git.el: Fix typo in git-update-saved-file error handling.
[git] / builtin-rerere.c
1 #include "builtin.h"
2 #include "cache.h"
3 #include "path-list.h"
4 #include "xdiff/xdiff.h"
5 #include "xdiff-interface.h"
6
7 #include <time.h>
8
9 static const char git_rerere_usage[] =
10 "git-rerere [clear | status | diff | gc]";
11
12 /* these values are days */
13 static int cutoff_noresolve = 15;
14 static int cutoff_resolve = 60;
15
16 /* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
17 static int rerere_enabled = -1;
18
19 static char *merge_rr_path;
20
21 static const char *rr_path(const char *name, const char *file)
22 {
23         return git_path("rr-cache/%s/%s", name, file);
24 }
25
26 static void read_rr(struct path_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                 path_list_insert(buf, rr)->util = xstrdup(name);
47         }
48         fclose(in);
49 }
50
51 static struct lock_file write_lock;
52
53 static int write_rr(struct path_list *rr, int out_fd)
54 {
55         int i;
56         for (i = 0; i < rr->nr; i++) {
57                 const char *path = rr->items[i].path;
58                 int length = strlen(path) + 1;
59                 if (write_in_full(out_fd, rr->items[i].util, 40) != 40 ||
60                     write_in_full(out_fd, "\t", 1) != 1 ||
61                     write_in_full(out_fd, path, length) != length)
62                         die("unable to write rerere record");
63         }
64         if (close(out_fd) != 0)
65                 die("unable to write rerere record");
66         return commit_lock_file(&write_lock);
67 }
68
69 static int handle_file(const char *path,
70          unsigned char *sha1, const char *output)
71 {
72         SHA_CTX ctx;
73         char buf[1024];
74         int hunk = 0, hunk_no = 0;
75         struct strbuf one, two;
76         FILE *f = fopen(path, "r");
77         FILE *out = NULL;
78
79         if (!f)
80                 return error("Could not open %s", path);
81
82         if (output) {
83                 out = fopen(output, "w");
84                 if (!out) {
85                         fclose(f);
86                         return error("Could not write %s", output);
87                 }
88         }
89
90         if (sha1)
91                 SHA1_Init(&ctx);
92
93         strbuf_init(&one, 0);
94         strbuf_init(&two,  0);
95         while (fgets(buf, sizeof(buf), f)) {
96                 if (!prefixcmp(buf, "<<<<<<< "))
97                         hunk = 1;
98                 else if (!prefixcmp(buf, "======="))
99                         hunk = 2;
100                 else if (!prefixcmp(buf, ">>>>>>> ")) {
101                         int cmp = strbuf_cmp(&one, &two);
102
103                         hunk_no++;
104                         hunk = 0;
105                         if (cmp > 0) {
106                                 strbuf_swap(&one, &two);
107                         }
108                         if (out) {
109                                 fputs("<<<<<<<\n", out);
110                                 fwrite(one.buf, one.len, 1, out);
111                                 fputs("=======\n", out);
112                                 fwrite(two.buf, two.len, 1, out);
113                                 fputs(">>>>>>>\n", out);
114                         }
115                         if (sha1) {
116                                 SHA1_Update(&ctx, one.buf ? one.buf : "",
117                                             one.len + 1);
118                                 SHA1_Update(&ctx, two.buf ? two.buf : "",
119                                             two.len + 1);
120                         }
121                         strbuf_reset(&one);
122                         strbuf_reset(&two);
123                 } else if (hunk == 1)
124                         strbuf_addstr(&one, buf);
125                 else if (hunk == 2)
126                         strbuf_addstr(&two, buf);
127                 else if (out)
128                         fputs(buf, out);
129         }
130         strbuf_release(&one);
131         strbuf_release(&two);
132
133         fclose(f);
134         if (out)
135                 fclose(out);
136         if (sha1)
137                 SHA1_Final(sha1, &ctx);
138         return hunk_no;
139 }
140
141 static int find_conflict(struct path_list *conflict)
142 {
143         int i;
144         if (read_cache() < 0)
145                 return error("Could not read index");
146         for (i = 0; i+1 < active_nr; i++) {
147                 struct cache_entry *e2 = active_cache[i];
148                 struct cache_entry *e3 = active_cache[i+1];
149                 if (ce_stage(e2) == 2 &&
150                     ce_stage(e3) == 3 &&
151                     ce_same_name(e2, e3) &&
152                     S_ISREG(ntohl(e2->ce_mode)) &&
153                     S_ISREG(ntohl(e3->ce_mode))) {
154                         path_list_insert((const char *)e2->name, conflict);
155                         i++; /* skip over both #2 and #3 */
156                 }
157         }
158         return 0;
159 }
160
161 static int merge(const char *name, const char *path)
162 {
163         int ret;
164         mmfile_t cur, base, other;
165         mmbuffer_t result = {NULL, 0};
166         xpparam_t xpp = {XDF_NEED_MINIMAL};
167
168         if (handle_file(path, NULL, rr_path(name, "thisimage")) < 0)
169                 return 1;
170
171         if (read_mmfile(&cur, rr_path(name, "thisimage")) ||
172                         read_mmfile(&base, rr_path(name, "preimage")) ||
173                         read_mmfile(&other, rr_path(name, "postimage")))
174                 return 1;
175         ret = xdl_merge(&base, &cur, "", &other, "",
176                         &xpp, XDL_MERGE_ZEALOUS, &result);
177         if (!ret) {
178                 FILE *f = fopen(path, "w");
179                 if (!f)
180                         return error("Could not write to %s", path);
181                 fwrite(result.ptr, result.size, 1, f);
182                 fclose(f);
183         }
184
185         free(cur.ptr);
186         free(base.ptr);
187         free(other.ptr);
188         free(result.ptr);
189
190         return ret;
191 }
192
193 static void unlink_rr_item(const char *name)
194 {
195         unlink(rr_path(name, "thisimage"));
196         unlink(rr_path(name, "preimage"));
197         unlink(rr_path(name, "postimage"));
198         rmdir(git_path("rr-cache/%s", name));
199 }
200
201 static void garbage_collect(struct path_list *rr)
202 {
203         struct path_list to_remove = { NULL, 0, 0, 1 };
204         char buf[1024];
205         DIR *dir;
206         struct dirent *e;
207         int len, i, cutoff;
208         time_t now = time(NULL), then;
209
210         strlcpy(buf, git_path("rr-cache"), sizeof(buf));
211         len = strlen(buf);
212         dir = opendir(buf);
213         strcpy(buf + len++, "/");
214         while ((e = readdir(dir))) {
215                 const char *name = e->d_name;
216                 struct stat st;
217                 if (name[0] == '.' && (name[1] == '\0' ||
218                                         (name[1] == '.' && name[2] == '\0')))
219                         continue;
220                 i = snprintf(buf + len, sizeof(buf) - len, "%s", name);
221                 strlcpy(buf + len + i, "/preimage", sizeof(buf) - len - i);
222                 if (stat(buf, &st))
223                         continue;
224                 then = st.st_mtime;
225                 strlcpy(buf + len + i, "/postimage", sizeof(buf) - len - i);
226                 cutoff = stat(buf, &st) ? cutoff_noresolve : cutoff_resolve;
227                 if (then < now - cutoff * 86400) {
228                         buf[len + i] = '\0';
229                         path_list_insert(xstrdup(name), &to_remove);
230                 }
231         }
232         for (i = 0; i < to_remove.nr; i++)
233                 unlink_rr_item(to_remove.items[i].path);
234         path_list_clear(&to_remove, 0);
235 }
236
237 static int outf(void *dummy, mmbuffer_t *ptr, int nbuf)
238 {
239         int i;
240         for (i = 0; i < nbuf; i++)
241                 if (write_in_full(1, ptr[i].ptr, ptr[i].size) != ptr[i].size)
242                         return -1;
243         return 0;
244 }
245
246 static int diff_two(const char *file1, const char *label1,
247                 const char *file2, const char *label2)
248 {
249         xpparam_t xpp;
250         xdemitconf_t xecfg;
251         xdemitcb_t ecb;
252         mmfile_t minus, plus;
253
254         if (read_mmfile(&minus, file1) || read_mmfile(&plus, file2))
255                 return 1;
256
257         printf("--- a/%s\n+++ b/%s\n", label1, label2);
258         fflush(stdout);
259         xpp.flags = XDF_NEED_MINIMAL;
260         memset(&xecfg, 0, sizeof(xecfg));
261         xecfg.ctxlen = 3;
262         ecb.outf = outf;
263         xdl_diff(&minus, &plus, &xpp, &xecfg, &ecb);
264
265         free(minus.ptr);
266         free(plus.ptr);
267         return 0;
268 }
269
270 static int copy_file(const char *src, const char *dest)
271 {
272         FILE *in, *out;
273         char buffer[32768];
274         int count;
275
276         if (!(in = fopen(src, "r")))
277                 return error("Could not open %s", src);
278         if (!(out = fopen(dest, "w")))
279                 return error("Could not open %s", dest);
280         while ((count = fread(buffer, 1, sizeof(buffer), in)))
281                 fwrite(buffer, 1, count, out);
282         fclose(in);
283         fclose(out);
284         return 0;
285 }
286
287 static int do_plain_rerere(struct path_list *rr, int fd)
288 {
289         struct path_list conflict = { NULL, 0, 0, 1 };
290         int i;
291
292         find_conflict(&conflict);
293
294         /*
295          * MERGE_RR records paths with conflicts immediately after merge
296          * failed.  Some of the conflicted paths might have been hand resolved
297          * in the working tree since then, but the initial run would catch all
298          * and register their preimages.
299          */
300
301         for (i = 0; i < conflict.nr; i++) {
302                 const char *path = conflict.items[i].path;
303                 if (!path_list_has_path(rr, path)) {
304                         unsigned char sha1[20];
305                         char *hex;
306                         int ret;
307                         ret = handle_file(path, sha1, NULL);
308                         if (ret < 1)
309                                 continue;
310                         hex = xstrdup(sha1_to_hex(sha1));
311                         path_list_insert(path, rr)->util = hex;
312                         if (mkdir(git_path("rr-cache/%s", hex), 0755))
313                                 continue;;
314                         handle_file(path, NULL, rr_path(hex, "preimage"));
315                         fprintf(stderr, "Recorded preimage for '%s'\n", path);
316                 }
317         }
318
319         /*
320          * Now some of the paths that had conflicts earlier might have been
321          * hand resolved.  Others may be similar to a conflict already that
322          * was resolved before.
323          */
324
325         for (i = 0; i < rr->nr; i++) {
326                 struct stat st;
327                 int ret;
328                 const char *path = rr->items[i].path;
329                 const char *name = (const char *)rr->items[i].util;
330
331                 if (!stat(rr_path(name, "preimage"), &st) &&
332                                 !stat(rr_path(name, "postimage"), &st)) {
333                         if (!merge(name, path)) {
334                                 fprintf(stderr, "Resolved '%s' using "
335                                                 "previous resolution.\n", path);
336                                 goto tail_optimization;
337                         }
338                 }
339
340                 /* Let's see if we have resolved it. */
341                 ret = handle_file(path, NULL, NULL);
342                 if (ret)
343                         continue;
344
345                 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
346                 copy_file(path, rr_path(name, "postimage"));
347 tail_optimization:
348                 if (i < rr->nr - 1)
349                         memmove(rr->items + i,
350                                 rr->items + i + 1,
351                                 sizeof(rr->items[0]) * (rr->nr - i - 1));
352                 rr->nr--;
353                 i--;
354         }
355
356         return write_rr(rr, fd);
357 }
358
359 static int git_rerere_config(const char *var, const char *value)
360 {
361         if (!strcmp(var, "gc.rerereresolved"))
362                 cutoff_resolve = git_config_int(var, value);
363         else if (!strcmp(var, "gc.rerereunresolved"))
364                 cutoff_noresolve = git_config_int(var, value);
365         else if (!strcmp(var, "rerere.enabled"))
366                 rerere_enabled = git_config_bool(var, value);
367         else
368                 return git_default_config(var, value);
369         return 0;
370 }
371
372 static int is_rerere_enabled(void)
373 {
374         struct stat st;
375         const char *rr_cache;
376         int rr_cache_exists;
377
378         if (!rerere_enabled)
379                 return 0;
380
381         rr_cache = git_path("rr-cache");
382         rr_cache_exists = !stat(rr_cache, &st) && S_ISDIR(st.st_mode);
383         if (rerere_enabled < 0)
384                 return rr_cache_exists;
385
386         if (!rr_cache_exists &&
387             (mkdir(rr_cache, 0777) || adjust_shared_perm(rr_cache)))
388                 die("Could not create directory %s", rr_cache);
389         return 1;
390 }
391
392 int cmd_rerere(int argc, const char **argv, const char *prefix)
393 {
394         struct path_list merge_rr = { NULL, 0, 0, 1 };
395         int i, fd = -1;
396
397         git_config(git_rerere_config);
398         if (!is_rerere_enabled())
399                 return 0;
400
401         merge_rr_path = xstrdup(git_path("rr-cache/MERGE_RR"));
402         fd = hold_lock_file_for_update(&write_lock, merge_rr_path, 1);
403         read_rr(&merge_rr);
404
405         if (argc < 2)
406                 return do_plain_rerere(&merge_rr, fd);
407         else if (!strcmp(argv[1], "clear")) {
408                 for (i = 0; i < merge_rr.nr; i++) {
409                         struct stat st;
410                         const char *name = (const char *)merge_rr.items[i].util;
411                         if (!stat(git_path("rr-cache/%s", name), &st) &&
412                                         S_ISDIR(st.st_mode) &&
413                                         stat(rr_path(name, "postimage"), &st))
414                                 unlink_rr_item(name);
415                 }
416                 unlink(merge_rr_path);
417         } else if (!strcmp(argv[1], "gc"))
418                 garbage_collect(&merge_rr);
419         else if (!strcmp(argv[1], "status"))
420                 for (i = 0; i < merge_rr.nr; i++)
421                         printf("%s\n", merge_rr.items[i].path);
422         else if (!strcmp(argv[1], "diff"))
423                 for (i = 0; i < merge_rr.nr; i++) {
424                         const char *path = merge_rr.items[i].path;
425                         const char *name = (const char *)merge_rr.items[i].util;
426                         diff_two(rr_path(name, "preimage"), path, path, path);
427                 }
428         else
429                 usage(git_rerere_usage);
430
431         path_list_clear(&merge_rr, 1);
432         return 0;
433 }