not a tree", rev);
365 return buf;
366 }
367
368 int cmd_merge_tree(int argc, const char **argv, const char *prefix)
369 {
370 struct tree_desc t[3];
371 void *buf1, *buf2, *buf3;
372
373 if (argc != 4)
374 usage(merge_tree_usage);
375
376 buf1 = get_tree_descriptor(t+0, argv[1]);
377 buf2 = get_tree_descriptor(t+1, argv[2]);
378 buf3 = get_tree_descriptor(t+2, argv[3]);
379 merge_trees(t, "");
380 free(buf1);
381 free(buf2);
382 free(buf3);
383
384 show_result();
385 return 0;
386 }