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 #include "quote.h"
  13
  14 struct ll_merge_driver;
  15
  16 typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
  17                            mmbuffer_t *result,
  18                            const char *path,
  19                            mmfile_t *orig, const char *orig_name,
  20                            mmfile_t *src1, const char *name1,
  21                            mmfile_t *src2, const char *name2,
  22                            const struct ll_merge_options *opts,
  23                            int marker_size);
  24
  25 struct ll_merge_driver {
  26         const char *name;
  27         const char *description;
  28         ll_merge_fn fn;
  29         const char *recursive;
  30         struct ll_merge_driver *next;
  31         char *cmdline;
  32 };
  33
  34 /*
  35  * Built-in low-levels
  36  */
  37 static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
  38                            mmbuffer_t *result,
  39                            const char *path,
  40                            mmfile_t *orig, const char *orig_name,
  41                            mmfile_t *src1, const char *name1,
  42                            mmfile_t *src2, const char *name2,
  43                            const struct ll_merge_options *opts,
  44                            int marker_size)
  45 {
  46         mmfile_t *stolen;
  47         assert(opts);
  48
  49         /*
  50          * The tentative merge result is the common ancestor for an
  51          * internal merge.  For the final merge, it is "ours" by
  52          * default but -Xours/-Xtheirs can tweak the choice.
  53          */
  54         if (opts->virtual_ancestor) {
  55                 stolen = orig;
  56         } else {
  57                 switch (opts->variant) {
  58                 default:
  59                         warning("Cannot merge binary files: %s (%s vs. %s)",
  60                                 path, name1, name2);
  61                         /* fallthru */
  62                 case XDL_MERGE_FAVOR_OURS:
  63                         stolen = src1;
  64                         break;
  65                 case XDL_MERGE_FAVOR_THEIRS:
  66                         stolen = src2;
  67                         break;
  68                 }
  69         }
  70
  71         result->ptr = stolen->ptr;
  72         result->size = stolen->size;
  73         stolen->ptr = NULL;
  74
  75         /*
  76          * With -Xtheirs or -Xours, we have cleanly merged;
  77          * otherwise we got a conflict.
  78          */
  79         return (opts->variant ? 0 : 1);
  80 }
  81
  82 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
  83                         mmbuffer_t *result,
  84                         const char *path,
  85                         mmfile_t *orig, const char *orig_name,
  86                         mmfile_t *src1, const char *name1,
  87                         mmfile_t *src2, const char *name2,
  88                         const struct ll_merge_options *opts,
  89                         int marker_size)
  90 {
  91         xmparam_t xmp;
  92         assert(opts);
  93
  94         if (orig->size > MAX_XDIFF_SIZE ||
  95             src1->size > MAX_XDIFF_SIZE ||
  96             src2->size > MAX_XDIFF_SIZE ||
  97             buffer_is_binary(orig->ptr, orig->size) ||
  98             buffer_is_binary(src1->ptr, src1->size) ||
  99             buffer_is_binary(src2->ptr, src2->size)) {
 100                 return ll_binary_merge(drv_unused, result,
 101                                        path,
 102                                        orig, orig_name,
 103                                        src1, name1,
 104                                        src2, name2,
 105                                        opts, marker_size);
 106         }
 107
 108         memset(&xmp, 0, sizeof(xmp));
 109         xmp.level = XDL_MERGE_ZEALOUS;
 110         xmp.favor = opts->variant;
 111         xmp.xpp.flags = opts->xdl_opts;
 112         if (git_xmerge_style >= 0)
 113                 xmp.style = git_xmerge_style;
 114         if (marker_size > 0)
 115                 xmp.marker_size = marker_size;
 116         xmp.ancestor = orig_name;
 117         xmp.file1 = name1;
 118         xmp.file2 = name2;
 119         return xdl_merge(orig, src1, src2, &xmp, result);
 120 }
 121
 122 static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 123                           mmbuffer_t *result,
 124                           const char *path_unused,
 125                           mmfile_t *orig, const char *orig_name,
 126                           mmfile_t *src1, const char *name1,
 127                           mmfile_t *src2, const char *name2,
 128                           const struct ll_merge_options *opts,
 129                           int marker_size)
 130 {
 131         /* Use union favor */
 132         struct ll_merge_options o;
 133         assert(opts);
 134         o = *opts;
 135         o.variant = XDL_MERGE_FAVOR_UNION;
 136         return ll_xdl_merge(drv_unused, result, path_unused,
 137                             orig, NULL, src1, NULL, src2, NULL,
 138                             &o, marker_size);
 139 }
 140
 141 #define LL_BINARY_MERGE 0
 142 #define LL_TEXT_MERGE 1
 143 #define LL_UNION_MERGE 2
 144 static struct ll_merge_driver ll_merge_drv[] = {
 145         { "binary", "built-in binary merge", ll_binary_merge },
 146         { "text", "built-in 3-way text merge", ll_xdl_merge },
 147         { "union", "built-in union merge", ll_union_merge },
 148 };
 149
 150 static void create_temp(mmfile_t *src, char *path, size_t len)
 151 {
 152         int fd;
 153
 154         xsnprintf(path, len, ".merge_file_XXXXXX");
 155         fd = xmkstemp(path);
 156         if (write_in_full(fd, src->ptr, src->size) != src->size)
 157                 die_errno("unable to write temp-file");
 158         close(fd);
 159 }
 160
 161 /*
 162  * User defined low-level merge driver support.
 163  */
 164 static int ll_ext_merge(const struct ll_merge_driver *fn,
 165                         mmbuffer_t *result,
 166                         const char *path,
 167                         mmfile_t *orig, const char *orig_name,
 168                         mmfile_t *src1, const char *name1,
 169                         mmfile_t *src2, const char *name2,
 170                         const struct ll_merge_options *opts,
 171                         int marker_size)
 172 {
 173         char temp[4][50];
 174         struct strbuf cmd = STRBUF_INIT;
 175         struct strbuf_expand_dict_entry dict[6];
 176         struct strbuf path_sq = STRBUF_INIT;
 177         const char *args[] = { NULL, NULL };
 178         int status, fd, i;
 179         struct stat st;
 180         assert(opts);
 181
 182         sq_quote_buf(&path_sq, path);
 183         dict[0].placeholder = "O"; dict[0].value = temp[0];
 184         dict[1].placeholder = "A"; dict[1].value = temp[1];
 185         dict[2].placeholder = "B"; dict[2].value = temp[2];
 186         dict[3].placeholder = "L"; dict[3].value = temp[3];
 187         dict[4].placeholder = "P"; dict[4].value = path_sq.buf;
 188         dict[5].placeholder = NULL; dict[5].value = NULL;
 189
 190         if (fn->cmdline == NULL)
 191                 die("custom merge driver %s lacks command line.", fn->name);
 192
 193         result->ptr = NULL;
 194         result->size = 0;
 195         create_temp(orig, temp[0], sizeof(temp[0]));
 196         create_temp(src1, temp[1], sizeof(temp[1]));
 197         create_temp(src2, temp[2], sizeof(temp[2]));
 198         xsnprintf(temp[3], sizeof(temp[3]), "%d", marker_size);
 199
 200         strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
 201
 202         args[0] = cmd.buf;
 203         status = run_command_v_opt(args, RUN_USING_SHELL);
 204         fd = open(temp[1], O_RDONLY);
 205         if (fd < 0)
 206                 goto bad;
 207         if (fstat(fd, &st))
 208                 goto close_bad;
 209         result->size = st.st_size;
 210         result->ptr = xmallocz(result->size);
 211         if (read_in_full(fd, result->ptr, result->size) != result->size) {
 212                 free(result->ptr);
 213                 result->ptr = NULL;
 214                 result->size = 0;
 215         }
 216  close_bad:
 217         close(fd);
 218  bad:
 219         for (i = 0; i < 3; i++)
 220                 unlink_or_warn(temp[i]);
 221         strbuf_release(&cmd);
 222         strbuf_release(&path_sq);
 223         return status;
 224 }
 225
 226 /*
 227  * merge.default and merge.driver configuration items
 228  */
 229 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 230 static const char *default_ll_merge;
 231
 232 static int read_merge_config(const char *var, const char *value, void *cb)
 233 {
 234         struct ll_merge_driver *fn;
 235         const char *key, *name;
 236         int namelen;
 237
 238         if (!strcmp(var, "merge.default"))
 239                 return git_config_string(&default_ll_merge, var, value);
 240
 241         /*
 242          * We are not interested in anything but "merge.<name>.variable";
 243          * especially, we do not want to look at variables such as
 244          * "merge.summary", "merge.tool", and "merge.verbosity".
 245          */
 246         if (parse_config_key(var, "merge", &name, &namelen, &key) < 0 || !name)
 247                 return 0;
 248
 249         /*
 250          * Find existing one as we might be processing merge.<name>.var2
 251          * after seeing merge.<name>.var1.
 252          */
 253         for (fn = ll_user_merge; fn; fn = fn->next)
 254                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 255                         break;
 256         if (!fn) {
 257                 fn = xcalloc(1, sizeof(struct ll_merge_driver));
 258                 fn->name = xmemdupz(name, namelen);
 259                 fn->fn = ll_ext_merge;
 260                 *ll_user_merge_tail = fn;
 261                 ll_user_merge_tail = &(fn->next);
 262         }
 263
 264         if (!strcmp("name", key))
 265                 return git_config_string(&fn->description, var, value);
 266
 267         if (!strcmp("driver", key)) {
 268                 if (!value)
 269                         return error("%s: lacks value", var);
 270                 /*
 271                  * merge.<name>.driver specifies the command line:
 272                  *
 273                  *      command-line
 274                  *
 275                  * The command-line will be interpolated with the following
 276                  * tokens and is given to the shell:
 277                  *
 278                  *    %O - temporary file name for the merge base.
 279                  *    %A - temporary file name for our version.
 280                  *    %B - temporary file name for the other branches' version.
 281                  *    %L - conflict marker length
 282                  *    %P - the original path (safely quoted for the shell)
 283                  *
 284                  * The external merge driver should write the results in the
 285                  * file named by %A, and signal that it has done with zero exit
 286                  * status.
 287                  */
 288                 fn->cmdline = xstrdup(value);
 289                 return 0;
 290         }
 291
 292         if (!strcmp("recursive", key))
 293                 return git_config_string(&fn->recursive, var, value);
 294
 295         return 0;
 296 }
 297
 298 static void initialize_ll_merge(void)
 299 {
 300         if (ll_user_merge_tail)
 301                 return;
 302         ll_user_merge_tail = &ll_user_merge;
 303         git_config(read_merge_config, NULL);
 304 }
 305
 306 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 307 {
 308         struct ll_merge_driver *fn;
 309         const char *name;
 310         int i;
 311
 312         initialize_ll_merge();
 313
 314         if (ATTR_TRUE(merge_attr))
 315                 return &ll_merge_drv[LL_TEXT_MERGE];
 316         else if (ATTR_FALSE(merge_attr))
 317                 return &ll_merge_drv[LL_BINARY_MERGE];
 318         else if (ATTR_UNSET(merge_attr)) {
 319                 if (!default_ll_merge)
 320                         return &ll_merge_drv[LL_TEXT_MERGE];
 321                 else
 322                         name = default_ll_merge;
 323         }
 324         else
 325                 name = merge_attr;
 326
 327         for (fn = ll_user_merge; fn; fn = fn->next)
 328                 if (!strcmp(fn->name, name))
 329                         return fn;
 330
 331         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 332                 if (!strcmp(ll_merge_drv[i].name, name))
 333                         return &ll_merge_drv[i];
 334
 335         /* default to the 3-way */
 336         return &ll_merge_drv[LL_TEXT_MERGE];
 337 }
 338
 339 static int git_path_check_merge(const char *path, struct git_attr_check check[2])
 340 {
 341         if (!check[0].attr) {
 342                 check[0].attr = git_attr("merge");
 343                 check[1].attr = git_attr("conflict-marker-size");
 344         }
 345         return git_check_attr(path, 2, check);
 346 }
 347
 348 static void normalize_file(mmfile_t *mm, const char *path)
 349 {
 350         struct strbuf strbuf = STRBUF_INIT;
 351         if (renormalize_buffer(path, mm->ptr, mm->size, &strbuf)) {
 352                 free(mm->ptr);
 353                 mm->size = strbuf.len;
 354                 mm->ptr = strbuf_detach(&strbuf, NULL);
 355         }
 356 }
 357
 358 int ll_merge(mmbuffer_t *result_buf,
 359              const char *path,
 360              mmfile_t *ancestor, const char *ancestor_label,
 361              mmfile_t *ours, const char *our_label,
 362              mmfile_t *theirs, const char *their_label,
 363              const struct ll_merge_options *opts)
 364 {
 365         static struct git_attr_check check[2];
 366         static const struct ll_merge_options default_opts;
 367         const char *ll_driver_name = NULL;
 368         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 369         const struct ll_merge_driver *driver;
 370
 371         if (!opts)
 372                 opts = &default_opts;
 373
 374         if (opts->renormalize) {
 375                 normalize_file(ancestor, path);
 376                 normalize_file(ours, path);
 377                 normalize_file(theirs, path);
 378         }
 379         if (!git_path_check_merge(path, check)) {
 380                 ll_driver_name = check[0].value;
 381                 if (check[1].value) {
 382                         marker_size = atoi(check[1].value);
 383                         if (marker_size <= 0)
 384                                 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 385                 }
 386         }
 387         driver = find_ll_merge_driver(ll_driver_name);
 388
 389         if (opts->virtual_ancestor) {
 390                 if (driver->recursive)
 391                         driver = find_ll_merge_driver(driver->recursive);
 392                 marker_size += 2;
 393         }
 394         return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
 395                           ours, our_label, theirs, their_label,
 396                           opts, marker_size);
 397 }
 398
 399 int ll_merge_marker_size(const char *path)
 400 {
 401         static struct git_attr_check check;
 402         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 403
 404         if (!check.attr)
 405                 check.attr = git_attr("conflict-marker-size");
 406         if (!git_check_attr(path, 1, &check) && check.value) {
 407                 marker_size = atoi(check.value);
 408                 if (marker_size <= 0)
 409                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 410         }
 411         return marker_size;
 412 }