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 static const char *rr_path(const char *name, const char *file)
  16 {
  17         return git_path("rr-cache/%s/%s", name, file);
  18 }
  19
  20 static int has_resolution(const char *name)
  21 {
  22         struct stat st;
  23         return !stat(rr_path(name, "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_in_full(out_fd, "\t", 1) != 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 int handle_file(const char *path,
  74          unsigned char *sha1, const char *output)
  75 {
  76         SHA_CTX ctx;
  77         char buf[1024];
  78         int hunk = 0, hunk_no = 0;
  79         struct strbuf one, two;
  80         FILE *f = fopen(path, "r");
  81         FILE *out = NULL;
  82
  83         if (!f)
  84                 return error("Could not open %s", path);
  85
  86         if (output) {
  87                 out = fopen(output, "w");
  88                 if (!out) {
  89                         fclose(f);
  90                         return error("Could not write %s", output);
  91                 }
  92         }
  93
  94         if (sha1)
  95                 SHA1_Init(&ctx);
  96
  97         strbuf_init(&one, 0);
  98         strbuf_init(&two,  0);
  99         while (fgets(buf, sizeof(buf), f)) {
 100                 if (!prefixcmp(buf, "<<<<<<< ")) {
 101                         if (hunk)
 102                                 goto bad;
 103                         hunk = 1;
 104                 } else if (!prefixcmp(buf, "=======") && isspace(buf[7])) {
 105                         if (hunk != 1)
 106                                 goto bad;
 107                         hunk = 2;
 108                 } else if (!prefixcmp(buf, ">>>>>>> ")) {
 109                         if (hunk != 2)
 110                                 goto bad;
 111                         if (strbuf_cmp(&one, &two) > 0)
 112                                 strbuf_swap(&one, &two);
 113                         hunk_no++;
 114                         hunk = 0;
 115                         if (out) {
 116                                 fputs("<<<<<<<\n", out);
 117                                 fwrite(one.buf, one.len, 1, out);
 118                                 fputs("=======\n", out);
 119                                 fwrite(two.buf, two.len, 1, out);
 120                                 fputs(">>>>>>>\n", out);
 121                         }
 122                         if (sha1) {
 123                                 SHA1_Update(&ctx, one.buf ? one.buf : "",
 124                                             one.len + 1);
 125                                 SHA1_Update(&ctx, two.buf ? two.buf : "",
 126                                             two.len + 1);
 127                         }
 128                         strbuf_reset(&one);
 129                         strbuf_reset(&two);
 130                 } else if (hunk == 1)
 131                         strbuf_addstr(&one, buf);
 132                 else if (hunk == 2)
 133                         strbuf_addstr(&two, buf);
 134                 else if (out)
 135                         fputs(buf, out);
 136                 continue;
 137         bad:
 138                 hunk = 99; /* force error exit */
 139                 break;
 140         }
 141         strbuf_release(&one);
 142         strbuf_release(&two);
 143
 144         fclose(f);
 145         if (out)
 146                 fclose(out);
 147         if (sha1)
 148                 SHA1_Final(sha1, &ctx);
 149         if (hunk) {
 150                 if (output)
 151                         unlink(output);
 152                 return error("Could not parse conflict hunks in %s", path);
 153         }
 154         return hunk_no;
 155 }
 156
 157 static int find_conflict(struct string_list *conflict)
 158 {
 159         int i;
 160         if (read_cache() < 0)
 161                 return error("Could not read index");
 162         for (i = 0; i+1 < active_nr; i++) {
 163                 struct cache_entry *e2 = active_cache[i];
 164                 struct cache_entry *e3 = active_cache[i+1];
 165                 if (ce_stage(e2) == 2 &&
 166                     ce_stage(e3) == 3 &&
 167                     ce_same_name(e2, e3) &&
 168                     S_ISREG(e2->ce_mode) &&
 169                     S_ISREG(e3->ce_mode)) {
 170                         string_list_insert((const char *)e2->name, conflict);
 171                         i++; /* skip over both #2 and #3 */
 172                 }
 173         }
 174         return 0;
 175 }
 176
 177 static int merge(const char *name, const char *path)
 178 {
 179         int ret;
 180         mmfile_t cur, base, other;
 181         mmbuffer_t result = {NULL, 0};
 182         xpparam_t xpp = {XDF_NEED_MINIMAL};
 183
 184         if (handle_file(path, NULL, rr_path(name, "thisimage")) < 0)
 185                 return 1;
 186
 187         if (read_mmfile(&cur, rr_path(name, "thisimage")) ||
 188                         read_mmfile(&base, rr_path(name, "preimage")) ||
 189                         read_mmfile(&other, rr_path(name, "postimage")))
 190                 return 1;
 191         ret = xdl_merge(&base, &cur, "", &other, "",
 192                         &xpp, XDL_MERGE_ZEALOUS, &result);
 193         if (!ret) {
 194                 FILE *f = fopen(path, "w");
 195                 if (!f)
 196                         return error("Could not write to %s", path);
 197                 fwrite(result.ptr, result.size, 1, f);
 198                 fclose(f);
 199         }
 200
 201         free(cur.ptr);
 202         free(base.ptr);
 203         free(other.ptr);
 204         free(result.ptr);
 205
 206         return ret;
 207 }
 208
 209 static struct lock_file index_lock;
 210
 211 static int update_paths(struct string_list *update)
 212 {
 213         int i;
 214         int fd = hold_locked_index(&index_lock, 0);
 215         int status = 0;
 216
 217         if (fd < 0)
 218                 return -1;
 219
 220         for (i = 0; i < update->nr; i++) {
 221                 struct string_list_item *item = &update->items[i];
 222                 if (add_file_to_cache(item->string, ADD_CACHE_IGNORE_ERRORS))
 223                         status = -1;
 224         }
 225
 226         if (!status && active_cache_changed) {
 227                 if (write_cache(fd, active_cache, active_nr) ||
 228                     commit_locked_index(&index_lock))
 229                         die("Unable to write new index file");
 230         } else if (fd >= 0)
 231                 rollback_lock_file(&index_lock);
 232         return status;
 233 }
 234
 235 static int do_plain_rerere(struct string_list *rr, int fd)
 236 {
 237         struct string_list conflict = { NULL, 0, 0, 1 };
 238         struct string_list update = { NULL, 0, 0, 1 };
 239         int i;
 240
 241         find_conflict(&conflict);
 242
 243         /*
 244          * MERGE_RR records paths with conflicts immediately after merge
 245          * failed.  Some of the conflicted paths might have been hand resolved
 246          * in the working tree since then, but the initial run would catch all
 247          * and register their preimages.
 248          */
 249
 250         for (i = 0; i < conflict.nr; i++) {
 251                 const char *path = conflict.items[i].string;
 252                 if (!string_list_has_string(rr, path)) {
 253                         unsigned char sha1[20];
 254                         char *hex;
 255                         int ret;
 256                         ret = handle_file(path, sha1, NULL);
 257                         if (ret < 1)
 258                                 continue;
 259                         hex = xstrdup(sha1_to_hex(sha1));
 260                         string_list_insert(path, rr)->util = hex;
 261                         if (mkdir(git_path("rr-cache/%s", hex), 0755))
 262                                 continue;;
 263                         handle_file(path, NULL, rr_path(hex, "preimage"));
 264                         fprintf(stderr, "Recorded preimage for '%s'\n", path);
 265                 }
 266         }
 267
 268         /*
 269          * Now some of the paths that had conflicts earlier might have been
 270          * hand resolved.  Others may be similar to a conflict already that
 271          * was resolved before.
 272          */
 273
 274         for (i = 0; i < rr->nr; i++) {
 275                 int ret;
 276                 const char *path = rr->items[i].string;
 277                 const char *name = (const char *)rr->items[i].util;
 278
 279                 if (has_resolution(name)) {
 280                         if (!merge(name, path)) {
 281                                 if (rerere_autoupdate)
 282                                         string_list_insert(path, &update);
 283                                 fprintf(stderr,
 284                                         "%s '%s' using previous resolution.\n",
 285                                         rerere_autoupdate
 286                                         ? "Staged" : "Resolved",
 287                                         path);
 288                                 goto mark_resolved;
 289                         }
 290                 }
 291
 292                 /* Let's see if we have resolved it. */
 293                 ret = handle_file(path, NULL, NULL);
 294                 if (ret)
 295                         continue;
 296
 297                 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
 298                 copy_file(rr_path(name, "postimage"), path, 0666);
 299         mark_resolved:
 300                 rr->items[i].util = NULL;
 301         }
 302
 303         if (update.nr)
 304                 update_paths(&update);
 305
 306         return write_rr(rr, fd);
 307 }
 308
 309 static int git_rerere_config(const char *var, const char *value, void *cb)
 310 {
 311         if (!strcmp(var, "rerere.enabled"))
 312                 rerere_enabled = git_config_bool(var, value);
 313         else if (!strcmp(var, "rerere.autoupdate"))
 314                 rerere_autoupdate = git_config_bool(var, value);
 315         else
 316                 return git_default_config(var, value, cb);
 317         return 0;
 318 }
 319
 320 static int is_rerere_enabled(void)
 321 {
 322         struct stat st;
 323         const char *rr_cache;
 324         int rr_cache_exists;
 325
 326         if (!rerere_enabled)
 327                 return 0;
 328
 329         rr_cache = git_path("rr-cache");
 330         rr_cache_exists = !stat(rr_cache, &st) && S_ISDIR(st.st_mode);
 331         if (rerere_enabled < 0)
 332                 return rr_cache_exists;
 333
 334         if (!rr_cache_exists &&
 335             (mkdir(rr_cache, 0777) || adjust_shared_perm(rr_cache)))
 336                 die("Could not create directory %s", rr_cache);
 337         return 1;
 338 }
 339
 340 int setup_rerere(struct string_list *merge_rr)
 341 {
 342         int fd;
 343
 344         git_config(git_rerere_config, NULL);
 345         if (!is_rerere_enabled())
 346                 return -1;
 347
 348         merge_rr_path = git_pathdup("MERGE_RR");
 349         fd = hold_lock_file_for_update(&write_lock, merge_rr_path,
 350                                        LOCK_DIE_ON_ERROR);
 351         read_rr(merge_rr);
 352         return fd;
 353 }
 354
 355 int rerere(void)
 356 {
 357         struct string_list merge_rr = { NULL, 0, 0, 1 };
 358         int fd;
 359
 360         fd = setup_rerere(&merge_rr);
 361         if (fd < 0)
 362                 return 0;
 363         return do_plain_rerere(&merge_rr, fd);
 364 }