ll-merge.c

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