use write_str_in_full helper to avoid literal string lengths
[git/git.git] / rerere.c
1 #include "cache.h"
2 #include "string-list.h"
3 #include "rerere.h"
4 #include "xdiff/xdiff.h"
5 #include "xdiff-interface.h"
6
7 /* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
8 static int rerere_enabled = -1;
9
10 /* automatically update cleanly resolved paths to the index */
11 static int rerere_autoupdate;
12
13 static char *merge_rr_path;
14
15 const char *rerere_path(const char *hex, const char *file)
16 {
17 return git_path("rr-cache/%s/%s", hex, file);
18 }
19
20 int has_rerere_resolution(const char *hex)
21 {
22 struct stat st;
23 return !stat(rerere_path(hex, "postimage"), &st);
24 }
25
26 static void read_rr(struct string_list *rr)
27 {
28 unsigned char sha1[20];
29 char buf[PATH_MAX];
30 FILE *in = fopen(merge_rr_path, "r");
31 if (!in)
32 return;
33 while (fread(buf, 40, 1, in) == 1) {
34 int i;
35 char *name;
36 if (get_sha1_hex(buf, sha1))
37 die("corrupt MERGE_RR");
38 buf[40] = '\0';
39 name = xstrdup(buf);
40 if (fgetc(in) != '\t')
41 die("corrupt MERGE_RR");
42 for (i = 0; i < sizeof(buf) && (buf[i] = fgetc(in)); i++)
43 ; /* do nothing */
44 if (i == sizeof(buf))
45 die("filename too long");
46 string_list_insert(buf, rr)->util = name;
47 }
48 fclose(in);
49 }
50
51 static struct lock_file write_lock;
52
53 static int write_rr(struct string_list *rr, int out_fd)
54 {
55 int i;
56 for (i = 0; i < rr->nr; i++) {
57 const char *path;
58 int length;
59 if (!rr->items[i].util)
60 continue;
61 path = rr->items[i].string;
62 length = strlen(path) + 1;
63 if (write_in_full(out_fd, rr->items[i].util, 40) != 40 ||
64 write_str_in_full(out_fd, "\t") != 1 ||
65 write_in_full(out_fd, path, length) != length)
66 die("unable to write rerere record");
67 }
68 if (commit_lock_file(&write_lock) != 0)
69 die("unable to write rerere record");
70 return 0;
71 }
72
73 static void ferr_write(const void *p, size_t count, FILE *fp, int *err)
74 {
75 if (!count || *err)
76 return;
77 if (fwrite(p, count, 1, fp) != 1)
78 *err = errno;
79 }
80
81 static inline void ferr_puts(const char *s, FILE *fp, int *err)
82 {
83 ferr_write(s, strlen(s), fp, err);
84 }
85
86 static int handle_file(const char *path,
87 unsigned char *sha1, const char *output)
88 {
89 git_SHA_CTX ctx;
90 char buf[1024];
91 int hunk_no = 0;
92 enum {
93 RR_CONTEXT = 0, RR_SIDE_1, RR_SIDE_2, RR_ORIGINAL,
94 } hunk = RR_CONTEXT;
95 struct strbuf one = STRBUF_INIT, two = STRBUF_INIT;
96 FILE *f = fopen(path, "r");
97 FILE *out = NULL;
98 int wrerror = 0;
99
100 if (!f)
101 return error("Could not open %s", path);
102
103 if (output) {
104 out = fopen(output, "w");
105 if (!out) {
106 fclose(f);
107 return error("Could not write %s", output);
108 }
109 }
110
111 if (sha1)
112 git_SHA1_Init(&ctx);
113
114 while (fgets(buf, sizeof(buf), f)) {
115 if (!prefixcmp(buf, "<<<<<<< ")) {
116 if (hunk != RR_CONTEXT)
117 goto bad;
118 hunk = RR_SIDE_1;
119 } else if (!prefixcmp(buf, "|||||||") && isspace(buf[7])) {
120 if (hunk != RR_SIDE_1)
121 goto bad;
122 hunk = RR_ORIGINAL;
123 } else if (!prefixcmp(buf, "=======") && isspace(buf[7])) {
124 if (hunk != RR_SIDE_1 && hunk != RR_ORIGINAL)
125 goto bad;
126 hunk = RR_SIDE_2;
127 } else if (!prefixcmp(buf, ">>>>>>> ")) {
128 if (hunk != RR_SIDE_2)
129 goto bad;
130 if (strbuf_cmp(&one, &two) > 0)
131 strbuf_swap(&one, &two);
132 hunk_no++;
133 hunk = RR_CONTEXT;
134 if (out) {
135 ferr_puts("<<<<<<<\n", out, &wrerror);
136 ferr_write(one.buf, one.len, out, &wrerror);
137 ferr_puts("=======\n", out, &wrerror);
138 ferr_write(two.buf, two.len, out, &wrerror);
139 ferr_puts(">>>>>>>\n", out, &wrerror);
140 }
141 if (sha1) {
142 git_SHA1_Update(&ctx, one.buf ? one.buf : "",
143 one.len + 1);
144 git_SHA1_Update(&ctx, two.buf ? two.buf : "",
145 two.len + 1);
146 }
147 strbuf_reset(&one);
148 strbuf_reset(&two);
149 } else if (hunk == RR_SIDE_1)
150 strbuf_addstr(&one, buf);
151 else if (hunk == RR_ORIGINAL)
152 ; /* discard */
153 else if (hunk == RR_SIDE_2)
154 strbuf_addstr(&two, buf);
155 else if (out)
156 ferr_puts(buf, out, &wrerror);
157 continue;
158 bad:
159 hunk = 99; /* force error exit */
160 break;
161 }
162 strbuf_release(&one);
163 strbuf_release(&two);
164
165 fclose(f);
166 if (wrerror)
167 error("There were errors while writing %s (%s)",
168 path, strerror(wrerror));
169 if (out && fclose(out))
170 wrerror = error("Failed to flush %s: %s",
171 path, strerror(errno));
172 if (sha1)
173 git_SHA1_Final(sha1, &ctx);
174 if (hunk != RR_CONTEXT) {
175 if (output)
176 unlink_or_warn(output);
177 return error("Could not parse conflict hunks in %s", path);
178 }
179 if (wrerror)
180 return -1;
181 return hunk_no;
182 }
183
184 static int find_conflict(struct string_list *conflict)
185 {
186 int i;
187 if (read_cache() < 0)
188 return error("Could not read index");
189 for (i = 0; i+1 < active_nr; i++) {
190 struct cache_entry *e2 = active_cache[i];
191 struct cache_entry *e3 = active_cache[i+1];
192 if (ce_stage(e2) == 2 &&
193 ce_stage(e3) == 3 &&
194 ce_same_name(e2, e3) &&
195 S_ISREG(e2->ce_mode) &&
196 S_ISREG(e3->ce_mode)) {
197 string_list_insert((const char *)e2->name, conflict);
198 i++; /* skip over both #2 and #3 */
199 }
200 }
201 return 0;
202 }
203
204 static int merge(const char *name, const char *path)
205 {
206 int ret;
207 mmfile_t cur, base, other;
208 mmbuffer_t result = {NULL, 0};
209 xpparam_t xpp = {XDF_NEED_MINIMAL};
210
211 if (handle_file(path, NULL, rerere_path(name, "thisimage")) < 0)
212 return 1;
213
214 if (read_mmfile(&cur, rerere_path(name, "thisimage")) ||
215 read_mmfile(&base, rerere_path(name, "preimage")) ||
216 read_mmfile(&other, rerere_path(name, "postimage")))
217 return 1;
218 ret = xdl_merge(&base, &cur, "", &other, "",
219 &xpp, XDL_MERGE_ZEALOUS, &result);
220 if (!ret) {
221 FILE *f = fopen(path, "w");
222 if (!f)
223 return error("Could not open %s: %s", path,
224 strerror(errno));
225 if (fwrite(result.ptr, result.size, 1, f) != 1)
226 error("Could not write %s: %s", path, strerror(errno));
227 if (fclose(f))
228 return error("Writing %s failed: %s", path,
229 strerror(errno));
230 }
231
232 free(cur.ptr);
233 free(base.ptr);
234 free(other.ptr);
235 free(result.ptr);
236
237 return ret;
238 }
239
240 static struct lock_file index_lock;
241
242 static int update_paths(struct string_list *update)
243 {
244 int i;
245 int fd = hold_locked_index(&index_lock, 0);
246 int status = 0;
247
248 if (fd < 0)
249 return -1;
250
251 for (i = 0; i < update->nr; i++) {
252 struct string_list_item *item = &update->items[i];
253 if (add_file_to_cache(item->string, ADD_CACHE_IGNORE_ERRORS))
254 status = -1;
255 }
256
257 if (!status && active_cache_changed) {
258 if (write_cache(fd, active_cache, active_nr) ||
259 commit_locked_index(&index_lock))
260 die("Unable to write new index file");
261 } else if (fd >= 0)
262 rollback_lock_file(&index_lock);
263 return status;
264 }
265
266 static int do_plain_rerere(struct string_list *rr, int fd)
267 {
268 struct string_list conflict = { NULL, 0, 0, 1 };
269 struct string_list update = { NULL, 0, 0, 1 };
270 int i;
271
272 find_conflict(&conflict);
273
274 /*
275 * MERGE_RR records paths with conflicts immediately after merge
276 * failed. Some of the conflicted paths might have been hand resolved
277 * in the working tree since then, but the initial run would catch all
278 * and register their preimages.
279 */
280
281 for (i = 0; i < conflict.nr; i++) {
282 const char *path = conflict.items[i].string;
283 if (!string_list_has_string(rr, path)) {
284 unsigned char sha1[20];
285 char *hex;
286 int ret;
287 ret = handle_file(path, sha1, NULL);
288 if (ret < 1)
289 continue;
290 hex = xstrdup(sha1_to_hex(sha1));
291 string_list_insert(path, rr)->util = hex;
292 if (mkdir(git_path("rr-cache/%s", hex), 0755))
293 continue;
294 handle_file(path, NULL, rerere_path(hex, "preimage"));
295 fprintf(stderr, "Recorded preimage for '%s'\n", path);
296 }
297 }
298
299 /*
300 * Now some of the paths that had conflicts earlier might have been
301 * hand resolved. Others may be similar to a conflict already that
302 * was resolved before.
303 */
304
305 for (i = 0; i < rr->nr; i++) {
306 int ret;
307 const char *path = rr->items[i].string;
308 const char *name = (const char *)rr->items[i].util;
309
310 if (has_rerere_resolution(name)) {
311 if (!merge(name, path)) {
312 if (rerere_autoupdate)
313 string_list_insert(path, &update);
314 fprintf(stderr,
315 "%s '%s' using previous resolution.\n",
316 rerere_autoupdate
317 ? "Staged" : "Resolved",
318 path);
319 goto mark_resolved;
320 }
321 }
322
323 /* Let's see if we have resolved it. */
324 ret = handle_file(path, NULL, NULL);
325 if (ret)
326 continue;
327
328 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
329 copy_file(rerere_path(name, "postimage"), path, 0666);
330 mark_resolved:
331 rr->items[i].util = NULL;
332 }
333
334 if (update.nr)
335 update_paths(&update);
336
337 return write_rr(rr, fd);
338 }
339
340 static int git_rerere_config(const char *var, const char *value, void *cb)
341 {
342 if (!strcmp(var, "rerere.enabled"))
343 rerere_enabled = git_config_bool(var, value);
344 else if (!strcmp(var, "rerere.autoupdate"))
345 rerere_autoupdate = git_config_bool(var, value);
346 else
347 return git_default_config(var, value, cb);
348 return 0;
349 }
350
351 static int is_rerere_enabled(void)
352 {
353 const char *rr_cache;
354 int rr_cache_exists;
355
356 if (!rerere_enabled)
357 return 0;
358
359 rr_cache = git_path("rr-cache");
360 rr_cache_exists = is_directory(rr_cache);
361 if (rerere_enabled < 0)
362 return rr_cache_exists;
363
364 if (!rr_cache_exists &&
365 (mkdir(rr_cache, 0777) || adjust_shared_perm(rr_cache)))
366 die("Could not create directory %s", rr_cache);
367 return 1;
368 }
369
370 int setup_rerere(struct string_list *merge_rr)
371 {
372 int fd;
373
374 git_config(git_rerere_config, NULL);
375 if (!is_rerere_enabled())
376 return -1;
377
378 merge_rr_path = git_pathdup("MERGE_RR");
379 fd = hold_lock_file_for_update(&write_lock, merge_rr_path,
380 LOCK_DIE_ON_ERROR);
381 read_rr(merge_rr);
382 return fd;
383 }
384
385 int rerere(void)
386 {
387 struct string_list merge_rr = { NULL, 0, 0, 1 };
388 int fd;
389
390 fd = setup_rerere(&merge_rr);
391 if (fd < 0)
392 return 0;
393 return do_plain_rerere(&merge_rr, fd);
394 }