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 & LL_OPT_VIRTUAL_ANCESTOR) ? 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 = ll_opt_favor(flag);
  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 &= ~LL_OPT_FAVOR_MASK;
 103         flag |= create_ll_flag(XDL_MERGE_FAVOR_UNION);
 104         return ll_xdl_merge(drv_unused, result, path_unused,
 105                             orig, NULL, src1, NULL, src2, NULL,
 106                             flag, marker_size);
 107         return 0;
 108 }
 109
 110 #define LL_BINARY_MERGE 0
 111 #define LL_TEXT_MERGE 1
 112 #define LL_UNION_MERGE 2
 113 static struct ll_merge_driver ll_merge_drv[] = {
 114         { "binary", "built-in binary merge", ll_binary_merge },
 115         { "text", "built-in 3-way text merge", ll_xdl_merge },
 116         { "union", "built-in union merge", ll_union_merge },
 117 };
 118
 119 static void create_temp(mmfile_t *src, char *path)
 120 {
 121         int fd;
 122
 123         strcpy(path, ".merge_file_XXXXXX");
 124         fd = xmkstemp(path);
 125         if (write_in_full(fd, src->ptr, src->size) != src->size)
 126                 die_errno("unable to write temp-file");
 127         close(fd);
 128 }
 129
 130 /*
 131  * User defined low-level merge driver support.
 132  */
 133 static int ll_ext_merge(const struct ll_merge_driver *fn,
 134                         mmbuffer_t *result,
 135                         const char *path,
 136                         mmfile_t *orig, const char *orig_name,
 137                         mmfile_t *src1, const char *name1,
 138                         mmfile_t *src2, const char *name2,
 139                         int flag, int marker_size)
 140 {
 141         char temp[4][50];
 142         struct strbuf cmd = STRBUF_INIT;
 143         struct strbuf_expand_dict_entry dict[5];
 144         const char *args[] = { NULL, NULL };
 145         int status, fd, i;
 146         struct stat st;
 147
 148         dict[0].placeholder = "O"; dict[0].value = temp[0];
 149         dict[1].placeholder = "A"; dict[1].value = temp[1];
 150         dict[2].placeholder = "B"; dict[2].value = temp[2];
 151         dict[3].placeholder = "L"; dict[3].value = temp[3];
 152         dict[4].placeholder = NULL; dict[4].value = NULL;
 153
 154         if (fn->cmdline == NULL)
 155                 die("custom merge driver %s lacks command line.", fn->name);
 156
 157         result->ptr = NULL;
 158         result->size = 0;
 159         create_temp(orig, temp[0]);
 160         create_temp(src1, temp[1]);
 161         create_temp(src2, temp[2]);
 162         sprintf(temp[3], "%d", marker_size);
 163
 164         strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
 165
 166         args[0] = cmd.buf;
 167         status = run_command_v_opt(args, RUN_USING_SHELL);
 168         fd = open(temp[1], O_RDONLY);
 169         if (fd < 0)
 170                 goto bad;
 171         if (fstat(fd, &st))
 172                 goto close_bad;
 173         result->size = st.st_size;
 174         result->ptr = xmalloc(result->size + 1);
 175         if (read_in_full(fd, result->ptr, result->size) != result->size) {
 176                 free(result->ptr);
 177                 result->ptr = NULL;
 178                 result->size = 0;
 179         }
 180  close_bad:
 181         close(fd);
 182  bad:
 183         for (i = 0; i < 3; i++)
 184                 unlink_or_warn(temp[i]);
 185         strbuf_release(&cmd);
 186         return status;
 187 }
 188
 189 /*
 190  * merge.default and merge.driver configuration items
 191  */
 192 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 193 static const char *default_ll_merge;
 194
 195 static int read_merge_config(const char *var, const char *value, void *cb)
 196 {
 197         struct ll_merge_driver *fn;
 198         const char *ep, *name;
 199         int namelen;
 200
 201         if (!strcmp(var, "merge.default")) {
 202                 if (value)
 203                         default_ll_merge = xstrdup(value);
 204                 return 0;
 205         }
 206
 207         /*
 208          * We are not interested in anything but "merge.<name>.variable";
 209          * especially, we do not want to look at variables such as
 210          * "merge.summary", "merge.tool", and "merge.verbosity".
 211          */
 212         if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
 213                 return 0;
 214
 215         /*
 216          * Find existing one as we might be processing merge.<name>.var2
 217          * after seeing merge.<name>.var1.
 218          */
 219         name = var + 6;
 220         namelen = ep - name;
 221         for (fn = ll_user_merge; fn; fn = fn->next)
 222                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 223                         break;
 224         if (!fn) {
 225                 fn = xcalloc(1, sizeof(struct ll_merge_driver));
 226                 fn->name = xmemdupz(name, namelen);
 227                 fn->fn = ll_ext_merge;
 228                 *ll_user_merge_tail = fn;
 229                 ll_user_merge_tail = &(fn->next);
 230         }
 231
 232         ep++;
 233
 234         if (!strcmp("name", ep)) {
 235                 if (!value)
 236                         return error("%s: lacks value", var);
 237                 fn->description = xstrdup(value);
 238                 return 0;
 239         }
 240
 241         if (!strcmp("driver", ep)) {
 242                 if (!value)
 243                         return error("%s: lacks value", var);
 244                 /*
 245                  * merge.<name>.driver specifies the command line:
 246                  *
 247                  *      command-line
 248                  *
 249                  * The command-line will be interpolated with the following
 250                  * tokens and is given to the shell:
 251                  *
 252                  *    %O - temporary file name for the merge base.
 253                  *    %A - temporary file name for our version.
 254                  *    %B - temporary file name for the other branches' version.
 255                  *    %L - conflict marker length
 256                  *
 257                  * The external merge driver should write the results in the
 258                  * file named by %A, and signal that it has done with zero exit
 259                  * status.
 260                  */
 261                 fn->cmdline = xstrdup(value);
 262                 return 0;
 263         }
 264
 265         if (!strcmp("recursive", ep)) {
 266                 if (!value)
 267                         return error("%s: lacks value", var);
 268                 fn->recursive = xstrdup(value);
 269                 return 0;
 270         }
 271
 272         return 0;
 273 }
 274
 275 static void initialize_ll_merge(void)
 276 {
 277         if (ll_user_merge_tail)
 278                 return;
 279         ll_user_merge_tail = &ll_user_merge;
 280         git_config(read_merge_config, NULL);
 281 }
 282
 283 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 284 {
 285         struct ll_merge_driver *fn;
 286         const char *name;
 287         int i;
 288
 289         initialize_ll_merge();
 290
 291         if (ATTR_TRUE(merge_attr))
 292                 return &ll_merge_drv[LL_TEXT_MERGE];
 293         else if (ATTR_FALSE(merge_attr))
 294                 return &ll_merge_drv[LL_BINARY_MERGE];
 295         else if (ATTR_UNSET(merge_attr)) {
 296                 if (!default_ll_merge)
 297                         return &ll_merge_drv[LL_TEXT_MERGE];
 298                 else
 299                         name = default_ll_merge;
 300         }
 301         else
 302                 name = merge_attr;
 303
 304         for (fn = ll_user_merge; fn; fn = fn->next)
 305                 if (!strcmp(fn->name, name))
 306                         return fn;
 307
 308         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 309                 if (!strcmp(ll_merge_drv[i].name, name))
 310                         return &ll_merge_drv[i];
 311
 312         /* default to the 3-way */
 313         return &ll_merge_drv[LL_TEXT_MERGE];
 314 }
 315
 316 static int git_path_check_merge(const char *path, struct git_attr_check check[2])
 317 {
 318         if (!check[0].attr) {
 319                 check[0].attr = git_attr("merge");
 320                 check[1].attr = git_attr("conflict-marker-size");
 321         }
 322         return git_checkattr(path, 2, check);
 323 }
 324
 325 static void normalize_file(mmfile_t *mm, const char *path)
 326 {
 327         struct strbuf strbuf = STRBUF_INIT;
 328         if (renormalize_buffer(path, mm->ptr, mm->size, &strbuf)) {
 329                 free(mm->ptr);
 330                 mm->size = strbuf.len;
 331                 mm->ptr = strbuf_detach(&strbuf, NULL);
 332         }
 333 }
 334
 335 int ll_merge(mmbuffer_t *result_buf,
 336              const char *path,
 337              mmfile_t *ancestor, const char *ancestor_label,
 338              mmfile_t *ours, const char *our_label,
 339              mmfile_t *theirs, const char *their_label,
 340              int flag)
 341 {
 342         static struct git_attr_check check[2];
 343         const char *ll_driver_name = NULL;
 344         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 345         const struct ll_merge_driver *driver;
 346         int virtual_ancestor = flag & LL_OPT_VIRTUAL_ANCESTOR;
 347
 348         if (flag & LL_OPT_RENORMALIZE) {
 349                 normalize_file(ancestor, path);
 350                 normalize_file(ours, path);
 351                 normalize_file(theirs, path);
 352         }
 353         if (!git_path_check_merge(path, check)) {
 354                 ll_driver_name = check[0].value;
 355                 if (check[1].value) {
 356                         marker_size = atoi(check[1].value);
 357                         if (marker_size <= 0)
 358                                 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 359                 }
 360         }
 361         driver = find_ll_merge_driver(ll_driver_name);
 362         if (virtual_ancestor && driver->recursive)
 363                 driver = find_ll_merge_driver(driver->recursive);
 364         return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
 365                           ours, our_label, theirs, their_label,
 366                           flag, marker_size);
 367 }
 368
 369 int ll_merge_marker_size(const char *path)
 370 {
 371         static struct git_attr_check check;
 372         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 373
 374         if (!check.attr)
 375                 check.attr = git_attr("conflict-marker-size");
 376         if (!git_checkattr(path, 1, &check) && check.value) {
 377                 marker_size = atoi(check.value);
 378                 if (marker_size <= 0)
 379                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 380         }
 381         return marker_size;
 382 }