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