1/*
2 * Low level 3-way in-core file merge.
3 *
4 * Copyright (c) 2007 Junio C Hamano
5 */
6#include "cache.h"
8#include "attr.h"
9#include "xdiff-interface.h"
10#include "run-command.h"
11#include "ll-merge.h"
12struct ll_merge_driver;
14typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
16 mmbuffer_t *result,
17 const char *path,
18 mmfile_t *orig,
19 mmfile_t *src1, const char *name1,
20 mmfile_t *src2, const char *name2,
21 int flag,
22 int marker_size);
23struct 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/*
34 * Built-in low-levels
35 */
36static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
37 mmbuffer_t *result,
38 const char *path_unused,
39 mmfile_t *orig,
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 result->ptr = stolen->ptr;
52 result->size = stolen->size;
53 stolen->ptr = NULL;
54 return 1;
55}
56static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
58 mmbuffer_t *result,
59 const char *path,
60 mmfile_t *orig,
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 int style = 0;
67 int favor = (flag >> 1) & 03;
68 if (buffer_is_binary(orig->ptr, orig->size) ||
70 buffer_is_binary(src1->ptr, src1->size) ||
71 buffer_is_binary(src2->ptr, src2->size)) {
72 warning("Cannot merge binary files: %s (%s vs. %s)\n",
73 path, name1, name2);
74 return ll_binary_merge(drv_unused, result,
75 path,
76 orig, src1, name1,
77 src2, name2,
78 flag, marker_size);
79 }
80 memset(&xmp, 0, sizeof(xmp));
82 if (git_xmerge_style >= 0)
83 style = git_xmerge_style;
84 if (marker_size > 0)
85 xmp.marker_size = marker_size;
86 return xdl_merge(orig,
87 src1, name1,
88 src2, name2,
89 &xmp, XDL_MERGE_FLAGS(XDL_MERGE_ZEALOUS, style, favor),
90 result);
91}
92static int ll_union_merge(const struct ll_merge_driver *drv_unused,
94 mmbuffer_t *result,
95 const char *path_unused,
96 mmfile_t *orig,
97 mmfile_t *src1, const char *name1,
98 mmfile_t *src2, const char *name2,
99 int flag, int marker_size)
100{
101 char *src, *dst;
102 long size;
103 int status, saved_style;
104 /* We have to force the RCS "merge" style */
106 saved_style = git_xmerge_style;
107 git_xmerge_style = 0;
108 status = ll_xdl_merge(drv_unused, result, path_unused,
109 orig, src1, NULL, src2, NULL,
110 flag, marker_size);
111 git_xmerge_style = saved_style;
112 if (status <= 0)
113 return status;
114 size = result->size;
115 src = dst = result->ptr;
116 while (size) {
117 char ch;
118 if ((marker_size < size) &&
119 (*src == '<' || *src == '=' || *src == '>')) {
120 int i;
121 ch = *src;
122 for (i = 0; i < marker_size; i++)
123 if (src[i] != ch)
124 goto not_a_marker;
125 if (src[marker_size] != '\n')
126 goto not_a_marker;
127 src += marker_size + 1;
128 size -= marker_size + 1;
129 continue;
130 }
131 not_a_marker:
132 do {
133 ch = *src++;
134 *dst++ = ch;
135 size--;
136 } while (ch != '\n' && size);
137 }
138 result->size = dst - result->ptr;
139 return 0;
140}
141#define LL_BINARY_MERGE 0
143#define LL_TEXT_MERGE 1
144#define LL_UNION_MERGE 2
145static struct ll_merge_driver ll_merge_drv[] = {
146 { "binary", "built-in binary merge", ll_binary_merge },
147 { "text", "built-in 3-way text merge", ll_xdl_merge },
148 { "union", "built-in union merge", ll_union_merge },
149};
150static void create_temp(mmfile_t *src, char *path)
152{
153 int fd;
154 strcpy(path, ".merge_file_XXXXXX");
156 fd = xmkstemp(path);
157 if (write_in_full(fd, src->ptr, src->size) != src->size)
158 die_errno("unable to write temp-file");
159 close(fd);
160}
161/*
163 * User defined low-level merge driver support.
164 */
165static int ll_ext_merge(const struct ll_merge_driver *fn,
166 mmbuffer_t *result,
167 const char *path,
168 mmfile_t *orig,
169 mmfile_t *src1, const char *name1,
170 mmfile_t *src2, const char *name2,
171 int flag, int marker_size)
172{
173 char temp[4][50];
174 struct strbuf cmd = STRBUF_INIT;
175 struct strbuf_expand_dict_entry dict[] = {
176 { "O", temp[0] },
177 { "A", temp[1] },
178 { "B", temp[2] },
179 { "L", temp[3] },
180 { NULL }
181 };
182 const char *args[] = { NULL, NULL };
183 int status, fd, i;
184 struct stat st;
185 if (fn->cmdline == NULL)
187 die("custom merge driver %s lacks command line.", fn->name);
188 result->ptr = NULL;
190 result->size = 0;
191 create_temp(orig, temp[0]);
192 create_temp(src1, temp[1]);
193 create_temp(src2, temp[2]);
194 sprintf(temp[3], "%d", marker_size);
195 strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
197 args[0] = cmd.buf;
199 status = run_command_v_opt(args, RUN_USING_SHELL);
200 fd = open(temp[1], O_RDONLY);
201 if (fd < 0)
202 goto bad;
203 if (fstat(fd, &st))
204 goto close_bad;
205 result->size = st.st_size;
206 result->ptr = xmalloc(result->size + 1);
207 if (read_in_full(fd, result->ptr, result->size) != result->size) {
208 free(result->ptr);
209 result->ptr = NULL;
210 result->size = 0;
211 }
212 close_bad:
213 close(fd);
214 bad:
215 for (i = 0; i < 3; i++)
216 unlink_or_warn(temp[i]);
217 strbuf_release(&cmd);
218 return status;
219}
220/*
222 * merge.default and merge.driver configuration items
223 */
224static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
225static const char *default_ll_merge;
226static int read_merge_config(const char *var, const char *value, void *cb)
228{
229 struct ll_merge_driver *fn;
230 const char *ep, *name;
231 int namelen;
232 if (!strcmp(var, "merge.default")) {
234 if (value)
235 default_ll_merge = xstrdup(value);
236 return 0;
237 }
238 /*
240 * We are not interested in anything but "merge.<name>.variable";
241 * especially, we do not want to look at variables such as
242 * "merge.summary", "merge.tool", and "merge.verbosity".
243 */
244 if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
245 return 0;
246 /*
248 * Find existing one as we might be processing merge.<name>.var2
249 * after seeing merge.<name>.var1.
250 */
251 name = var + 6;
252 namelen = ep - name;
253 for (fn = ll_user_merge; fn; fn = fn->next)
254 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
255 break;
256 if (!fn) {
257 fn = xcalloc(1, sizeof(struct ll_merge_driver));
258 fn->name = xmemdupz(name, namelen);
259 fn->fn = ll_ext_merge;
260 *ll_user_merge_tail = fn;
261 ll_user_merge_tail = &(fn->next);
262 }
263 ep++;
265 if (!strcmp("name", ep)) {
267 if (!value)
268 return error("%s: lacks value", var);
269 fn->description = xstrdup(value);
270 return 0;
271 }
272 if (!strcmp("driver", ep)) {
274 if (!value)
275 return error("%s: lacks value", var);
276 /*
277 * merge.<name>.driver specifies the command line:
278 *
279 * command-line
280 *
281 * The command-line will be interpolated with the following
282 * tokens and is given to the shell:
283 *
284 * %O - temporary file name for the merge base.
285 * %A - temporary file name for our version.
286 * %B - temporary file name for the other branches' version.
287 * %L - conflict marker length
288 *
289 * The external merge driver should write the results in the
290 * file named by %A, and signal that it has done with zero exit
291 * status.
292 */
293 fn->cmdline = xstrdup(value);
294 return 0;
295 }
296 if (!strcmp("recursive", ep)) {
298 if (!value)
299 return error("%s: lacks value", var);
300 fn->recursive = xstrdup(value);
301 return 0;
302 }
303 return 0;
305}
306static void initialize_ll_merge(void)
308{
309 if (ll_user_merge_tail)
310 return;
311 ll_user_merge_tail = &ll_user_merge;
312 git_config(read_merge_config, NULL);
313}
314static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
316{
317 struct ll_merge_driver *fn;
318 const char *name;
319 int i;
320 initialize_ll_merge();
322 if (ATTR_TRUE(merge_attr))
324 return &ll_merge_drv[LL_TEXT_MERGE];
325 else if (ATTR_FALSE(merge_attr))
326 return &ll_merge_drv[LL_BINARY_MERGE];
327 else if (ATTR_UNSET(merge_attr)) {
328 if (!default_ll_merge)
329 return &ll_merge_drv[LL_TEXT_MERGE];
330 else
331 name = default_ll_merge;
332 }
333 else
334 name = merge_attr;
335 for (fn = ll_user_merge; fn; fn = fn->next)
337 if (!strcmp(fn->name, name))
338 return fn;
339 for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
341 if (!strcmp(ll_merge_drv[i].name, name))
342 return &ll_merge_drv[i];
343 /* default to the 3-way */
345 return &ll_merge_drv[LL_TEXT_MERGE];
346}
347static int git_path_check_merge(const char *path, struct git_attr_check check[2])
349{
350 if (!check[0].attr) {
351 check[0].attr = git_attr("merge");
352 check[1].attr = git_attr("conflict-marker-size");
353 }
354 return git_checkattr(path, 2, check);
355}
356int ll_merge(mmbuffer_t *result_buf,
358 const char *path,
359 mmfile_t *ancestor,
360 mmfile_t *ours, const char *our_label,
361 mmfile_t *theirs, const char *their_label,
362 int flag)
363{
364 static struct git_attr_check check[2];
365 const char *ll_driver_name = NULL;
366 int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
367 const struct ll_merge_driver *driver;
368 int virtual_ancestor = flag & 01;
369 if (!git_path_check_merge(path, check)) {
371 ll_driver_name = check[0].value;
372 if (check[1].value) {
373 marker_size = atoi(check[1].value);
374 if (marker_size <= 0)
375 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
376 }
377 }
378 driver = find_ll_merge_driver(ll_driver_name);
379 if (virtual_ancestor && driver->recursive)
380 driver = find_ll_merge_driver(driver->recursive);
381 return driver->fn(driver, result_buf, path, ancestor,
382 ours, our_label, theirs, their_label,
383 flag, marker_size);
384}
385int ll_merge_marker_size(const char *path)
387{
388 static struct git_attr_check check;
389 int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
390 if (!check.attr)
392 check.attr = git_attr("conflict-marker-size");
393 if (!git_checkattr(path, 1, &check) && check.value) {
394 marker_size = atoi(check.value);
395 if (marker_size <= 0)
396 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
397 }
398 return marker_size;
399}