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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 == XDL_MERGE_FAVOR_OURS ||
  95                opts->variant == XDL_MERGE_FAVOR_THEIRS ?
  96                0 : 1;
  97 }
  98
  99 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
 100                         mmbuffer_t *result,
 101                         const char *path,
 102                         mmfile_t *orig, const char *orig_name,
 103                         mmfile_t *src1, const char *name1,
 104                         mmfile_t *src2, const char *name2,
 105                         const struct ll_merge_options *opts,
 106                         int marker_size)
 107 {
 108         xmparam_t xmp;
 109         assert(opts);
 110
 111         if (orig->size > MAX_XDIFF_SIZE ||
 112             src1->size > MAX_XDIFF_SIZE ||
 113             src2->size > MAX_XDIFF_SIZE ||
 114             buffer_is_binary(orig->ptr, orig->size) ||
 115             buffer_is_binary(src1->ptr, src1->size) ||
 116             buffer_is_binary(src2->ptr, src2->size)) {
 117                 return ll_binary_merge(drv_unused, result,
 118                                        path,
 119                                        orig, orig_name,
 120                                        src1, name1,
 121                                        src2, name2,
 122                                        opts, marker_size);
 123         }
 124
 125         memset(&xmp, 0, sizeof(xmp));
 126         xmp.level = XDL_MERGE_ZEALOUS;
 127         xmp.favor = opts->variant;
 128         xmp.xpp.flags = opts->xdl_opts;
 129         if (git_xmerge_style >= 0)
 130                 xmp.style = git_xmerge_style;
 131         if (marker_size > 0)
 132                 xmp.marker_size = marker_size;
 133         xmp.ancestor = orig_name;
 134         xmp.file1 = name1;
 135         xmp.file2 = name2;
 136         return xdl_merge(orig, src1, src2, &xmp, result);
 137 }
 138
 139 static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 140                           mmbuffer_t *result,
 141                           const char *path,
 142                           mmfile_t *orig, const char *orig_name,
 143                           mmfile_t *src1, const char *name1,
 144                           mmfile_t *src2, const char *name2,
 145                           const struct ll_merge_options *opts,
 146                           int marker_size)
 147 {
 148         /* Use union favor */
 149         struct ll_merge_options o;
 150         assert(opts);
 151         o = *opts;
 152         o.variant = XDL_MERGE_FAVOR_UNION;
 153         return ll_xdl_merge(drv_unused, result, path,
 154                             orig, orig_name, src1, name1, src2, name2,
 155                             &o, marker_size);
 156 }
 157
 158 #define LL_BINARY_MERGE 0
 159 #define LL_TEXT_MERGE 1
 160 #define LL_UNION_MERGE 2
 161 static struct ll_merge_driver ll_merge_drv[] = {
 162         { "binary", "built-in binary merge", ll_binary_merge },
 163         { "text", "built-in 3-way text merge", ll_xdl_merge },
 164         { "union", "built-in union merge", ll_union_merge },
 165 };
 166
 167 static void create_temp(mmfile_t *src, char *path, size_t len)
 168 {
 169         int fd;
 170
 171         xsnprintf(path, len, ".merge_file_XXXXXX");
 172         fd = xmkstemp(path);
 173         if (write_in_full(fd, src->ptr, src->size) < 0)
 174                 die_errno("unable to write temp-file");
 175         close(fd);
 176 }
 177
 178 /*
 179  * User defined low-level merge driver support.
 180  */
 181 static int ll_ext_merge(const struct ll_merge_driver *fn,
 182                         mmbuffer_t *result,
 183                         const char *path,
 184                         mmfile_t *orig, const char *orig_name,
 185                         mmfile_t *src1, const char *name1,
 186                         mmfile_t *src2, const char *name2,
 187                         const struct ll_merge_options *opts,
 188                         int marker_size)
 189 {
 190         char temp[4][50];
 191         struct strbuf cmd = STRBUF_INIT;
 192         struct strbuf_expand_dict_entry dict[6];
 193         struct strbuf path_sq = STRBUF_INIT;
 194         const char *args[] = { NULL, NULL };
 195         int status, fd, i;
 196         struct stat st;
 197         assert(opts);
 198
 199         sq_quote_buf(&path_sq, path);
 200         dict[0].placeholder = "O"; dict[0].value = temp[0];
 201         dict[1].placeholder = "A"; dict[1].value = temp[1];
 202         dict[2].placeholder = "B"; dict[2].value = temp[2];
 203         dict[3].placeholder = "L"; dict[3].value = temp[3];
 204         dict[4].placeholder = "P"; dict[4].value = path_sq.buf;
 205         dict[5].placeholder = NULL; dict[5].value = NULL;
 206
 207         if (fn->cmdline == NULL)
 208                 die("custom merge driver %s lacks command line.", fn->name);
 209
 210         result->ptr = NULL;
 211         result->size = 0;
 212         create_temp(orig, temp[0], sizeof(temp[0]));
 213         create_temp(src1, temp[1], sizeof(temp[1]));
 214         create_temp(src2, temp[2], sizeof(temp[2]));
 215         xsnprintf(temp[3], sizeof(temp[3]), "%d", marker_size);
 216
 217         strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
 218
 219         args[0] = cmd.buf;
 220         status = run_command_v_opt(args, RUN_USING_SHELL);
 221         fd = open(temp[1], O_RDONLY);
 222         if (fd < 0)
 223                 goto bad;
 224         if (fstat(fd, &st))
 225                 goto close_bad;
 226         result->size = st.st_size;
 227         result->ptr = xmallocz(result->size);
 228         if (read_in_full(fd, result->ptr, result->size) != result->size) {
 229                 FREE_AND_NULL(result->ptr);
 230                 result->size = 0;
 231         }
 232  close_bad:
 233         close(fd);
 234  bad:
 235         for (i = 0; i < 3; i++)
 236                 unlink_or_warn(temp[i]);
 237         strbuf_release(&cmd);
 238         strbuf_release(&path_sq);
 239         return status;
 240 }
 241
 242 /*
 243  * merge.default and merge.driver configuration items
 244  */
 245 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 246 static const char *default_ll_merge;
 247
 248 static int read_merge_config(const char *var, const char *value, void *cb)
 249 {
 250         struct ll_merge_driver *fn;
 251         const char *key, *name;
 252         size_t namelen;
 253
 254         if (!strcmp(var, "merge.default"))
 255                 return git_config_string(&default_ll_merge, var, value);
 256
 257         /*
 258          * We are not interested in anything but "merge.<name>.variable";
 259          * especially, we do not want to look at variables such as
 260          * "merge.summary", "merge.tool", and "merge.verbosity".
 261          */
 262         if (parse_config_key(var, "merge", &name, &namelen, &key) < 0 || !name)
 263                 return 0;
 264
 265         /*
 266          * Find existing one as we might be processing merge.<name>.var2
 267          * after seeing merge.<name>.var1.
 268          */
 269         for (fn = ll_user_merge; fn; fn = fn->next)
 270                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 271                         break;
 272         if (!fn) {
 273                 CALLOC_ARRAY(fn, 1);
 274                 fn->name = xmemdupz(name, namelen);
 275                 fn->fn = ll_ext_merge;
 276                 *ll_user_merge_tail = fn;
 277                 ll_user_merge_tail = &(fn->next);
 278         }
 279
 280         if (!strcmp("name", key))
 281                 return git_config_string(&fn->description, var, value);
 282
 283         if (!strcmp("driver", key)) {
 284                 if (!value)
 285                         return error("%s: lacks value", var);
 286                 /*
 287                  * merge.<name>.driver specifies the command line:
 288                  *
 289                  *      command-line
 290                  *
 291                  * The command-line will be interpolated with the following
 292                  * tokens and is given to the shell:
 293                  *
 294                  *    %O - temporary file name for the merge base.
 295                  *    %A - temporary file name for our version.
 296                  *    %B - temporary file name for the other branches' version.
 297                  *    %L - conflict marker length
 298                  *    %P - the original path (safely quoted for the shell)
 299                  *
 300                  * The external merge driver should write the results in the
 301                  * file named by %A, and signal that it has done with zero exit
 302                  * status.
 303                  */
 304                 fn->cmdline = xstrdup(value);
 305                 return 0;
 306         }
 307
 308         if (!strcmp("recursive", key))
 309                 return git_config_string(&fn->recursive, var, value);
 310
 311         return 0;
 312 }
 313
 314 static void initialize_ll_merge(void)
 315 {
 316         if (ll_user_merge_tail)
 317                 return;
 318         ll_user_merge_tail = &ll_user_merge;
 319         git_config(read_merge_config, NULL);
 320 }
 321
 322 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 323 {
 324         struct ll_merge_driver *fn;
 325         const char *name;
 326         int i;
 327
 328         initialize_ll_merge();
 329
 330         if (ATTR_TRUE(merge_attr))
 331                 return &ll_merge_drv[LL_TEXT_MERGE];
 332         else if (ATTR_FALSE(merge_attr))
 333                 return &ll_merge_drv[LL_BINARY_MERGE];
 334         else if (ATTR_UNSET(merge_attr)) {
 335                 if (!default_ll_merge)
 336                         return &ll_merge_drv[LL_TEXT_MERGE];
 337                 else
 338                         name = default_ll_merge;
 339         }
 340         else
 341                 name = merge_attr;
 342
 343         for (fn = ll_user_merge; fn; fn = fn->next)
 344                 if (!strcmp(fn->name, name))
 345                         return fn;
 346
 347         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 348                 if (!strcmp(ll_merge_drv[i].name, name))
 349                         return &ll_merge_drv[i];
 350
 351         /* default to the 3-way */
 352         return &ll_merge_drv[LL_TEXT_MERGE];
 353 }
 354
 355 static void normalize_file(mmfile_t *mm, const char *path, struct index_state *istate)
 356 {
 357         struct strbuf strbuf = STRBUF_INIT;
 358         if (renormalize_buffer(istate, path, mm->ptr, mm->size, &strbuf)) {
 359                 free(mm->ptr);
 360                 mm->size = strbuf.len;
 361                 mm->ptr = strbuf_detach(&strbuf, NULL);
 362         }
 363 }
 364
 365 int ll_merge(mmbuffer_t *result_buf,
 366              const char *path,
 367              mmfile_t *ancestor, const char *ancestor_label,
 368              mmfile_t *ours, const char *our_label,
 369              mmfile_t *theirs, const char *their_label,
 370              struct index_state *istate,
 371              const struct ll_merge_options *opts)
 372 {
 373         struct attr_check *check = load_merge_attributes();
 374         static const struct ll_merge_options default_opts;
 375         const char *ll_driver_name = NULL;
 376         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 377         const struct ll_merge_driver *driver;
 378
 379         if (!opts)
 380                 opts = &default_opts;
 381
 382         if (opts->renormalize) {
 383                 normalize_file(ancestor, path, istate);
 384                 normalize_file(ours, path, istate);
 385                 normalize_file(theirs, path, istate);
 386         }
 387
 388         git_check_attr(istate, path, check);
 389         ll_driver_name = check->items[0].value;
 390         if (check->items[1].value) {
 391                 marker_size = atoi(check->items[1].value);
 392                 if (marker_size <= 0)
 393                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 394         }
 395         driver = find_ll_merge_driver(ll_driver_name);
 396
 397         if (opts->virtual_ancestor) {
 398                 if (driver->recursive)
 399                         driver = find_ll_merge_driver(driver->recursive);
 400         }
 401         if (opts->extra_marker_size) {
 402                 marker_size += opts->extra_marker_size;
 403         }
 404         return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
 405                           ours, our_label, theirs, their_label,
 406                           opts, marker_size);
 407 }
 408
 409 int ll_merge_marker_size(struct index_state *istate, const char *path)
 410 {
 411         static struct attr_check *check;
 412         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 413
 414         if (!check)
 415                 check = attr_check_initl("conflict-marker-size", NULL);
 416         git_check_attr(istate, path, check);
 417         if (check->items[0].value) {
 418                 marker_size = atoi(check->items[0].value);
 419                 if (marker_size <= 0)
 420                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 421         }
 422         return marker_size;
 423 }