mem-pool: add convenience functions for strdup and strndup
[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 "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;
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
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  */
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
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
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
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  */
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
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         size_t 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
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
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
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
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
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 }