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 "convert.h"
  10 #include "attr.h"
  11 #include "xdiff-interface.h"
  12 #include "run-command.h"
  13 #include "ll-merge.h"
  14 #include "quote.h"
  15 #include "wrapper.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[4][50];
 195         struct strbuf cmd = STRBUF_INIT;
 196         struct strbuf_expand_dict_entry dict[6];
 197         struct strbuf path_sq = STRBUF_INIT;
 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         sq_quote_buf(&path_sq, path);
 205         dict[0].placeholder = "O"; dict[0].value = temp[0];
 206         dict[1].placeholder = "A"; dict[1].value = temp[1];
 207         dict[2].placeholder = "B"; dict[2].value = temp[2];
 208         dict[3].placeholder = "L"; dict[3].value = temp[3];
 209         dict[4].placeholder = "P"; dict[4].value = path_sq.buf;
 210         dict[5].placeholder = NULL; dict[5].value = NULL;
 211
 212         if (!fn->cmdline)
 213                 die("custom merge driver %s lacks command line.", fn->name);
 214
 215         result->ptr = NULL;
 216         result->size = 0;
 217         create_temp(orig, temp[0], sizeof(temp[0]));
 218         create_temp(src1, temp[1], sizeof(temp[1]));
 219         create_temp(src2, temp[2], sizeof(temp[2]));
 220         xsnprintf(temp[3], sizeof(temp[3]), "%d", marker_size);
 221
 222         strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
 223
 224         child.use_shell = 1;
 225         strvec_push(&child.args, cmd.buf);
 226         status = run_command(&child);
 227         fd = open(temp[1], O_RDONLY);
 228         if (fd < 0)
 229                 goto bad;
 230         if (fstat(fd, &st))
 231                 goto close_bad;
 232         result->size = st.st_size;
 233         result->ptr = xmallocz(result->size);
 234         if (read_in_full(fd, result->ptr, result->size) != result->size) {
 235                 FREE_AND_NULL(result->ptr);
 236                 result->size = 0;
 237         }
 238  close_bad:
 239         close(fd);
 240  bad:
 241         for (i = 0; i < 3; i++)
 242                 unlink_or_warn(temp[i]);
 243         strbuf_release(&cmd);
 244         strbuf_release(&path_sq);
 245         ret = (status > 0) ? LL_MERGE_CONFLICT : status;
 246         return ret;
 247 }
 248
 249 /*
 250  * merge.default and merge.driver configuration items
 251  */
 252 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 253 static const char *default_ll_merge;
 254
 255 static int read_merge_config(const char *var, const char *value,
 256                              void *cb UNUSED)
 257 {
 258         struct ll_merge_driver *fn;
 259         const char *key, *name;
 260         size_t namelen;
 261
 262         if (!strcmp(var, "merge.default"))
 263                 return git_config_string(&default_ll_merge, var, value);
 264
 265         /*
 266          * We are not interested in anything but "merge.<name>.variable";
 267          * especially, we do not want to look at variables such as
 268          * "merge.summary", "merge.tool", and "merge.verbosity".
 269          */
 270         if (parse_config_key(var, "merge", &name, &namelen, &key) < 0 || !name)
 271                 return 0;
 272
 273         /*
 274          * Find existing one as we might be processing merge.<name>.var2
 275          * after seeing merge.<name>.var1.
 276          */
 277         for (fn = ll_user_merge; fn; fn = fn->next)
 278                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 279                         break;
 280         if (!fn) {
 281                 CALLOC_ARRAY(fn, 1);
 282                 fn->name = xmemdupz(name, namelen);
 283                 fn->fn = ll_ext_merge;
 284                 *ll_user_merge_tail = fn;
 285                 ll_user_merge_tail = &(fn->next);
 286         }
 287
 288         if (!strcmp("name", key))
 289                 return git_config_string(&fn->description, var, value);
 290
 291         if (!strcmp("driver", key)) {
 292                 if (!value)
 293                         return error("%s: lacks value", var);
 294                 /*
 295                  * merge.<name>.driver specifies the command line:
 296                  *
 297                  *      command-line
 298                  *
 299                  * The command-line will be interpolated with the following
 300                  * tokens and is given to the shell:
 301                  *
 302                  *    %O - temporary file name for the merge base.
 303                  *    %A - temporary file name for our version.
 304                  *    %B - temporary file name for the other branches' version.
 305                  *    %L - conflict marker length
 306                  *    %P - the original path (safely quoted for the shell)
 307                  *
 308                  * The external merge driver should write the results in the
 309                  * file named by %A, and signal that it has done with zero exit
 310                  * status.
 311                  */
 312                 fn->cmdline = xstrdup(value);
 313                 return 0;
 314         }
 315
 316         if (!strcmp("recursive", key))
 317                 return git_config_string(&fn->recursive, var, value);
 318
 319         return 0;
 320 }
 321
 322 static void initialize_ll_merge(void)
 323 {
 324         if (ll_user_merge_tail)
 325                 return;
 326         ll_user_merge_tail = &ll_user_merge;
 327         git_config(read_merge_config, NULL);
 328 }
 329
 330 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 331 {
 332         struct ll_merge_driver *fn;
 333         const char *name;
 334         int i;
 335
 336         initialize_ll_merge();
 337
 338         if (ATTR_TRUE(merge_attr))
 339                 return &ll_merge_drv[LL_TEXT_MERGE];
 340         else if (ATTR_FALSE(merge_attr))
 341                 return &ll_merge_drv[LL_BINARY_MERGE];
 342         else if (ATTR_UNSET(merge_attr)) {
 343                 if (!default_ll_merge)
 344                         return &ll_merge_drv[LL_TEXT_MERGE];
 345                 else
 346                         name = default_ll_merge;
 347         }
 348         else
 349                 name = merge_attr;
 350
 351         for (fn = ll_user_merge; fn; fn = fn->next)
 352                 if (!strcmp(fn->name, name))
 353                         return fn;
 354
 355         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 356                 if (!strcmp(ll_merge_drv[i].name, name))
 357                         return &ll_merge_drv[i];
 358
 359         /* default to the 3-way */
 360         return &ll_merge_drv[LL_TEXT_MERGE];
 361 }
 362
 363 static void normalize_file(mmfile_t *mm, const char *path, struct index_state *istate)
 364 {
 365         struct strbuf strbuf = STRBUF_INIT;
 366         if (renormalize_buffer(istate, path, mm->ptr, mm->size, &strbuf)) {
 367                 free(mm->ptr);
 368                 mm->size = strbuf.len;
 369                 mm->ptr = strbuf_detach(&strbuf, NULL);
 370         }
 371 }
 372
 373 enum ll_merge_result ll_merge(mmbuffer_t *result_buf,
 374              const char *path,
 375              mmfile_t *ancestor, const char *ancestor_label,
 376              mmfile_t *ours, const char *our_label,
 377              mmfile_t *theirs, const char *their_label,
 378              struct index_state *istate,
 379              const struct ll_merge_options *opts)
 380 {
 381         struct attr_check *check = load_merge_attributes();
 382         static const struct ll_merge_options default_opts;
 383         const char *ll_driver_name = NULL;
 384         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 385         const struct ll_merge_driver *driver;
 386
 387         if (!opts)
 388                 opts = &default_opts;
 389
 390         if (opts->renormalize) {
 391                 normalize_file(ancestor, path, istate);
 392                 normalize_file(ours, path, istate);
 393                 normalize_file(theirs, path, istate);
 394         }
 395
 396         git_check_attr(istate, NULL, path, check);
 397         ll_driver_name = check->items[0].value;
 398         if (check->items[1].value) {
 399                 marker_size = atoi(check->items[1].value);
 400                 if (marker_size <= 0)
 401                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 402         }
 403         driver = find_ll_merge_driver(ll_driver_name);
 404
 405         if (opts->virtual_ancestor) {
 406                 if (driver->recursive)
 407                         driver = find_ll_merge_driver(driver->recursive);
 408         }
 409         if (opts->extra_marker_size) {
 410                 marker_size += opts->extra_marker_size;
 411         }
 412         return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
 413                           ours, our_label, theirs, their_label,
 414                           opts, marker_size);
 415 }
 416
 417 int ll_merge_marker_size(struct index_state *istate, const char *path)
 418 {
 419         static struct attr_check *check;
 420         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 421
 422         if (!check)
 423                 check = attr_check_initl("conflict-marker-size", NULL);
 424         git_check_attr(istate, NULL, path, check);
 425         if (check->items[0].value) {
 426                 marker_size = atoi(check->items[0].value);
 427                 if (marker_size <= 0)
 428                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 429         }
 430         return marker_size;
 431 }