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