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 #include "wrapper.h"
  17
  18 struct ll_merge_driver;
  19
  20 typedef enum ll_merge_result (*ll_merge_fn)(const struct ll_merge_driver *,
  21                            mmbuffer_t *result,
  22                            const char *path,
  23                            mmfile_t *orig, const char *orig_name,
  24                            mmfile_t *src1, const char *name1,
  25                            mmfile_t *src2, const char *name2,
  26                            const struct ll_merge_options *opts,
  27                            int marker_size);
  28
  29 struct ll_merge_driver {
  30         const char *name;
  31         const char *description;
  32         ll_merge_fn fn;
  33         const char *recursive;
  34         struct ll_merge_driver *next;
  35         char *cmdline;
  36 };
  37
  38 static struct attr_check *merge_attributes;
  39 static struct attr_check *load_merge_attributes(void)
  40 {
  41         if (!merge_attributes)
  42                 merge_attributes = attr_check_initl("merge", "conflict-marker-size", NULL);
  43         return merge_attributes;
  44 }
  45
  46 void reset_merge_attributes(void)
  47 {
  48         attr_check_free(merge_attributes);
  49         merge_attributes = NULL;
  50 }
  51
  52 /*
  53  * Built-in low-levels
  54  */
  55 static enum ll_merge_result ll_binary_merge(const struct ll_merge_driver *drv UNUSED,
  56                            mmbuffer_t *result,
  57                            const char *path UNUSED,
  58                            mmfile_t *orig, const char *orig_name UNUSED,
  59                            mmfile_t *src1, const char *name1 UNUSED,
  60                            mmfile_t *src2, const char *name2 UNUSED,
  61                            const struct ll_merge_options *opts,
  62                            int marker_size UNUSED)
  63 {
  64         enum ll_merge_result ret;
  65         mmfile_t *stolen;
  66         assert(opts);
  67
  68         /*
  69          * The tentative merge result is the common ancestor for an
  70          * internal merge.  For the final merge, it is "ours" by
  71          * default but -Xours/-Xtheirs can tweak the choice.
  72          */
  73         if (opts->virtual_ancestor) {
  74                 stolen = orig;
  75                 ret = LL_MERGE_OK;
  76         } else {
  77                 switch (opts->variant) {
  78                 default:
  79                         ret = LL_MERGE_BINARY_CONFLICT;
  80                         stolen = src1;
  81                         break;
  82                 case XDL_MERGE_FAVOR_OURS:
  83                         ret = LL_MERGE_OK;
  84                         stolen = src1;
  85                         break;
  86                 case XDL_MERGE_FAVOR_THEIRS:
  87                         ret = LL_MERGE_OK;
  88                         stolen = src2;
  89                         break;
  90                 }
  91         }
  92
  93         result->ptr = stolen->ptr;
  94         result->size = stolen->size;
  95         stolen->ptr = NULL;
  96
  97         return ret;
  98 }
  99
 100 static enum ll_merge_result ll_xdl_merge(const struct ll_merge_driver *drv_unused,
 101                         mmbuffer_t *result,
 102                         const char *path,
 103                         mmfile_t *orig, const char *orig_name,
 104                         mmfile_t *src1, const char *name1,
 105                         mmfile_t *src2, const char *name2,
 106                         const struct ll_merge_options *opts,
 107                         int marker_size)
 108 {
 109         enum ll_merge_result ret;
 110         xmparam_t xmp;
 111         int status;
 112         assert(opts);
 113
 114         if (orig->size > MAX_XDIFF_SIZE ||
 115             src1->size > MAX_XDIFF_SIZE ||
 116             src2->size > MAX_XDIFF_SIZE ||
 117             buffer_is_binary(orig->ptr, orig->size) ||
 118             buffer_is_binary(src1->ptr, src1->size) ||
 119             buffer_is_binary(src2->ptr, src2->size)) {
 120                 return ll_binary_merge(drv_unused, result,
 121                                        path,
 122                                        orig, orig_name,
 123                                        src1, name1,
 124                                        src2, name2,
 125                                        opts, marker_size);
 126         }
 127
 128         memset(&xmp, 0, sizeof(xmp));
 129         xmp.level = XDL_MERGE_ZEALOUS;
 130         xmp.favor = opts->variant;
 131         xmp.xpp.flags = opts->xdl_opts;
 132         if (git_xmerge_style >= 0)
 133                 xmp.style = git_xmerge_style;
 134         if (marker_size > 0)
 135                 xmp.marker_size = marker_size;
 136         xmp.ancestor = orig_name;
 137         xmp.file1 = name1;
 138         xmp.file2 = name2;
 139         status = xdl_merge(orig, src1, src2, &xmp, result);
 140         ret = (status > 0) ? LL_MERGE_CONFLICT : status;
 141         return ret;
 142 }
 143
 144 static enum ll_merge_result ll_union_merge(const struct ll_merge_driver *drv_unused,
 145                           mmbuffer_t *result,
 146                           const char *path,
 147                           mmfile_t *orig, const char *orig_name,
 148                           mmfile_t *src1, const char *name1,
 149                           mmfile_t *src2, const char *name2,
 150                           const struct ll_merge_options *opts,
 151                           int marker_size)
 152 {
 153         /* Use union favor */
 154         struct ll_merge_options o;
 155         assert(opts);
 156         o = *opts;
 157         o.variant = XDL_MERGE_FAVOR_UNION;
 158         return ll_xdl_merge(drv_unused, result, path,
 159                             orig, orig_name, src1, name1, src2, name2,
 160                             &o, marker_size);
 161 }
 162
 163 #define LL_BINARY_MERGE 0
 164 #define LL_TEXT_MERGE 1
 165 #define LL_UNION_MERGE 2
 166 static struct ll_merge_driver ll_merge_drv[] = {
 167         { "binary", "built-in binary merge", ll_binary_merge },
 168         { "text", "built-in 3-way text merge", ll_xdl_merge },
 169         { "union", "built-in union merge", ll_union_merge },
 170 };
 171
 172 static void create_temp(mmfile_t *src, char *path, size_t len)
 173 {
 174         int fd;
 175
 176         xsnprintf(path, len, ".merge_file_XXXXXX");
 177         fd = xmkstemp(path);
 178         if (write_in_full(fd, src->ptr, src->size) < 0)
 179                 die_errno("unable to write temp-file");
 180         close(fd);
 181 }
 182
 183 /*
 184  * User defined low-level merge driver support.
 185  */
 186 static enum ll_merge_result ll_ext_merge(const struct ll_merge_driver *fn,
 187                         mmbuffer_t *result,
 188                         const char *path,
 189                         mmfile_t *orig, const char *orig_name UNUSED,
 190                         mmfile_t *src1, const char *name1 UNUSED,
 191                         mmfile_t *src2, const char *name2 UNUSED,
 192                         const struct ll_merge_options *opts,
 193                         int marker_size)
 194 {
 195         char temp[3][50];
 196         struct strbuf cmd = STRBUF_INIT;
 197         const char *format = fn->cmdline;
 198         struct child_process child = CHILD_PROCESS_INIT;
 199         int status, fd, i;
 200         struct stat st;
 201         enum ll_merge_result ret;
 202         assert(opts);
 203
 204         if (!fn->cmdline)
 205                 die("custom merge driver %s lacks command line.", fn->name);
 206
 207         result->ptr = NULL;
 208         result->size = 0;
 209         create_temp(orig, temp[0], sizeof(temp[0]));
 210         create_temp(src1, temp[1], sizeof(temp[1]));
 211         create_temp(src2, temp[2], sizeof(temp[2]));
 212
 213         while (strbuf_expand_step(&cmd, &format)) {
 214                 if (skip_prefix(format, "%", &format))
 215                         strbuf_addch(&cmd, '%');
 216                 else if (skip_prefix(format, "O", &format))
 217                         strbuf_addstr(&cmd, temp[0]);
 218                 else if (skip_prefix(format, "A", &format))
 219                         strbuf_addstr(&cmd, temp[1]);
 220                 else if (skip_prefix(format, "B", &format))
 221                         strbuf_addstr(&cmd, temp[2]);
 222                 else if (skip_prefix(format, "L", &format))
 223                         strbuf_addf(&cmd, "%d", marker_size);
 224                 else if (skip_prefix(format, "P", &format))
 225                         sq_quote_buf(&cmd, path);
 226                 else
 227                         strbuf_addch(&cmd, '%');
 228         }
 229
 230         child.use_shell = 1;
 231         strvec_push(&child.args, cmd.buf);
 232         status = run_command(&child);
 233         fd = open(temp[1], O_RDONLY);
 234         if (fd < 0)
 235                 goto bad;
 236         if (fstat(fd, &st))
 237                 goto close_bad;
 238         result->size = st.st_size;
 239         result->ptr = xmallocz(result->size);
 240         if (read_in_full(fd, result->ptr, result->size) != result->size) {
 241                 FREE_AND_NULL(result->ptr);
 242                 result->size = 0;
 243         }
 244  close_bad:
 245         close(fd);
 246  bad:
 247         for (i = 0; i < 3; i++)
 248                 unlink_or_warn(temp[i]);
 249         strbuf_release(&cmd);
 250         if (!status)
 251                 ret = LL_MERGE_OK;
 252         else if (status <= 128)
 253                 ret = LL_MERGE_CONFLICT;
 254         else
 255                 /* died due to a signal: WTERMSIG(status) + 128 */
 256                 ret = LL_MERGE_ERROR;
 257         return ret;
 258 }
 259
 260 /*
 261  * merge.default and merge.driver configuration items
 262  */
 263 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 264 static const char *default_ll_merge;
 265
 266 static int read_merge_config(const char *var, const char *value,
 267                              const struct config_context *ctx UNUSED,
 268                              void *cb UNUSED)
 269 {
 270         struct ll_merge_driver *fn;
 271         const char *key, *name;
 272         size_t namelen;
 273
 274         if (!strcmp(var, "merge.default"))
 275                 return git_config_string(&default_ll_merge, var, value);
 276
 277         /*
 278          * We are not interested in anything but "merge.<name>.variable";
 279          * especially, we do not want to look at variables such as
 280          * "merge.summary", "merge.tool", and "merge.verbosity".
 281          */
 282         if (parse_config_key(var, "merge", &name, &namelen, &key) < 0 || !name)
 283                 return 0;
 284
 285         /*
 286          * Find existing one as we might be processing merge.<name>.var2
 287          * after seeing merge.<name>.var1.
 288          */
 289         for (fn = ll_user_merge; fn; fn = fn->next)
 290                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 291                         break;
 292         if (!fn) {
 293                 CALLOC_ARRAY(fn, 1);
 294                 fn->name = xmemdupz(name, namelen);
 295                 fn->fn = ll_ext_merge;
 296                 *ll_user_merge_tail = fn;
 297                 ll_user_merge_tail = &(fn->next);
 298         }
 299
 300         if (!strcmp("name", key))
 301                 return git_config_string(&fn->description, var, value);
 302
 303         if (!strcmp("driver", key)) {
 304                 if (!value)
 305                         return error("%s: lacks value", var);
 306                 /*
 307                  * merge.<name>.driver specifies the command line:
 308                  *
 309                  *      command-line
 310                  *
 311                  * The command-line will be interpolated with the following
 312                  * tokens and is given to the shell:
 313                  *
 314                  *    %O - temporary file name for the merge base.
 315                  *    %A - temporary file name for our version.
 316                  *    %B - temporary file name for the other branches' version.
 317                  *    %L - conflict marker length
 318                  *    %P - the original path (safely quoted for the shell)
 319                  *
 320                  * The external merge driver should write the results in the
 321                  * file named by %A, and signal that it has done with zero exit
 322                  * status.
 323                  */
 324                 fn->cmdline = xstrdup(value);
 325                 return 0;
 326         }
 327
 328         if (!strcmp("recursive", key))
 329                 return git_config_string(&fn->recursive, var, value);
 330
 331         return 0;
 332 }
 333
 334 static void initialize_ll_merge(void)
 335 {
 336         if (ll_user_merge_tail)
 337                 return;
 338         ll_user_merge_tail = &ll_user_merge;
 339         git_config(read_merge_config, NULL);
 340 }
 341
 342 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 343 {
 344         struct ll_merge_driver *fn;
 345         const char *name;
 346         int i;
 347
 348         initialize_ll_merge();
 349
 350         if (ATTR_TRUE(merge_attr))
 351                 return &ll_merge_drv[LL_TEXT_MERGE];
 352         else if (ATTR_FALSE(merge_attr))
 353                 return &ll_merge_drv[LL_BINARY_MERGE];
 354         else if (ATTR_UNSET(merge_attr)) {
 355                 if (!default_ll_merge)
 356                         return &ll_merge_drv[LL_TEXT_MERGE];
 357                 else
 358                         name = default_ll_merge;
 359         }
 360         else
 361                 name = merge_attr;
 362
 363         for (fn = ll_user_merge; fn; fn = fn->next)
 364                 if (!strcmp(fn->name, name))
 365                         return fn;
 366
 367         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 368                 if (!strcmp(ll_merge_drv[i].name, name))
 369                         return &ll_merge_drv[i];
 370
 371         /* default to the 3-way */
 372         return &ll_merge_drv[LL_TEXT_MERGE];
 373 }
 374
 375 static void normalize_file(mmfile_t *mm, const char *path, struct index_state *istate)
 376 {
 377         struct strbuf strbuf = STRBUF_INIT;
 378         if (renormalize_buffer(istate, path, mm->ptr, mm->size, &strbuf)) {
 379                 free(mm->ptr);
 380                 mm->size = strbuf.len;
 381                 mm->ptr = strbuf_detach(&strbuf, NULL);
 382         }
 383 }
 384
 385 enum ll_merge_result ll_merge(mmbuffer_t *result_buf,
 386              const char *path,
 387              mmfile_t *ancestor, const char *ancestor_label,
 388              mmfile_t *ours, const char *our_label,
 389              mmfile_t *theirs, const char *their_label,
 390              struct index_state *istate,
 391              const struct ll_merge_options *opts)
 392 {
 393         struct attr_check *check = load_merge_attributes();
 394         static const struct ll_merge_options default_opts;
 395         const char *ll_driver_name = NULL;
 396         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 397         const struct ll_merge_driver *driver;
 398
 399         if (!opts)
 400                 opts = &default_opts;
 401
 402         if (opts->renormalize) {
 403                 normalize_file(ancestor, path, istate);
 404                 normalize_file(ours, path, istate);
 405                 normalize_file(theirs, path, istate);
 406         }
 407
 408         git_check_attr(istate, path, check);
 409         ll_driver_name = check->items[0].value;
 410         if (check->items[1].value) {
 411                 marker_size = atoi(check->items[1].value);
 412                 if (marker_size <= 0)
 413                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 414         }
 415         driver = find_ll_merge_driver(ll_driver_name);
 416
 417         if (opts->virtual_ancestor) {
 418                 if (driver->recursive)
 419                         driver = find_ll_merge_driver(driver->recursive);
 420         }
 421         if (opts->extra_marker_size) {
 422                 marker_size += opts->extra_marker_size;
 423         }
 424         return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
 425                           ours, our_label, theirs, their_label,
 426                           opts, marker_size);
 427 }
 428
 429 int ll_merge_marker_size(struct index_state *istate, const char *path)
 430 {
 431         static struct attr_check *check;
 432         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 433
 434         if (!check)
 435                 check = attr_check_initl("conflict-marker-size", NULL);
 436         git_check_attr(istate, path, check);
 437         if (check->items[0].value) {
 438                 marker_size = atoi(check->items[0].value);
 439                 if (marker_size <= 0)
 440                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 441         }
 442         return marker_size;
 443 }