Merge branch '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 "interpolate.h"
12 #include "ll-merge.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,
20                            mmfile_t *src1, const char *name1,
21                            mmfile_t *src2, const char *name2,
22                            int virtual_ancestor);
23
24 struct 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
33 /*
34  * Built-in low-levels
35  */
36 static 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 virtual_ancestor)
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 = virtual_ancestor ? orig : src1;
50
51         result->ptr = stolen->ptr;
52         result->size = stolen->size;
53         stolen->ptr = NULL;
54         return 1;
55 }
56
57 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
58                         mmbuffer_t *result,
59                         const char *path_unused,
60                         mmfile_t *orig,
61                         mmfile_t *src1, const char *name1,
62                         mmfile_t *src2, const char *name2,
63                         int virtual_ancestor)
64 {
65         xpparam_t xpp;
66         int style = 0;
67
68         if (buffer_is_binary(orig->ptr, orig->size) ||
69             buffer_is_binary(src1->ptr, src1->size) ||
70             buffer_is_binary(src2->ptr, src2->size)) {
71                 warning("Cannot merge binary files: %s vs. %s\n",
72                         name1, name2);
73                 return ll_binary_merge(drv_unused, result,
74                                        path_unused,
75                                        orig, src1, name1,
76                                        src2, name2,
77                                        virtual_ancestor);
78         }
79
80         memset(&xpp, 0, sizeof(xpp));
81         if (git_xmerge_style >= 0)
82                 style = git_xmerge_style;
83         return xdl_merge(orig,
84                          src1, name1,
85                          src2, name2,
86                          &xpp, XDL_MERGE_ZEALOUS | style,
87                          result);
88 }
89
90 static int ll_union_merge(const struct ll_merge_driver *drv_unused,
91                           mmbuffer_t *result,
92                           const char *path_unused,
93                           mmfile_t *orig,
94                           mmfile_t *src1, const char *name1,
95                           mmfile_t *src2, const char *name2,
96                           int virtual_ancestor)
97 {
98         char *src, *dst;
99         long size;
100         const int marker_size = 7;
101         int status, saved_style;
102
103         /* We have to force the RCS "merge" style */
104         saved_style = git_xmerge_style;
105         git_xmerge_style = 0;
106         status = ll_xdl_merge(drv_unused, result, path_unused,
107                               orig, src1, NULL, src2, NULL,
108                               virtual_ancestor);
109         git_xmerge_style = saved_style;
110         if (status <= 0)
111                 return status;
112         size = result->size;
113         src = dst = result->ptr;
114         while (size) {
115                 char ch;
116                 if ((marker_size < size) &&
117                     (*src == '<' || *src == '=' || *src == '>')) {
118                         int i;
119                         ch = *src;
120                         for (i = 0; i < marker_size; i++)
121                                 if (src[i] != ch)
122                                         goto not_a_marker;
123                         if (src[marker_size] != '\n')
124                                 goto not_a_marker;
125                         src += marker_size + 1;
126                         size -= marker_size + 1;
127                         continue;
128                 }
129         not_a_marker:
130                 do {
131                         ch = *src++;
132                         *dst++ = ch;
133                         size--;
134                 } while (ch != '\n' && size);
135         }
136         result->size = dst - result->ptr;
137         return 0;
138 }
139
140 #define LL_BINARY_MERGE 0
141 #define LL_TEXT_MERGE 1
142 #define LL_UNION_MERGE 2
143 static struct ll_merge_driver ll_merge_drv[] = {
144         { "binary", "built-in binary merge", ll_binary_merge },
145         { "text", "built-in 3-way text merge", ll_xdl_merge },
146         { "union", "built-in union merge", ll_union_merge },
147 };
148
149 static void create_temp(mmfile_t *src, char *path)
150 {
151         int fd;
152
153         strcpy(path, ".merge_file_XXXXXX");
154         fd = xmkstemp(path);
155         if (write_in_full(fd, src->ptr, src->size) != src->size)
156                 die("unable to write temp-file");
157         close(fd);
158 }
159
160 /*
161  * User defined low-level merge driver support.
162  */
163 static int ll_ext_merge(const struct ll_merge_driver *fn,
164                         mmbuffer_t *result,
165                         const char *path,
166                         mmfile_t *orig,
167                         mmfile_t *src1, const char *name1,
168                         mmfile_t *src2, const char *name2,
169                         int virtual_ancestor)
170 {
171         char temp[3][50];
172         char cmdbuf[2048];
173         struct interp table[] = {
174                 { "%O" },
175                 { "%A" },
176                 { "%B" },
177         };
178         struct child_process child;
179         const char *args[20];
180         int status, fd, i;
181         struct stat st;
182
183         if (fn->cmdline == NULL)
184                 die("custom merge driver %s lacks command line.", fn->name);
185
186         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
192         interp_set_entry(table, 0, temp[0]);
193         interp_set_entry(table, 1, temp[1]);
194         interp_set_entry(table, 2, temp[2]);
195
196         interpolate(cmdbuf, sizeof(cmdbuf), fn->cmdline, table, 3);
197
198         memset(&child, 0, sizeof(child));
199         child.argv = args;
200         args[0] = "sh";
201         args[1] = "-c";
202         args[2] = cmdbuf;
203         args[3] = NULL;
204
205         status = run_command(&child);
206         if (status < -ERR_RUN_COMMAND_FORK)
207                 ; /* failure in run-command */
208         else
209                 status = -status;
210         fd = open(temp[1], O_RDONLY);
211         if (fd < 0)
212                 goto bad;
213         if (fstat(fd, &st))
214                 goto close_bad;
215         result->size = st.st_size;
216         result->ptr = xmalloc(result->size + 1);
217         if (read_in_full(fd, result->ptr, result->size) != result->size) {
218                 free(result->ptr);
219                 result->ptr = NULL;
220                 result->size = 0;
221         }
222  close_bad:
223         close(fd);
224  bad:
225         for (i = 0; i < 3; i++)
226                 unlink(temp[i]);
227         return status;
228 }
229
230 /*
231  * merge.default and merge.driver configuration items
232  */
233 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
234 static const char *default_ll_merge;
235
236 static int read_merge_config(const char *var, const char *value, void *cb)
237 {
238         struct ll_merge_driver *fn;
239         const char *ep, *name;
240         int namelen;
241
242         if (!strcmp(var, "merge.default")) {
243                 if (value)
244                         default_ll_merge = strdup(value);
245                 return 0;
246         }
247
248         /*
249          * We are not interested in anything but "merge.<name>.variable";
250          * especially, we do not want to look at variables such as
251          * "merge.summary", "merge.tool", and "merge.verbosity".
252          */
253         if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
254                 return 0;
255
256         /*
257          * Find existing one as we might be processing merge.<name>.var2
258          * after seeing merge.<name>.var1.
259          */
260         name = var + 6;
261         namelen = ep - name;
262         for (fn = ll_user_merge; fn; fn = fn->next)
263                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
264                         break;
265         if (!fn) {
266                 fn = xcalloc(1, sizeof(struct ll_merge_driver));
267                 fn->name = xmemdupz(name, namelen);
268                 fn->fn = ll_ext_merge;
269                 *ll_user_merge_tail = fn;
270                 ll_user_merge_tail = &(fn->next);
271         }
272
273         ep++;
274
275         if (!strcmp("name", ep)) {
276                 if (!value)
277                         return error("%s: lacks value", var);
278                 fn->description = strdup(value);
279                 return 0;
280         }
281
282         if (!strcmp("driver", ep)) {
283                 if (!value)
284                         return error("%s: lacks value", var);
285                 /*
286                  * merge.<name>.driver specifies the command line:
287                  *
288                  *      command-line
289                  *
290                  * The command-line will be interpolated with the following
291                  * tokens and is given to the shell:
292                  *
293                  *    %O - temporary file name for the merge base.
294                  *    %A - temporary file name for our version.
295                  *    %B - temporary file name for the other branches' version.
296                  *
297                  * The external merge driver should write the results in the
298                  * file named by %A, and signal that it has done with zero exit
299                  * status.
300                  */
301                 fn->cmdline = strdup(value);
302                 return 0;
303         }
304
305         if (!strcmp("recursive", ep)) {
306                 if (!value)
307                         return error("%s: lacks value", var);
308                 fn->recursive = strdup(value);
309                 return 0;
310         }
311
312         return 0;
313 }
314
315 static void initialize_ll_merge(void)
316 {
317         if (ll_user_merge_tail)
318                 return;
319         ll_user_merge_tail = &ll_user_merge;
320         git_config(read_merge_config, NULL);
321 }
322
323 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
324 {
325         struct ll_merge_driver *fn;
326         const char *name;
327         int i;
328
329         initialize_ll_merge();
330
331         if (ATTR_TRUE(merge_attr))
332                 return &ll_merge_drv[LL_TEXT_MERGE];
333         else if (ATTR_FALSE(merge_attr))
334                 return &ll_merge_drv[LL_BINARY_MERGE];
335         else if (ATTR_UNSET(merge_attr)) {
336                 if (!default_ll_merge)
337                         return &ll_merge_drv[LL_TEXT_MERGE];
338                 else
339                         name = default_ll_merge;
340         }
341         else
342                 name = merge_attr;
343
344         for (fn = ll_user_merge; fn; fn = fn->next)
345                 if (!strcmp(fn->name, name))
346                         return fn;
347
348         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
349                 if (!strcmp(ll_merge_drv[i].name, name))
350                         return &ll_merge_drv[i];
351
352         /* default to the 3-way */
353         return &ll_merge_drv[LL_TEXT_MERGE];
354 }
355
356 static const char *git_path_check_merge(const char *path)
357 {
358         static struct git_attr_check attr_merge_check;
359
360         if (!attr_merge_check.attr)
361                 attr_merge_check.attr = git_attr("merge", 5);
362
363         if (git_checkattr(path, 1, &attr_merge_check))
364                 return NULL;
365         return attr_merge_check.value;
366 }
367
368 int ll_merge(mmbuffer_t *result_buf,
369              const char *path,
370              mmfile_t *ancestor,
371              mmfile_t *ours, const char *our_label,
372              mmfile_t *theirs, const char *their_label,
373              int virtual_ancestor)
374 {
375         const char *ll_driver_name;
376         const struct ll_merge_driver *driver;
377
378         ll_driver_name = git_path_check_merge(path);
379         driver = find_ll_merge_driver(ll_driver_name);
380
381         if (virtual_ancestor && driver->recursive)
382                 driver = find_ll_merge_driver(driver->recursive);
383         return driver->fn(driver, result_buf, path,
384                           ancestor,
385                           ours, our_label,
386                           theirs, their_label, virtual_ancestor);
387 }