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,
  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                         warning("Cannot merge binary files: %s (%s vs. %s)",
  57                                 path, name1, name2);
  58                         /* fallthru */
  59                 case XDL_MERGE_FAVOR_OURS:
  60                         stolen = src1;
  61                         break;
  62                 case XDL_MERGE_FAVOR_THEIRS:
  63                         stolen = src2;
  64                         break;
  65                 }
  66         }
  67
  68         result->ptr = stolen->ptr;
  69         result->size = stolen->size;
  70         stolen->ptr = NULL;
  71
  72         /*
  73          * With -Xtheirs or -Xours, we have cleanly merged;
  74          * otherwise we got a conflict.
  75          */
  76         return (opts->variant ? 0 : 1);
  77 }
  78
  79 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
  80                         mmbuffer_t *result,
  81                         const char *path,
  82                         mmfile_t *orig, const char *orig_name,
  83                         mmfile_t *src1, const char *name1,
  84                         mmfile_t *src2, const char *name2,
  85                         const struct ll_merge_options *opts,
  86                         int marker_size)
  87 {
  88         xmparam_t xmp;
  89         assert(opts);
  90
  91         if (orig->size > MAX_XDIFF_SIZE ||
  92             src1->size > MAX_XDIFF_SIZE ||
  93             src2->size > MAX_XDIFF_SIZE ||
  94             buffer_is_binary(orig->ptr, orig->size) ||
  95             buffer_is_binary(src1->ptr, src1->size) ||
  96             buffer_is_binary(src2->ptr, src2->size)) {
  97                 return ll_binary_merge(drv_unused, result,
  98                                        path,
  99                                        orig, orig_name,
 100                                        src1, name1,
 101                                        src2, name2,
 102                                        opts, marker_size);
 103         }
 104
 105         memset(&xmp, 0, sizeof(xmp));
 106         xmp.level = XDL_MERGE_ZEALOUS;
 107         xmp.favor = opts->variant;
 108         xmp.xpp.flags = opts->xdl_opts;
 109         if (git_xmerge_style >= 0)
 110                 xmp.style = git_xmerge_style;
 111         if (marker_size > 0)
 112                 xmp.marker_size = marker_size;
 113         xmp.ancestor = orig_name;
 114         xmp.file1 = name1;
 115         xmp.file2 = name2;
 116         return xdl_merge(orig, src1, src2, &xmp, result);
 117 }
 118
 119 static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 120                           mmbuffer_t *result,
 121                           const char *path_unused,
 122                           mmfile_t *orig, const char *orig_name,
 123                           mmfile_t *src1, const char *name1,
 124                           mmfile_t *src2, const char *name2,
 125                           const struct ll_merge_options *opts,
 126                           int marker_size)
 127 {
 128         /* Use union favor */
 129         struct ll_merge_options o;
 130         assert(opts);
 131         o = *opts;
 132         o.variant = XDL_MERGE_FAVOR_UNION;
 133         return ll_xdl_merge(drv_unused, result, path_unused,
 134                             orig, NULL, src1, NULL, src2, NULL,
 135                             &o, marker_size);
 136 }
 137
 138 #define LL_BINARY_MERGE 0
 139 #define LL_TEXT_MERGE 1
 140 #define LL_UNION_MERGE 2
 141 static struct ll_merge_driver ll_merge_drv[] = {
 142         { "binary", "built-in binary merge", ll_binary_merge },
 143         { "text", "built-in 3-way text merge", ll_xdl_merge },
 144         { "union", "built-in union merge", ll_union_merge },
 145 };
 146
 147 static void create_temp(mmfile_t *src, char *path)
 148 {
 149         int fd;
 150
 151         strcpy(path, ".merge_file_XXXXXX");
 152         fd = xmkstemp(path);
 153         if (write_in_full(fd, src->ptr, src->size) != src->size)
 154                 die_errno("unable to write temp-file");
 155         close(fd);
 156 }
 157
 158 /*
 159  * User defined low-level merge driver support.
 160  */
 161 static int ll_ext_merge(const struct ll_merge_driver *fn,
 162                         mmbuffer_t *result,
 163                         const char *path,
 164                         mmfile_t *orig, const char *orig_name,
 165                         mmfile_t *src1, const char *name1,
 166                         mmfile_t *src2, const char *name2,
 167                         const struct ll_merge_options *opts,
 168                         int marker_size)
 169 {
 170         char temp[4][50];
 171         struct strbuf cmd = STRBUF_INIT;
 172         struct strbuf_expand_dict_entry dict[5];
 173         const char *args[] = { NULL, NULL };
 174         int status, fd, i;
 175         struct stat st;
 176         assert(opts);
 177
 178         dict[0].placeholder = "O"; dict[0].value = temp[0];
 179         dict[1].placeholder = "A"; dict[1].value = temp[1];
 180         dict[2].placeholder = "B"; dict[2].value = temp[2];
 181         dict[3].placeholder = "L"; dict[3].value = temp[3];
 182         dict[4].placeholder = NULL; dict[4].value = NULL;
 183
 184         if (fn->cmdline == NULL)
 185                 die("custom merge driver %s lacks command line.", fn->name);
 186
 187         result->ptr = NULL;
 188         result->size = 0;
 189         create_temp(orig, temp[0]);
 190         create_temp(src1, temp[1]);
 191         create_temp(src2, temp[2]);
 192         sprintf(temp[3], "%d", marker_size);
 193
 194         strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
 195
 196         args[0] = cmd.buf;
 197         status = run_command_v_opt(args, RUN_USING_SHELL);
 198         fd = open(temp[1], O_RDONLY);
 199         if (fd < 0)
 200                 goto bad;
 201         if (fstat(fd, &st))
 202                 goto close_bad;
 203         result->size = st.st_size;
 204         result->ptr = xmalloc(result->size + 1);
 205         if (read_in_full(fd, result->ptr, result->size) != result->size) {
 206                 free(result->ptr);
 207                 result->ptr = NULL;
 208                 result->size = 0;
 209         }
 210  close_bad:
 211         close(fd);
 212  bad:
 213         for (i = 0; i < 3; i++)
 214                 unlink_or_warn(temp[i]);
 215         strbuf_release(&cmd);
 216         return status;
 217 }
 218
 219 /*
 220  * merge.default and merge.driver configuration items
 221  */
 222 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 223 static const char *default_ll_merge;
 224
 225 static int read_merge_config(const char *var, const char *value, void *cb)
 226 {
 227         struct ll_merge_driver *fn;
 228         const char *key, *name;
 229         int namelen;
 230
 231         if (!strcmp(var, "merge.default"))
 232                 return git_config_string(&default_ll_merge, var, value);
 233
 234         /*
 235          * We are not interested in anything but "merge.<name>.variable";
 236          * especially, we do not want to look at variables such as
 237          * "merge.summary", "merge.tool", and "merge.verbosity".
 238          */
 239         if (parse_config_key(var, "merge", &name, &namelen, &key) < 0 || !name)
 240                 return 0;
 241
 242         /*
 243          * Find existing one as we might be processing merge.<name>.var2
 244          * after seeing merge.<name>.var1.
 245          */
 246         for (fn = ll_user_merge; fn; fn = fn->next)
 247                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 248                         break;
 249         if (!fn) {
 250                 fn = xcalloc(1, sizeof(struct ll_merge_driver));
 251                 fn->name = xmemdupz(name, namelen);
 252                 fn->fn = ll_ext_merge;
 253                 *ll_user_merge_tail = fn;
 254                 ll_user_merge_tail = &(fn->next);
 255         }
 256
 257         if (!strcmp("name", key))
 258                 return git_config_string(&fn->description, var, value);
 259
 260         if (!strcmp("driver", key)) {
 261                 if (!value)
 262                         return error("%s: lacks value", var);
 263                 /*
 264                  * merge.<name>.driver specifies the command line:
 265                  *
 266                  *      command-line
 267                  *
 268                  * The command-line will be interpolated with the following
 269                  * tokens and is given to the shell:
 270                  *
 271                  *    %O - temporary file name for the merge base.
 272                  *    %A - temporary file name for our version.
 273                  *    %B - temporary file name for the other branches' version.
 274                  *    %L - conflict marker length
 275                  *
 276                  * The external merge driver should write the results in the
 277                  * file named by %A, and signal that it has done with zero exit
 278                  * status.
 279                  */
 280                 fn->cmdline = xstrdup(value);
 281                 return 0;
 282         }
 283
 284         if (!strcmp("recursive", key))
 285                 return git_config_string(&fn->recursive, var, value);
 286
 287         return 0;
 288 }
 289
 290 static void initialize_ll_merge(void)
 291 {
 292         if (ll_user_merge_tail)
 293                 return;
 294         ll_user_merge_tail = &ll_user_merge;
 295         git_config(read_merge_config, NULL);
 296 }
 297
 298 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 299 {
 300         struct ll_merge_driver *fn;
 301         const char *name;
 302         int i;
 303
 304         initialize_ll_merge();
 305
 306         if (ATTR_TRUE(merge_attr))
 307                 return &ll_merge_drv[LL_TEXT_MERGE];
 308         else if (ATTR_FALSE(merge_attr))
 309                 return &ll_merge_drv[LL_BINARY_MERGE];
 310         else if (ATTR_UNSET(merge_attr)) {
 311                 if (!default_ll_merge)
 312                         return &ll_merge_drv[LL_TEXT_MERGE];
 313                 else
 314                         name = default_ll_merge;
 315         }
 316         else
 317                 name = merge_attr;
 318
 319         for (fn = ll_user_merge; fn; fn = fn->next)
 320                 if (!strcmp(fn->name, name))
 321                         return fn;
 322
 323         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 324                 if (!strcmp(ll_merge_drv[i].name, name))
 325                         return &ll_merge_drv[i];
 326
 327         /* default to the 3-way */
 328         return &ll_merge_drv[LL_TEXT_MERGE];
 329 }
 330
 331 static int git_path_check_merge(const char *path, struct git_attr_check check[2])
 332 {
 333         if (!check[0].attr) {
 334                 check[0].attr = git_attr("merge");
 335                 check[1].attr = git_attr("conflict-marker-size");
 336         }
 337         return git_check_attr(path, 2, check);
 338 }
 339
 340 static void normalize_file(mmfile_t *mm, const char *path)
 341 {
 342         struct strbuf strbuf = STRBUF_INIT;
 343         if (renormalize_buffer(path, mm->ptr, mm->size, &strbuf)) {
 344                 free(mm->ptr);
 345                 mm->size = strbuf.len;
 346                 mm->ptr = strbuf_detach(&strbuf, NULL);
 347         }
 348 }
 349
 350 int ll_merge(mmbuffer_t *result_buf,
 351              const char *path,
 352              mmfile_t *ancestor, const char *ancestor_label,
 353              mmfile_t *ours, const char *our_label,
 354              mmfile_t *theirs, const char *their_label,
 355              const struct ll_merge_options *opts)
 356 {
 357         static struct git_attr_check check[2];
 358         static const struct ll_merge_options default_opts;
 359         const char *ll_driver_name = NULL;
 360         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 361         const struct ll_merge_driver *driver;
 362
 363         if (!opts)
 364                 opts = &default_opts;
 365
 366         if (opts->renormalize) {
 367                 normalize_file(ancestor, path);
 368                 normalize_file(ours, path);
 369                 normalize_file(theirs, path);
 370         }
 371         if (!git_path_check_merge(path, check)) {
 372                 ll_driver_name = check[0].value;
 373                 if (check[1].value) {
 374                         marker_size = atoi(check[1].value);
 375                         if (marker_size <= 0)
 376                                 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 377                 }
 378         }
 379         driver = find_ll_merge_driver(ll_driver_name);
 380         if (opts->virtual_ancestor && driver->recursive)
 381                 driver = find_ll_merge_driver(driver->recursive);
 382         return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
 383                           ours, our_label, theirs, their_label,
 384                           opts, marker_size);
 385 }
 386
 387 int ll_merge_marker_size(const char *path)
 388 {
 389         static struct git_attr_check check;
 390         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 391
 392         if (!check.attr)
 393                 check.attr = git_attr("conflict-marker-size");
 394         if (!git_check_attr(path, 1, &check) && check.value) {
 395                 marker_size = atoi(check.value);
 396                 if (marker_size <= 0)
 397                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 398         }
 399         return marker_size;
 400 }