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