revision: do not include sibling history in --ancestry-path output
[git] / ll-merge.c
1 /*
2  * Low level 3-way in-core file merge.
3  *
4  * Copyright (c) 2007 Junio C Hamano
5  */
6
7 #include "cache.h"
8 #include "attr.h"
9 #include "xdiff-interface.h"
10 #include "run-command.h"
11 #include "ll-merge.h"
12
13 struct ll_merge_driver;
14
15 typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
16                            mmbuffer_t *result,
17                            const char *path,
18                            mmfile_t *orig, const char *orig_name,
19                            mmfile_t *src1, const char *name1,
20                            mmfile_t *src2, const char *name2,
21                            int flag,
22                            int marker_size);
23
24 struct ll_merge_driver {
25         const char *name;
26         const char *description;
27         ll_merge_fn fn;
28         const char *recursive;
29         struct ll_merge_driver *next;
30         char *cmdline;
31 };
32
33 /*
34  * Built-in low-levels
35  */
36 static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
37                            mmbuffer_t *result,
38                            const char *path_unused,
39                            mmfile_t *orig, const char *orig_name,
40                            mmfile_t *src1, const char *name1,
41                            mmfile_t *src2, const char *name2,
42                            int flag, int marker_size)
43 {
44         /*
45          * The tentative merge result is "ours" for the final round,
46          * or common ancestor for an internal merge.  Still return
47          * "conflicted merge" status.
48          */
49         mmfile_t *stolen = (flag & 01) ? orig : src1;
50
51         result->ptr = stolen->ptr;
52         result->size = stolen->size;
53         stolen->ptr = NULL;
54         return 1;
55 }
56
57 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
58                         mmbuffer_t *result,
59                         const char *path,
60                         mmfile_t *orig, const char *orig_name,
61                         mmfile_t *src1, const char *name1,
62                         mmfile_t *src2, const char *name2,
63                         int flag, int marker_size)
64 {
65         xmparam_t xmp;
66
67         if (buffer_is_binary(orig->ptr, orig->size) ||
68             buffer_is_binary(src1->ptr, src1->size) ||
69             buffer_is_binary(src2->ptr, src2->size)) {
70                 warning("Cannot merge binary files: %s (%s vs. %s)\n",
71                         path, name1, name2);
72                 return ll_binary_merge(drv_unused, result,
73                                        path,
74                                        orig, orig_name,
75                                        src1, name1,
76                                        src2, name2,
77                                        flag, marker_size);
78         }
79
80         memset(&xmp, 0, sizeof(xmp));
81         xmp.level = XDL_MERGE_ZEALOUS;
82         xmp.favor= (flag >> 1) & 03;
83         if (git_xmerge_style >= 0)
84                 xmp.style = git_xmerge_style;
85         if (marker_size > 0)
86                 xmp.marker_size = marker_size;
87         xmp.ancestor = orig_name;
88         xmp.file1 = name1;
89         xmp.file2 = name2;
90         return xdl_merge(orig, src1, src2, &xmp, result);
91 }
92
93 static int ll_union_merge(const struct ll_merge_driver *drv_unused,
94                           mmbuffer_t *result,
95                           const char *path_unused,
96                           mmfile_t *orig, const char *orig_name,
97                           mmfile_t *src1, const char *name1,
98                           mmfile_t *src2, const char *name2,
99                           int flag, int marker_size)
100 {
101         /* Use union favor */
102         flag = (flag & 1) | (XDL_MERGE_FAVOR_UNION << 1);
103         return ll_xdl_merge(drv_unused, result, path_unused,
104                             orig, NULL, src1, NULL, src2, NULL,
105                             flag, marker_size);
106         return 0;
107 }
108
109 #define LL_BINARY_MERGE 0
110 #define LL_TEXT_MERGE 1
111 #define LL_UNION_MERGE 2
112 static struct ll_merge_driver ll_merge_drv[] = {
113         { "binary", "built-in binary merge", ll_binary_merge },
114         { "text", "built-in 3-way text merge", ll_xdl_merge },
115         { "union", "built-in union merge", ll_union_merge },
116 };
117
118 static void create_temp(mmfile_t *src, char *path)
119 {
120         int fd;
121
122         strcpy(path, ".merge_file_XXXXXX");
123         fd = xmkstemp(path);
124         if (write_in_full(fd, src->ptr, src->size) != src->size)
125                 die_errno("unable to write temp-file");
126         close(fd);
127 }
128
129 /*
130  * User defined low-level merge driver support.
131  */
132 static int ll_ext_merge(const struct ll_merge_driver *fn,
133                         mmbuffer_t *result,
134                         const char *path,
135                         mmfile_t *orig, const char *orig_name,
136                         mmfile_t *src1, const char *name1,
137                         mmfile_t *src2, const char *name2,
138                         int flag, int marker_size)
139 {
140         char temp[4][50];
141         struct strbuf cmd = STRBUF_INIT;
142         struct strbuf_expand_dict_entry dict[] = {
143                 { "O", temp[0] },
144                 { "A", temp[1] },
145                 { "B", temp[2] },
146                 { "L", temp[3] },
147                 { NULL }
148         };
149         const char *args[] = { NULL, NULL };
150         int status, fd, i;
151         struct stat st;
152
153         if (fn->cmdline == NULL)
154                 die("custom merge driver %s lacks command line.", fn->name);
155
156         result->ptr = NULL;
157         result->size = 0;
158         create_temp(orig, temp[0]);
159         create_temp(src1, temp[1]);
160         create_temp(src2, temp[2]);
161         sprintf(temp[3], "%d", marker_size);
162
163         strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
164
165         args[0] = cmd.buf;
166         status = run_command_v_opt(args, RUN_USING_SHELL);
167         fd = open(temp[1], O_RDONLY);
168         if (fd < 0)
169                 goto bad;
170         if (fstat(fd, &st))
171                 goto close_bad;
172         result->size = st.st_size;
173         result->ptr = xmalloc(result->size + 1);
174         if (read_in_full(fd, result->ptr, result->size) != result->size) {
175                 free(result->ptr);
176                 result->ptr = NULL;
177                 result->size = 0;
178         }
179  close_bad:
180         close(fd);
181  bad:
182         for (i = 0; i < 3; i++)
183                 unlink_or_warn(temp[i]);
184         strbuf_release(&cmd);
185         return status;
186 }
187
188 /*
189  * merge.default and merge.driver configuration items
190  */
191 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
192 static const char *default_ll_merge;
193
194 static int read_merge_config(const char *var, const char *value, void *cb)
195 {
196         struct ll_merge_driver *fn;
197         const char *ep, *name;
198         int namelen;
199
200         if (!strcmp(var, "merge.default")) {
201                 if (value)
202                         default_ll_merge = xstrdup(value);
203                 return 0;
204         }
205
206         /*
207          * We are not interested in anything but "merge.<name>.variable";
208          * especially, we do not want to look at variables such as
209          * "merge.summary", "merge.tool", and "merge.verbosity".
210          */
211         if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
212                 return 0;
213
214         /*
215          * Find existing one as we might be processing merge.<name>.var2
216          * after seeing merge.<name>.var1.
217          */
218         name = var + 6;
219         namelen = ep - name;
220         for (fn = ll_user_merge; fn; fn = fn->next)
221                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
222                         break;
223         if (!fn) {
224                 fn = xcalloc(1, sizeof(struct ll_merge_driver));
225                 fn->name = xmemdupz(name, namelen);
226                 fn->fn = ll_ext_merge;
227                 *ll_user_merge_tail = fn;
228                 ll_user_merge_tail = &(fn->next);
229         }
230
231         ep++;
232
233         if (!strcmp("name", ep)) {
234                 if (!value)
235                         return error("%s: lacks value", var);
236                 fn->description = xstrdup(value);
237                 return 0;
238         }
239
240         if (!strcmp("driver", ep)) {
241                 if (!value)
242                         return error("%s: lacks value", var);
243                 /*
244                  * merge.<name>.driver specifies the command line:
245                  *
246                  *      command-line
247                  *
248                  * The command-line will be interpolated with the following
249                  * tokens and is given to the shell:
250                  *
251                  *    %O - temporary file name for the merge base.
252                  *    %A - temporary file name for our version.
253                  *    %B - temporary file name for the other branches' version.
254                  *    %L - conflict marker length
255                  *
256                  * The external merge driver should write the results in the
257                  * file named by %A, and signal that it has done with zero exit
258                  * status.
259                  */
260                 fn->cmdline = xstrdup(value);
261                 return 0;
262         }
263
264         if (!strcmp("recursive", ep)) {
265                 if (!value)
266                         return error("%s: lacks value", var);
267                 fn->recursive = xstrdup(value);
268                 return 0;
269         }
270
271         return 0;
272 }
273
274 static void initialize_ll_merge(void)
275 {
276         if (ll_user_merge_tail)
277                 return;
278         ll_user_merge_tail = &ll_user_merge;
279         git_config(read_merge_config, NULL);
280 }
281
282 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
283 {
284         struct ll_merge_driver *fn;
285         const char *name;
286         int i;
287
288         initialize_ll_merge();
289
290         if (ATTR_TRUE(merge_attr))
291                 return &ll_merge_drv[LL_TEXT_MERGE];
292         else if (ATTR_FALSE(merge_attr))
293                 return &ll_merge_drv[LL_BINARY_MERGE];
294         else if (ATTR_UNSET(merge_attr)) {
295                 if (!default_ll_merge)
296                         return &ll_merge_drv[LL_TEXT_MERGE];
297                 else
298                         name = default_ll_merge;
299         }
300         else
301                 name = merge_attr;
302
303         for (fn = ll_user_merge; fn; fn = fn->next)
304                 if (!strcmp(fn->name, name))
305                         return fn;
306
307         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
308                 if (!strcmp(ll_merge_drv[i].name, name))
309                         return &ll_merge_drv[i];
310
311         /* default to the 3-way */
312         return &ll_merge_drv[LL_TEXT_MERGE];
313 }
314
315 static int git_path_check_merge(const char *path, struct git_attr_check check[2])
316 {
317         if (!check[0].attr) {
318                 check[0].attr = git_attr("merge");
319                 check[1].attr = git_attr("conflict-marker-size");
320         }
321         return git_checkattr(path, 2, check);
322 }
323
324 int ll_merge(mmbuffer_t *result_buf,
325              const char *path,
326              mmfile_t *ancestor, const char *ancestor_label,
327              mmfile_t *ours, const char *our_label,
328              mmfile_t *theirs, const char *their_label,
329              int flag)
330 {
331         static struct git_attr_check check[2];
332         const char *ll_driver_name = NULL;
333         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
334         const struct ll_merge_driver *driver;
335         int virtual_ancestor = flag & 01;
336
337         if (!git_path_check_merge(path, check)) {
338                 ll_driver_name = check[0].value;
339                 if (check[1].value) {
340                         marker_size = atoi(check[1].value);
341                         if (marker_size <= 0)
342                                 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
343                 }
344         }
345         driver = find_ll_merge_driver(ll_driver_name);
346         if (virtual_ancestor && driver->recursive)
347                 driver = find_ll_merge_driver(driver->recursive);
348         return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
349                           ours, our_label, theirs, their_label,
350                           flag, marker_size);
351 }
352
353 int ll_merge_marker_size(const char *path)
354 {
355         static struct git_attr_check check;
356         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
357
358         if (!check.attr)
359                 check.attr = git_attr("conflict-marker-size");
360         if (!git_checkattr(path, 1, &check) && check.value) {
361                 marker_size = atoi(check.value);
362                 if (marker_size <= 0)
363                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
364         }
365         return marker_size;
366 }