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