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