diff --color-words: bit of clean-up
[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
13 struct ll_merge_driver;
14
15 typedef 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);
22
23 struct 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
32 /*
33  * Built-in low-levels
34  */
35 static 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
50         result->ptr = stolen->ptr;
51         result->size = stolen->size;
52         stolen->ptr = NULL;
53         return 1;
54 }
55
56 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
57                         mmbuffer_t *result,
58                         const char *path,
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
67         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                                        virtual_ancestor);
77         }
78
79         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 }
88
89 static 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
102         /* 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
139 #define LL_BINARY_MERGE 0
140 #define LL_TEXT_MERGE 1
141 #define LL_UNION_MERGE 2
142 static 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 };
147
148 static void create_temp(mmfile_t *src, char *path)
149 {
150         int fd;
151
152         strcpy(path, ".merge_file_XXXXXX");
153         fd = xmkstemp(path);
154         if (write_in_full(fd, src->ptr, src->size) != src->size)
155                 die_errno("unable to write temp-file");
156         close(fd);
157 }
158
159 /*
160  * User defined low-level merge driver support.
161  */
162 static 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         const char *args[] = { "sh", "-c", NULL, NULL };
179         int status, fd, i;
180         struct stat st;
181
182         if (fn->cmdline == NULL)
183                 die("custom merge driver %s lacks command line.", fn->name);
184
185         result->ptr = NULL;
186         result->size = 0;
187         create_temp(orig, temp[0]);
188         create_temp(src1, temp[1]);
189         create_temp(src2, temp[2]);
190
191         strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
192
193         args[2] = cmd.buf;
194         status = run_command_v_opt(args, 0);
195         fd = open(temp[1], O_RDONLY);
196         if (fd < 0)
197                 goto bad;
198         if (fstat(fd, &st))
199                 goto close_bad;
200         result->size = st.st_size;
201         result->ptr = xmalloc(result->size + 1);
202         if (read_in_full(fd, result->ptr, result->size) != result->size) {
203                 free(result->ptr);
204                 result->ptr = NULL;
205                 result->size = 0;
206         }
207  close_bad:
208         close(fd);
209  bad:
210         for (i = 0; i < 3; i++)
211                 unlink_or_warn(temp[i]);
212         strbuf_release(&cmd);
213         return status;
214 }
215
216 /*
217  * merge.default and merge.driver configuration items
218  */
219 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
220 static const char *default_ll_merge;
221
222 static int read_merge_config(const char *var, const char *value, void *cb)
223 {
224         struct ll_merge_driver *fn;
225         const char *ep, *name;
226         int namelen;
227
228         if (!strcmp(var, "merge.default")) {
229                 if (value)
230                         default_ll_merge = xstrdup(value);
231                 return 0;
232         }
233
234         /*
235          * We are not interested in anything but "merge.<name>.variable";
236          * especially, we do not want to look at variables such as
237          * "merge.summary", "merge.tool", and "merge.verbosity".
238          */
239         if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
240                 return 0;
241
242         /*
243          * Find existing one as we might be processing merge.<name>.var2
244          * after seeing merge.<name>.var1.
245          */
246         name = var + 6;
247         namelen = ep - name;
248         for (fn = ll_user_merge; fn; fn = fn->next)
249                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
250                         break;
251         if (!fn) {
252                 fn = xcalloc(1, sizeof(struct ll_merge_driver));
253                 fn->name = xmemdupz(name, namelen);
254                 fn->fn = ll_ext_merge;
255                 *ll_user_merge_tail = fn;
256                 ll_user_merge_tail = &(fn->next);
257         }
258
259         ep++;
260
261         if (!strcmp("name", ep)) {
262                 if (!value)
263                         return error("%s: lacks value", var);
264                 fn->description = xstrdup(value);
265                 return 0;
266         }
267
268         if (!strcmp("driver", ep)) {
269                 if (!value)
270                         return error("%s: lacks value", var);
271                 /*
272                  * merge.<name>.driver specifies the command line:
273                  *
274                  *      command-line
275                  *
276                  * The command-line will be interpolated with the following
277                  * tokens and is given to the shell:
278                  *
279                  *    %O - temporary file name for the merge base.
280                  *    %A - temporary file name for our version.
281                  *    %B - temporary file name for the other branches' version.
282                  *
283                  * The external merge driver should write the results in the
284                  * file named by %A, and signal that it has done with zero exit
285                  * status.
286                  */
287                 fn->cmdline = xstrdup(value);
288                 return 0;
289         }
290
291         if (!strcmp("recursive", ep)) {
292                 if (!value)
293                         return error("%s: lacks value", var);
294                 fn->recursive = xstrdup(value);
295                 return 0;
296         }
297
298         return 0;
299 }
300
301 static void initialize_ll_merge(void)
302 {
303         if (ll_user_merge_tail)
304                 return;
305         ll_user_merge_tail = &ll_user_merge;
306         git_config(read_merge_config, NULL);
307 }
308
309 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
310 {
311         struct ll_merge_driver *fn;
312         const char *name;
313         int i;
314
315         initialize_ll_merge();
316
317         if (ATTR_TRUE(merge_attr))
318                 return &ll_merge_drv[LL_TEXT_MERGE];
319         else if (ATTR_FALSE(merge_attr))
320                 return &ll_merge_drv[LL_BINARY_MERGE];
321         else if (ATTR_UNSET(merge_attr)) {
322                 if (!default_ll_merge)
323                         return &ll_merge_drv[LL_TEXT_MERGE];
324                 else
325                         name = default_ll_merge;
326         }
327         else
328                 name = merge_attr;
329
330         for (fn = ll_user_merge; fn; fn = fn->next)
331                 if (!strcmp(fn->name, name))
332                         return fn;
333
334         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
335                 if (!strcmp(ll_merge_drv[i].name, name))
336                         return &ll_merge_drv[i];
337
338         /* default to the 3-way */
339         return &ll_merge_drv[LL_TEXT_MERGE];
340 }
341
342 static const char *git_path_check_merge(const char *path)
343 {
344         static struct git_attr_check attr_merge_check;
345
346         if (!attr_merge_check.attr)
347                 attr_merge_check.attr = git_attr("merge", 5);
348
349         if (git_checkattr(path, 1, &attr_merge_check))
350                 return NULL;
351         return attr_merge_check.value;
352 }
353
354 int ll_merge(mmbuffer_t *result_buf,
355              const char *path,
356              mmfile_t *ancestor,
357              mmfile_t *ours, const char *our_label,
358              mmfile_t *theirs, const char *their_label,
359              int virtual_ancestor)
360 {
361         const char *ll_driver_name;
362         const struct ll_merge_driver *driver;
363
364         ll_driver_name = git_path_check_merge(path);
365         driver = find_ll_merge_driver(ll_driver_name);
366
367         if (virtual_ancestor && driver->recursive)
368                 driver = find_ll_merge_driver(driver->recursive);
369         return driver->fn(driver, result_buf, path,
370                           ancestor,
371                           ours, our_label,
372                           theirs, their_label, virtual_ancestor);
373 }