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, two;
  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         strbuf_init(&one, 0);
 101         strbuf_init(&two,  0);
 102         while (fgets(buf, sizeof(buf), f)) {
 103                 if (!prefixcmp(buf, "<<<<<<< ")) {
 104                         if (hunk != RR_CONTEXT)
 105                                 goto bad;
 106                         hunk = RR_SIDE_1;
 107                 } else if (!prefixcmp(buf, "|||||||") && isspace(buf[7])) {
 108                         if (hunk != RR_SIDE_1)
 109                                 goto bad;
 110                         hunk = RR_ORIGINAL;
 111                 } else if (!prefixcmp(buf, "=======") && isspace(buf[7])) {
 112                         if (hunk != RR_SIDE_1 && hunk != RR_ORIGINAL)
 113                                 goto bad;
 114                         hunk = RR_SIDE_2;
 115                 } else if (!prefixcmp(buf, ">>>>>>> ")) {
 116                         if (hunk != RR_SIDE_2)
 117                                 goto bad;
 118                         if (strbuf_cmp(&one, &two) > 0)
 119                                 strbuf_swap(&one, &two);
 120                         hunk_no++;
 121                         hunk = RR_CONTEXT;
 122                         if (out) {
 123                                 fputs("<<<<<<<\n", out);
 124                                 fwrite(one.buf, one.len, 1, out);
 125                                 fputs("=======\n", out);
 126                                 fwrite(two.buf, two.len, 1, out);
 127                                 fputs(">>>>>>>\n", out);
 128                         }
 129                         if (sha1) {
 130                                 git_SHA1_Update(&ctx, one.buf ? one.buf : "",
 131                                             one.len + 1);
 132                                 git_SHA1_Update(&ctx, two.buf ? two.buf : "",
 133                                             two.len + 1);
 134                         }
 135                         strbuf_reset(&one);
 136                         strbuf_reset(&two);
 137                 } else if (hunk == RR_SIDE_1)
 138                         strbuf_addstr(&one, buf);
 139                 else if (hunk == RR_ORIGINAL)
 140                         ; /* discard */
 141                 else if (hunk == RR_SIDE_2)
 142                         strbuf_addstr(&two, buf);
 143                 else if (out)
 144                         fputs(buf, out);
 145                 continue;
 146         bad:
 147                 hunk = 99; /* force error exit */
 148                 break;
 149         }
 150         strbuf_release(&one);
 151         strbuf_release(&two);
 152
 153         fclose(f);
 154         if (out)
 155                 fclose(out);
 156         if (sha1)
 157                 git_SHA1_Final(sha1, &ctx);
 158         if (hunk != RR_CONTEXT) {
 159                 if (output)
 160                         unlink(output);
 161                 return error("Could not parse conflict hunks in %s", path);
 162         }
 163         return hunk_no;
 164 }
 165
 166 static int find_conflict(struct string_list *conflict)
 167 {
 168         int i;
 169         if (read_cache() < 0)
 170                 return error("Could not read index");
 171         for (i = 0; i+1 < active_nr; i++) {
 172                 struct cache_entry *e2 = active_cache[i];
 173                 struct cache_entry *e3 = active_cache[i+1];
 174                 if (ce_stage(e2) == 2 &&
 175                     ce_stage(e3) == 3 &&
 176                     ce_same_name(e2, e3) &&
 177                     S_ISREG(e2->ce_mode) &&
 178                     S_ISREG(e3->ce_mode)) {
 179                         string_list_insert((const char *)e2->name, conflict);
 180                         i++; /* skip over both #2 and #3 */
 181                 }
 182         }
 183         return 0;
 184 }
 185
 186 static int merge(const char *name, const char *path)
 187 {
 188         int ret;
 189         mmfile_t cur, base, other;
 190         mmbuffer_t result = {NULL, 0};
 191         xpparam_t xpp = {XDF_NEED_MINIMAL};
 192
 193         if (handle_file(path, NULL, rr_path(name, "thisimage")) < 0)
 194                 return 1;
 195
 196         if (read_mmfile(&cur, rr_path(name, "thisimage")) ||
 197                         read_mmfile(&base, rr_path(name, "preimage")) ||
 198                         read_mmfile(&other, rr_path(name, "postimage")))
 199                 return 1;
 200         ret = xdl_merge(&base, &cur, "", &other, "",
 201                         &xpp, XDL_MERGE_ZEALOUS, &result);
 202         if (!ret) {
 203                 FILE *f = fopen(path, "w");
 204                 if (!f)
 205                         return error("Could not write to %s", path);
 206                 fwrite(result.ptr, result.size, 1, f);
 207                 fclose(f);
 208         }
 209
 210         free(cur.ptr);
 211         free(base.ptr);
 212         free(other.ptr);
 213         free(result.ptr);
 214
 215         return ret;
 216 }
 217
 218 static struct lock_file index_lock;
 219
 220 static int update_paths(struct string_list *update)
 221 {
 222         int i;
 223         int fd = hold_locked_index(&index_lock, 0);
 224         int status = 0;
 225
 226         if (fd < 0)
 227                 return -1;
 228
 229         for (i = 0; i < update->nr; i++) {
 230                 struct string_list_item *item = &update->items[i];
 231                 if (add_file_to_cache(item->string, ADD_CACHE_IGNORE_ERRORS))
 232                         status = -1;
 233         }
 234
 235         if (!status && active_cache_changed) {
 236                 if (write_cache(fd, active_cache, active_nr) ||
 237                     commit_locked_index(&index_lock))
 238                         die("Unable to write new index file");
 239         } else if (fd >= 0)
 240                 rollback_lock_file(&index_lock);
 241         return status;
 242 }
 243
 244 static int do_plain_rerere(struct string_list *rr, int fd)
 245 {
 246         struct string_list conflict = { NULL, 0, 0, 1 };
 247         struct string_list update = { NULL, 0, 0, 1 };
 248         int i;
 249
 250         find_conflict(&conflict);
 251
 252         /*
 253          * MERGE_RR records paths with conflicts immediately after merge
 254          * failed.  Some of the conflicted paths might have been hand resolved
 255          * in the working tree since then, but the initial run would catch all
 256          * and register their preimages.
 257          */
 258
 259         for (i = 0; i < conflict.nr; i++) {
 260                 const char *path = conflict.items[i].string;
 261                 if (!string_list_has_string(rr, path)) {
 262                         unsigned char sha1[20];
 263                         char *hex;
 264                         int ret;
 265                         ret = handle_file(path, sha1, NULL);
 266                         if (ret < 1)
 267                                 continue;
 268                         hex = xstrdup(sha1_to_hex(sha1));
 269                         string_list_insert(path, rr)->util = hex;
 270                         if (mkdir(git_path("rr-cache/%s", hex), 0755))
 271                                 continue;;
 272                         handle_file(path, NULL, rr_path(hex, "preimage"));
 273                         fprintf(stderr, "Recorded preimage for '%s'\n", path);
 274                 }
 275         }
 276
 277         /*
 278          * Now some of the paths that had conflicts earlier might have been
 279          * hand resolved.  Others may be similar to a conflict already that
 280          * was resolved before.
 281          */
 282
 283         for (i = 0; i < rr->nr; i++) {
 284                 int ret;
 285                 const char *path = rr->items[i].string;
 286                 const char *name = (const char *)rr->items[i].util;
 287
 288                 if (has_resolution(name)) {
 289                         if (!merge(name, path)) {
 290                                 if (rerere_autoupdate)
 291                                         string_list_insert(path, &update);
 292                                 fprintf(stderr,
 293                                         "%s '%s' using previous resolution.\n",
 294                                         rerere_autoupdate
 295                                         ? "Staged" : "Resolved",
 296                                         path);
 297                                 goto mark_resolved;
 298                         }
 299                 }
 300
 301                 /* Let's see if we have resolved it. */
 302                 ret = handle_file(path, NULL, NULL);
 303                 if (ret)
 304                         continue;
 305
 306                 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
 307                 copy_file(rr_path(name, "postimage"), path, 0666);
 308         mark_resolved:
 309                 rr->items[i].util = NULL;
 310         }
 311
 312         if (update.nr)
 313                 update_paths(&update);
 314
 315         return write_rr(rr, fd);
 316 }
 317
 318 static int git_rerere_config(const char *var, const char *value, void *cb)
 319 {
 320         if (!strcmp(var, "rerere.enabled"))
 321                 rerere_enabled = git_config_bool(var, value);
 322         else if (!strcmp(var, "rerere.autoupdate"))
 323                 rerere_autoupdate = git_config_bool(var, value);
 324         else
 325                 return git_default_config(var, value, cb);
 326         return 0;
 327 }
 328
 329 static int is_rerere_enabled(void)
 330 {
 331         const char *rr_cache;
 332         int rr_cache_exists;
 333
 334         if (!rerere_enabled)
 335                 return 0;
 336
 337         rr_cache = git_path("rr-cache");
 338         rr_cache_exists = is_directory(rr_cache);
 339         if (rerere_enabled < 0)
 340                 return rr_cache_exists;
 341
 342         if (!rr_cache_exists &&
 343             (mkdir(rr_cache, 0777) || adjust_shared_perm(rr_cache)))
 344                 die("Could not create directory %s", rr_cache);
 345         return 1;
 346 }
 347
 348 int setup_rerere(struct string_list *merge_rr)
 349 {
 350         int fd;
 351
 352         git_config(git_rerere_config, NULL);
 353         if (!is_rerere_enabled())
 354                 return -1;
 355
 356         merge_rr_path = xstrdup(git_path("MERGE_RR"));
 357         fd = hold_lock_file_for_update(&write_lock, merge_rr_path, 1);
 358         read_rr(merge_rr);
 359         return fd;
 360 }
 361
 362 int rerere(void)
 363 {
 364         struct string_list merge_rr = { NULL, 0, 0, 1 };
 365         int fd;
 366
 367         fd = setup_rerere(&merge_rr);
 368         if (fd < 0)
 369                 return 0;
 370         return do_plain_rerere(&merge_rr, fd);
 371 }