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                            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, const char *orig_name,
  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, const char *orig_name,
  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, orig_name,
  75                                        src1, name1,
  76                                        src2, name2,
  77                                        flag, marker_size);
  78         }
  79
  80         memset(&xmp, 0, sizeof(xmp));
  81         xmp.level = XDL_MERGE_ZEALOUS;
  82         xmp.favor= (flag >> 1) & 03;
  83         if (git_xmerge_style >= 0)
  84                 xmp.style = git_xmerge_style;
  85         if (marker_size > 0)
  86                 xmp.marker_size = marker_size;
  87         xmp.ancestor = orig_name;
  88         xmp.file1 = name1;
  89         xmp.file2 = name2;
  90         return xdl_merge(orig, src1, src2, &xmp, result);
  91 }
  92
  93 static int ll_union_merge(const struct ll_merge_driver *drv_unused,
  94                           mmbuffer_t *result,
  95                           const char *path_unused,
  96                           mmfile_t *orig, const char *orig_name,
  97                           mmfile_t *src1, const char *name1,
  98                           mmfile_t *src2, const char *name2,
  99                           int flag, int marker_size)
 100 {
 101         /* Use union favor */
 102         flag = (flag & 1) | (XDL_MERGE_FAVOR_UNION << 1);
 103         return ll_xdl_merge(drv_unused, result, path_unused,
 104                             orig, NULL, src1, NULL, src2, NULL,
 105                             flag, marker_size);
 106         return 0;
 107 }
 108
 109 #define LL_BINARY_MERGE 0
 110 #define LL_TEXT_MERGE 1
 111 #define LL_UNION_MERGE 2
 112 static struct ll_merge_driver ll_merge_drv[] = {
 113         { "binary", "built-in binary merge", ll_binary_merge },
 114         { "text", "built-in 3-way text merge", ll_xdl_merge },
 115         { "union", "built-in union merge", ll_union_merge },
 116 };
 117
 118 static void create_temp(mmfile_t *src, char *path)
 119 {
 120         int fd;
 121
 122         strcpy(path, ".merge_file_XXXXXX");
 123         fd = xmkstemp(path);
 124         if (write_in_full(fd, src->ptr, src->size) != src->size)
 125                 die_errno("unable to write temp-file");
 126         close(fd);
 127 }
 128
 129 /*
 130  * User defined low-level merge driver support.
 131  */
 132 static int ll_ext_merge(const struct ll_merge_driver *fn,
 133                         mmbuffer_t *result,
 134                         const char *path,
 135                         mmfile_t *orig, const char *orig_name,
 136                         mmfile_t *src1, const char *name1,
 137                         mmfile_t *src2, const char *name2,
 138                         int flag, int marker_size)
 139 {
 140         char temp[4][50];
 141         struct strbuf cmd = STRBUF_INIT;
 142         struct strbuf_expand_dict_entry dict[5];
 143         const char *args[] = { NULL, NULL };
 144         int status, fd, i;
 145         struct stat st;
 146
 147         dict[0].placeholder = "O"; dict[0].value = temp[0];
 148         dict[1].placeholder = "A"; dict[1].value = temp[1];
 149         dict[2].placeholder = "B"; dict[2].value = temp[2];
 150         dict[3].placeholder = "L"; dict[3].value = temp[3];
 151         dict[4].placeholder = NULL; dict[4].value = NULL;
 152
 153         if (fn->cmdline == NULL)
 154                 die("custom merge driver %s lacks command line.", fn->name);
 155
 156         result->ptr = NULL;
 157         result->size = 0;
 158         create_temp(orig, temp[0]);
 159         create_temp(src1, temp[1]);
 160         create_temp(src2, temp[2]);
 161         sprintf(temp[3], "%d", marker_size);
 162
 163         strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
 164
 165         args[0] = cmd.buf;
 166         status = run_command_v_opt(args, RUN_USING_SHELL);
 167         fd = open(temp[1], O_RDONLY);
 168         if (fd < 0)
 169                 goto bad;
 170         if (fstat(fd, &st))
 171                 goto close_bad;
 172         result->size = st.st_size;
 173         result->ptr = xmalloc(result->size + 1);
 174         if (read_in_full(fd, result->ptr, result->size) != result->size) {
 175                 free(result->ptr);
 176                 result->ptr = NULL;
 177                 result->size = 0;
 178         }
 179  close_bad:
 180         close(fd);
 181  bad:
 182         for (i = 0; i < 3; i++)
 183                 unlink_or_warn(temp[i]);
 184         strbuf_release(&cmd);
 185         return status;
 186 }
 187
 188 /*
 189  * merge.default and merge.driver configuration items
 190  */
 191 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 192 static const char *default_ll_merge;
 193
 194 static int read_merge_config(const char *var, const char *value, void *cb)
 195 {
 196         struct ll_merge_driver *fn;
 197         const char *ep, *name;
 198         int namelen;
 199
 200         if (!strcmp(var, "merge.default")) {
 201                 if (value)
 202                         default_ll_merge = xstrdup(value);
 203                 return 0;
 204         }
 205
 206         /*
 207          * We are not interested in anything but "merge.<name>.variable";
 208          * especially, we do not want to look at variables such as
 209          * "merge.summary", "merge.tool", and "merge.verbosity".
 210          */
 211         if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
 212                 return 0;
 213
 214         /*
 215          * Find existing one as we might be processing merge.<name>.var2
 216          * after seeing merge.<name>.var1.
 217          */
 218         name = var + 6;
 219         namelen = ep - name;
 220         for (fn = ll_user_merge; fn; fn = fn->next)
 221                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 222                         break;
 223         if (!fn) {
 224                 fn = xcalloc(1, sizeof(struct ll_merge_driver));
 225                 fn->name = xmemdupz(name, namelen);
 226                 fn->fn = ll_ext_merge;
 227                 *ll_user_merge_tail = fn;
 228                 ll_user_merge_tail = &(fn->next);
 229         }
 230
 231         ep++;
 232
 233         if (!strcmp("name", ep)) {
 234                 if (!value)
 235                         return error("%s: lacks value", var);
 236                 fn->description = xstrdup(value);
 237                 return 0;
 238         }
 239
 240         if (!strcmp("driver", ep)) {
 241                 if (!value)
 242                         return error("%s: lacks value", var);
 243                 /*
 244                  * merge.<name>.driver specifies the command line:
 245                  *
 246                  *      command-line
 247                  *
 248                  * The command-line will be interpolated with the following
 249                  * tokens and is given to the shell:
 250                  *
 251                  *    %O - temporary file name for the merge base.
 252                  *    %A - temporary file name for our version.
 253                  *    %B - temporary file name for the other branches' version.
 254                  *    %L - conflict marker length
 255                  *
 256                  * The external merge driver should write the results in the
 257                  * file named by %A, and signal that it has done with zero exit
 258                  * status.
 259                  */
 260                 fn->cmdline = xstrdup(value);
 261                 return 0;
 262         }
 263
 264         if (!strcmp("recursive", ep)) {
 265                 if (!value)
 266                         return error("%s: lacks value", var);
 267                 fn->recursive = xstrdup(value);
 268                 return 0;
 269         }
 270
 271         return 0;
 272 }
 273
 274 static void initialize_ll_merge(void)
 275 {
 276         if (ll_user_merge_tail)
 277                 return;
 278         ll_user_merge_tail = &ll_user_merge;
 279         git_config(read_merge_config, NULL);
 280 }
 281
 282 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 283 {
 284         struct ll_merge_driver *fn;
 285         const char *name;
 286         int i;
 287
 288         initialize_ll_merge();
 289
 290         if (ATTR_TRUE(merge_attr))
 291                 return &ll_merge_drv[LL_TEXT_MERGE];
 292         else if (ATTR_FALSE(merge_attr))
 293                 return &ll_merge_drv[LL_BINARY_MERGE];
 294         else if (ATTR_UNSET(merge_attr)) {
 295                 if (!default_ll_merge)
 296                         return &ll_merge_drv[LL_TEXT_MERGE];
 297                 else
 298                         name = default_ll_merge;
 299         }
 300         else
 301                 name = merge_attr;
 302
 303         for (fn = ll_user_merge; fn; fn = fn->next)
 304                 if (!strcmp(fn->name, name))
 305                         return fn;
 306
 307         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 308                 if (!strcmp(ll_merge_drv[i].name, name))
 309                         return &ll_merge_drv[i];
 310
 311         /* default to the 3-way */
 312         return &ll_merge_drv[LL_TEXT_MERGE];
 313 }
 314
 315 static int git_path_check_merge(const char *path, struct git_attr_check check[2])
 316 {
 317         if (!check[0].attr) {
 318                 check[0].attr = git_attr("merge");
 319                 check[1].attr = git_attr("conflict-marker-size");
 320         }
 321         return git_checkattr(path, 2, check);
 322 }
 323
 324 int ll_merge(mmbuffer_t *result_buf,
 325              const char *path,
 326              mmfile_t *ancestor, const char *ancestor_label,
 327              mmfile_t *ours, const char *our_label,
 328              mmfile_t *theirs, const char *their_label,
 329              int flag)
 330 {
 331         static struct git_attr_check check[2];
 332         const char *ll_driver_name = NULL;
 333         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 334         const struct ll_merge_driver *driver;
 335         int virtual_ancestor = flag & 01;
 336
 337         if (!git_path_check_merge(path, check)) {
 338                 ll_driver_name = check[0].value;
 339                 if (check[1].value) {
 340                         marker_size = atoi(check[1].value);
 341                         if (marker_size <= 0)
 342                                 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 343                 }
 344         }
 345         driver = find_ll_merge_driver(ll_driver_name);
 346         if (virtual_ancestor && driver->recursive)
 347                 driver = find_ll_merge_driver(driver->recursive);
 348         return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
 349                           ours, our_label, theirs, their_label,
 350                           flag, marker_size);
 351 }
 352
 353 int ll_merge_marker_size(const char *path)
 354 {
 355         static struct git_attr_check check;
 356         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 357
 358         if (!check.attr)
 359                 check.attr = git_attr("conflict-marker-size");
 360         if (!git_checkattr(path, 1, &check) && check.value) {
 361                 marker_size = atoi(check.value);
 362                 if (marker_size <= 0)
 363                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 364         }
 365         return marker_size;
 366 }