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   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 "config.h"
   9 #include "attr.h"
  10 #include "xdiff-interface.h"
  11 #include "run-command.h"
  12 #include "ll-merge.h"
  13 #include "quote.h"
  14
  15 struct ll_merge_driver;
  16
  17 typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
  18                            mmbuffer_t *result,
  19                            const char *path,
  20                            mmfile_t *orig, const char *orig_name,
  21                            mmfile_t *src1, const char *name1,
  22                            mmfile_t *src2, const char *name2,
  23                            const struct ll_merge_options *opts,
  24                            int marker_size);
  25
  26 struct ll_merge_driver {
  27         const char *name;
  28         const char *description;
  29         ll_merge_fn fn;
  30         const char *recursive;
  31         struct ll_merge_driver *next;
  32         char *cmdline;
  33 };
  34
  35 static struct attr_check *merge_attributes;
  36 static struct attr_check *load_merge_attributes(void)
  37 {
  38         if (!merge_attributes)
  39                 merge_attributes = attr_check_initl("merge", "conflict-marker-size", NULL);
  40         return merge_attributes;
  41 }
  42
  43 void reset_merge_attributes(void)
  44 {
  45         attr_check_free(merge_attributes);
  46         merge_attributes = NULL;
  47 }
  48
  49 /*
  50  * Built-in low-levels
  51  */
  52 static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
  53                            mmbuffer_t *result,
  54                            const char *path,
  55                            mmfile_t *orig, const char *orig_name,
  56                            mmfile_t *src1, const char *name1,
  57                            mmfile_t *src2, const char *name2,
  58                            const struct ll_merge_options *opts,
  59                            int marker_size)
  60 {
  61         mmfile_t *stolen;
  62         assert(opts);
  63
  64         /*
  65          * The tentative merge result is the common ancestor for an
  66          * internal merge.  For the final merge, it is "ours" by
  67          * default but -Xours/-Xtheirs can tweak the choice.
  68          */
  69         if (opts->virtual_ancestor) {
  70                 stolen = orig;
  71         } else {
  72                 switch (opts->variant) {
  73                 default:
  74                         warning("Cannot merge binary files: %s (%s vs. %s)",
  75                                 path, name1, name2);
  76                         /* fallthru */
  77                 case XDL_MERGE_FAVOR_OURS:
  78                         stolen = src1;
  79                         break;
  80                 case XDL_MERGE_FAVOR_THEIRS:
  81                         stolen = src2;
  82                         break;
  83                 }
  84         }
  85
  86         result->ptr = stolen->ptr;
  87         result->size = stolen->size;
  88         stolen->ptr = NULL;
  89
  90         /*
  91          * With -Xtheirs or -Xours, we have cleanly merged;
  92          * otherwise we got a conflict.
  93          */
  94         return (opts->variant ? 0 : 1);
  95 }
  96
  97 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
  98                         mmbuffer_t *result,
  99                         const char *path,
 100                         mmfile_t *orig, const char *orig_name,
 101                         mmfile_t *src1, const char *name1,
 102                         mmfile_t *src2, const char *name2,
 103                         const struct ll_merge_options *opts,
 104                         int marker_size)
 105 {
 106         xmparam_t xmp;
 107         assert(opts);
 108
 109         if (orig->size > MAX_XDIFF_SIZE ||
 110             src1->size > MAX_XDIFF_SIZE ||
 111             src2->size > MAX_XDIFF_SIZE ||
 112             buffer_is_binary(orig->ptr, orig->size) ||
 113             buffer_is_binary(src1->ptr, src1->size) ||
 114             buffer_is_binary(src2->ptr, src2->size)) {
 115                 return ll_binary_merge(drv_unused, result,
 116                                        path,
 117                                        orig, orig_name,
 118                                        src1, name1,
 119                                        src2, name2,
 120                                        opts, marker_size);
 121         }
 122
 123         memset(&xmp, 0, sizeof(xmp));
 124         xmp.level = XDL_MERGE_ZEALOUS;
 125         xmp.favor = opts->variant;
 126         xmp.xpp.flags = opts->xdl_opts;
 127         if (git_xmerge_style >= 0)
 128                 xmp.style = git_xmerge_style;
 129         if (marker_size > 0)
 130                 xmp.marker_size = marker_size;
 131         xmp.ancestor = orig_name;
 132         xmp.file1 = name1;
 133         xmp.file2 = name2;
 134         return xdl_merge(orig, src1, src2, &xmp, result);
 135 }
 136
 137 static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 138                           mmbuffer_t *result,
 139                           const char *path_unused,
 140                           mmfile_t *orig, const char *orig_name,
 141                           mmfile_t *src1, const char *name1,
 142                           mmfile_t *src2, const char *name2,
 143                           const struct ll_merge_options *opts,
 144                           int marker_size)
 145 {
 146         /* Use union favor */
 147         struct ll_merge_options o;
 148         assert(opts);
 149         o = *opts;
 150         o.variant = XDL_MERGE_FAVOR_UNION;
 151         return ll_xdl_merge(drv_unused, result, path_unused,
 152                             orig, NULL, src1, NULL, src2, NULL,
 153                             &o, marker_size);
 154 }
 155
 156 #define LL_BINARY_MERGE 0
 157 #define LL_TEXT_MERGE 1
 158 #define LL_UNION_MERGE 2
 159 static struct ll_merge_driver ll_merge_drv[] = {
 160         { "binary", "built-in binary merge", ll_binary_merge },
 161         { "text", "built-in 3-way text merge", ll_xdl_merge },
 162         { "union", "built-in union merge", ll_union_merge },
 163 };
 164
 165 static void create_temp(mmfile_t *src, char *path, size_t len)
 166 {
 167         int fd;
 168
 169         xsnprintf(path, len, ".merge_file_XXXXXX");
 170         fd = xmkstemp(path);
 171         if (write_in_full(fd, src->ptr, src->size) < 0)
 172                 die_errno("unable to write temp-file");
 173         close(fd);
 174 }
 175
 176 /*
 177  * User defined low-level merge driver support.
 178  */
 179 static int ll_ext_merge(const struct ll_merge_driver *fn,
 180                         mmbuffer_t *result,
 181                         const char *path,
 182                         mmfile_t *orig, const char *orig_name,
 183                         mmfile_t *src1, const char *name1,
 184                         mmfile_t *src2, const char *name2,
 185                         const struct ll_merge_options *opts,
 186                         int marker_size)
 187 {
 188         char temp[4][50];
 189         struct strbuf cmd = STRBUF_INIT;
 190         struct strbuf_expand_dict_entry dict[6];
 191         struct strbuf path_sq = STRBUF_INIT;
 192         const char *args[] = { NULL, NULL };
 193         int status, fd, i;
 194         struct stat st;
 195         assert(opts);
 196
 197         sq_quote_buf(&path_sq, path);
 198         dict[0].placeholder = "O"; dict[0].value = temp[0];
 199         dict[1].placeholder = "A"; dict[1].value = temp[1];
 200         dict[2].placeholder = "B"; dict[2].value = temp[2];
 201         dict[3].placeholder = "L"; dict[3].value = temp[3];
 202         dict[4].placeholder = "P"; dict[4].value = path_sq.buf;
 203         dict[5].placeholder = NULL; dict[5].value = NULL;
 204
 205         if (fn->cmdline == NULL)
 206                 die("custom merge driver %s lacks command line.", fn->name);
 207
 208         result->ptr = NULL;
 209         result->size = 0;
 210         create_temp(orig, temp[0], sizeof(temp[0]));
 211         create_temp(src1, temp[1], sizeof(temp[1]));
 212         create_temp(src2, temp[2], sizeof(temp[2]));
 213         xsnprintf(temp[3], sizeof(temp[3]), "%d", marker_size);
 214
 215         strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
 216
 217         args[0] = cmd.buf;
 218         status = run_command_v_opt(args, RUN_USING_SHELL);
 219         fd = open(temp[1], O_RDONLY);
 220         if (fd < 0)
 221                 goto bad;
 222         if (fstat(fd, &st))
 223                 goto close_bad;
 224         result->size = st.st_size;
 225         result->ptr = xmallocz(result->size);
 226         if (read_in_full(fd, result->ptr, result->size) != result->size) {
 227                 FREE_AND_NULL(result->ptr);
 228                 result->size = 0;
 229         }
 230  close_bad:
 231         close(fd);
 232  bad:
 233         for (i = 0; i < 3; i++)
 234                 unlink_or_warn(temp[i]);
 235         strbuf_release(&cmd);
 236         strbuf_release(&path_sq);
 237         return status;
 238 }
 239
 240 /*
 241  * merge.default and merge.driver configuration items
 242  */
 243 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 244 static const char *default_ll_merge;
 245
 246 static int read_merge_config(const char *var, const char *value, void *cb)
 247 {
 248         struct ll_merge_driver *fn;
 249         const char *key, *name;
 250         size_t namelen;
 251
 252         if (!strcmp(var, "merge.default"))
 253                 return git_config_string(&default_ll_merge, var, value);
 254
 255         /*
 256          * We are not interested in anything but "merge.<name>.variable";
 257          * especially, we do not want to look at variables such as
 258          * "merge.summary", "merge.tool", and "merge.verbosity".
 259          */
 260         if (parse_config_key(var, "merge", &name, &namelen, &key) < 0 || !name)
 261                 return 0;
 262
 263         /*
 264          * Find existing one as we might be processing merge.<name>.var2
 265          * after seeing merge.<name>.var1.
 266          */
 267         for (fn = ll_user_merge; fn; fn = fn->next)
 268                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 269                         break;
 270         if (!fn) {
 271                 fn = xcalloc(1, sizeof(struct ll_merge_driver));
 272                 fn->name = xmemdupz(name, namelen);
 273                 fn->fn = ll_ext_merge;
 274                 *ll_user_merge_tail = fn;
 275                 ll_user_merge_tail = &(fn->next);
 276         }
 277
 278         if (!strcmp("name", key))
 279                 return git_config_string(&fn->description, var, value);
 280
 281         if (!strcmp("driver", key)) {
 282                 if (!value)
 283                         return error("%s: lacks value", var);
 284                 /*
 285                  * merge.<name>.driver specifies the command line:
 286                  *
 287                  *      command-line
 288                  *
 289                  * The command-line will be interpolated with the following
 290                  * tokens and is given to the shell:
 291                  *
 292                  *    %O - temporary file name for the merge base.
 293                  *    %A - temporary file name for our version.
 294                  *    %B - temporary file name for the other branches' version.
 295                  *    %L - conflict marker length
 296                  *    %P - the original path (safely quoted for the shell)
 297                  *
 298                  * The external merge driver should write the results in the
 299                  * file named by %A, and signal that it has done with zero exit
 300                  * status.
 301                  */
 302                 fn->cmdline = xstrdup(value);
 303                 return 0;
 304         }
 305
 306         if (!strcmp("recursive", key))
 307                 return git_config_string(&fn->recursive, var, value);
 308
 309         return 0;
 310 }
 311
 312 static void initialize_ll_merge(void)
 313 {
 314         if (ll_user_merge_tail)
 315                 return;
 316         ll_user_merge_tail = &ll_user_merge;
 317         git_config(read_merge_config, NULL);
 318 }
 319
 320 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 321 {
 322         struct ll_merge_driver *fn;
 323         const char *name;
 324         int i;
 325
 326         initialize_ll_merge();
 327
 328         if (ATTR_TRUE(merge_attr))
 329                 return &ll_merge_drv[LL_TEXT_MERGE];
 330         else if (ATTR_FALSE(merge_attr))
 331                 return &ll_merge_drv[LL_BINARY_MERGE];
 332         else if (ATTR_UNSET(merge_attr)) {
 333                 if (!default_ll_merge)
 334                         return &ll_merge_drv[LL_TEXT_MERGE];
 335                 else
 336                         name = default_ll_merge;
 337         }
 338         else
 339                 name = merge_attr;
 340
 341         for (fn = ll_user_merge; fn; fn = fn->next)
 342                 if (!strcmp(fn->name, name))
 343                         return fn;
 344
 345         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 346                 if (!strcmp(ll_merge_drv[i].name, name))
 347                         return &ll_merge_drv[i];
 348
 349         /* default to the 3-way */
 350         return &ll_merge_drv[LL_TEXT_MERGE];
 351 }
 352
 353 static void normalize_file(mmfile_t *mm, const char *path, struct index_state *istate)
 354 {
 355         struct strbuf strbuf = STRBUF_INIT;
 356         if (renormalize_buffer(istate, path, mm->ptr, mm->size, &strbuf)) {
 357                 free(mm->ptr);
 358                 mm->size = strbuf.len;
 359                 mm->ptr = strbuf_detach(&strbuf, NULL);
 360         }
 361 }
 362
 363 int ll_merge(mmbuffer_t *result_buf,
 364              const char *path,
 365              mmfile_t *ancestor, const char *ancestor_label,
 366              mmfile_t *ours, const char *our_label,
 367              mmfile_t *theirs, const char *their_label,
 368              struct index_state *istate,
 369              const struct ll_merge_options *opts)
 370 {
 371         struct attr_check *check = load_merge_attributes();
 372         static const struct ll_merge_options default_opts;
 373         const char *ll_driver_name = NULL;
 374         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 375         const struct ll_merge_driver *driver;
 376
 377         if (!opts)
 378                 opts = &default_opts;
 379
 380         if (opts->renormalize) {
 381                 normalize_file(ancestor, path, istate);
 382                 normalize_file(ours, path, istate);
 383                 normalize_file(theirs, path, istate);
 384         }
 385
 386         git_check_attr(istate, path, check);
 387         ll_driver_name = check->items[0].value;
 388         if (check->items[1].value) {
 389                 marker_size = atoi(check->items[1].value);
 390                 if (marker_size <= 0)
 391                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 392         }
 393         driver = find_ll_merge_driver(ll_driver_name);
 394
 395         if (opts->virtual_ancestor) {
 396                 if (driver->recursive)
 397                         driver = find_ll_merge_driver(driver->recursive);
 398         }
 399         if (opts->extra_marker_size) {
 400                 marker_size += opts->extra_marker_size;
 401         }
 402         return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
 403                           ours, our_label, theirs, their_label,
 404                           opts, marker_size);
 405 }
 406
 407 int ll_merge_marker_size(struct index_state *istate, const char *path)
 408 {
 409         static struct attr_check *check;
 410         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 411
 412         if (!check)
 413                 check = attr_check_initl("conflict-marker-size", NULL);
 414         git_check_attr(istate, path, check);
 415         if (check->items[0].value) {
 416                 marker_size = atoi(check->items[0].value);
 417                 if (marker_size <= 0)
 418                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 419         }
 420         return marker_size;
 421 }