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 virtual_ancestor);
22struct ll_merge_driver {
24 const char *name;
25 const char *description;
26 ll_merge_fn fn;
27 const char *recursive;
28 struct ll_merge_driver *next;
29 char *cmdline;
30};
31/*
33 * Built-in low-levels
34 */
35static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
36 mmbuffer_t *result,
37 const char *path_unused,
38 mmfile_t *orig,
39 mmfile_t *src1, const char *name1,
40 mmfile_t *src2, const char *name2,
41 int virtual_ancestor)
42{
43 /*
44 * The tentative merge result is "ours" for the final round,
45 * or common ancestor for an internal merge. Still return
46 * "conflicted merge" status.
47 */
48 mmfile_t *stolen = virtual_ancestor ? orig : src1;
49 result->ptr = stolen->ptr;
51 result->size = stolen->size;
52 stolen->ptr = NULL;
53 return 1;
54}
55static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
57 mmbuffer_t *result,
58 const char *path_unused,
59 mmfile_t *orig,
60 mmfile_t *src1, const char *name1,
61 mmfile_t *src2, const char *name2,
62 int virtual_ancestor)
63{
64 xpparam_t xpp;
65 int style = 0;
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 vs. %s\n",
71 name1, name2);
72 return ll_binary_merge(drv_unused, result,
73 path_unused,
74 orig, src1, name1,
75 src2, name2,
76 virtual_ancestor);
77 }
78 memset(&xpp, 0, sizeof(xpp));
80 if (git_xmerge_style >= 0)
81 style = git_xmerge_style;
82 return xdl_merge(orig,
83 src1, name1,
84 src2, name2,
85 &xpp, XDL_MERGE_ZEALOUS | style,
86 result);
87}
88static int ll_union_merge(const struct ll_merge_driver *drv_unused,
90 mmbuffer_t *result,
91 const char *path_unused,
92 mmfile_t *orig,
93 mmfile_t *src1, const char *name1,
94 mmfile_t *src2, const char *name2,
95 int virtual_ancestor)
96{
97 char *src, *dst;
98 long size;
99 const int marker_size = 7;
100 int status, saved_style;
101 /* We have to force the RCS "merge" style */
103 saved_style = git_xmerge_style;
104 git_xmerge_style = 0;
105 status = ll_xdl_merge(drv_unused, result, path_unused,
106 orig, src1, NULL, src2, NULL,
107 virtual_ancestor);
108 git_xmerge_style = saved_style;
109 if (status <= 0)
110 return status;
111 size = result->size;
112 src = dst = result->ptr;
113 while (size) {
114 char ch;
115 if ((marker_size < size) &&
116 (*src == '<' || *src == '=' || *src == '>')) {
117 int i;
118 ch = *src;
119 for (i = 0; i < marker_size; i++)
120 if (src[i] != ch)
121 goto not_a_marker;
122 if (src[marker_size] != '\n')
123 goto not_a_marker;
124 src += marker_size + 1;
125 size -= marker_size + 1;
126 continue;
127 }
128 not_a_marker:
129 do {
130 ch = *src++;
131 *dst++ = ch;
132 size--;
133 } while (ch != '\n' && size);
134 }
135 result->size = dst - result->ptr;
136 return 0;
137}
138#define LL_BINARY_MERGE 0
140#define LL_TEXT_MERGE 1
141#define LL_UNION_MERGE 2
142static struct ll_merge_driver ll_merge_drv[] = {
143 { "binary", "built-in binary merge", ll_binary_merge },
144 { "text", "built-in 3-way text merge", ll_xdl_merge },
145 { "union", "built-in union merge", ll_union_merge },
146};
147static void create_temp(mmfile_t *src, char *path)
149{
150 int fd;
151 strcpy(path, ".merge_file_XXXXXX");
153 fd = xmkstemp(path);
154 if (write_in_full(fd, src->ptr, src->size) != src->size)
155 die("unable to write temp-file");
156 close(fd);
157}
158/*
160 * User defined low-level merge driver support.
161 */
162static int ll_ext_merge(const struct ll_merge_driver *fn,
163 mmbuffer_t *result,
164 const char *path,
165 mmfile_t *orig,
166 mmfile_t *src1, const char *name1,
167 mmfile_t *src2, const char *name2,
168 int virtual_ancestor)
169{
170 char temp[3][50];
171 struct strbuf cmd = STRBUF_INIT;
172 struct strbuf_expand_dict_entry dict[] = {
173 { "O", temp[0] },
174 { "A", temp[1] },
175 { "B", temp[2] },
176 { NULL }
177 };
178 struct child_process child;
179 const char *args[20];
180 int status, fd, i;
181 struct stat st;
182 if (fn->cmdline == NULL)
184 die("custom merge driver %s lacks command line.", fn->name);
185 result->ptr = NULL;
187 result->size = 0;
188 create_temp(orig, temp[0]);
189 create_temp(src1, temp[1]);
190 create_temp(src2, temp[2]);
191 strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
193 memset(&child, 0, sizeof(child));
195 child.argv = args;
196 args[0] = "sh";
197 args[1] = "-c";
198 args[2] = cmd.buf;
199 args[3] = NULL;
200 status = run_command(&child);
202 if (status < -ERR_RUN_COMMAND_FORK)
203 ; /* failure in run-command */
204 else
205 status = -status;
206 fd = open(temp[1], O_RDONLY);
207 if (fd < 0)
208 goto bad;
209 if (fstat(fd, &st))
210 goto close_bad;
211 result->size = st.st_size;
212 result->ptr = xmalloc(result->size + 1);
213 if (read_in_full(fd, result->ptr, result->size) != result->size) {
214 free(result->ptr);
215 result->ptr = NULL;
216 result->size = 0;
217 }
218 close_bad:
219 close(fd);
220 bad:
221 for (i = 0; i < 3; i++)
222 unlink_or_warn(temp[i]);
223 strbuf_release(&cmd);
224 return status;
225}
226/*
228 * merge.default and merge.driver configuration items
229 */
230static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
231static const char *default_ll_merge;
232static int read_merge_config(const char *var, const char *value, void *cb)
234{
235 struct ll_merge_driver *fn;
236 const char *ep, *name;
237 int namelen;
238 if (!strcmp(var, "merge.default")) {
240 if (value)
241 default_ll_merge = strdup(value);
242 return 0;
243 }
244 /*
246 * We are not interested in anything but "merge.<name>.variable";
247 * especially, we do not want to look at variables such as
248 * "merge.summary", "merge.tool", and "merge.verbosity".
249 */
250 if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
251 return 0;
252 /*
254 * Find existing one as we might be processing merge.<name>.var2
255 * after seeing merge.<name>.var1.
256 */
257 name = var + 6;
258 namelen = ep - name;
259 for (fn = ll_user_merge; fn; fn = fn->next)
260 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
261 break;
262 if (!fn) {
263 fn = xcalloc(1, sizeof(struct ll_merge_driver));
264 fn->name = xmemdupz(name, namelen);
265 fn->fn = ll_ext_merge;
266 *ll_user_merge_tail = fn;
267 ll_user_merge_tail = &(fn->next);
268 }
269 ep++;
271 if (!strcmp("name", ep)) {
273 if (!value)
274 return error("%s: lacks value", var);
275 fn->description = strdup(value);
276 return 0;
277 }
278 if (!strcmp("driver", ep)) {
280 if (!value)
281 return error("%s: lacks value", var);
282 /*
283 * merge.<name>.driver specifies the command line:
284 *
285 * command-line
286 *
287 * The command-line will be interpolated with the following
288 * tokens and is given to the shell:
289 *
290 * %O - temporary file name for the merge base.
291 * %A - temporary file name for our version.
292 * %B - temporary file name for the other branches' version.
293 *
294 * The external merge driver should write the results in the
295 * file named by %A, and signal that it has done with zero exit
296 * status.
297 */
298 fn->cmdline = strdup(value);
299 return 0;
300 }
301 if (!strcmp("recursive", ep)) {
303 if (!value)
304 return error("%s: lacks value", var);
305 fn->recursive = strdup(value);
306 return 0;
307 }
308 return 0;
310}
311static 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}
319static 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 initialize_ll_merge();
327 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 for (fn = ll_user_merge; fn; fn = fn->next)
342 if (!strcmp(fn->name, name))
343 return fn;
344 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 /* default to the 3-way */
350 return &ll_merge_drv[LL_TEXT_MERGE];
351}
352static const char *git_path_check_merge(const char *path)
354{
355 static struct git_attr_check attr_merge_check;
356 if (!attr_merge_check.attr)
358 attr_merge_check.attr = git_attr("merge", 5);
359 if (git_checkattr(path, 1, &attr_merge_check))
361 return NULL;
362 return attr_merge_check.value;
363}
364int ll_merge(mmbuffer_t *result_buf,
366 const char *path,
367 mmfile_t *ancestor,
368 mmfile_t *ours, const char *our_label,
369 mmfile_t *theirs, const char *their_label,
370 int virtual_ancestor)
371{
372 const char *ll_driver_name;
373 const struct ll_merge_driver *driver;
374 ll_driver_name = git_path_check_merge(path);
376 driver = find_ll_merge_driver(ll_driver_name);
377 if (virtual_ancestor && driver->recursive)
379 driver = find_ll_merge_driver(driver->recursive);
380 return driver->fn(driver, result_buf, path,
381 ancestor,
382 ours, our_label,
383 theirs, their_label, virtual_ancestor);
384}