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,
  19                            mmfile_t *src1, const char *name1,
  20                            mmfile_t *src2, const char *name2,
  21                            int flag,
  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,
  40                            mmfile_t *src1, const char *name1,
  41                            mmfile_t *src2, const char *name2,
  42                            int flag, int marker_size)
  43 {
  44         /*
  45          * The tentative merge result is "ours" for the final round,
  46          * or common ancestor for an internal merge.  Still return
  47          * "conflicted merge" status.
  48          */
  49         mmfile_t *stolen = (flag & 01) ? orig : src1;
  50
  51         result->ptr = stolen->ptr;
  52         result->size = stolen->size;
  53         stolen->ptr = NULL;
  54         return 1;
  55 }
  56
  57 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
  58                         mmbuffer_t *result,
  59                         const char *path,
  60                         mmfile_t *orig,
  61                         mmfile_t *src1, const char *name1,
  62                         mmfile_t *src2, const char *name2,
  63                         int flag, int marker_size)
  64 {
  65         xmparam_t xmp;
  66
  67         if (buffer_is_binary(orig->ptr, orig->size) ||
  68             buffer_is_binary(src1->ptr, src1->size) ||
  69             buffer_is_binary(src2->ptr, src2->size)) {
  70                 warning("Cannot merge binary files: %s (%s vs. %s)\n",
  71                         path, name1, name2);
  72                 return ll_binary_merge(drv_unused, result,
  73                                        path,
  74                                        orig, src1, name1,
  75                                        src2, name2,
  76                                        flag, marker_size);
  77         }
  78
  79         memset(&xmp, 0, sizeof(xmp));
  80         xmp.level = XDL_MERGE_ZEALOUS;
  81         xmp.favor= (flag >> 1) & 03;
  82         if (git_xmerge_style >= 0)
  83                 xmp.style = git_xmerge_style;
  84         if (marker_size > 0)
  85                 xmp.marker_size = marker_size;
  86         xmp.file1 = name1;
  87         xmp.file2 = name2;
  88         return xdl_merge(orig, src1, src2, &xmp, result);
  89 }
  90
  91 static int ll_union_merge(const struct ll_merge_driver *drv_unused,
  92                           mmbuffer_t *result,
  93                           const char *path_unused,
  94                           mmfile_t *orig,
  95                           mmfile_t *src1, const char *name1,
  96                           mmfile_t *src2, const char *name2,
  97                           int flag, int marker_size)
  98 {
  99         /* Use union favor */
 100         flag = (flag & 1) | (XDL_MERGE_FAVOR_UNION << 1);
 101         return ll_xdl_merge(drv_unused, result, path_unused,
 102                             orig, src1, NULL, src2, NULL,
 103                             flag, marker_size);
 104         return 0;
 105 }
 106
 107 #define LL_BINARY_MERGE 0
 108 #define LL_TEXT_MERGE 1
 109 #define LL_UNION_MERGE 2
 110 static struct ll_merge_driver ll_merge_drv[] = {
 111         { "binary", "built-in binary merge", ll_binary_merge },
 112         { "text", "built-in 3-way text merge", ll_xdl_merge },
 113         { "union", "built-in union merge", ll_union_merge },
 114 };
 115
 116 static void create_temp(mmfile_t *src, char *path)
 117 {
 118         int fd;
 119
 120         strcpy(path, ".merge_file_XXXXXX");
 121         fd = xmkstemp(path);
 122         if (write_in_full(fd, src->ptr, src->size) != src->size)
 123                 die_errno("unable to write temp-file");
 124         close(fd);
 125 }
 126
 127 /*
 128  * User defined low-level merge driver support.
 129  */
 130 static int ll_ext_merge(const struct ll_merge_driver *fn,
 131                         mmbuffer_t *result,
 132                         const char *path,
 133                         mmfile_t *orig,
 134                         mmfile_t *src1, const char *name1,
 135                         mmfile_t *src2, const char *name2,
 136                         int flag, int marker_size)
 137 {
 138         char temp[4][50];
 139         struct strbuf cmd = STRBUF_INIT;
 140         struct strbuf_expand_dict_entry dict[] = {
 141                 { "O", temp[0] },
 142                 { "A", temp[1] },
 143                 { "B", temp[2] },
 144                 { "L", temp[3] },
 145                 { NULL }
 146         };
 147         const char *args[] = { NULL, NULL };
 148         int status, fd, i;
 149         struct stat st;
 150
 151         if (fn->cmdline == NULL)
 152                 die("custom merge driver %s lacks command line.", fn->name);
 153
 154         result->ptr = NULL;
 155         result->size = 0;
 156         create_temp(orig, temp[0]);
 157         create_temp(src1, temp[1]);
 158         create_temp(src2, temp[2]);
 159         sprintf(temp[3], "%d", marker_size);
 160
 161         strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
 162
 163         args[0] = cmd.buf;
 164         status = run_command_v_opt(args, RUN_USING_SHELL);
 165         fd = open(temp[1], O_RDONLY);
 166         if (fd < 0)
 167                 goto bad;
 168         if (fstat(fd, &st))
 169                 goto close_bad;
 170         result->size = st.st_size;
 171         result->ptr = xmalloc(result->size + 1);
 172         if (read_in_full(fd, result->ptr, result->size) != result->size) {
 173                 free(result->ptr);
 174                 result->ptr = NULL;
 175                 result->size = 0;
 176         }
 177  close_bad:
 178         close(fd);
 179  bad:
 180         for (i = 0; i < 3; i++)
 181                 unlink_or_warn(temp[i]);
 182         strbuf_release(&cmd);
 183         return status;
 184 }
 185
 186 /*
 187  * merge.default and merge.driver configuration items
 188  */
 189 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 190 static const char *default_ll_merge;
 191
 192 static int read_merge_config(const char *var, const char *value, void *cb)
 193 {
 194         struct ll_merge_driver *fn;
 195         const char *ep, *name;
 196         int namelen;
 197
 198         if (!strcmp(var, "merge.default")) {
 199                 if (value)
 200                         default_ll_merge = xstrdup(value);
 201                 return 0;
 202         }
 203
 204         /*
 205          * We are not interested in anything but "merge.<name>.variable";
 206          * especially, we do not want to look at variables such as
 207          * "merge.summary", "merge.tool", and "merge.verbosity".
 208          */
 209         if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
 210                 return 0;
 211
 212         /*
 213          * Find existing one as we might be processing merge.<name>.var2
 214          * after seeing merge.<name>.var1.
 215          */
 216         name = var + 6;
 217         namelen = ep - name;
 218         for (fn = ll_user_merge; fn; fn = fn->next)
 219                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 220                         break;
 221         if (!fn) {
 222                 fn = xcalloc(1, sizeof(struct ll_merge_driver));
 223                 fn->name = xmemdupz(name, namelen);
 224                 fn->fn = ll_ext_merge;
 225                 *ll_user_merge_tail = fn;
 226                 ll_user_merge_tail = &(fn->next);
 227         }
 228
 229         ep++;
 230
 231         if (!strcmp("name", ep)) {
 232                 if (!value)
 233                         return error("%s: lacks value", var);
 234                 fn->description = xstrdup(value);
 235                 return 0;
 236         }
 237
 238         if (!strcmp("driver", ep)) {
 239                 if (!value)
 240                         return error("%s: lacks value", var);
 241                 /*
 242                  * merge.<name>.driver specifies the command line:
 243                  *
 244                  *      command-line
 245                  *
 246                  * The command-line will be interpolated with the following
 247                  * tokens and is given to the shell:
 248                  *
 249                  *    %O - temporary file name for the merge base.
 250                  *    %A - temporary file name for our version.
 251                  *    %B - temporary file name for the other branches' version.
 252                  *    %L - conflict marker length
 253                  *
 254                  * The external merge driver should write the results in the
 255                  * file named by %A, and signal that it has done with zero exit
 256                  * status.
 257                  */
 258                 fn->cmdline = xstrdup(value);
 259                 return 0;
 260         }
 261
 262         if (!strcmp("recursive", ep)) {
 263                 if (!value)
 264                         return error("%s: lacks value", var);
 265                 fn->recursive = xstrdup(value);
 266                 return 0;
 267         }
 268
 269         return 0;
 270 }
 271
 272 static void initialize_ll_merge(void)
 273 {
 274         if (ll_user_merge_tail)
 275                 return;
 276         ll_user_merge_tail = &ll_user_merge;
 277         git_config(read_merge_config, NULL);
 278 }
 279
 280 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 281 {
 282         struct ll_merge_driver *fn;
 283         const char *name;
 284         int i;
 285
 286         initialize_ll_merge();
 287
 288         if (ATTR_TRUE(merge_attr))
 289                 return &ll_merge_drv[LL_TEXT_MERGE];
 290         else if (ATTR_FALSE(merge_attr))
 291                 return &ll_merge_drv[LL_BINARY_MERGE];
 292         else if (ATTR_UNSET(merge_attr)) {
 293                 if (!default_ll_merge)
 294                         return &ll_merge_drv[LL_TEXT_MERGE];
 295                 else
 296                         name = default_ll_merge;
 297         }
 298         else
 299                 name = merge_attr;
 300
 301         for (fn = ll_user_merge; fn; fn = fn->next)
 302                 if (!strcmp(fn->name, name))
 303                         return fn;
 304
 305         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 306                 if (!strcmp(ll_merge_drv[i].name, name))
 307                         return &ll_merge_drv[i];
 308
 309         /* default to the 3-way */
 310         return &ll_merge_drv[LL_TEXT_MERGE];
 311 }
 312
 313 static int git_path_check_merge(const char *path, struct git_attr_check check[2])
 314 {
 315         if (!check[0].attr) {
 316                 check[0].attr = git_attr("merge");
 317                 check[1].attr = git_attr("conflict-marker-size");
 318         }
 319         return git_checkattr(path, 2, check);
 320 }
 321
 322 int ll_merge(mmbuffer_t *result_buf,
 323              const char *path,
 324              mmfile_t *ancestor,
 325              mmfile_t *ours, const char *our_label,
 326              mmfile_t *theirs, const char *their_label,
 327              int flag)
 328 {
 329         static struct git_attr_check check[2];
 330         const char *ll_driver_name = NULL;
 331         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 332         const struct ll_merge_driver *driver;
 333         int virtual_ancestor = flag & 01;
 334
 335         if (!git_path_check_merge(path, check)) {
 336                 ll_driver_name = check[0].value;
 337                 if (check[1].value) {
 338                         marker_size = atoi(check[1].value);
 339                         if (marker_size <= 0)
 340                                 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 341                 }
 342         }
 343         driver = find_ll_merge_driver(ll_driver_name);
 344         if (virtual_ancestor && driver->recursive)
 345                 driver = find_ll_merge_driver(driver->recursive);
 346         return driver->fn(driver, result_buf, path, ancestor,
 347                           ours, our_label, theirs, their_label,
 348                           flag, marker_size);
 349 }
 350
 351 int ll_merge_marker_size(const char *path)
 352 {
 353         static struct git_attr_check check;
 354         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 355
 356         if (!check.attr)
 357                 check.attr = git_attr("conflict-marker-size");
 358         if (!git_checkattr(path, 1, &check) && check.value) {
 359                 marker_size = atoi(check.value);
 360                 if (marker_size <= 0)
 361                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 362         }
 363         return marker_size;
 364 }