t2300: run git-sh-setup in an environment that better mimics the real life
[git/git.git] / builtin / merge-tree.c
1 #include "builtin.h"
2 #include "tree-walk.h"
3 #include "xdiff-interface.h"
4 #include "blob.h"
5 #include "exec_cmd.h"
6 #include "merge-blobs.h"
7
8 static const char merge_tree_usage[] = "git merge-tree <base-tree> <branch1> <branch2>";
9
10 struct merge_list {
11 struct merge_list *next;
12 struct merge_list *link; /* other stages for this object */
13
14 unsigned int stage : 2;
15 unsigned int mode;
16 const char *path;
17 struct blob *blob;
18 };
19
20 static struct merge_list *merge_result, **merge_result_end = &merge_result;
21
22 static void add_merge_entry(struct merge_list *entry)
23 {
24 *merge_result_end = entry;
25 merge_result_end = &entry->next;
26 }
27
28 static void merge_trees(struct tree_desc t[3], const char *base);
29
30 static const char *explanation(struct merge_list *entry)
31 {
32 switch (entry->stage) {
33 case 0:
34 return "merged";
35 case 3:
36 return "added in remote";
37 case 2:
38 if (entry->link)
39 return "added in both";
40 return "added in local";
41 }
42
43 /* Existed in base */
44 entry = entry->link;
45 if (!entry)
46 return "removed in both";
47
48 if (entry->link)
49 return "changed in both";
50
51 if (entry->stage == 3)
52 return "removed in local";
53 return "removed in remote";
54 }
55
56 static void *result(struct merge_list *entry, unsigned long *size)
57 {
58 enum object_type type;
59 struct blob *base, *our, *their;
60 const char *path = entry->path;
61
62 if (!entry->stage)
63 return read_sha1_file(entry->blob->object.oid.hash, &type, size);
64 base = NULL;
65 if (entry->stage == 1) {
66 base = entry->blob;
67 entry = entry->link;
68 }
69 our = NULL;
70 if (entry && entry->stage == 2) {
71 our = entry->blob;
72 entry = entry->link;
73 }
74 their = NULL;
75 if (entry)
76 their = entry->blob;
77 return merge_blobs(path, base, our, their, size);
78 }
79
80 static void *origin(struct merge_list *entry, unsigned long *size)
81 {
82 enum object_type type;
83 while (entry) {
84 if (entry->stage == 2)
85 return read_sha1_file(entry->blob->object.oid.hash, &type, size);
86 entry = entry->link;
87 }
88 return NULL;
89 }
90
91 static int show_outf(void *priv_, mmbuffer_t *mb, int nbuf)
92 {
93 int i;
94 for (i = 0; i < nbuf; i++)
95 printf("%.*s", (int) mb[i].size, mb[i].ptr);
96 return 0;
97 }
98
99 static void show_diff(struct merge_list *entry)
100 {
101 unsigned long size;
102 mmfile_t src, dst;
103 xpparam_t xpp;
104 xdemitconf_t xecfg;
105 xdemitcb_t ecb;
106
107 xpp.flags = 0;
108 memset(&xecfg, 0, sizeof(xecfg));
109 xecfg.ctxlen = 3;
110 ecb.outf = show_outf;
111 ecb.priv = NULL;
112
113 src.ptr = origin(entry, &size);
114 if (!src.ptr)
115 size = 0;
116 src.size = size;
117 dst.ptr = result(entry, &size);
118 if (!dst.ptr)
119 size = 0;
120 dst.size = size;
121 if (xdi_diff(&src, &dst, &xpp, &xecfg, &ecb))
122 die("unable to generate diff");
123 free(src.ptr);
124 free(dst.ptr);
125 }
126
127 static void show_result_list(struct merge_list *entry)
128 {
129 printf("%s\n", explanation(entry));
130 do {
131 struct merge_list *link = entry->link;
132 static const char *desc[4] = { "result", "base", "our", "their" };
133 printf(" %-6s %o %s %s\n", desc[entry->stage], entry->mode, oid_to_hex(&entry->blob->object.oid), entry->path);
134 entry = link;
135 } while (entry);
136 }
137
138 static void show_result(void)
139 {
140 struct merge_list *walk;
141
142 walk = merge_result;
143 while (walk) {
144 show_result_list(walk);
145 show_diff(walk);
146 walk = walk->next;
147 }
148 }
149
150 /* An empty entry never compares same, not even to another empty entry */
151 static int same_entry(struct name_entry *a, struct name_entry *b)
152 {
153 return a->sha1 &&
154 b->sha1 &&
155 !hashcmp(a->sha1, b->sha1) &&
156 a->mode == b->mode;
157 }
158
159 static int both_empty(struct name_entry *a, struct name_entry *b)
160 {
161 return !(a->sha1 || b->sha1);
162 }
163
164 static struct merge_list *create_entry(unsigned stage, unsigned mode, const unsigned char *sha1, const char *path)
165 {
166 struct merge_list *res = xcalloc(1, sizeof(*res));
167
168 res->stage = stage;
169 res->path = path;
170 res->mode = mode;
171 res->blob = lookup_blob(sha1);
172 return res;
173 }
174
175 static char *traverse_path(const struct traverse_info *info, const struct name_entry *n)
176 {
177 char *path = xmallocz(traverse_path_len(info, n));
178 return make_traverse_path(path, info, n);
179 }
180
181 static void resolve(const struct traverse_info *info, struct name_entry *ours, struct name_entry *result)
182 {
183 struct merge_list *orig, *final;
184 const char *path;
185
186 /* If it's already ours, don't bother showing it */
187 if (!ours)
188 return;
189
190 path = traverse_path(info, result);
191 orig = create_entry(2, ours->mode, ours->sha1, path);
192 final = create_entry(0, result->mode, result->sha1, path);
193
194 final->link = orig;
195
196 add_merge_entry(final);
197 }
198
199 static void unresolved_directory(const struct traverse_info *info,
200 struct name_entry n[3])
201 {
202 char *newbase;
203 struct name_entry *p;
204 struct tree_desc t[3];
205 void *buf0, *buf1, *buf2;
206
207 for (p = n; p < n + 3; p++) {
208 if (p->mode && S_ISDIR(p->mode))
209 break;
210 }
211 if (n + 3 <= p)
212 return; /* there is no tree here */
213
214 newbase = traverse_path(info, p);
215
216 #define ENTRY_SHA1(e) (((e)->mode && S_ISDIR((e)->mode)) ? (e)->sha1 : NULL)
217 buf0 = fill_tree_descriptor(t+0, ENTRY_SHA1(n + 0));
218 buf1 = fill_tree_descriptor(t+1, ENTRY_SHA1(n + 1));
219 buf2 = fill_tree_descriptor(t+2, ENTRY_SHA1(n + 2));
220 #undef ENTRY_SHA1
221
222 merge_trees(t, newbase);
223
224 free(buf0);
225 free(buf1);
226 free(buf2);
227 free(newbase);
228 }
229
230
231 static struct merge_list *link_entry(unsigned stage, const struct traverse_info *info, struct name_entry *n, struct merge_list *entry)
232 {
233 const char *path;
234 struct merge_list *link;
235
236 if (!n->mode)
237 return entry;
238 if (entry)
239 path = entry->path;
240 else
241 path = traverse_path(info, n);
242 link = create_entry(stage, n->mode, n->sha1, path);
243 link->link = entry;
244 return link;
245 }
246
247 static void unresolved(const struct traverse_info *info, struct name_entry n[3])
248 {
249 struct merge_list *entry = NULL;
250 int i;
251 unsigned dirmask = 0, mask = 0;
252
253 for (i = 0; i < 3; i++) {
254 mask |= (1 << i);
255 /*
256 * Treat missing entries as directories so that we return
257 * after unresolved_directory has handled this.
258 */
259 if (!n[i].mode || S_ISDIR(n[i].mode))
260 dirmask |= (1 << i);
261 }
262
263 unresolved_directory(info, n);
264
265 if (dirmask == mask)
266 return;
267
268 if (n[2].mode && !S_ISDIR(n[2].mode))
269 entry = link_entry(3, info, n + 2, entry);
270 if (n[1].mode && !S_ISDIR(n[1].mode))
271 entry = link_entry(2, info, n + 1, entry);
272 if (n[0].mode && !S_ISDIR(n[0].mode))
273 entry = link_entry(1, info, n + 0, entry);
274
275 add_merge_entry(entry);
276 }
277
278 /*
279 * Merge two trees together (t[1] and t[2]), using a common base (t[0])
280 * as the origin.
281 *
282 * This walks the (sorted) trees in lock-step, checking every possible
283 * name. Note that directories automatically sort differently from other
284 * files (see "base_name_compare"), so you'll never see file/directory
285 * conflicts, because they won't ever compare the same.
286 *
287 * IOW, if a directory changes to a filename, it will automatically be
288 * seen as the directory going away, and the filename being created.
289 *
290 * Think of this as a three-way diff.
291 *
292 * The output will be either:
293 * - successful merge
294 * "0 mode sha1 filename"
295 * NOTE NOTE NOTE! FIXME! We really really need to walk the index
296 * in parallel with this too!
297 *
298 * - conflict:
299 * "1 mode sha1 filename"
300 * "2 mode sha1 filename"
301 * "3 mode sha1 filename"
302 * where not all of the 1/2/3 lines may exist, of course.
303 *
304 * The successful merge rules are the same as for the three-way merge
305 * in git-read-tree.
306 */
307 static int threeway_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *entry, struct traverse_info *info)
308 {
309 /* Same in both? */
310 if (same_entry(entry+1, entry+2) || both_empty(entry+1, entry+2)) {
311 /* Modified, added or removed identically */
312 resolve(info, NULL, entry+1);
313 return mask;
314 }
315
316 if (same_entry(entry+0, entry+1)) {
317 if (entry[2].sha1 && !S_ISDIR(entry[2].mode)) {
318 /* We did not touch, they modified -- take theirs */
319 resolve(info, entry+1, entry+2);
320 return mask;
321 }
322 /*
323 * If we did not touch a directory but they made it
324 * into a file, we fall through and unresolved()
325 * recurses down. Likewise for the opposite case.
326 */
327 }
328
329 if (same_entry(entry+0, entry+2) || both_empty(entry+0, entry+2)) {
330 /* We added, modified or removed, they did not touch -- take ours */
331 resolve(info, NULL, entry+1);
332 return mask;
333 }
334
335 unresolved(info, entry);
336 return mask;
337 }
338
339 static void merge_trees(struct tree_desc t[3], const char *base)
340 {
341 struct traverse_info info;
342
343 setup_traverse_info(&info, base);
344 info.fn = threeway_callback;
345 traverse_trees(3, t, &info);
346 }
347
348 static void *get_tree_descriptor(struct tree_desc *desc, const char *rev)
349 {
350 unsigned char sha1[20];
351 void *buf;
352
353 if (get_sha1(rev, sha1))
354 die("unknown rev %s", rev);
355 buf = fill_tree_descriptor(desc, sha1);
356 if (!buf)
357 die("%s is not a tree", rev);
358 return buf;
359 }
360
361 int cmd_merge_tree(int argc, const char **argv, const char *prefix)
362 {
363 struct tree_desc t[3];
364 void *buf1, *buf2, *buf3;
365
366 if (argc != 4)
367 usage(merge_tree_usage);
368
369 buf1 = get_tree_descriptor(t+0, argv[1]);
370 buf2 = get_tree_descriptor(t+1, argv[2]);
371 buf3 = get_tree_descriptor(t+2, argv[3]);
372 merge_trees(t, "");
373 free(buf1);
374 free(buf2);
375 free(buf3);
376
377 show_result();
378 return 0;
379 }