merge-ll.c

   1 /*
   2  * Low level 3-way in-core file merge.
   3  *
   4  * Copyright (c) 2007 Junio C Hamano
   5  */
   6
   7 #define USE_THE_REPOSITORY_VARIABLE
   8 #define DISABLE_SIGN_COMPARE_WARNINGS
   9
  10 #include "git-compat-util.h"
  11 #include "config.h"
  12 #include "convert.h"
  13 #include "attr.h"
  14 #include "xdiff-interface.h"
  15 #include "run-command.h"
  16 #include "merge-ll.h"
  17 #include "quote.h"
  18 #include "strbuf.h"
  19 #include "gettext.h"
  20
  21 struct ll_merge_driver;
  22
  23 typedef enum ll_merge_result (*ll_merge_fn)(const struct ll_merge_driver *,
  24                            mmbuffer_t *result,
  25                            const char *path,
  26                            mmfile_t *orig, const char *orig_name,
  27                            mmfile_t *src1, const char *name1,
  28                            mmfile_t *src2, const char *name2,
  29                            const struct ll_merge_options *opts,
  30                            int marker_size);
  31
  32 struct ll_merge_driver {
  33         const char *name;
  34         const char *description;
  35         ll_merge_fn fn;
  36         char *recursive;
  37         struct ll_merge_driver *next;
  38         char *cmdline;
  39 };
  40
  41 static struct attr_check *merge_attributes;
  42 static struct attr_check *load_merge_attributes(void)
  43 {
  44         if (!merge_attributes)
  45                 merge_attributes = attr_check_initl("merge", "conflict-marker-size", NULL);
  46         return merge_attributes;
  47 }
  48
  49 void reset_merge_attributes(void)
  50 {
  51         attr_check_free(merge_attributes);
  52         merge_attributes = NULL;
  53 }
  54
  55 /*
  56  * Built-in low-levels
  57  */
  58 static enum ll_merge_result ll_binary_merge(const struct ll_merge_driver *drv UNUSED,
  59                            mmbuffer_t *result,
  60                            const char *path UNUSED,
  61                            mmfile_t *orig, const char *orig_name UNUSED,
  62                            mmfile_t *src1, const char *name1 UNUSED,
  63                            mmfile_t *src2, const char *name2 UNUSED,
  64                            const struct ll_merge_options *opts,
  65                            int marker_size UNUSED)
  66 {
  67         enum ll_merge_result ret;
  68         mmfile_t *stolen;
  69         assert(opts);
  70
  71         /*
  72          * The tentative merge result is the common ancestor for an
  73          * internal merge.  For the final merge, it is "ours" by
  74          * default but -Xours/-Xtheirs can tweak the choice.
  75          */
  76         if (opts->virtual_ancestor) {
  77                 stolen = orig;
  78                 ret = LL_MERGE_OK;
  79         } else {
  80                 switch (opts->variant) {
  81                 default:
  82                         ret = LL_MERGE_BINARY_CONFLICT;
  83                         stolen = src1;
  84                         break;
  85                 case XDL_MERGE_FAVOR_OURS:
  86                         ret = LL_MERGE_OK;
  87                         stolen = src1;
  88                         break;
  89                 case XDL_MERGE_FAVOR_THEIRS:
  90                         ret = LL_MERGE_OK;
  91                         stolen = src2;
  92                         break;
  93                 }
  94         }
  95
  96         result->ptr = stolen->ptr;
  97         result->size = stolen->size;
  98         stolen->ptr = NULL;
  99
 100         return ret;
 101 }
 102
 103 static enum ll_merge_result ll_xdl_merge(const struct ll_merge_driver *drv_unused,
 104                         mmbuffer_t *result,
 105                         const char *path,
 106                         mmfile_t *orig, const char *orig_name,
 107                         mmfile_t *src1, const char *name1,
 108                         mmfile_t *src2, const char *name2,
 109                         const struct ll_merge_options *opts,
 110                         int marker_size)
 111 {
 112         enum ll_merge_result ret;
 113         xmparam_t xmp;
 114         int status;
 115         assert(opts);
 116
 117         if (orig->size > MAX_XDIFF_SIZE ||
 118             src1->size > MAX_XDIFF_SIZE ||
 119             src2->size > MAX_XDIFF_SIZE ||
 120             buffer_is_binary(orig->ptr, orig->size) ||
 121             buffer_is_binary(src1->ptr, src1->size) ||
 122             buffer_is_binary(src2->ptr, src2->size)) {
 123                 return ll_binary_merge(drv_unused, result,
 124                                        path,
 125                                        orig, orig_name,
 126                                        src1, name1,
 127                                        src2, name2,
 128                                        opts, marker_size);
 129         }
 130
 131         memset(&xmp, 0, sizeof(xmp));
 132         xmp.level = XDL_MERGE_ZEALOUS;
 133         xmp.favor = opts->variant;
 134         xmp.xpp.flags = opts->xdl_opts;
 135         if (opts->conflict_style >= 0)
 136                 xmp.style = opts->conflict_style;
 137         else if (git_xmerge_style >= 0)
 138                 xmp.style = git_xmerge_style;
 139         if (marker_size > 0)
 140                 xmp.marker_size = marker_size;
 141         xmp.ancestor = orig_name;
 142         xmp.file1 = name1;
 143         xmp.file2 = name2;
 144         status = xdl_merge(orig, src1, src2, &xmp, result);
 145         ret = (status > 0) ? LL_MERGE_CONFLICT : status;
 146         return ret;
 147 }
 148
 149 static enum ll_merge_result ll_union_merge(const struct ll_merge_driver *drv_unused,
 150                           mmbuffer_t *result,
 151                           const char *path,
 152                           mmfile_t *orig, const char *orig_name,
 153                           mmfile_t *src1, const char *name1,
 154                           mmfile_t *src2, const char *name2,
 155                           const struct ll_merge_options *opts,
 156                           int marker_size)
 157 {
 158         /* Use union favor */
 159         struct ll_merge_options o;
 160         assert(opts);
 161         o = *opts;
 162         o.variant = XDL_MERGE_FAVOR_UNION;
 163         return ll_xdl_merge(drv_unused, result, path,
 164                             orig, orig_name, src1, name1, src2, name2,
 165                             &o, marker_size);
 166 }
 167
 168 #define LL_BINARY_MERGE 0
 169 #define LL_TEXT_MERGE 1
 170 #define LL_UNION_MERGE 2
 171 static struct ll_merge_driver ll_merge_drv[] = {
 172         { "binary", "built-in binary merge", ll_binary_merge },
 173         { "text", "built-in 3-way text merge", ll_xdl_merge },
 174         { "union", "built-in union merge", ll_union_merge },
 175 };
 176
 177 static void create_temp(mmfile_t *src, char *path, size_t len)
 178 {
 179         int fd;
 180
 181         xsnprintf(path, len, ".merge_file_XXXXXX");
 182         fd = xmkstemp(path);
 183         if (write_in_full(fd, src->ptr, src->size) < 0)
 184                 die_errno("unable to write temp-file");
 185         close(fd);
 186 }
 187
 188 /*
 189  * User defined low-level merge driver support.
 190  */
 191 static enum ll_merge_result ll_ext_merge(const struct ll_merge_driver *fn,
 192                         mmbuffer_t *result,
 193                         const char *path,
 194                         mmfile_t *orig, const char *orig_name,
 195                         mmfile_t *src1, const char *name1,
 196                         mmfile_t *src2, const char *name2,
 197                         const struct ll_merge_options *opts,
 198                         int marker_size)
 199 {
 200         char temp[3][50];
 201         struct strbuf cmd = STRBUF_INIT;
 202         const char *format = fn->cmdline;
 203         struct child_process child = CHILD_PROCESS_INIT;
 204         int status, fd, i;
 205         struct stat st;
 206         enum ll_merge_result ret;
 207         assert(opts);
 208
 209         if (!fn->cmdline)
 210                 die("custom merge driver %s lacks command line.", fn->name);
 211
 212         result->ptr = NULL;
 213         result->size = 0;
 214         create_temp(orig, temp[0], sizeof(temp[0]));
 215         create_temp(src1, temp[1], sizeof(temp[1]));
 216         create_temp(src2, temp[2], sizeof(temp[2]));
 217
 218         while (strbuf_expand_step(&cmd, &format)) {
 219                 if (skip_prefix(format, "%", &format))
 220                         strbuf_addch(&cmd, '%');
 221                 else if (skip_prefix(format, "O", &format))
 222                         strbuf_addstr(&cmd, temp[0]);
 223                 else if (skip_prefix(format, "A", &format))
 224                         strbuf_addstr(&cmd, temp[1]);
 225                 else if (skip_prefix(format, "B", &format))
 226                         strbuf_addstr(&cmd, temp[2]);
 227                 else if (skip_prefix(format, "L", &format))
 228                         strbuf_addf(&cmd, "%d", marker_size);
 229                 else if (skip_prefix(format, "P", &format))
 230                         sq_quote_buf(&cmd, path);
 231                 else if (skip_prefix(format, "S", &format))
 232                         sq_quote_buf(&cmd, orig_name ? orig_name : "");
 233                 else if (skip_prefix(format, "X", &format))
 234                         sq_quote_buf(&cmd, name1 ? name1 : "");
 235                 else if (skip_prefix(format, "Y", &format))
 236                         sq_quote_buf(&cmd, name2 ? name2 : "");
 237                 else
 238                         strbuf_addch(&cmd, '%');
 239         }
 240
 241         child.use_shell = 1;
 242         strvec_push(&child.args, cmd.buf);
 243         status = run_command(&child);
 244         fd = open(temp[1], O_RDONLY);
 245         if (fd < 0)
 246                 goto bad;
 247         if (fstat(fd, &st))
 248                 goto close_bad;
 249         result->size = st.st_size;
 250         result->ptr = xmallocz(result->size);
 251         if (read_in_full(fd, result->ptr, result->size) != result->size) {
 252                 FREE_AND_NULL(result->ptr);
 253                 result->size = 0;
 254         }
 255  close_bad:
 256         close(fd);
 257  bad:
 258         for (i = 0; i < 3; i++)
 259                 unlink_or_warn(temp[i]);
 260         strbuf_release(&cmd);
 261         if (!status)
 262                 ret = LL_MERGE_OK;
 263         else if (status <= 128)
 264                 ret = LL_MERGE_CONFLICT;
 265         else
 266                 /* died due to a signal: WTERMSIG(status) + 128 */
 267                 ret = LL_MERGE_ERROR;
 268         return ret;
 269 }
 270
 271 /*
 272  * merge.default and merge.driver configuration items
 273  */
 274 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 275 static char *default_ll_merge;
 276
 277 static int read_merge_config(const char *var, const char *value,
 278                              const struct config_context *ctx UNUSED,
 279                              void *cb UNUSED)
 280 {
 281         struct ll_merge_driver *fn;
 282         const char *key, *name;
 283         size_t namelen;
 284
 285         if (!strcmp(var, "merge.default"))
 286                 return git_config_string(&default_ll_merge, var, value);
 287
 288         /*
 289          * We are not interested in anything but "merge.<name>.variable";
 290          * especially, we do not want to look at variables such as
 291          * "merge.summary", "merge.tool", and "merge.verbosity".
 292          */
 293         if (parse_config_key(var, "merge", &name, &namelen, &key) < 0 || !name)
 294                 return 0;
 295
 296         /*
 297          * Find existing one as we might be processing merge.<name>.var2
 298          * after seeing merge.<name>.var1.
 299          */
 300         for (fn = ll_user_merge; fn; fn = fn->next)
 301                 if (!xstrncmpz(fn->name, name, namelen))
 302                         break;
 303         if (!fn) {
 304                 CALLOC_ARRAY(fn, 1);
 305                 fn->name = xmemdupz(name, namelen);
 306                 fn->fn = ll_ext_merge;
 307                 *ll_user_merge_tail = fn;
 308                 ll_user_merge_tail = &(fn->next);
 309         }
 310
 311         if (!strcmp("name", key)) {
 312                 /*
 313                  * The description is leaking, but that's okay as we want to
 314                  * keep around the merge drivers anyway.
 315                  */
 316                 return git_config_string((char **) &fn->description, var, value);
 317         }
 318
 319         if (!strcmp("driver", key)) {
 320                 if (!value)
 321                         return config_error_nonbool(var);
 322                 /*
 323                  * merge.<name>.driver specifies the command line:
 324                  *
 325                  *      command-line
 326                  *
 327                  * The command-line will be interpolated with the following
 328                  * tokens and is given to the shell:
 329                  *
 330                  *    %O - temporary file name for the merge base.
 331                  *    %A - temporary file name for our version.
 332                  *    %B - temporary file name for the other branches' version.
 333                  *    %L - conflict marker length
 334                  *    %P - the original path (safely quoted for the shell)
 335                  *    %S - the revision for the merge base
 336                  *    %X - the revision for our version
 337                  *    %Y - the revision for their version
 338                  *
 339                  * If the file is not named identically in all versions, then each
 340                  * revision is joined with the corresponding path, separated by a colon.
 341                  * The external merge driver should write the results in the
 342                  * file named by %A, and signal that it has done with zero exit
 343                  * status.
 344                  */
 345                 fn->cmdline = xstrdup(value);
 346                 return 0;
 347         }
 348
 349         if (!strcmp("recursive", key))
 350                 return git_config_string(&fn->recursive, var, value);
 351
 352         return 0;
 353 }
 354
 355 static void initialize_ll_merge(void)
 356 {
 357         if (ll_user_merge_tail)
 358                 return;
 359         ll_user_merge_tail = &ll_user_merge;
 360         git_config(read_merge_config, NULL);
 361 }
 362
 363 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 364 {
 365         struct ll_merge_driver *fn;
 366         const char *name;
 367         int i;
 368
 369         initialize_ll_merge();
 370
 371         if (ATTR_TRUE(merge_attr))
 372                 return &ll_merge_drv[LL_TEXT_MERGE];
 373         else if (ATTR_FALSE(merge_attr))
 374                 return &ll_merge_drv[LL_BINARY_MERGE];
 375         else if (ATTR_UNSET(merge_attr)) {
 376                 if (!default_ll_merge)
 377                         return &ll_merge_drv[LL_TEXT_MERGE];
 378                 else
 379                         name = default_ll_merge;
 380         }
 381         else
 382                 name = merge_attr;
 383
 384         for (fn = ll_user_merge; fn; fn = fn->next)
 385                 if (!strcmp(fn->name, name))
 386                         return fn;
 387
 388         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 389                 if (!strcmp(ll_merge_drv[i].name, name))
 390                         return &ll_merge_drv[i];
 391
 392         /* default to the 3-way */
 393         return &ll_merge_drv[LL_TEXT_MERGE];
 394 }
 395
 396 static void normalize_file(mmfile_t *mm, const char *path, struct index_state *istate)
 397 {
 398         struct strbuf strbuf = STRBUF_INIT;
 399         if (renormalize_buffer(istate, path, mm->ptr, mm->size, &strbuf)) {
 400                 free(mm->ptr);
 401                 mm->size = strbuf.len;
 402                 mm->ptr = strbuf_detach(&strbuf, NULL);
 403         }
 404 }
 405
 406 enum ll_merge_result ll_merge(mmbuffer_t *result_buf,
 407              const char *path,
 408              mmfile_t *ancestor, const char *ancestor_label,
 409              mmfile_t *ours, const char *our_label,
 410              mmfile_t *theirs, const char *their_label,
 411              struct index_state *istate,
 412              const struct ll_merge_options *opts)
 413 {
 414         struct attr_check *check = load_merge_attributes();
 415         static const struct ll_merge_options default_opts = LL_MERGE_OPTIONS_INIT;
 416         const char *ll_driver_name = NULL;
 417         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 418         const struct ll_merge_driver *driver;
 419
 420         if (!opts)
 421                 opts = &default_opts;
 422
 423         if (opts->renormalize) {
 424                 normalize_file(ancestor, path, istate);
 425                 normalize_file(ours, path, istate);
 426                 normalize_file(theirs, path, istate);
 427         }
 428
 429         git_check_attr(istate, path, check);
 430         ll_driver_name = check->items[0].value;
 431         if (check->items[1].value) {
 432                 if (strtol_i(check->items[1].value, 10, &marker_size)) {
 433                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 434                         warning(_("invalid marker-size '%s', expecting an integer"), check->items[1].value);
 435                 }
 436                 if (marker_size <= 0)
 437                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 438         }
 439         driver = find_ll_merge_driver(ll_driver_name);
 440
 441         if (opts->virtual_ancestor) {
 442                 if (driver->recursive)
 443                         driver = find_ll_merge_driver(driver->recursive);
 444         }
 445         if (opts->extra_marker_size) {
 446                 marker_size += opts->extra_marker_size;
 447         }
 448         return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
 449                           ours, our_label, theirs, their_label,
 450                           opts, marker_size);
 451 }
 452
 453 int ll_merge_marker_size(struct index_state *istate, const char *path)
 454 {
 455         static struct attr_check *check;
 456         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 457
 458         if (!check)
 459                 check = attr_check_initl("conflict-marker-size", NULL);
 460         git_check_attr(istate, path, check);
 461         if (check->items[0].value) {
 462                 if (strtol_i(check->items[0].value, 10, &marker_size)) {
 463                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 464                         warning(_("invalid marker-size '%s', expecting an integer"), check->items[0].value);
 465                 }
 466                 if (marker_size <= 0)
 467                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 468         }
 469         return marker_size;
 470 }