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