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 "attr.h"
   9 #include "xdiff-interface.h"
  10 #include "run-command.h"
  11 #include "ll-merge.h"
  12
  13 struct ll_merge_driver;
  14
  15 typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
  16                            mmbuffer_t *result,
  17                            const char *path,
  18                            mmfile_t *orig, const char *orig_name,
  19                            mmfile_t *src1, const char *name1,
  20                            mmfile_t *src2, const char *name2,
  21                            const struct ll_merge_options *opts,
  22                            int marker_size);
  23
  24 struct ll_merge_driver {
  25         const char *name;
  26         const char *description;
  27         ll_merge_fn fn;
  28         const char *recursive;
  29         struct ll_merge_driver *next;
  30         char *cmdline;
  31 };
  32
  33 /*
  34  * Built-in low-levels
  35  */
  36 static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
  37                            mmbuffer_t *result,
  38                            const char *path,
  39                            mmfile_t *orig, const char *orig_name,
  40                            mmfile_t *src1, const char *name1,
  41                            mmfile_t *src2, const char *name2,
  42                            const struct ll_merge_options *opts,
  43                            int marker_size)
  44 {
  45         mmfile_t *stolen;
  46         assert(opts);
  47
  48         /*
  49          * The tentative merge result is the common ancestor for an
  50          * internal merge.  For the final merge, it is "ours" by
  51          * default but -Xours/-Xtheirs can tweak the choice.
  52          */
  53         if (opts->virtual_ancestor) {
  54                 stolen = orig;
  55         } else {
  56                 switch (opts->variant) {
  57                 default:
  58                         warning("Cannot merge binary files: %s (%s vs. %s)",
  59                                 path, name1, name2);
  60                         /* fallthru */
  61                 case XDL_MERGE_FAVOR_OURS:
  62                         stolen = src1;
  63                         break;
  64                 case XDL_MERGE_FAVOR_THEIRS:
  65                         stolen = src2;
  66                         break;
  67                 }
  68         }
  69
  70         result->ptr = stolen->ptr;
  71         result->size = stolen->size;
  72         stolen->ptr = NULL;
  73
  74         /*
  75          * With -Xtheirs or -Xours, we have cleanly merged;
  76          * otherwise we got a conflict.
  77          */
  78         return (opts->variant ? 0 : 1);
  79 }
  80
  81 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
  82                         mmbuffer_t *result,
  83                         const char *path,
  84                         mmfile_t *orig, const char *orig_name,
  85                         mmfile_t *src1, const char *name1,
  86                         mmfile_t *src2, const char *name2,
  87                         const struct ll_merge_options *opts,
  88                         int marker_size)
  89 {
  90         xmparam_t xmp;
  91         assert(opts);
  92
  93         if (buffer_is_binary(orig->ptr, orig->size) ||
  94             buffer_is_binary(src1->ptr, src1->size) ||
  95             buffer_is_binary(src2->ptr, src2->size)) {
  96                 return ll_binary_merge(drv_unused, result,
  97                                        path,
  98                                        orig, orig_name,
  99                                        src1, name1,
 100                                        src2, name2,
 101                                        opts, marker_size);
 102         }
 103
 104         memset(&xmp, 0, sizeof(xmp));
 105         xmp.level = XDL_MERGE_ZEALOUS;
 106         xmp.favor = opts->variant;
 107         xmp.xpp.flags = opts->xdl_opts;
 108         if (git_xmerge_style >= 0)
 109                 xmp.style = git_xmerge_style;
 110         if (marker_size > 0)
 111                 xmp.marker_size = marker_size;
 112         xmp.ancestor = orig_name;
 113         xmp.file1 = name1;
 114         xmp.file2 = name2;
 115         return xdl_merge(orig, src1, src2, &xmp, result);
 116 }
 117
 118 static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 119                           mmbuffer_t *result,
 120                           const char *path_unused,
 121                           mmfile_t *orig, const char *orig_name,
 122                           mmfile_t *src1, const char *name1,
 123                           mmfile_t *src2, const char *name2,
 124                           const struct ll_merge_options *opts,
 125                           int marker_size)
 126 {
 127         /* Use union favor */
 128         struct ll_merge_options o;
 129         assert(opts);
 130         o = *opts;
 131         o.variant = XDL_MERGE_FAVOR_UNION;
 132         return ll_xdl_merge(drv_unused, result, path_unused,
 133                             orig, NULL, src1, NULL, src2, NULL,
 134                             &o, marker_size);
 135 }
 136
 137 #define LL_BINARY_MERGE 0
 138 #define LL_TEXT_MERGE 1
 139 #define LL_UNION_MERGE 2
 140 static struct ll_merge_driver ll_merge_drv[] = {
 141         { "binary", "built-in binary merge", ll_binary_merge },
 142         { "text", "built-in 3-way text merge", ll_xdl_merge },
 143         { "union", "built-in union merge", ll_union_merge },
 144 };
 145
 146 static void create_temp(mmfile_t *src, char *path)
 147 {
 148         int fd;
 149
 150         strcpy(path, ".merge_file_XXXXXX");
 151         fd = xmkstemp(path);
 152         if (write_in_full(fd, src->ptr, src->size) != src->size)
 153                 die_errno("unable to write temp-file");
 154         close(fd);
 155 }
 156
 157 /*
 158  * User defined low-level merge driver support.
 159  */
 160 static int ll_ext_merge(const struct ll_merge_driver *fn,
 161                         mmbuffer_t *result,
 162                         const char *path,
 163                         mmfile_t *orig, const char *orig_name,
 164                         mmfile_t *src1, const char *name1,
 165                         mmfile_t *src2, const char *name2,
 166                         const struct ll_merge_options *opts,
 167                         int marker_size)
 168 {
 169         char temp[4][50];
 170         struct strbuf cmd = STRBUF_INIT;
 171         struct strbuf_expand_dict_entry dict[5];
 172         const char *args[] = { NULL, NULL };
 173         int status, fd, i;
 174         struct stat st;
 175         assert(opts);
 176
 177         dict[0].placeholder = "O"; dict[0].value = temp[0];
 178         dict[1].placeholder = "A"; dict[1].value = temp[1];
 179         dict[2].placeholder = "B"; dict[2].value = temp[2];
 180         dict[3].placeholder = "L"; dict[3].value = temp[3];
 181         dict[4].placeholder = NULL; dict[4].value = NULL;
 182
 183         if (fn->cmdline == NULL)
 184                 die("custom merge driver %s lacks command line.", fn->name);
 185
 186         result->ptr = NULL;
 187         result->size = 0;
 188         create_temp(orig, temp[0]);
 189         create_temp(src1, temp[1]);
 190         create_temp(src2, temp[2]);
 191         sprintf(temp[3], "%d", marker_size);
 192
 193         strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
 194
 195         args[0] = cmd.buf;
 196         status = run_command_v_opt(args, RUN_USING_SHELL);
 197         fd = open(temp[1], O_RDONLY);
 198         if (fd < 0)
 199                 goto bad;
 200         if (fstat(fd, &st))
 201                 goto close_bad;
 202         result->size = st.st_size;
 203         result->ptr = xmalloc(result->size + 1);
 204         if (read_in_full(fd, result->ptr, result->size) != result->size) {
 205                 free(result->ptr);
 206                 result->ptr = NULL;
 207                 result->size = 0;
 208         }
 209  close_bad:
 210         close(fd);
 211  bad:
 212         for (i = 0; i < 3; i++)
 213                 unlink_or_warn(temp[i]);
 214         strbuf_release(&cmd);
 215         return status;
 216 }
 217
 218 /*
 219  * merge.default and merge.driver configuration items
 220  */
 221 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 222 static const char *default_ll_merge;
 223
 224 static int read_merge_config(const char *var, const char *value, void *cb)
 225 {
 226         struct ll_merge_driver *fn;
 227         const char *key, *name;
 228         int namelen;
 229
 230         if (!strcmp(var, "merge.default"))
 231                 return git_config_string(&default_ll_merge, var, value);
 232
 233         /*
 234          * We are not interested in anything but "merge.<name>.variable";
 235          * especially, we do not want to look at variables such as
 236          * "merge.summary", "merge.tool", and "merge.verbosity".
 237          */
 238         if (parse_config_key(var, "merge", &name, &namelen, &key) < 0 || !name)
 239                 return 0;
 240
 241         /*
 242          * Find existing one as we might be processing merge.<name>.var2
 243          * after seeing merge.<name>.var1.
 244          */
 245         for (fn = ll_user_merge; fn; fn = fn->next)
 246                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 247                         break;
 248         if (!fn) {
 249                 fn = xcalloc(1, sizeof(struct ll_merge_driver));
 250                 fn->name = xmemdupz(name, namelen);
 251                 fn->fn = ll_ext_merge;
 252                 *ll_user_merge_tail = fn;
 253                 ll_user_merge_tail = &(fn->next);
 254         }
 255
 256         if (!strcmp("name", key))
 257                 return git_config_string(&fn->description, var, value);
 258
 259         if (!strcmp("driver", key)) {
 260                 if (!value)
 261                         return error("%s: lacks value", var);
 262                 /*
 263                  * merge.<name>.driver specifies the command line:
 264                  *
 265                  *      command-line
 266                  *
 267                  * The command-line will be interpolated with the following
 268                  * tokens and is given to the shell:
 269                  *
 270                  *    %O - temporary file name for the merge base.
 271                  *    %A - temporary file name for our version.
 272                  *    %B - temporary file name for the other branches' version.
 273                  *    %L - conflict marker length
 274                  *
 275                  * The external merge driver should write the results in the
 276                  * file named by %A, and signal that it has done with zero exit
 277                  * status.
 278                  */
 279                 fn->cmdline = xstrdup(value);
 280                 return 0;
 281         }
 282
 283         if (!strcmp("recursive", key))
 284                 return git_config_string(&fn->recursive, var, value);
 285
 286         return 0;
 287 }
 288
 289 static void initialize_ll_merge(void)
 290 {
 291         if (ll_user_merge_tail)
 292                 return;
 293         ll_user_merge_tail = &ll_user_merge;
 294         git_config(read_merge_config, NULL);
 295 }
 296
 297 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 298 {
 299         struct ll_merge_driver *fn;
 300         const char *name;
 301         int i;
 302
 303         initialize_ll_merge();
 304
 305         if (ATTR_TRUE(merge_attr))
 306                 return &ll_merge_drv[LL_TEXT_MERGE];
 307         else if (ATTR_FALSE(merge_attr))
 308                 return &ll_merge_drv[LL_BINARY_MERGE];
 309         else if (ATTR_UNSET(merge_attr)) {
 310                 if (!default_ll_merge)
 311                         return &ll_merge_drv[LL_TEXT_MERGE];
 312                 else
 313                         name = default_ll_merge;
 314         }
 315         else
 316                 name = merge_attr;
 317
 318         for (fn = ll_user_merge; fn; fn = fn->next)
 319                 if (!strcmp(fn->name, name))
 320                         return fn;
 321
 322         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 323                 if (!strcmp(ll_merge_drv[i].name, name))
 324                         return &ll_merge_drv[i];
 325
 326         /* default to the 3-way */
 327         return &ll_merge_drv[LL_TEXT_MERGE];
 328 }
 329
 330 static int git_path_check_merge(const char *path, struct git_attr_check check[2])
 331 {
 332         if (!check[0].attr) {
 333                 check[0].attr = git_attr("merge");
 334                 check[1].attr = git_attr("conflict-marker-size");
 335         }
 336         return git_check_attr(path, 2, check);
 337 }
 338
 339 static void normalize_file(mmfile_t *mm, const char *path)
 340 {
 341         struct strbuf strbuf = STRBUF_INIT;
 342         if (renormalize_buffer(path, mm->ptr, mm->size, &strbuf)) {
 343                 free(mm->ptr);
 344                 mm->size = strbuf.len;
 345                 mm->ptr = strbuf_detach(&strbuf, NULL);
 346         }
 347 }
 348
 349 int ll_merge(mmbuffer_t *result_buf,
 350              const char *path,
 351              mmfile_t *ancestor, const char *ancestor_label,
 352              mmfile_t *ours, const char *our_label,
 353              mmfile_t *theirs, const char *their_label,
 354              const struct ll_merge_options *opts)
 355 {
 356         static struct git_attr_check check[2];
 357         static const struct ll_merge_options default_opts;
 358         const char *ll_driver_name = NULL;
 359         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 360         const struct ll_merge_driver *driver;
 361
 362         if (!opts)
 363                 opts = &default_opts;
 364
 365         if (opts->renormalize) {
 366                 normalize_file(ancestor, path);
 367                 normalize_file(ours, path);
 368                 normalize_file(theirs, path);
 369         }
 370         if (!git_path_check_merge(path, check)) {
 371                 ll_driver_name = check[0].value;
 372                 if (check[1].value) {
 373                         marker_size = atoi(check[1].value);
 374                         if (marker_size <= 0)
 375                                 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 376                 }
 377         }
 378         driver = find_ll_merge_driver(ll_driver_name);
 379
 380         if (opts->virtual_ancestor) {
 381                 if (driver->recursive)
 382                         driver = find_ll_merge_driver(driver->recursive);
 383                 marker_size += 2;
 384         }
 385         return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
 386                           ours, our_label, theirs, their_label,
 387                           opts, marker_size);
 388 }
 389
 390 int ll_merge_marker_size(const char *path)
 391 {
 392         static struct git_attr_check check;
 393         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 394
 395         if (!check.attr)
 396                 check.attr = git_attr("conflict-marker-size");
 397         if (!git_check_attr(path, 1, &check) && check.value) {
 398                 marker_size = atoi(check.value);
 399                 if (marker_size <= 0)
 400                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 401         }
 402         return marker_size;
 403 }