Source

git / builtin-rerere.c

  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
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
#include "builtin.h"
#include "cache.h"
#include "path-list.h"
#include "xdiff/xdiff.h"
#include "xdiff-interface.h"

#include <time.h>

static const char git_rerere_usage[] =
"git-rerere [clear | status | diff | gc]";

/* these values are days */
static int cutoff_noresolve = 15;
static int cutoff_resolve = 60;

/* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
static int rerere_enabled = -1;

static char *merge_rr_path;

static const char *rr_path(const char *name, const char *file)
{
	return git_path("rr-cache/%s/%s", name, file);
}

static void read_rr(struct path_list *rr)
{
	unsigned char sha1[20];
	char buf[PATH_MAX];
	FILE *in = fopen(merge_rr_path, "r");
	if (!in)
		return;
	while (fread(buf, 40, 1, in) == 1) {
		int i;
		char *name;
		if (get_sha1_hex(buf, sha1))
			die("corrupt MERGE_RR");
		buf[40] = '\0';
		name = xstrdup(buf);
		if (fgetc(in) != '\t')
			die("corrupt MERGE_RR");
		for (i = 0; i < sizeof(buf) && (buf[i] = fgetc(in)); i++)
			; /* do nothing */
		if (i == sizeof(buf))
			die("filename too long");
		path_list_insert(buf, rr)->util = xstrdup(name);
	}
	fclose(in);
}

static struct lock_file write_lock;

static int write_rr(struct path_list *rr, int out_fd)
{
	int i;
	for (i = 0; i < rr->nr; i++) {
		const char *path = rr->items[i].path;
		int length = strlen(path) + 1;
		if (write_in_full(out_fd, rr->items[i].util, 40) != 40 ||
		    write_in_full(out_fd, "\t", 1) != 1 ||
		    write_in_full(out_fd, path, length) != length)
			die("unable to write rerere record");
	}
	if (close(out_fd) != 0)
		die("unable to write rerere record");
	return commit_lock_file(&write_lock);
}

struct buffer {
	char *ptr;
	int nr, alloc;
};

static void append_line(struct buffer *buffer, const char *line)
{
	int len = strlen(line);

	if (buffer->nr + len > buffer->alloc) {
		buffer->alloc = alloc_nr(buffer->nr + len);
		buffer->ptr = xrealloc(buffer->ptr, buffer->alloc);
	}
	memcpy(buffer->ptr + buffer->nr, line, len);
	buffer->nr += len;
}

static void clear_buffer(struct buffer *buffer)
{
	free(buffer->ptr);
	buffer->ptr = NULL;
	buffer->nr = buffer->alloc = 0;
}

static int handle_file(const char *path,
	 unsigned char *sha1, const char *output)
{
	SHA_CTX ctx;
	char buf[1024];
	int hunk = 0, hunk_no = 0;
	struct buffer minus = { NULL, 0, 0 }, plus = { NULL, 0, 0 };
	struct buffer *one = &minus, *two = &plus;
	FILE *f = fopen(path, "r");
	FILE *out;

	if (!f)
		return error("Could not open %s", path);

	if (output) {
		out = fopen(output, "w");
		if (!out) {
			fclose(f);
			return error("Could not write %s", output);
		}
	} else
		out = NULL;

	if (sha1)
		SHA1_Init(&ctx);

	while (fgets(buf, sizeof(buf), f)) {
		if (!prefixcmp(buf, "<<<<<<< "))
			hunk = 1;
		else if (!prefixcmp(buf, "======="))
			hunk = 2;
		else if (!prefixcmp(buf, ">>>>>>> ")) {
			int one_is_longer = (one->nr > two->nr);
			int common_len = one_is_longer ? two->nr : one->nr;
			int cmp = memcmp(one->ptr, two->ptr, common_len);

			hunk_no++;
			hunk = 0;
			if ((cmp > 0) || ((cmp == 0) && one_is_longer)) {
				struct buffer *swap = one;
				one = two;
				two = swap;
			}
			if (out) {
				fputs("<<<<<<<\n", out);
				fwrite(one->ptr, one->nr, 1, out);
				fputs("=======\n", out);
				fwrite(two->ptr, two->nr, 1, out);
				fputs(">>>>>>>\n", out);
			}
			if (sha1) {
				SHA1_Update(&ctx, one->ptr, one->nr);
				SHA1_Update(&ctx, "\0", 1);
				SHA1_Update(&ctx, two->ptr, two->nr);
				SHA1_Update(&ctx, "\0", 1);
			}
			clear_buffer(one);
			clear_buffer(two);
		} else if (hunk == 1)
			append_line(one, buf);
		else if (hunk == 2)
			append_line(two, buf);
		else if (out)
			fputs(buf, out);
	}

	fclose(f);
	if (out)
		fclose(out);
	if (sha1)
		SHA1_Final(sha1, &ctx);
	return hunk_no;
}

static int find_conflict(struct path_list *conflict)
{
	int i;
	if (read_cache() < 0)
		return error("Could not read index");
	for (i = 0; i+1 < active_nr; i++) {
		struct cache_entry *e2 = active_cache[i];
		struct cache_entry *e3 = active_cache[i+1];
		if (ce_stage(e2) == 2 &&
		    ce_stage(e3) == 3 &&
		    ce_same_name(e2, e3) &&
		    S_ISREG(ntohl(e2->ce_mode)) &&
		    S_ISREG(ntohl(e3->ce_mode))) {
			path_list_insert((const char *)e2->name, conflict);
			i++; /* skip over both #2 and #3 */
		}
	}
	return 0;
}

static int merge(const char *name, const char *path)
{
	int ret;
	mmfile_t cur, base, other;
	mmbuffer_t result = {NULL, 0};
	xpparam_t xpp = {XDF_NEED_MINIMAL};

	if (handle_file(path, NULL, rr_path(name, "thisimage")) < 0)
		return 1;

	if (read_mmfile(&cur, rr_path(name, "thisimage")) ||
			read_mmfile(&base, rr_path(name, "preimage")) ||
			read_mmfile(&other, rr_path(name, "postimage")))
		return 1;
	ret = xdl_merge(&base, &cur, "", &other, "",
			&xpp, XDL_MERGE_ZEALOUS, &result);
	if (!ret) {
		FILE *f = fopen(path, "w");
		if (!f)
			return error("Could not write to %s", path);
		fwrite(result.ptr, result.size, 1, f);
		fclose(f);
	}

	free(cur.ptr);
	free(base.ptr);
	free(other.ptr);
	free(result.ptr);

	return ret;
}

static void unlink_rr_item(const char *name)
{
	unlink(rr_path(name, "thisimage"));
	unlink(rr_path(name, "preimage"));
	unlink(rr_path(name, "postimage"));
	rmdir(git_path("rr-cache/%s", name));
}

static void garbage_collect(struct path_list *rr)
{
	struct path_list to_remove = { NULL, 0, 0, 1 };
	char buf[1024];
	DIR *dir;
	struct dirent *e;
	int len, i, cutoff;
	time_t now = time(NULL), then;

	strlcpy(buf, git_path("rr-cache"), sizeof(buf));
	len = strlen(buf);
	dir = opendir(buf);
	strcpy(buf + len++, "/");
	while ((e = readdir(dir))) {
		const char *name = e->d_name;
		struct stat st;
		if (name[0] == '.' && (name[1] == '\0' ||
					(name[1] == '.' && name[2] == '\0')))
			continue;
		i = snprintf(buf + len, sizeof(buf) - len, "%s", name);
		strlcpy(buf + len + i, "/preimage", sizeof(buf) - len - i);
		if (stat(buf, &st))
			continue;
		then = st.st_mtime;
		strlcpy(buf + len + i, "/postimage", sizeof(buf) - len - i);
		cutoff = stat(buf, &st) ? cutoff_noresolve : cutoff_resolve;
		if (then < now - cutoff * 86400) {
			buf[len + i] = '\0';
			path_list_insert(xstrdup(name), &to_remove);
		}
	}
	for (i = 0; i < to_remove.nr; i++)
		unlink_rr_item(to_remove.items[i].path);
	path_list_clear(&to_remove, 0);
}

static int outf(void *dummy, mmbuffer_t *ptr, int nbuf)
{
	int i;
	for (i = 0; i < nbuf; i++)
		if (write_in_full(1, ptr[i].ptr, ptr[i].size) != ptr[i].size)
			return -1;
	return 0;
}

static int diff_two(const char *file1, const char *label1,
		const char *file2, const char *label2)
{
	xpparam_t xpp;
	xdemitconf_t xecfg;
	xdemitcb_t ecb;
	mmfile_t minus, plus;

	if (read_mmfile(&minus, file1) || read_mmfile(&plus, file2))
		return 1;

	printf("--- a/%s\n+++ b/%s\n", label1, label2);
	fflush(stdout);
	xpp.flags = XDF_NEED_MINIMAL;
	memset(&xecfg, 0, sizeof(xecfg));
	xecfg.ctxlen = 3;
	ecb.outf = outf;
	xdl_diff(&minus, &plus, &xpp, &xecfg, &ecb);

	free(minus.ptr);
	free(plus.ptr);
	return 0;
}

static int copy_file(const char *src, const char *dest)
{
	FILE *in, *out;
	char buffer[32768];
	int count;

	if (!(in = fopen(src, "r")))
		return error("Could not open %s", src);
	if (!(out = fopen(dest, "w")))
		return error("Could not open %s", dest);
	while ((count = fread(buffer, 1, sizeof(buffer), in)))
		fwrite(buffer, 1, count, out);
	fclose(in);
	fclose(out);
	return 0;
}

static int do_plain_rerere(struct path_list *rr, int fd)
{
	struct path_list conflict = { NULL, 0, 0, 1 };
	int i;

	find_conflict(&conflict);

	/*
	 * MERGE_RR records paths with conflicts immediately after merge
	 * failed.  Some of the conflicted paths might have been hand resolved
	 * in the working tree since then, but the initial run would catch all
	 * and register their preimages.
	 */

	for (i = 0; i < conflict.nr; i++) {
		const char *path = conflict.items[i].path;
		if (!path_list_has_path(rr, path)) {
			unsigned char sha1[20];
			char *hex;
			int ret;
			ret = handle_file(path, sha1, NULL);
			if (ret < 1)
				continue;
			hex = xstrdup(sha1_to_hex(sha1));
			path_list_insert(path, rr)->util = hex;
			if (mkdir(git_path("rr-cache/%s", hex), 0755))
				continue;;
			handle_file(path, NULL, rr_path(hex, "preimage"));
			fprintf(stderr, "Recorded preimage for '%s'\n", path);
		}
	}

	/*
	 * Now some of the paths that had conflicts earlier might have been
	 * hand resolved.  Others may be similar to a conflict already that
	 * was resolved before.
	 */

	for (i = 0; i < rr->nr; i++) {
		struct stat st;
		int ret;
		const char *path = rr->items[i].path;
		const char *name = (const char *)rr->items[i].util;

		if (!stat(rr_path(name, "preimage"), &st) &&
				!stat(rr_path(name, "postimage"), &st)) {
			if (!merge(name, path)) {
				fprintf(stderr, "Resolved '%s' using "
						"previous resolution.\n", path);
				goto tail_optimization;
			}
		}

		/* Let's see if we have resolved it. */
		ret = handle_file(path, NULL, NULL);
		if (ret)
			continue;

		fprintf(stderr, "Recorded resolution for '%s'.\n", path);
		copy_file(path, rr_path(name, "postimage"));
tail_optimization:
		if (i < rr->nr - 1)
			memmove(rr->items + i,
				rr->items + i + 1,
				sizeof(rr->items[0]) * (rr->nr - i - 1));
		rr->nr--;
		i--;
	}

	return write_rr(rr, fd);
}

static int git_rerere_config(const char *var, const char *value)
{
	if (!strcmp(var, "gc.rerereresolved"))
		cutoff_resolve = git_config_int(var, value);
	else if (!strcmp(var, "gc.rerereunresolved"))
		cutoff_noresolve = git_config_int(var, value);
	else if (!strcmp(var, "rerere.enabled"))
		rerere_enabled = git_config_bool(var, value);
	else
		return git_default_config(var, value);
	return 0;
}

static int is_rerere_enabled(void)
{
	struct stat st;
	const char *rr_cache;
	int rr_cache_exists;

	if (!rerere_enabled)
		return 0;

	rr_cache = git_path("rr-cache");
	rr_cache_exists = !stat(rr_cache, &st) && S_ISDIR(st.st_mode);
	if (rerere_enabled < 0)
		return rr_cache_exists;

	if (!rr_cache_exists &&
	    (mkdir(rr_cache, 0777) || adjust_shared_perm(rr_cache)))
		die("Could not create directory %s", rr_cache);
	return 1;
}

int cmd_rerere(int argc, const char **argv, const char *prefix)
{
	struct path_list merge_rr = { NULL, 0, 0, 1 };
	int i, fd = -1;

	git_config(git_rerere_config);
	if (!is_rerere_enabled())
		return 0;

	merge_rr_path = xstrdup(git_path("rr-cache/MERGE_RR"));
	fd = hold_lock_file_for_update(&write_lock, merge_rr_path, 1);
	read_rr(&merge_rr);

	if (argc < 2)
		return do_plain_rerere(&merge_rr, fd);
	else if (!strcmp(argv[1], "clear")) {
		for (i = 0; i < merge_rr.nr; i++) {
			struct stat st;
			const char *name = (const char *)merge_rr.items[i].util;
			if (!stat(git_path("rr-cache/%s", name), &st) &&
					S_ISDIR(st.st_mode) &&
					stat(rr_path(name, "postimage"), &st))
				unlink_rr_item(name);
		}
		unlink(merge_rr_path);
	} else if (!strcmp(argv[1], "gc"))
		garbage_collect(&merge_rr);
	else if (!strcmp(argv[1], "status"))
		for (i = 0; i < merge_rr.nr; i++)
			printf("%s\n", merge_rr.items[i].path);
	else if (!strcmp(argv[1], "diff"))
		for (i = 0; i < merge_rr.nr; i++) {
			const char *path = merge_rr.items[i].path;
			const char *name = (const char *)merge_rr.items[i].util;
			diff_two(rr_path(name, "preimage"), path, path, path);
		}
	else
		usage(git_rerere_usage);

	path_list_clear(&merge_rr, 1);
	return 0;
}