merge-ll.c

   1 /*
   2  * Low level 3-way in-core file merge.
   3  *
   4  * Copyright (c) 2007 Junio C Hamano
   5  */
   6
   7 #include "git-compat-util.h"
   8 #include "config.h"
   9 #include "convert.h"
  10 #include "attr.h"
  11 #include "xdiff-interface.h"
  12 #include "run-command.h"
  13 #include "merge-ll.h"
  14 #include "quote.h"
  15 #include "strbuf.h"
  16
  17 struct ll_merge_driver;
  18
  19 typedef enum ll_merge_result (*ll_merge_fn)(const struct ll_merge_driver *,
  20                            mmbuffer_t *result,
  21                            const char *path,
  22                            mmfile_t *orig, const char *orig_name,
  23                            mmfile_t *src1, const char *name1,
  24                            mmfile_t *src2, const char *name2,
  25                            const struct ll_merge_options *opts,
  26                            int marker_size);
  27
  28 struct ll_merge_driver {
  29         const char *name;
  30         const char *description;
  31         ll_merge_fn fn;
  32         const char *recursive;
  33         struct ll_merge_driver *next;
  34         char *cmdline;
  35 };
  36
  37 static struct attr_check *merge_attributes;
  38 static struct attr_check *load_merge_attributes(void)
  39 {
  40         if (!merge_attributes)
  41                 merge_attributes = attr_check_initl("merge", "conflict-marker-size", NULL);
  42         return merge_attributes;
  43 }
  44
  45 void reset_merge_attributes(void)
  46 {
  47         attr_check_free(merge_attributes);
  48         merge_attributes = NULL;
  49 }
  50
  51 /*
  52  * Built-in low-levels
  53  */
  54 static enum ll_merge_result ll_binary_merge(const struct ll_merge_driver *drv UNUSED,
  55                            mmbuffer_t *result,
  56                            const char *path UNUSED,
  57                            mmfile_t *orig, const char *orig_name UNUSED,
  58                            mmfile_t *src1, const char *name1 UNUSED,
  59                            mmfile_t *src2, const char *name2 UNUSED,
  60                            const struct ll_merge_options *opts,
  61                            int marker_size UNUSED)
  62 {
  63         enum ll_merge_result ret;
  64         mmfile_t *stolen;
  65         assert(opts);
  66
  67         /*
  68          * The tentative merge result is the common ancestor for an
  69          * internal merge.  For the final merge, it is "ours" by
  70          * default but -Xours/-Xtheirs can tweak the choice.
  71          */
  72         if (opts->virtual_ancestor) {
  73                 stolen = orig;
  74                 ret = LL_MERGE_OK;
  75         } else {
  76                 switch (opts->variant) {
  77                 default:
  78                         ret = LL_MERGE_BINARY_CONFLICT;
  79                         stolen = src1;
  80                         break;
  81                 case XDL_MERGE_FAVOR_OURS:
  82                         ret = LL_MERGE_OK;
  83                         stolen = src1;
  84                         break;
  85                 case XDL_MERGE_FAVOR_THEIRS:
  86                         ret = LL_MERGE_OK;
  87                         stolen = src2;
  88                         break;
  89                 }
  90         }
  91
  92         result->ptr = stolen->ptr;
  93         result->size = stolen->size;
  94         stolen->ptr = NULL;
  95
  96         return ret;
  97 }
  98
  99 static enum ll_merge_result 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         enum ll_merge_result ret;
 109         xmparam_t xmp;
 110         int status;
 111         assert(opts);
 112
 113         if (orig->size > MAX_XDIFF_SIZE ||
 114             src1->size > MAX_XDIFF_SIZE ||
 115             src2->size > MAX_XDIFF_SIZE ||
 116             buffer_is_binary(orig->ptr, orig->size) ||
 117             buffer_is_binary(src1->ptr, src1->size) ||
 118             buffer_is_binary(src2->ptr, src2->size)) {
 119                 return ll_binary_merge(drv_unused, result,
 120                                        path,
 121                                        orig, orig_name,
 122                                        src1, name1,
 123                                        src2, name2,
 124                                        opts, marker_size);
 125         }
 126
 127         memset(&xmp, 0, sizeof(xmp));
 128         xmp.level = XDL_MERGE_ZEALOUS;
 129         xmp.favor = opts->variant;
 130         xmp.xpp.flags = opts->xdl_opts;
 131         if (git_xmerge_style >= 0)
 132                 xmp.style = git_xmerge_style;
 133         if (marker_size > 0)
 134                 xmp.marker_size = marker_size;
 135         xmp.ancestor = orig_name;
 136         xmp.file1 = name1;
 137         xmp.file2 = name2;
 138         status = xdl_merge(orig, src1, src2, &xmp, result);
 139         ret = (status > 0) ? LL_MERGE_CONFLICT : status;
 140         return ret;
 141 }
 142
 143 static enum ll_merge_result ll_union_merge(const struct ll_merge_driver *drv_unused,
 144                           mmbuffer_t *result,
 145                           const char *path,
 146                           mmfile_t *orig, const char *orig_name,
 147                           mmfile_t *src1, const char *name1,
 148                           mmfile_t *src2, const char *name2,
 149                           const struct ll_merge_options *opts,
 150                           int marker_size)
 151 {
 152         /* Use union favor */
 153         struct ll_merge_options o;
 154         assert(opts);
 155         o = *opts;
 156         o.variant = XDL_MERGE_FAVOR_UNION;
 157         return ll_xdl_merge(drv_unused, result, path,
 158                             orig, orig_name, src1, name1, src2, name2,
 159                             &o, marker_size);
 160 }
 161
 162 #define LL_BINARY_MERGE 0
 163 #define LL_TEXT_MERGE 1
 164 #define LL_UNION_MERGE 2
 165 static struct ll_merge_driver ll_merge_drv[] = {
 166         { "binary", "built-in binary merge", ll_binary_merge },
 167         { "text", "built-in 3-way text merge", ll_xdl_merge },
 168         { "union", "built-in union merge", ll_union_merge },
 169 };
 170
 171 static void create_temp(mmfile_t *src, char *path, size_t len)
 172 {
 173         int fd;
 174
 175         xsnprintf(path, len, ".merge_file_XXXXXX");
 176         fd = xmkstemp(path);
 177         if (write_in_full(fd, src->ptr, src->size) < 0)
 178                 die_errno("unable to write temp-file");
 179         close(fd);
 180 }
 181
 182 /*
 183  * User defined low-level merge driver support.
 184  */
 185 static enum ll_merge_result ll_ext_merge(const struct ll_merge_driver *fn,
 186                         mmbuffer_t *result,
 187                         const char *path,
 188                         mmfile_t *orig, const char *orig_name UNUSED,
 189                         mmfile_t *src1, const char *name1 UNUSED,
 190                         mmfile_t *src2, const char *name2 UNUSED,
 191                         const struct ll_merge_options *opts,
 192                         int marker_size)
 193 {
 194         char temp[3][50];
 195         struct strbuf cmd = STRBUF_INIT;
 196         const char *format = fn->cmdline;
 197         struct child_process child = CHILD_PROCESS_INIT;
 198         int status, fd, i;
 199         struct stat st;
 200         enum ll_merge_result ret;
 201         assert(opts);
 202
 203         if (!fn->cmdline)
 204                 die("custom merge driver %s lacks command line.", fn->name);
 205
 206         result->ptr = NULL;
 207         result->size = 0;
 208         create_temp(orig, temp[0], sizeof(temp[0]));
 209         create_temp(src1, temp[1], sizeof(temp[1]));
 210         create_temp(src2, temp[2], sizeof(temp[2]));
 211
 212         while (strbuf_expand_step(&cmd, &format)) {
 213                 if (skip_prefix(format, "%", &format))
 214                         strbuf_addch(&cmd, '%');
 215                 else if (skip_prefix(format, "O", &format))
 216                         strbuf_addstr(&cmd, temp[0]);
 217                 else if (skip_prefix(format, "A", &format))
 218                         strbuf_addstr(&cmd, temp[1]);
 219                 else if (skip_prefix(format, "B", &format))
 220                         strbuf_addstr(&cmd, temp[2]);
 221                 else if (skip_prefix(format, "L", &format))
 222                         strbuf_addf(&cmd, "%d", marker_size);
 223                 else if (skip_prefix(format, "P", &format))
 224                         sq_quote_buf(&cmd, path);
 225                 else
 226                         strbuf_addch(&cmd, '%');
 227         }
 228
 229         child.use_shell = 1;
 230         strvec_push(&child.args, cmd.buf);
 231         status = run_command(&child);
 232         fd = open(temp[1], O_RDONLY);
 233         if (fd < 0)
 234                 goto bad;
 235         if (fstat(fd, &st))
 236                 goto close_bad;
 237         result->size = st.st_size;
 238         result->ptr = xmallocz(result->size);
 239         if (read_in_full(fd, result->ptr, result->size) != result->size) {
 240                 FREE_AND_NULL(result->ptr);
 241                 result->size = 0;
 242         }
 243  close_bad:
 244         close(fd);
 245  bad:
 246         for (i = 0; i < 3; i++)
 247                 unlink_or_warn(temp[i]);
 248         strbuf_release(&cmd);
 249         if (!status)
 250                 ret = LL_MERGE_OK;
 251         else if (status <= 128)
 252                 ret = LL_MERGE_CONFLICT;
 253         else
 254                 /* died due to a signal: WTERMSIG(status) + 128 */
 255                 ret = LL_MERGE_ERROR;
 256         return ret;
 257 }
 258
 259 /*
 260  * merge.default and merge.driver configuration items
 261  */
 262 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 263 static const char *default_ll_merge;
 264
 265 static int read_merge_config(const char *var, const char *value,
 266                              const struct config_context *ctx UNUSED,
 267                              void *cb UNUSED)
 268 {
 269         struct ll_merge_driver *fn;
 270         const char *key, *name;
 271         size_t namelen;
 272
 273         if (!strcmp(var, "merge.default"))
 274                 return git_config_string(&default_ll_merge, var, value);
 275
 276         /*
 277          * We are not interested in anything but "merge.<name>.variable";
 278          * especially, we do not want to look at variables such as
 279          * "merge.summary", "merge.tool", and "merge.verbosity".
 280          */
 281         if (parse_config_key(var, "merge", &name, &namelen, &key) < 0 || !name)
 282                 return 0;
 283
 284         /*
 285          * Find existing one as we might be processing merge.<name>.var2
 286          * after seeing merge.<name>.var1.
 287          */
 288         for (fn = ll_user_merge; fn; fn = fn->next)
 289                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 290                         break;
 291         if (!fn) {
 292                 CALLOC_ARRAY(fn, 1);
 293                 fn->name = xmemdupz(name, namelen);
 294                 fn->fn = ll_ext_merge;
 295                 *ll_user_merge_tail = fn;
 296                 ll_user_merge_tail = &(fn->next);
 297         }
 298
 299         if (!strcmp("name", key))
 300                 return git_config_string(&fn->description, var, value);
 301
 302         if (!strcmp("driver", key)) {
 303                 if (!value)
 304                         return error("%s: lacks value", var);
 305                 /*
 306                  * merge.<name>.driver specifies the command line:
 307                  *
 308                  *      command-line
 309                  *
 310                  * The command-line will be interpolated with the following
 311                  * tokens and is given to the shell:
 312                  *
 313                  *    %O - temporary file name for the merge base.
 314                  *    %A - temporary file name for our version.
 315                  *    %B - temporary file name for the other branches' version.
 316                  *    %L - conflict marker length
 317                  *    %P - the original path (safely quoted for the shell)
 318                  *
 319                  * The external merge driver should write the results in the
 320                  * file named by %A, and signal that it has done with zero exit
 321                  * status.
 322                  */
 323                 fn->cmdline = xstrdup(value);
 324                 return 0;
 325         }
 326
 327         if (!strcmp("recursive", key))
 328                 return git_config_string(&fn->recursive, var, value);
 329
 330         return 0;
 331 }
 332
 333 static void initialize_ll_merge(void)
 334 {
 335         if (ll_user_merge_tail)
 336                 return;
 337         ll_user_merge_tail = &ll_user_merge;
 338         git_config(read_merge_config, NULL);
 339 }
 340
 341 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 342 {
 343         struct ll_merge_driver *fn;
 344         const char *name;
 345         int i;
 346
 347         initialize_ll_merge();
 348
 349         if (ATTR_TRUE(merge_attr))
 350                 return &ll_merge_drv[LL_TEXT_MERGE];
 351         else if (ATTR_FALSE(merge_attr))
 352                 return &ll_merge_drv[LL_BINARY_MERGE];
 353         else if (ATTR_UNSET(merge_attr)) {
 354                 if (!default_ll_merge)
 355                         return &ll_merge_drv[LL_TEXT_MERGE];
 356                 else
 357                         name = default_ll_merge;
 358         }
 359         else
 360                 name = merge_attr;
 361
 362         for (fn = ll_user_merge; fn; fn = fn->next)
 363                 if (!strcmp(fn->name, name))
 364                         return fn;
 365
 366         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 367                 if (!strcmp(ll_merge_drv[i].name, name))
 368                         return &ll_merge_drv[i];
 369
 370         /* default to the 3-way */
 371         return &ll_merge_drv[LL_TEXT_MERGE];
 372 }
 373
 374 static void normalize_file(mmfile_t *mm, const char *path, struct index_state *istate)
 375 {
 376         struct strbuf strbuf = STRBUF_INIT;
 377         if (renormalize_buffer(istate, path, mm->ptr, mm->size, &strbuf)) {
 378                 free(mm->ptr);
 379                 mm->size = strbuf.len;
 380                 mm->ptr = strbuf_detach(&strbuf, NULL);
 381         }
 382 }
 383
 384 enum ll_merge_result ll_merge(mmbuffer_t *result_buf,
 385              const char *path,
 386              mmfile_t *ancestor, const char *ancestor_label,
 387              mmfile_t *ours, const char *our_label,
 388              mmfile_t *theirs, const char *their_label,
 389              struct index_state *istate,
 390              const struct ll_merge_options *opts)
 391 {
 392         struct attr_check *check = load_merge_attributes();
 393         static const struct ll_merge_options default_opts;
 394         const char *ll_driver_name = NULL;
 395         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 396         const struct ll_merge_driver *driver;
 397
 398         if (!opts)
 399                 opts = &default_opts;
 400
 401         if (opts->renormalize) {
 402                 normalize_file(ancestor, path, istate);
 403                 normalize_file(ours, path, istate);
 404                 normalize_file(theirs, path, istate);
 405         }
 406
 407         git_check_attr(istate, path, check);
 408         ll_driver_name = check->items[0].value;
 409         if (check->items[1].value) {
 410                 marker_size = atoi(check->items[1].value);
 411                 if (marker_size <= 0)
 412                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 413         }
 414         driver = find_ll_merge_driver(ll_driver_name);
 415
 416         if (opts->virtual_ancestor) {
 417                 if (driver->recursive)
 418                         driver = find_ll_merge_driver(driver->recursive);
 419         }
 420         if (opts->extra_marker_size) {
 421                 marker_size += opts->extra_marker_size;
 422         }
 423         return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
 424                           ours, our_label, theirs, their_label,
 425                           opts, marker_size);
 426 }
 427
 428 int ll_merge_marker_size(struct index_state *istate, const char *path)
 429 {
 430         static struct attr_check *check;
 431         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 432
 433         if (!check)
 434                 check = attr_check_initl("conflict-marker-size", NULL);
 435         git_check_attr(istate, path, check);
 436         if (check->items[0].value) {
 437                 marker_size = atoi(check->items[0].value);
 438                 if (marker_size <= 0)
 439                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 440         }
 441         return marker_size;
 442 }