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 the or common ancestor for an internal merge.
  50          */
  51         if (opts->virtual_ancestor) {
  52                 stolen = orig;
  53         } else {
  54                 switch (opts->variant) {
  55                 default:
  56                 case XDL_MERGE_FAVOR_OURS:
  57                         stolen = src1;
  58                         break;
  59                 case XDL_MERGE_FAVOR_THEIRS:
  60                         stolen = src2;
  61                         break;
  62                 }
  63         }
  64
  65         result->ptr = stolen->ptr;
  66         result->size = stolen->size;
  67         stolen->ptr = NULL;
  68
  69         /*
  70          * With -Xtheirs or -Xours, we have cleanly merged;
  71          * otherwise we got a conflict.
  72          */
  73         return (opts->variant ? 0 : 1);
  74 }
  75
  76 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
  77                         mmbuffer_t *result,
  78                         const char *path,
  79                         mmfile_t *orig, const char *orig_name,
  80                         mmfile_t *src1, const char *name1,
  81                         mmfile_t *src2, const char *name2,
  82                         const struct ll_merge_options *opts,
  83                         int marker_size)
  84 {
  85         xmparam_t xmp;
  86         assert(opts);
  87
  88         if (buffer_is_binary(orig->ptr, orig->size) ||
  89             buffer_is_binary(src1->ptr, src1->size) ||
  90             buffer_is_binary(src2->ptr, src2->size)) {
  91                 warning("Cannot merge binary files: %s (%s vs. %s)\n",
  92                         path, name1, name2);
  93                 return ll_binary_merge(drv_unused, result,
  94                                        path,
  95                                        orig, orig_name,
  96                                        src1, name1,
  97                                        src2, name2,
  98                                        opts, marker_size);
  99         }
 100
 101         memset(&xmp, 0, sizeof(xmp));
 102         xmp.level = XDL_MERGE_ZEALOUS;
 103         xmp.favor = opts->variant;
 104         xmp.xpp.flags = opts->xdl_opts;
 105         if (git_xmerge_style >= 0)
 106                 xmp.style = git_xmerge_style;
 107         if (marker_size > 0)
 108                 xmp.marker_size = marker_size;
 109         xmp.ancestor = orig_name;
 110         xmp.file1 = name1;
 111         xmp.file2 = name2;
 112         return xdl_merge(orig, src1, src2, &xmp, result);
 113 }
 114
 115 static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 116                           mmbuffer_t *result,
 117                           const char *path_unused,
 118                           mmfile_t *orig, const char *orig_name,
 119                           mmfile_t *src1, const char *name1,
 120                           mmfile_t *src2, const char *name2,
 121                           const struct ll_merge_options *opts,
 122                           int marker_size)
 123 {
 124         /* Use union favor */
 125         struct ll_merge_options o;
 126         assert(opts);
 127         o = *opts;
 128         o.variant = XDL_MERGE_FAVOR_UNION;
 129         return ll_xdl_merge(drv_unused, result, path_unused,
 130                             orig, NULL, src1, NULL, src2, NULL,
 131                             &o, marker_size);
 132 }
 133
 134 #define LL_BINARY_MERGE 0
 135 #define LL_TEXT_MERGE 1
 136 #define LL_UNION_MERGE 2
 137 static struct ll_merge_driver ll_merge_drv[] = {
 138         { "binary", "built-in binary merge", ll_binary_merge },
 139         { "text", "built-in 3-way text merge", ll_xdl_merge },
 140         { "union", "built-in union merge", ll_union_merge },
 141 };
 142
 143 static void create_temp(mmfile_t *src, char *path)
 144 {
 145         int fd;
 146
 147         strcpy(path, ".merge_file_XXXXXX");
 148         fd = xmkstemp(path);
 149         if (write_in_full(fd, src->ptr, src->size) != src->size)
 150                 die_errno("unable to write temp-file");
 151         close(fd);
 152 }
 153
 154 /*
 155  * User defined low-level merge driver support.
 156  */
 157 static int ll_ext_merge(const struct ll_merge_driver *fn,
 158                         mmbuffer_t *result,
 159                         const char *path,
 160                         mmfile_t *orig, const char *orig_name,
 161                         mmfile_t *src1, const char *name1,
 162                         mmfile_t *src2, const char *name2,
 163                         const struct ll_merge_options *opts,
 164                         int marker_size)
 165 {
 166         char temp[4][50];
 167         struct strbuf cmd = STRBUF_INIT;
 168         struct strbuf_expand_dict_entry dict[5];
 169         const char *args[] = { NULL, NULL };
 170         int status, fd, i;
 171         struct stat st;
 172         assert(opts);
 173
 174         dict[0].placeholder = "O"; dict[0].value = temp[0];
 175         dict[1].placeholder = "A"; dict[1].value = temp[1];
 176         dict[2].placeholder = "B"; dict[2].value = temp[2];
 177         dict[3].placeholder = "L"; dict[3].value = temp[3];
 178         dict[4].placeholder = NULL; dict[4].value = NULL;
 179
 180         if (fn->cmdline == NULL)
 181                 die("custom merge driver %s lacks command line.", fn->name);
 182
 183         result->ptr = NULL;
 184         result->size = 0;
 185         create_temp(orig, temp[0]);
 186         create_temp(src1, temp[1]);
 187         create_temp(src2, temp[2]);
 188         sprintf(temp[3], "%d", marker_size);
 189
 190         strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
 191
 192         args[0] = cmd.buf;
 193         status = run_command_v_opt(args, RUN_USING_SHELL);
 194         fd = open(temp[1], O_RDONLY);
 195         if (fd < 0)
 196                 goto bad;
 197         if (fstat(fd, &st))
 198                 goto close_bad;
 199         result->size = st.st_size;
 200         result->ptr = xmalloc(result->size + 1);
 201         if (read_in_full(fd, result->ptr, result->size) != result->size) {
 202                 free(result->ptr);
 203                 result->ptr = NULL;
 204                 result->size = 0;
 205         }
 206  close_bad:
 207         close(fd);
 208  bad:
 209         for (i = 0; i < 3; i++)
 210                 unlink_or_warn(temp[i]);
 211         strbuf_release(&cmd);
 212         return status;
 213 }
 214
 215 /*
 216  * merge.default and merge.driver configuration items
 217  */
 218 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 219 static const char *default_ll_merge;
 220
 221 static int read_merge_config(const char *var, const char *value, void *cb)
 222 {
 223         struct ll_merge_driver *fn;
 224         const char *ep, *name;
 225         int namelen;
 226
 227         if (!strcmp(var, "merge.default")) {
 228                 if (value)
 229                         default_ll_merge = xstrdup(value);
 230                 return 0;
 231         }
 232
 233         /*
 234          * We are not interested in anything but "merge.<name>.variable";
 235          * especially, we do not want to look at variables such as
 236          * "merge.summary", "merge.tool", and "merge.verbosity".
 237          */
 238         if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
 239                 return 0;
 240
 241         /*
 242          * Find existing one as we might be processing merge.<name>.var2
 243          * after seeing merge.<name>.var1.
 244          */
 245         name = var + 6;
 246         namelen = ep - name;
 247         for (fn = ll_user_merge; fn; fn = fn->next)
 248                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 249                         break;
 250         if (!fn) {
 251                 fn = xcalloc(1, sizeof(struct ll_merge_driver));
 252                 fn->name = xmemdupz(name, namelen);
 253                 fn->fn = ll_ext_merge;
 254                 *ll_user_merge_tail = fn;
 255                 ll_user_merge_tail = &(fn->next);
 256         }
 257
 258         ep++;
 259
 260         if (!strcmp("name", ep)) {
 261                 if (!value)
 262                         return error("%s: lacks value", var);
 263                 fn->description = xstrdup(value);
 264                 return 0;
 265         }
 266
 267         if (!strcmp("driver", ep)) {
 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                  *
 283                  * The external merge driver should write the results in the
 284                  * file named by %A, and signal that it has done with zero exit
 285                  * status.
 286                  */
 287                 fn->cmdline = xstrdup(value);
 288                 return 0;
 289         }
 290
 291         if (!strcmp("recursive", ep)) {
 292                 if (!value)
 293                         return error("%s: lacks value", var);
 294                 fn->recursive = xstrdup(value);
 295                 return 0;
 296         }
 297
 298         return 0;
 299 }
 300
 301 static void initialize_ll_merge(void)
 302 {
 303         if (ll_user_merge_tail)
 304                 return;
 305         ll_user_merge_tail = &ll_user_merge;
 306         git_config(read_merge_config, NULL);
 307 }
 308
 309 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 310 {
 311         struct ll_merge_driver *fn;
 312         const char *name;
 313         int i;
 314
 315         initialize_ll_merge();
 316
 317         if (ATTR_TRUE(merge_attr))
 318                 return &ll_merge_drv[LL_TEXT_MERGE];
 319         else if (ATTR_FALSE(merge_attr))
 320                 return &ll_merge_drv[LL_BINARY_MERGE];
 321         else if (ATTR_UNSET(merge_attr)) {
 322                 if (!default_ll_merge)
 323                         return &ll_merge_drv[LL_TEXT_MERGE];
 324                 else
 325                         name = default_ll_merge;
 326         }
 327         else
 328                 name = merge_attr;
 329
 330         for (fn = ll_user_merge; fn; fn = fn->next)
 331                 if (!strcmp(fn->name, name))
 332                         return fn;
 333
 334         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 335                 if (!strcmp(ll_merge_drv[i].name, name))
 336                         return &ll_merge_drv[i];
 337
 338         /* default to the 3-way */
 339         return &ll_merge_drv[LL_TEXT_MERGE];
 340 }
 341
 342 static int git_path_check_merge(const char *path, struct git_attr_check check[2])
 343 {
 344         if (!check[0].attr) {
 345                 check[0].attr = git_attr("merge");
 346                 check[1].attr = git_attr("conflict-marker-size");
 347         }
 348         return git_check_attr(path, 2, check);
 349 }
 350
 351 static void normalize_file(mmfile_t *mm, const char *path)
 352 {
 353         struct strbuf strbuf = STRBUF_INIT;
 354         if (renormalize_buffer(path, mm->ptr, mm->size, &strbuf)) {
 355                 free(mm->ptr);
 356                 mm->size = strbuf.len;
 357                 mm->ptr = strbuf_detach(&strbuf, NULL);
 358         }
 359 }
 360
 361 int ll_merge(mmbuffer_t *result_buf,
 362              const char *path,
 363              mmfile_t *ancestor, const char *ancestor_label,
 364              mmfile_t *ours, const char *our_label,
 365              mmfile_t *theirs, const char *their_label,
 366              const struct ll_merge_options *opts)
 367 {
 368         static struct git_attr_check check[2];
 369         static const struct ll_merge_options default_opts;
 370         const char *ll_driver_name = NULL;
 371         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 372         const struct ll_merge_driver *driver;
 373
 374         if (!opts)
 375                 opts = &default_opts;
 376
 377         if (opts->renormalize) {
 378                 normalize_file(ancestor, path);
 379                 normalize_file(ours, path);
 380                 normalize_file(theirs, path);
 381         }
 382         if (!git_path_check_merge(path, check)) {
 383                 ll_driver_name = check[0].value;
 384                 if (check[1].value) {
 385                         marker_size = atoi(check[1].value);
 386                         if (marker_size <= 0)
 387                                 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 388                 }
 389         }
 390         driver = find_ll_merge_driver(ll_driver_name);
 391         if (opts->virtual_ancestor && driver->recursive)
 392                 driver = find_ll_merge_driver(driver->recursive);
 393         return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
 394                           ours, our_label, theirs, their_label,
 395                           opts, marker_size);
 396 }
 397
 398 int ll_merge_marker_size(const char *path)
 399 {
 400         static struct git_attr_check check;
 401         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 402
 403         if (!check.attr)
 404                 check.attr = git_attr("conflict-marker-size");
 405         if (!git_check_attr(path, 1, &check) && check.value) {
 406                 marker_size = atoi(check.value);
 407                 if (marker_size <= 0)
 408                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 409         }
 410         return marker_size;
 411 }