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