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 "config.h"
9 #include "attr.h"
10 #include "xdiff-interface.h"
11 #include "run-command.h"
12 #include "ll-merge.h"
13 #include "quote.h"
14
15 struct ll_merge_driver;
16
17 typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
18 mmbuffer_t *result,
19 const char *path,
20 mmfile_t *orig, const char *orig_name,
21 mmfile_t *src1, const char *name1,
22 mmfile_t *src2, const char *name2,
23 const struct ll_merge_options *opts,
24 int marker_size);
25
26 struct ll_merge_driver {
27 const char *name;
28 const char *description;
29 ll_merge_fn fn;
30 const char *recursive;
31 struct ll_merge_driver *next;
32 char *cmdline;
33 };
34
35 static struct attr_check *merge_attributes;
load_merge_attributes(void)36 static struct attr_check *load_merge_attributes(void)
37 {
38 if (!merge_attributes)
39 merge_attributes = attr_check_initl("merge", "conflict-marker-size", NULL);
40 return merge_attributes;
41 }
42
reset_merge_attributes(void)43 void reset_merge_attributes(void)
44 {
45 attr_check_free(merge_attributes);
46 merge_attributes = NULL;
47 }
48
49 /*
50 * Built-in low-levels
51 */
ll_binary_merge(const struct ll_merge_driver * drv_unused,mmbuffer_t * result,const char * path,mmfile_t * orig,const char * orig_name,mmfile_t * src1,const char * name1,mmfile_t * src2,const char * name2,const struct ll_merge_options * opts,int marker_size)52 static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
53 mmbuffer_t *result,
54 const char *path,
55 mmfile_t *orig, const char *orig_name,
56 mmfile_t *src1, const char *name1,
57 mmfile_t *src2, const char *name2,
58 const struct ll_merge_options *opts,
59 int marker_size)
60 {
61 mmfile_t *stolen;
62 assert(opts);
63
64 /*
65 * The tentative merge result is the common ancestor for an
66 * internal merge. For the final merge, it is "ours" by
67 * default but -Xours/-Xtheirs can tweak the choice.
68 */
69 if (opts->virtual_ancestor) {
70 stolen = orig;
71 } else {
72 switch (opts->variant) {
73 default:
74 warning("Cannot merge binary files: %s (%s vs. %s)",
75 path, name1, name2);
76 /* fallthru */
77 case XDL_MERGE_FAVOR_OURS:
78 stolen = src1;
79 break;
80 case XDL_MERGE_FAVOR_THEIRS:
81 stolen = src2;
82 break;
83 }
84 }
85
86 result->ptr = stolen->ptr;
87 result->size = stolen->size;
88 stolen->ptr = NULL;
89
90 /*
91 * With -Xtheirs or -Xours, we have cleanly merged;
92 * otherwise we got a conflict.
93 */
94 return (opts->variant ? 0 : 1);
95 }
96
ll_xdl_merge(const struct ll_merge_driver * drv_unused,mmbuffer_t * result,const char * path,mmfile_t * orig,const char * orig_name,mmfile_t * src1,const char * name1,mmfile_t * src2,const char * name2,const struct ll_merge_options * opts,int marker_size)97 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
98 mmbuffer_t *result,
99 const char *path,
100 mmfile_t *orig, const char *orig_name,
101 mmfile_t *src1, const char *name1,
102 mmfile_t *src2, const char *name2,
103 const struct ll_merge_options *opts,
104 int marker_size)
105 {
106 xmparam_t xmp;
107 assert(opts);
108
109 if (orig->size > MAX_XDIFF_SIZE ||
110 src1->size > MAX_XDIFF_SIZE ||
111 src2->size > MAX_XDIFF_SIZE ||
112 buffer_is_binary(orig->ptr, orig->size) ||
113 buffer_is_binary(src1->ptr, src1->size) ||
114 buffer_is_binary(src2->ptr, src2->size)) {
115 return ll_binary_merge(drv_unused, result,
116 path,
117 orig, orig_name,
118 src1, name1,
119 src2, name2,
120 opts, marker_size);
121 }
122
123 memset(&xmp, 0, sizeof(xmp));
124 xmp.level = XDL_MERGE_ZEALOUS;
125 xmp.favor = opts->variant;
126 xmp.xpp.flags = opts->xdl_opts;
127 if (git_xmerge_style >= 0)
128 xmp.style = git_xmerge_style;
129 if (marker_size > 0)
130 xmp.marker_size = marker_size;
131 xmp.ancestor = orig_name;
132 xmp.file1 = name1;
133 xmp.file2 = name2;
134 return xdl_merge(orig, src1, src2, &xmp, result);
135 }
136
ll_union_merge(const struct ll_merge_driver * drv_unused,mmbuffer_t * result,const char * path_unused,mmfile_t * orig,const char * orig_name,mmfile_t * src1,const char * name1,mmfile_t * src2,const char * name2,const struct ll_merge_options * opts,int marker_size)137 static int ll_union_merge(const struct ll_merge_driver *drv_unused,
138 mmbuffer_t *result,
139 const char *path_unused,
140 mmfile_t *orig, const char *orig_name,
141 mmfile_t *src1, const char *name1,
142 mmfile_t *src2, const char *name2,
143 const struct ll_merge_options *opts,
144 int marker_size)
145 {
146 /* Use union favor */
147 struct ll_merge_options o;
148 assert(opts);
149 o = *opts;
150 o.variant = XDL_MERGE_FAVOR_UNION;
151 return ll_xdl_merge(drv_unused, result, path_unused,
152 orig, NULL, src1, NULL, src2, NULL,
153 &o, marker_size);
154 }
155
156 #define LL_BINARY_MERGE 0
157 #define LL_TEXT_MERGE 1
158 #define LL_UNION_MERGE 2
159 static struct ll_merge_driver ll_merge_drv[] = {
160 { "binary", "built-in binary merge", ll_binary_merge },
161 { "text", "built-in 3-way text merge", ll_xdl_merge },
162 { "union", "built-in union merge", ll_union_merge },
163 };
164
create_temp(mmfile_t * src,char * path,size_t len)165 static void create_temp(mmfile_t *src, char *path, size_t len)
166 {
167 int fd;
168
169 xsnprintf(path, len, ".merge_file_XXXXXX");
170 fd = xmkstemp(path);
171 if (write_in_full(fd, src->ptr, src->size) < 0)
172 die_errno("unable to write temp-file");
173 close(fd);
174 }
175
176 /*
177 * User defined low-level merge driver support.
178 */
ll_ext_merge(const struct ll_merge_driver * fn,mmbuffer_t * result,const char * path,mmfile_t * orig,const char * orig_name,mmfile_t * src1,const char * name1,mmfile_t * src2,const char * name2,const struct ll_merge_options * opts,int marker_size)179 static int ll_ext_merge(const struct ll_merge_driver *fn,
180 mmbuffer_t *result,
181 const char *path,
182 mmfile_t *orig, const char *orig_name,
183 mmfile_t *src1, const char *name1,
184 mmfile_t *src2, const char *name2,
185 const struct ll_merge_options *opts,
186 int marker_size)
187 {
188 char temp[4][50];
189 struct strbuf cmd = STRBUF_INIT;
190 struct strbuf_expand_dict_entry dict[6];
191 struct strbuf path_sq = STRBUF_INIT;
192 const char *args[] = { NULL, NULL };
193 int status, fd, i;
194 struct stat st;
195 assert(opts);
196
197 sq_quote_buf(&path_sq, path);
198 dict[0].placeholder = "O"; dict[0].value = temp[0];
199 dict[1].placeholder = "A"; dict[1].value = temp[1];
200 dict[2].placeholder = "B"; dict[2].value = temp[2];
201 dict[3].placeholder = "L"; dict[3].value = temp[3];
202 dict[4].placeholder = "P"; dict[4].value = path_sq.buf;
203 dict[5].placeholder = NULL; dict[5].value = NULL;
204
205 if (fn->cmdline == NULL)
206 die("custom merge driver %s lacks command line.", fn->name);
207
208 result->ptr = NULL;
209 result->size = 0;
210 create_temp(orig, temp[0], sizeof(temp[0]));
211 create_temp(src1, temp[1], sizeof(temp[1]));
212 create_temp(src2, temp[2], sizeof(temp[2]));
213 xsnprintf(temp[3], sizeof(temp[3]), "%d", marker_size);
214
215 strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
216
217 args[0] = cmd.buf;
218 status = run_command_v_opt(args, RUN_USING_SHELL);
219 fd = open(temp[1], O_RDONLY);
220 if (fd < 0)
221 goto bad;
222 if (fstat(fd, &st))
223 goto close_bad;
224 result->size = st.st_size;
225 result->ptr = xmallocz(result->size);
226 if (read_in_full(fd, result->ptr, result->size) != result->size) {
227 FREE_AND_NULL(result->ptr);
228 result->size = 0;
229 }
230 close_bad:
231 close(fd);
232 bad:
233 for (i = 0; i < 3; i++)
234 unlink_or_warn(temp[i]);
235 strbuf_release(&cmd);
236 strbuf_release(&path_sq);
237 return status;
238 }
239
240 /*
241 * merge.default and merge.driver configuration items
242 */
243 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
244 static const char *default_ll_merge;
245
read_merge_config(const char * var,const char * value,void * cb)246 static int read_merge_config(const char *var, const char *value, void *cb)
247 {
248 struct ll_merge_driver *fn;
249 const char *key, *name;
250 int namelen;
251
252 if (!strcmp(var, "merge.default"))
253 return git_config_string(&default_ll_merge, var, value);
254
255 /*
256 * We are not interested in anything but "merge.<name>.variable";
257 * especially, we do not want to look at variables such as
258 * "merge.summary", "merge.tool", and "merge.verbosity".
259 */
260 if (parse_config_key(var, "merge", &name, &namelen, &key) < 0 || !name)
261 return 0;
262
263 /*
264 * Find existing one as we might be processing merge.<name>.var2
265 * after seeing merge.<name>.var1.
266 */
267 for (fn = ll_user_merge; fn; fn = fn->next)
268 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
269 break;
270 if (!fn) {
271 fn = xcalloc(1, sizeof(struct ll_merge_driver));
272 fn->name = xmemdupz(name, namelen);
273 fn->fn = ll_ext_merge;
274 *ll_user_merge_tail = fn;
275 ll_user_merge_tail = &(fn->next);
276 }
277
278 if (!strcmp("name", key))
279 return git_config_string(&fn->description, var, value);
280
281 if (!strcmp("driver", key)) {
282 if (!value)
283 return error("%s: lacks value", var);
284 /*
285 * merge.<name>.driver specifies the command line:
286 *
287 * command-line
288 *
289 * The command-line will be interpolated with the following
290 * tokens and is given to the shell:
291 *
292 * %O - temporary file name for the merge base.
293 * %A - temporary file name for our version.
294 * %B - temporary file name for the other branches' version.
295 * %L - conflict marker length
296 * %P - the original path (safely quoted for the shell)
297 *
298 * The external merge driver should write the results in the
299 * file named by %A, and signal that it has done with zero exit
300 * status.
301 */
302 fn->cmdline = xstrdup(value);
303 return 0;
304 }
305
306 if (!strcmp("recursive", key))
307 return git_config_string(&fn->recursive, var, value);
308
309 return 0;
310 }
311
initialize_ll_merge(void)312 static void initialize_ll_merge(void)
313 {
314 if (ll_user_merge_tail)
315 return;
316 ll_user_merge_tail = &ll_user_merge;
317 git_config(read_merge_config, NULL);
318 }
319
find_ll_merge_driver(const char * merge_attr)320 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
321 {
322 struct ll_merge_driver *fn;
323 const char *name;
324 int i;
325
326 initialize_ll_merge();
327
328 if (ATTR_TRUE(merge_attr))
329 return &ll_merge_drv[LL_TEXT_MERGE];
330 else if (ATTR_FALSE(merge_attr))
331 return &ll_merge_drv[LL_BINARY_MERGE];
332 else if (ATTR_UNSET(merge_attr)) {
333 if (!default_ll_merge)
334 return &ll_merge_drv[LL_TEXT_MERGE];
335 else
336 name = default_ll_merge;
337 }
338 else
339 name = merge_attr;
340
341 for (fn = ll_user_merge; fn; fn = fn->next)
342 if (!strcmp(fn->name, name))
343 return fn;
344
345 for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
346 if (!strcmp(ll_merge_drv[i].name, name))
347 return &ll_merge_drv[i];
348
349 /* default to the 3-way */
350 return &ll_merge_drv[LL_TEXT_MERGE];
351 }
352
normalize_file(mmfile_t * mm,const char * path,struct index_state * istate)353 static void normalize_file(mmfile_t *mm, const char *path, struct index_state *istate)
354 {
355 struct strbuf strbuf = STRBUF_INIT;
356 if (renormalize_buffer(istate, path, mm->ptr, mm->size, &strbuf)) {
357 free(mm->ptr);
358 mm->size = strbuf.len;
359 mm->ptr = strbuf_detach(&strbuf, NULL);
360 }
361 }
362
ll_merge(mmbuffer_t * result_buf,const char * path,mmfile_t * ancestor,const char * ancestor_label,mmfile_t * ours,const char * our_label,mmfile_t * theirs,const char * their_label,struct index_state * istate,const struct ll_merge_options * opts)363 int ll_merge(mmbuffer_t *result_buf,
364 const char *path,
365 mmfile_t *ancestor, const char *ancestor_label,
366 mmfile_t *ours, const char *our_label,
367 mmfile_t *theirs, const char *their_label,
368 struct index_state *istate,
369 const struct ll_merge_options *opts)
370 {
371 struct attr_check *check = load_merge_attributes();
372 static const struct ll_merge_options default_opts;
373 const char *ll_driver_name = NULL;
374 int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
375 const struct ll_merge_driver *driver;
376
377 if (!opts)
378 opts = &default_opts;
379
380 if (opts->renormalize) {
381 normalize_file(ancestor, path, istate);
382 normalize_file(ours, path, istate);
383 normalize_file(theirs, path, istate);
384 }
385
386 git_check_attr(istate, path, check);
387 ll_driver_name = check->items[0].value;
388 if (check->items[1].value) {
389 marker_size = atoi(check->items[1].value);
390 if (marker_size <= 0)
391 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
392 }
393 driver = find_ll_merge_driver(ll_driver_name);
394
395 if (opts->virtual_ancestor) {
396 if (driver->recursive)
397 driver = find_ll_merge_driver(driver->recursive);
398 }
399 if (opts->extra_marker_size) {
400 marker_size += opts->extra_marker_size;
401 }
402 return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
403 ours, our_label, theirs, their_label,
404 opts, marker_size);
405 }
406
ll_merge_marker_size(struct index_state * istate,const char * path)407 int ll_merge_marker_size(struct index_state *istate, const char *path)
408 {
409 static struct attr_check *check;
410 int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
411
412 if (!check)
413 check = attr_check_initl("conflict-marker-size", NULL);
414 git_check_attr(istate, path, check);
415 if (check->items[0].value) {
416 marker_size = atoi(check->items[0].value);
417 if (marker_size <= 0)
418 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
419 }
420 return marker_size;
421 }
422