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 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, src1, name1,
75 src2, name2,
76 flag, marker_size);
77 }
78 memset(&xmp, 0, sizeof(xmp));
80 xmp.level = XDL_MERGE_ZEALOUS;
81 xmp.favor= (flag >> 1) & 03;
82 if (git_xmerge_style >= 0)
83 xmp.style = git_xmerge_style;
84 if (marker_size > 0)
85 xmp.marker_size = marker_size;
86 xmp.file1 = name1;
87 xmp.file2 = name2;
88 return xdl_merge(orig, src1, src2, &xmp, result);
89}
90static int ll_union_merge(const struct ll_merge_driver *drv_unused,
92 mmbuffer_t *result,
93 const char *path_unused,
94 mmfile_t *orig,
95 mmfile_t *src1, const char *name1,
96 mmfile_t *src2, const char *name2,
97 int flag, int marker_size)
98{
99 /* Use union favor */
100 flag = (flag & 1) | (XDL_MERGE_FAVOR_UNION << 1);
101 return ll_xdl_merge(drv_unused, result, path_unused,
102 orig, src1, NULL, src2, NULL,
103 flag, marker_size);
104 return 0;
105}
106#define LL_BINARY_MERGE 0
108#define LL_TEXT_MERGE 1
109#define LL_UNION_MERGE 2
110static struct ll_merge_driver ll_merge_drv[] = {
111 { "binary", "built-in binary merge", ll_binary_merge },
112 { "text", "built-in 3-way text merge", ll_xdl_merge },
113 { "union", "built-in union merge", ll_union_merge },
114};
115static void create_temp(mmfile_t *src, char *path)
117{
118 int fd;
119 strcpy(path, ".merge_file_XXXXXX");
121 fd = xmkstemp(path);
122 if (write_in_full(fd, src->ptr, src->size) != src->size)
123 die_errno("unable to write temp-file");
124 close(fd);
125}
126/*
128 * User defined low-level merge driver support.
129 */
130static int ll_ext_merge(const struct ll_merge_driver *fn,
131 mmbuffer_t *result,
132 const char *path,
133 mmfile_t *orig,
134 mmfile_t *src1, const char *name1,
135 mmfile_t *src2, const char *name2,
136 int flag, int marker_size)
137{
138 char temp[4][50];
139 struct strbuf cmd = STRBUF_INIT;
140 struct strbuf_expand_dict_entry dict[] = {
141 { "O", temp[0] },
142 { "A", temp[1] },
143 { "B", temp[2] },
144 { "L", temp[3] },
145 { NULL }
146 };
147 const char *args[] = { NULL, NULL };
148 int status, fd, i;
149 struct stat st;
150 if (fn->cmdline == NULL)
152 die("custom merge driver %s lacks command line.", fn->name);
153 result->ptr = NULL;
155 result->size = 0;
156 create_temp(orig, temp[0]);
157 create_temp(src1, temp[1]);
158 create_temp(src2, temp[2]);
159 sprintf(temp[3], "%d", marker_size);
160 strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
162 args[0] = cmd.buf;
164 status = run_command_v_opt(args, RUN_USING_SHELL);
165 fd = open(temp[1], O_RDONLY);
166 if (fd < 0)
167 goto bad;
168 if (fstat(fd, &st))
169 goto close_bad;
170 result->size = st.st_size;
171 result->ptr = xmalloc(result->size + 1);
172 if (read_in_full(fd, result->ptr, result->size) != result->size) {
173 free(result->ptr);
174 result->ptr = NULL;
175 result->size = 0;
176 }
177 close_bad:
178 close(fd);
179 bad:
180 for (i = 0; i < 3; i++)
181 unlink_or_warn(temp[i]);
182 strbuf_release(&cmd);
183 return status;
184}
185/*
187 * merge.default and merge.driver configuration items
188 */
189static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
190static const char *default_ll_merge;
191static int read_merge_config(const char *var, const char *value, void *cb)
193{
194 struct ll_merge_driver *fn;
195 const char *ep, *name;
196 int namelen;
197 if (!strcmp(var, "merge.default")) {
199 if (value)
200 default_ll_merge = xstrdup(value);
201 return 0;
202 }
203 /*
205 * We are not interested in anything but "merge.<name>.variable";
206 * especially, we do not want to look at variables such as
207 * "merge.summary", "merge.tool", and "merge.verbosity".
208 */
209 if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
210 return 0;
211 /*
213 * Find existing one as we might be processing merge.<name>.var2
214 * after seeing merge.<name>.var1.
215 */
216 name = var + 6;
217 namelen = ep - name;
218 for (fn = ll_user_merge; fn; fn = fn->next)
219 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
220 break;
221 if (!fn) {
222 fn = xcalloc(1, sizeof(struct ll_merge_driver));
223 fn->name = xmemdupz(name, namelen);
224 fn->fn = ll_ext_merge;
225 *ll_user_merge_tail = fn;
226 ll_user_merge_tail = &(fn->next);
227 }
228 ep++;
230 if (!strcmp("name", ep)) {
232 if (!value)
233 return error("%s: lacks value", var);
234 fn->description = xstrdup(value);
235 return 0;
236 }
237 if (!strcmp("driver", ep)) {
239 if (!value)
240 return error("%s: lacks value", var);
241 /*
242 * merge.<name>.driver specifies the command line:
243 *
244 * command-line
245 *
246 * The command-line will be interpolated with the following
247 * tokens and is given to the shell:
248 *
249 * %O - temporary file name for the merge base.
250 * %A - temporary file name for our version.
251 * %B - temporary file name for the other branches' version.
252 * %L - conflict marker length
253 *
254 * The external merge driver should write the results in the
255 * file named by %A, and signal that it has done with zero exit
256 * status.
257 */
258 fn->cmdline = xstrdup(value);
259 return 0;
260 }
261 if (!strcmp("recursive", ep)) {
263 if (!value)
264 return error("%s: lacks value", var);
265 fn->recursive = xstrdup(value);
266 return 0;
267 }
268 return 0;
270}
271static void initialize_ll_merge(void)
273{
274 if (ll_user_merge_tail)
275 return;
276 ll_user_merge_tail = &ll_user_merge;
277 git_config(read_merge_config, NULL);
278}
279static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
281{
282 struct ll_merge_driver *fn;
283 const char *name;
284 int i;
285 initialize_ll_merge();
287 if (ATTR_TRUE(merge_attr))
289 return &ll_merge_drv[LL_TEXT_MERGE];
290 else if (ATTR_FALSE(merge_attr))
291 return &ll_merge_drv[LL_BINARY_MERGE];
292 else if (ATTR_UNSET(merge_attr)) {
293 if (!default_ll_merge)
294 return &ll_merge_drv[LL_TEXT_MERGE];
295 else
296 name = default_ll_merge;
297 }
298 else
299 name = merge_attr;
300 for (fn = ll_user_merge; fn; fn = fn->next)
302 if (!strcmp(fn->name, name))
303 return fn;
304 for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
306 if (!strcmp(ll_merge_drv[i].name, name))
307 return &ll_merge_drv[i];
308 /* default to the 3-way */
310 return &ll_merge_drv[LL_TEXT_MERGE];
311}
312static int git_path_check_merge(const char *path, struct git_attr_check check[2])
314{
315 if (!check[0].attr) {
316 check[0].attr = git_attr("merge");
317 check[1].attr = git_attr("conflict-marker-size");
318 }
319 return git_checkattr(path, 2, check);
320}
321int ll_merge(mmbuffer_t *result_buf,
323 const char *path,
324 mmfile_t *ancestor,
325 mmfile_t *ours, const char *our_label,
326 mmfile_t *theirs, const char *their_label,
327 int flag)
328{
329 static struct git_attr_check check[2];
330 const char *ll_driver_name = NULL;
331 int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
332 const struct ll_merge_driver *driver;
333 int virtual_ancestor = flag & 01;
334 if (!git_path_check_merge(path, check)) {
336 ll_driver_name = check[0].value;
337 if (check[1].value) {
338 marker_size = atoi(check[1].value);
339 if (marker_size <= 0)
340 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
341 }
342 }
343 driver = find_ll_merge_driver(ll_driver_name);
344 if (virtual_ancestor && driver->recursive)
345 driver = find_ll_merge_driver(driver->recursive);
346 return driver->fn(driver, result_buf, path, ancestor,
347 ours, our_label, theirs, their_label,
348 flag, marker_size);
349}
350int ll_merge_marker_size(const char *path)
352{
353 static struct git_attr_check check;
354 int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
355 if (!check.attr)
357 check.attr = git_attr("conflict-marker-size");
358 if (!git_checkattr(path, 1, &check) && check.value) {
359 marker_size = atoi(check.value);
360 if (marker_size <= 0)
361 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
362 }
363 return marker_size;
364}