aboutsummaryrefslogtreecommitdiff
path: root/ll-merge.c
blob: 81c02ad0531e98379d8cd11dc7c2d70214d67fb4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
/*
 * Low level 3-way in-core file merge.
 *
 * Copyright (c) 2007 Junio C Hamano
 */

#include "cache.h"
#include "attr.h"
#include "xdiff-interface.h"
#include "run-command.h"
#include "ll-merge.h"

struct ll_merge_driver;

typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
			   mmbuffer_t *result,
			   const char *path,
			   mmfile_t *orig,
			   mmfile_t *src1, const char *name1,
			   mmfile_t *src2, const char *name2,
			   int virtual_ancestor);

struct ll_merge_driver {
	const char *name;
	const char *description;
	ll_merge_fn fn;
	const char *recursive;
	struct ll_merge_driver *next;
	char *cmdline;
};

/*
 * Built-in low-levels
 */
static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
			   mmbuffer_t *result,
			   const char *path_unused,
			   mmfile_t *orig,
			   mmfile_t *src1, const char *name1,
			   mmfile_t *src2, const char *name2,
			   int virtual_ancestor)
{
	/*
	 * The tentative merge result is "ours" for the final round,
	 * or common ancestor for an internal merge.  Still return
	 * "conflicted merge" status.
	 */
	mmfile_t *stolen = virtual_ancestor ? orig : src1;

	result->ptr = stolen->ptr;
	result->size = stolen->size;
	stolen->ptr = NULL;
	return 1;
}

static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
			mmbuffer_t *result,
			const char *path_unused,
			mmfile_t *orig,
			mmfile_t *src1, const char *name1,
			mmfile_t *src2, const char *name2,
			int virtual_ancestor)
{
	xpparam_t xpp;
	int style = 0;

	if (buffer_is_binary(orig->ptr, orig->size) ||
	    buffer_is_binary(src1->ptr, src1->size) ||
	    buffer_is_binary(src2->ptr, src2->size)) {
		warning("Cannot merge binary files: %s vs. %s\n",
			name1, name2);
		return ll_binary_merge(drv_unused, result,
				       path_unused,
				       orig, src1, name1,
				       src2, name2,
				       virtual_ancestor);
	}

	memset(&xpp, 0, sizeof(xpp));
	if (git_xmerge_style >= 0)
		style = git_xmerge_style;
	return xdl_merge(orig,
			 src1, name1,
			 src2, name2,
			 &xpp, XDL_MERGE_ZEALOUS | style,
			 result);
}

static int ll_union_merge(const struct ll_merge_driver *drv_unused,
			  mmbuffer_t *result,
			  const char *path_unused,
			  mmfile_t *orig,
			  mmfile_t *src1, const char *name1,
			  mmfile_t *src2, const char *name2,
			  int virtual_ancestor)
{
	char *src, *dst;
	long size;
	const int marker_size = 7;
	int status, saved_style;

	/* We have to force the RCS "merge" style */
	saved_style = git_xmerge_style;
	git_xmerge_style = 0;
	status = ll_xdl_merge(drv_unused, result, path_unused,
			      orig, src1, NULL, src2, NULL,
			      virtual_ancestor);
	git_xmerge_style = saved_style;
	if (status <= 0)
		return status;
	size = result->size;
	src = dst = result->ptr;
	while (size) {
		char ch;
		if ((marker_size < size) &&
		    (*src == '<' || *src == '=' || *src == '>')) {
			int i;
			ch = *src;
			for (i = 0; i < marker_size; i++)
				if (src[i] != ch)
					goto not_a_marker;
			if (src[marker_size] != '\n')
				goto not_a_marker;
			src += marker_size + 1;
			size -= marker_size + 1;
			continue;
		}
	not_a_marker:
		do {
			ch = *src++;
			*dst++ = ch;
			size--;
		} while (ch != '\n' && size);
	}
	result->size = dst - result->ptr;
	return 0;
}

#define LL_BINARY_MERGE 0
#define LL_TEXT_MERGE 1
#define LL_UNION_MERGE 2
static struct ll_merge_driver ll_merge_drv[] = {
	{ "binary", "built-in binary merge", ll_binary_merge },
	{ "text", "built-in 3-way text merge", ll_xdl_merge },
	{ "union", "built-in union merge", ll_union_merge },
};

static void create_temp(mmfile_t *src, char *path)
{
	int fd;

	strcpy(path, ".merge_file_XXXXXX");
	fd = xmkstemp(path);
	if (write_in_full(fd, src->ptr, src->size) != src->size)
		die("unable to write temp-file");
	close(fd);
}

/*
 * User defined low-level merge driver support.
 */
static int ll_ext_merge(const struct ll_merge_driver *fn,
			mmbuffer_t *result,
			const char *path,
			mmfile_t *orig,
			mmfile_t *src1, const char *name1,
			mmfile_t *src2, const char *name2,
			int virtual_ancestor)
{
	char temp[3][50];
	struct strbuf cmd = STRBUF_INIT;
	struct strbuf_expand_dict_entry dict[] = {
		{ "O", temp[0] },
		{ "A", temp[1] },
		{ "B", temp[2] },
		{ NULL }
	};
	struct child_process child;
	const char *args[20];
	int status, fd, i;
	struct stat st;

	if (fn->cmdline == NULL)
		die("custom merge driver %s lacks command line.", fn->name);

	result->ptr = NULL;
	result->size = 0;
	create_temp(orig, temp[0]);
	create_temp(src1, temp[1]);
	create_temp(src2, temp[2]);

	strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);

	memset(&child, 0, sizeof(child));
	child.argv = args;
	args[0] = "sh";
	args[1] = "-c";
	args[2] = cmd.buf;
	args[3] = NULL;

	status = run_command(&child);
	if (status < -ERR_RUN_COMMAND_FORK)
		; /* failure in run-command */
	else
		status = -status;
	fd = open(temp[1], O_RDONLY);
	if (fd < 0)
		goto bad;
	if (fstat(fd, &st))
		goto close_bad;
	result->size = st.st_size;
	result->ptr = xmalloc(result->size + 1);
	if (read_in_full(fd, result->ptr, result->size) != result->size) {
		free(result->ptr);
		result->ptr = NULL;
		result->size = 0;
	}
 close_bad:
	close(fd);
 bad:
	for (i = 0; i < 3; i++)
		unlink_or_warn(temp[i]);
	strbuf_release(&cmd);
	return status;
}

/*
 * merge.default and merge.driver configuration items
 */
static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
static const char *default_ll_merge;

static int read_merge_config(const char *var, const char *value, void *cb)
{
	struct ll_merge_driver *fn;
	const char *ep, *name;
	int namelen;

	if (!strcmp(var, "merge.default")) {
		if (value)
			default_ll_merge = strdup(value);
		return 0;
	}

	/*
	 * We are not interested in anything but "merge.<name>.variable";
	 * especially, we do not want to look at variables such as
	 * "merge.summary", "merge.tool", and "merge.verbosity".
	 */
	if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
		return 0;

	/*
	 * Find existing one as we might be processing merge.<name>.var2
	 * after seeing merge.<name>.var1.
	 */
	name = var + 6;
	namelen = ep - name;
	for (fn = ll_user_merge; fn; fn = fn->next)
		if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
			break;
	if (!fn) {
		fn = xcalloc(1, sizeof(struct ll_merge_driver));
		fn->name = xmemdupz(name, namelen);
		fn->fn = ll_ext_merge;
		*ll_user_merge_tail = fn;
		ll_user_merge_tail = &(fn->next);
	}

	ep++;

	if (!strcmp("name", ep)) {
		if (!value)
			return error("%s: lacks value", var);
		fn->description = strdup(value);
		return 0;
	}

	if (!strcmp("driver", ep)) {
		if (!value)
			return error("%s: lacks value", var);
		/*
		 * merge.<name>.driver specifies the command line:
		 *
		 *	command-line
		 *
		 * The command-line will be interpolated with the following
		 * tokens and is given to the shell:
		 *
		 *    %O - temporary file name for the merge base.
		 *    %A - temporary file name for our version.
		 *    %B - temporary file name for the other branches' version.
		 *
		 * The external merge driver should write the results in the
		 * file named by %A, and signal that it has done with zero exit
		 * status.
		 */
		fn->cmdline = strdup(value);
		return 0;
	}

	if (!strcmp("recursive", ep)) {
		if (!value)
			return error("%s: lacks value", var);
		fn->recursive = strdup(value);
		return 0;
	}

	return 0;
}

static void initialize_ll_merge(void)
{
	if (ll_user_merge_tail)
		return;
	ll_user_merge_tail = &ll_user_merge;
	git_config(read_merge_config, NULL);
}

static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
{
	struct ll_merge_driver *fn;
	const char *name;
	int i;

	initialize_ll_merge();

	if (ATTR_TRUE(merge_attr))
		return &ll_merge_drv[LL_TEXT_MERGE];
	else if (ATTR_FALSE(merge_attr))
		return &ll_merge_drv[LL_BINARY_MERGE];
	else if (ATTR_UNSET(merge_attr)) {
		if (!default_ll_merge)
			return &ll_merge_drv[LL_TEXT_MERGE];
		else
			name = default_ll_merge;
	}
	else
		name = merge_attr;

	for (fn = ll_user_merge; fn; fn = fn->next)
		if (!strcmp(fn->name, name))
			return fn;

	for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
		if (!strcmp(ll_merge_drv[i].name, name))
			return &ll_merge_drv[i];

	/* default to the 3-way */
	return &ll_merge_drv[LL_TEXT_MERGE];
}

static const char *git_path_check_merge(const char *path)
{
	static struct git_attr_check attr_merge_check;

	if (!attr_merge_check.attr)
		attr_merge_check.attr = git_attr("merge", 5);

	if (git_checkattr(path, 1, &attr_merge_check))
		return NULL;
	return attr_merge_check.value;
}

int ll_merge(mmbuffer_t *result_buf,
	     const char *path,
	     mmfile_t *ancestor,
	     mmfile_t *ours, const char *our_label,
	     mmfile_t *theirs, const char *their_label,
	     int virtual_ancestor)
{
	const char *ll_driver_name;
	const struct ll_merge_driver *driver;

	ll_driver_name = git_path_check_merge(path);
	driver = find_ll_merge_driver(ll_driver_name);

	if (virtual_ancestor && driver->recursive)
		driver = find_ll_merge_driver(driver->recursive);
	return driver->fn(driver, result_buf, path,
			  ancestor,
			  ours, our_label,
			  theirs, their_label, virtual_ancestor);
}