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 "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 enum ll_merge_result (*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 enum ll_merge_result 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         enum ll_merge_result ret;
  62         mmfile_t *stolen;
  63         assert(opts);
  64
  65         /*
  66          * The tentative merge result is the common ancestor for an
  67          * internal merge.  For the final merge, it is "ours" by
  68          * default but -Xours/-Xtheirs can tweak the choice.
  69          */
  70         if (opts->virtual_ancestor) {
  71                 stolen = orig;
  72                 ret = LL_MERGE_OK;
  73         } else {
  74                 switch (opts->variant) {
  75                 default:
  76                         ret = LL_MERGE_BINARY_CONFLICT;
  77                         stolen = src1;
  78                         break;
  79                 case XDL_MERGE_FAVOR_OURS:
  80                         ret = LL_MERGE_OK;
  81                         stolen = src1;
  82                         break;
  83                 case XDL_MERGE_FAVOR_THEIRS:
  84                         ret = LL_MERGE_OK;
  85                         stolen = src2;
  86                         break;
  87                 }
  88         }
  89
  90         result->ptr = stolen->ptr;
  91         result->size = stolen->size;
  92         stolen->ptr = NULL;
  93
  94         return ret;
  95 }
  96
  97 static enum ll_merge_result 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         enum ll_merge_result ret;
 107         xmparam_t xmp;
 108         int status;
 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         status = xdl_merge(orig, src1, src2, &xmp, result);
 137         ret = (status > 0) ? LL_MERGE_CONFLICT : status;
 138         return ret;
 139 }
 140
 141 static enum ll_merge_result ll_union_merge(const struct ll_merge_driver *drv_unused,
 142                           mmbuffer_t *result,
 143                           const char *path,
 144                           mmfile_t *orig, const char *orig_name,
 145                           mmfile_t *src1, const char *name1,
 146                           mmfile_t *src2, const char *name2,
 147                           const struct ll_merge_options *opts,
 148                           int marker_size)
 149 {
 150         /* Use union favor */
 151         struct ll_merge_options o;
 152         assert(opts);
 153         o = *opts;
 154         o.variant = XDL_MERGE_FAVOR_UNION;
 155         return ll_xdl_merge(drv_unused, result, path,
 156                             orig, orig_name, src1, name1, src2, name2,
 157                             &o, marker_size);
 158 }
 159
 160 #define LL_BINARY_MERGE 0
 161 #define LL_TEXT_MERGE 1
 162 #define LL_UNION_MERGE 2
 163 static struct ll_merge_driver ll_merge_drv[] = {
 164         { "binary", "built-in binary merge", ll_binary_merge },
 165         { "text", "built-in 3-way text merge", ll_xdl_merge },
 166         { "union", "built-in union merge", ll_union_merge },
 167 };
 168
 169 static void create_temp(mmfile_t *src, char *path, size_t len)
 170 {
 171         int fd;
 172
 173         xsnprintf(path, len, ".merge_file_XXXXXX");
 174         fd = xmkstemp(path);
 175         if (write_in_full(fd, src->ptr, src->size) < 0)
 176                 die_errno("unable to write temp-file");
 177         close(fd);
 178 }
 179
 180 /*
 181  * User defined low-level merge driver support.
 182  */
 183 static enum ll_merge_result ll_ext_merge(const struct ll_merge_driver *fn,
 184                         mmbuffer_t *result,
 185                         const char *path,
 186                         mmfile_t *orig, const char *orig_name,
 187                         mmfile_t *src1, const char *name1,
 188                         mmfile_t *src2, const char *name2,
 189                         const struct ll_merge_options *opts,
 190                         int marker_size)
 191 {
 192         char temp[4][50];
 193         struct strbuf cmd = STRBUF_INIT;
 194         struct strbuf_expand_dict_entry dict[6];
 195         struct strbuf path_sq = STRBUF_INIT;
 196         struct child_process child = CHILD_PROCESS_INIT;
 197         int status, fd, i;
 198         struct stat st;
 199         enum ll_merge_result ret;
 200         assert(opts);
 201
 202         sq_quote_buf(&path_sq, path);
 203         dict[0].placeholder = "O"; dict[0].value = temp[0];
 204         dict[1].placeholder = "A"; dict[1].value = temp[1];
 205         dict[2].placeholder = "B"; dict[2].value = temp[2];
 206         dict[3].placeholder = "L"; dict[3].value = temp[3];
 207         dict[4].placeholder = "P"; dict[4].value = path_sq.buf;
 208         dict[5].placeholder = NULL; dict[5].value = NULL;
 209
 210         if (!fn->cmdline)
 211                 die("custom merge driver %s lacks command line.", fn->name);
 212
 213         result->ptr = NULL;
 214         result->size = 0;
 215         create_temp(orig, temp[0], sizeof(temp[0]));
 216         create_temp(src1, temp[1], sizeof(temp[1]));
 217         create_temp(src2, temp[2], sizeof(temp[2]));
 218         xsnprintf(temp[3], sizeof(temp[3]), "%d", marker_size);
 219
 220         strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
 221
 222         child.use_shell = 1;
 223         strvec_push(&child.args, cmd.buf);
 224         status = run_command(&child);
 225         fd = open(temp[1], O_RDONLY);
 226         if (fd < 0)
 227                 goto bad;
 228         if (fstat(fd, &st))
 229                 goto close_bad;
 230         result->size = st.st_size;
 231         result->ptr = xmallocz(result->size);
 232         if (read_in_full(fd, result->ptr, result->size) != result->size) {
 233                 FREE_AND_NULL(result->ptr);
 234                 result->size = 0;
 235         }
 236  close_bad:
 237         close(fd);
 238  bad:
 239         for (i = 0; i < 3; i++)
 240                 unlink_or_warn(temp[i]);
 241         strbuf_release(&cmd);
 242         strbuf_release(&path_sq);
 243         ret = (status > 0) ? LL_MERGE_CONFLICT : status;
 244         return ret;
 245 }
 246
 247 /*
 248  * merge.default and merge.driver configuration items
 249  */
 250 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 251 static const char *default_ll_merge;
 252
 253 static int read_merge_config(const char *var, const char *value,
 254                              void *cb UNUSED)
 255 {
 256         struct ll_merge_driver *fn;
 257         const char *key, *name;
 258         size_t namelen;
 259
 260         if (!strcmp(var, "merge.default"))
 261                 return git_config_string(&default_ll_merge, var, value);
 262
 263         /*
 264          * We are not interested in anything but "merge.<name>.variable";
 265          * especially, we do not want to look at variables such as
 266          * "merge.summary", "merge.tool", and "merge.verbosity".
 267          */
 268         if (parse_config_key(var, "merge", &name, &namelen, &key) < 0 || !name)
 269                 return 0;
 270
 271         /*
 272          * Find existing one as we might be processing merge.<name>.var2
 273          * after seeing merge.<name>.var1.
 274          */
 275         for (fn = ll_user_merge; fn; fn = fn->next)
 276                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 277                         break;
 278         if (!fn) {
 279                 CALLOC_ARRAY(fn, 1);
 280                 fn->name = xmemdupz(name, namelen);
 281                 fn->fn = ll_ext_merge;
 282                 *ll_user_merge_tail = fn;
 283                 ll_user_merge_tail = &(fn->next);
 284         }
 285
 286         if (!strcmp("name", key))
 287                 return git_config_string(&fn->description, var, value);
 288
 289         if (!strcmp("driver", key)) {
 290                 if (!value)
 291                         return error("%s: lacks value", var);
 292                 /*
 293                  * merge.<name>.driver specifies the command line:
 294                  *
 295                  *      command-line
 296                  *
 297                  * The command-line will be interpolated with the following
 298                  * tokens and is given to the shell:
 299                  *
 300                  *    %O - temporary file name for the merge base.
 301                  *    %A - temporary file name for our version.
 302                  *    %B - temporary file name for the other branches' version.
 303                  *    %L - conflict marker length
 304                  *    %P - the original path (safely quoted for the shell)
 305                  *
 306                  * The external merge driver should write the results in the
 307                  * file named by %A, and signal that it has done with zero exit
 308                  * status.
 309                  */
 310                 fn->cmdline = xstrdup(value);
 311                 return 0;
 312         }
 313
 314         if (!strcmp("recursive", key))
 315                 return git_config_string(&fn->recursive, var, value);
 316
 317         return 0;
 318 }
 319
 320 static void initialize_ll_merge(void)
 321 {
 322         if (ll_user_merge_tail)
 323                 return;
 324         ll_user_merge_tail = &ll_user_merge;
 325         git_config(read_merge_config, NULL);
 326 }
 327
 328 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 329 {
 330         struct ll_merge_driver *fn;
 331         const char *name;
 332         int i;
 333
 334         initialize_ll_merge();
 335
 336         if (ATTR_TRUE(merge_attr))
 337                 return &ll_merge_drv[LL_TEXT_MERGE];
 338         else if (ATTR_FALSE(merge_attr))
 339                 return &ll_merge_drv[LL_BINARY_MERGE];
 340         else if (ATTR_UNSET(merge_attr)) {
 341                 if (!default_ll_merge)
 342                         return &ll_merge_drv[LL_TEXT_MERGE];
 343                 else
 344                         name = default_ll_merge;
 345         }
 346         else
 347                 name = merge_attr;
 348
 349         for (fn = ll_user_merge; fn; fn = fn->next)
 350                 if (!strcmp(fn->name, name))
 351                         return fn;
 352
 353         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 354                 if (!strcmp(ll_merge_drv[i].name, name))
 355                         return &ll_merge_drv[i];
 356
 357         /* default to the 3-way */
 358         return &ll_merge_drv[LL_TEXT_MERGE];
 359 }
 360
 361 static void normalize_file(mmfile_t *mm, const char *path, struct index_state *istate)
 362 {
 363         struct strbuf strbuf = STRBUF_INIT;
 364         if (renormalize_buffer(istate, path, mm->ptr, mm->size, &strbuf)) {
 365                 free(mm->ptr);
 366                 mm->size = strbuf.len;
 367                 mm->ptr = strbuf_detach(&strbuf, NULL);
 368         }
 369 }
 370
 371 enum ll_merge_result ll_merge(mmbuffer_t *result_buf,
 372              const char *path,
 373              mmfile_t *ancestor, const char *ancestor_label,
 374              mmfile_t *ours, const char *our_label,
 375              mmfile_t *theirs, const char *their_label,
 376              struct index_state *istate,
 377              const struct ll_merge_options *opts)
 378 {
 379         struct attr_check *check = load_merge_attributes();
 380         static const struct ll_merge_options default_opts;
 381         const char *ll_driver_name = NULL;
 382         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 383         const struct ll_merge_driver *driver;
 384
 385         if (!opts)
 386                 opts = &default_opts;
 387
 388         if (opts->renormalize) {
 389                 normalize_file(ancestor, path, istate);
 390                 normalize_file(ours, path, istate);
 391                 normalize_file(theirs, path, istate);
 392         }
 393
 394         git_check_attr(istate, path, check);
 395         ll_driver_name = check->items[0].value;
 396         if (check->items[1].value) {
 397                 marker_size = atoi(check->items[1].value);
 398                 if (marker_size <= 0)
 399                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 400         }
 401         driver = find_ll_merge_driver(ll_driver_name);
 402
 403         if (opts->virtual_ancestor) {
 404                 if (driver->recursive)
 405                         driver = find_ll_merge_driver(driver->recursive);
 406         }
 407         if (opts->extra_marker_size) {
 408                 marker_size += opts->extra_marker_size;
 409         }
 410         return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
 411                           ours, our_label, theirs, their_label,
 412                           opts, marker_size);
 413 }
 414
 415 int ll_merge_marker_size(struct index_state *istate, const char *path)
 416 {
 417         static struct attr_check *check;
 418         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 419
 420         if (!check)
 421                 check = attr_check_initl("conflict-marker-size", NULL);
 422         git_check_attr(istate, path, check);
 423         if (check->items[0].value) {
 424                 marker_size = atoi(check->items[0].value);
 425                 if (marker_size <= 0)
 426                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 427         }
 428         return marker_size;
 429 }