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         git_SHA_CTX ctx;
  77         char buf[1024];
  78         int hunk_no = 0;
  79         enum {
  80                 RR_CONTEXT = 0, RR_SIDE_1, RR_SIDE_2, RR_ORIGINAL,
  81         } hunk = RR_CONTEXT;
  82         struct strbuf one = STRBUF_INIT, two = STRBUF_INIT;
  83         FILE *f = fopen(path, "r");
  84         FILE *out = NULL;
  85
  86         if (!f)
  87                 return error("Could not open %s", path);
  88
  89         if (output) {
  90                 out = fopen(output, "w");
  91                 if (!out) {
  92                         fclose(f);
  93                         return error("Could not write %s", output);
  94                 }
  95         }
  96
  97         if (sha1)
  98                 git_SHA1_Init(&ctx);
  99
 100         while (fgets(buf, sizeof(buf), f)) {
 101                 if (!prefixcmp(buf, "<<<<<<< ")) {
 102                         if (hunk != RR_CONTEXT)
 103                                 goto bad;
 104                         hunk = RR_SIDE_1;
 105                 } else if (!prefixcmp(buf, "|||||||") && isspace(buf[7])) {
 106                         if (hunk != RR_SIDE_1)
 107                                 goto bad;
 108                         hunk = RR_ORIGINAL;
 109                 } else if (!prefixcmp(buf, "=======") && isspace(buf[7])) {
 110                         if (hunk != RR_SIDE_1 && hunk != RR_ORIGINAL)
 111                                 goto bad;
 112                         hunk = RR_SIDE_2;
 113                 } else if (!prefixcmp(buf, ">>>>>>> ")) {
 114                         if (hunk != RR_SIDE_2)
 115                                 goto bad;
 116                         if (strbuf_cmp(&one, &two) > 0)
 117                                 strbuf_swap(&one, &two);
 118                         hunk_no++;
 119                         hunk = RR_CONTEXT;
 120                         if (out) {
 121                                 fputs("<<<<<<<\n", out);
 122                                 fwrite(one.buf, one.len, 1, out);
 123                                 fputs("=======\n", out);
 124                                 fwrite(two.buf, two.len, 1, out);
 125                                 fputs(">>>>>>>\n", out);
 126                         }
 127                         if (sha1) {
 128                                 git_SHA1_Update(&ctx, one.buf ? one.buf : "",
 129                                             one.len + 1);
 130                                 git_SHA1_Update(&ctx, two.buf ? two.buf : "",
 131                                             two.len + 1);
 132                         }
 133                         strbuf_reset(&one);
 134                         strbuf_reset(&two);
 135                 } else if (hunk == RR_SIDE_1)
 136                         strbuf_addstr(&one, buf);
 137                 else if (hunk == RR_ORIGINAL)
 138                         ; /* discard */
 139                 else if (hunk == RR_SIDE_2)
 140                         strbuf_addstr(&two, buf);
 141                 else if (out)
 142                         fputs(buf, out);
 143                 continue;
 144         bad:
 145                 hunk = 99; /* force error exit */
 146                 break;
 147         }
 148         strbuf_release(&one);
 149         strbuf_release(&two);
 150
 151         fclose(f);
 152         if (out)
 153                 fclose(out);
 154         if (sha1)
 155                 git_SHA1_Final(sha1, &ctx);
 156         if (hunk != RR_CONTEXT) {
 157                 if (output)
 158                         unlink(output);
 159                 return error("Could not parse conflict hunks in %s", path);
 160         }
 161         return hunk_no;
 162 }
 163
 164 static int find_conflict(struct string_list *conflict)
 165 {
 166         int i;
 167         if (read_cache() < 0)
 168                 return error("Could not read index");
 169         for (i = 0; i+1 < active_nr; i++) {
 170                 struct cache_entry *e2 = active_cache[i];
 171                 struct cache_entry *e3 = active_cache[i+1];
 172                 if (ce_stage(e2) == 2 &&
 173                     ce_stage(e3) == 3 &&
 174                     ce_same_name(e2, e3) &&
 175                     S_ISREG(e2->ce_mode) &&
 176                     S_ISREG(e3->ce_mode)) {
 177                         string_list_insert((const char *)e2->name, conflict);
 178                         i++; /* skip over both #2 and #3 */
 179                 }
 180         }
 181         return 0;
 182 }
 183
 184 static int merge(const char *name, const char *path)
 185 {
 186         int ret;
 187         mmfile_t cur, base, other;
 188         mmbuffer_t result = {NULL, 0};
 189         xpparam_t xpp = {XDF_NEED_MINIMAL};
 190
 191         if (handle_file(path, NULL, rr_path(name, "thisimage")) < 0)
 192                 return 1;
 193
 194         if (read_mmfile(&cur, rr_path(name, "thisimage")) ||
 195                         read_mmfile(&base, rr_path(name, "preimage")) ||
 196                         read_mmfile(&other, rr_path(name, "postimage")))
 197                 return 1;
 198         ret = xdl_merge(&base, &cur, "", &other, "",
 199                         &xpp, XDL_MERGE_ZEALOUS, &result);
 200         if (!ret) {
 201                 FILE *f = fopen(path, "w");
 202                 if (!f)
 203                         return error("Could not write to %s", path);
 204                 fwrite(result.ptr, result.size, 1, f);
 205                 fclose(f);
 206         }
 207
 208         free(cur.ptr);
 209         free(base.ptr);
 210         free(other.ptr);
 211         free(result.ptr);
 212
 213         return ret;
 214 }
 215
 216 static struct lock_file index_lock;
 217
 218 static int update_paths(struct string_list *update)
 219 {
 220         int i;
 221         int fd = hold_locked_index(&index_lock, 0);
 222         int status = 0;
 223
 224         if (fd < 0)
 225                 return -1;
 226
 227         for (i = 0; i < update->nr; i++) {
 228                 struct string_list_item *item = &update->items[i];
 229                 if (add_file_to_cache(item->string, ADD_CACHE_IGNORE_ERRORS))
 230                         status = -1;
 231         }
 232
 233         if (!status && active_cache_changed) {
 234                 if (write_cache(fd, active_cache, active_nr) ||
 235                     commit_locked_index(&index_lock))
 236                         die("Unable to write new index file");
 237         } else if (fd >= 0)
 238                 rollback_lock_file(&index_lock);
 239         return status;
 240 }
 241
 242 static int do_plain_rerere(struct string_list *rr, int fd)
 243 {
 244         struct string_list conflict = { NULL, 0, 0, 1 };
 245         struct string_list update = { NULL, 0, 0, 1 };
 246         int i;
 247
 248         find_conflict(&conflict);
 249
 250         /*
 251          * MERGE_RR records paths with conflicts immediately after merge
 252          * failed.  Some of the conflicted paths might have been hand resolved
 253          * in the working tree since then, but the initial run would catch all
 254          * and register their preimages.
 255          */
 256
 257         for (i = 0; i < conflict.nr; i++) {
 258                 const char *path = conflict.items[i].string;
 259                 if (!string_list_has_string(rr, path)) {
 260                         unsigned char sha1[20];
 261                         char *hex;
 262                         int ret;
 263                         ret = handle_file(path, sha1, NULL);
 264                         if (ret < 1)
 265                                 continue;
 266                         hex = xstrdup(sha1_to_hex(sha1));
 267                         string_list_insert(path, rr)->util = hex;
 268                         if (mkdir(git_path("rr-cache/%s", hex), 0755))
 269                                 continue;;
 270                         handle_file(path, NULL, rr_path(hex, "preimage"));
 271                         fprintf(stderr, "Recorded preimage for '%s'\n", path);
 272                 }
 273         }
 274
 275         /*
 276          * Now some of the paths that had conflicts earlier might have been
 277          * hand resolved.  Others may be similar to a conflict already that
 278          * was resolved before.
 279          */
 280
 281         for (i = 0; i < rr->nr; i++) {
 282                 int ret;
 283                 const char *path = rr->items[i].string;
 284                 const char *name = (const char *)rr->items[i].util;
 285
 286                 if (has_resolution(name)) {
 287                         if (!merge(name, path)) {
 288                                 if (rerere_autoupdate)
 289                                         string_list_insert(path, &update);
 290                                 fprintf(stderr,
 291                                         "%s '%s' using previous resolution.\n",
 292                                         rerere_autoupdate
 293                                         ? "Staged" : "Resolved",
 294                                         path);
 295                                 goto mark_resolved;
 296                         }
 297                 }
 298
 299                 /* Let's see if we have resolved it. */
 300                 ret = handle_file(path, NULL, NULL);
 301                 if (ret)
 302                         continue;
 303
 304                 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
 305                 copy_file(rr_path(name, "postimage"), path, 0666);
 306         mark_resolved:
 307                 rr->items[i].util = NULL;
 308         }
 309
 310         if (update.nr)
 311                 update_paths(&update);
 312
 313         return write_rr(rr, fd);
 314 }
 315
 316 static int git_rerere_config(const char *var, const char *value, void *cb)
 317 {
 318         if (!strcmp(var, "rerere.enabled"))
 319                 rerere_enabled = git_config_bool(var, value);
 320         else if (!strcmp(var, "rerere.autoupdate"))
 321                 rerere_autoupdate = git_config_bool(var, value);
 322         else
 323                 return git_default_config(var, value, cb);
 324         return 0;
 325 }
 326
 327 static int is_rerere_enabled(void)
 328 {
 329         const char *rr_cache;
 330         int rr_cache_exists;
 331
 332         if (!rerere_enabled)
 333                 return 0;
 334
 335         rr_cache = git_path("rr-cache");
 336         rr_cache_exists = is_directory(rr_cache);
 337         if (rerere_enabled < 0)
 338                 return rr_cache_exists;
 339
 340         if (!rr_cache_exists &&
 341             (mkdir(rr_cache, 0777) || adjust_shared_perm(rr_cache)))
 342                 die("Could not create directory %s", rr_cache);
 343         return 1;
 344 }
 345
 346 int setup_rerere(struct string_list *merge_rr)
 347 {
 348         int fd;
 349
 350         git_config(git_rerere_config, NULL);
 351         if (!is_rerere_enabled())
 352                 return -1;
 353
 354         merge_rr_path = git_pathdup("MERGE_RR");
 355         fd = hold_lock_file_for_update(&write_lock, merge_rr_path,
 356                                        LOCK_DIE_ON_ERROR);
 357         read_rr(merge_rr);
 358         return fd;
 359 }
 360
 361 int rerere(void)
 362 {
 363         struct string_list merge_rr = { NULL, 0, 0, 1 };
 364         int fd;
 365
 366         fd = setup_rerere(&merge_rr);
 367         if (fd < 0)
 368                 return 0;
 369         return do_plain_rerere(&merge_rr, fd);
 370 }