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 #include "quote.h"
  13
  14 struct ll_merge_driver;
  15
  16 typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
  17                            mmbuffer_t *result,
  18                            const char *path,
  19                            mmfile_t *orig, const char *orig_name,
  20                            mmfile_t *src1, const char *name1,
  21                            mmfile_t *src2, const char *name2,
  22                            const struct ll_merge_options *opts,
  23                            int marker_size);
  24
  25 struct ll_merge_driver {
  26         const char *name;
  27         const char *description;
  28         ll_merge_fn fn;
  29         const char *recursive;
  30         struct ll_merge_driver *next;
  31         char *cmdline;
  32 };
  33
  34 /*
  35  * Built-in low-levels
  36  */
  37 static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
  38                            mmbuffer_t *result,
  39                            const char *path,
  40                            mmfile_t *orig, const char *orig_name,
  41                            mmfile_t *src1, const char *name1,
  42                            mmfile_t *src2, const char *name2,
  43                            const struct ll_merge_options *opts,
  44                            int marker_size)
  45 {
  46         mmfile_t *stolen;
  47         assert(opts);
  48
  49         /*
  50          * The tentative merge result is the or common ancestor for an internal merge.
  51          */
  52         if (opts->virtual_ancestor) {
  53                 stolen = orig;
  54         } else {
  55                 switch (opts->variant) {
  56                 default:
  57                         warning("Cannot merge binary files: %s (%s vs. %s)",
  58                                 path, name1, name2);
  59                         /* fallthru */
  60                 case XDL_MERGE_FAVOR_OURS:
  61                         stolen = src1;
  62                         break;
  63                 case XDL_MERGE_FAVOR_THEIRS:
  64                         stolen = src2;
  65                         break;
  66                 }
  67         }
  68
  69         result->ptr = stolen->ptr;
  70         result->size = stolen->size;
  71         stolen->ptr = NULL;
  72
  73         /*
  74          * With -Xtheirs or -Xours, we have cleanly merged;
  75          * otherwise we got a conflict.
  76          */
  77         return (opts->variant ? 0 : 1);
  78 }
  79
  80 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
  81                         mmbuffer_t *result,
  82                         const char *path,
  83                         mmfile_t *orig, const char *orig_name,
  84                         mmfile_t *src1, const char *name1,
  85                         mmfile_t *src2, const char *name2,
  86                         const struct ll_merge_options *opts,
  87                         int marker_size)
  88 {
  89         xmparam_t xmp;
  90         assert(opts);
  91
  92         if (orig->size > MAX_XDIFF_SIZE ||
  93             src1->size > MAX_XDIFF_SIZE ||
  94             src2->size > MAX_XDIFF_SIZE ||
  95             buffer_is_binary(orig->ptr, orig->size) ||
  96             buffer_is_binary(src1->ptr, src1->size) ||
  97             buffer_is_binary(src2->ptr, src2->size)) {
  98                 return ll_binary_merge(drv_unused, result,
  99                                        path,
 100                                        orig, orig_name,
 101                                        src1, name1,
 102                                        src2, name2,
 103                                        opts, marker_size);
 104         }
 105
 106         memset(&xmp, 0, sizeof(xmp));
 107         xmp.level = XDL_MERGE_ZEALOUS;
 108         xmp.favor = opts->variant;
 109         xmp.xpp.flags = opts->xdl_opts;
 110         if (git_xmerge_style >= 0)
 111                 xmp.style = git_xmerge_style;
 112         if (marker_size > 0)
 113                 xmp.marker_size = marker_size;
 114         xmp.ancestor = orig_name;
 115         xmp.file1 = name1;
 116         xmp.file2 = name2;
 117         return xdl_merge(orig, src1, src2, &xmp, result);
 118 }
 119
 120 static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 121                           mmbuffer_t *result,
 122                           const char *path_unused,
 123                           mmfile_t *orig, const char *orig_name,
 124                           mmfile_t *src1, const char *name1,
 125                           mmfile_t *src2, const char *name2,
 126                           const struct ll_merge_options *opts,
 127                           int marker_size)
 128 {
 129         /* Use union favor */
 130         struct ll_merge_options o;
 131         assert(opts);
 132         o = *opts;
 133         o.variant = XDL_MERGE_FAVOR_UNION;
 134         return ll_xdl_merge(drv_unused, result, path_unused,
 135                             orig, NULL, src1, NULL, src2, NULL,
 136                             &o, marker_size);
 137 }
 138
 139 #define LL_BINARY_MERGE 0
 140 #define LL_TEXT_MERGE 1
 141 #define LL_UNION_MERGE 2
 142 static struct ll_merge_driver ll_merge_drv[] = {
 143         { "binary", "built-in binary merge", ll_binary_merge },
 144         { "text", "built-in 3-way text merge", ll_xdl_merge },
 145         { "union", "built-in union merge", ll_union_merge },
 146 };
 147
 148 static void create_temp(mmfile_t *src, char *path, size_t len)
 149 {
 150         int fd;
 151
 152         xsnprintf(path, len, ".merge_file_XXXXXX");
 153         fd = xmkstemp(path);
 154         if (write_in_full(fd, src->ptr, src->size) != src->size)
 155                 die_errno("unable to write temp-file");
 156         close(fd);
 157 }
 158
 159 /*
 160  * User defined low-level merge driver support.
 161  */
 162 static int ll_ext_merge(const struct ll_merge_driver *fn,
 163                         mmbuffer_t *result,
 164                         const char *path,
 165                         mmfile_t *orig, const char *orig_name,
 166                         mmfile_t *src1, const char *name1,
 167                         mmfile_t *src2, const char *name2,
 168                         const struct ll_merge_options *opts,
 169                         int marker_size)
 170 {
 171         char temp[4][50];
 172         struct strbuf cmd = STRBUF_INIT;
 173         struct strbuf_expand_dict_entry dict[6];
 174         struct strbuf path_sq = STRBUF_INIT;
 175         const char *args[] = { NULL, NULL };
 176         int status, fd, i;
 177         struct stat st;
 178         assert(opts);
 179
 180         sq_quote_buf(&path_sq, path);
 181         dict[0].placeholder = "O"; dict[0].value = temp[0];
 182         dict[1].placeholder = "A"; dict[1].value = temp[1];
 183         dict[2].placeholder = "B"; dict[2].value = temp[2];
 184         dict[3].placeholder = "L"; dict[3].value = temp[3];
 185         dict[4].placeholder = "P"; dict[4].value = path_sq.buf;
 186         dict[5].placeholder = NULL; dict[5].value = NULL;
 187
 188         if (fn->cmdline == NULL)
 189                 die("custom merge driver %s lacks command line.", fn->name);
 190
 191         result->ptr = NULL;
 192         result->size = 0;
 193         create_temp(orig, temp[0], sizeof(temp[0]));
 194         create_temp(src1, temp[1], sizeof(temp[1]));
 195         create_temp(src2, temp[2], sizeof(temp[2]));
 196         xsnprintf(temp[3], sizeof(temp[3]), "%d", marker_size);
 197
 198         strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
 199
 200         args[0] = cmd.buf;
 201         status = run_command_v_opt(args, RUN_USING_SHELL);
 202         fd = open(temp[1], O_RDONLY);
 203         if (fd < 0)
 204                 goto bad;
 205         if (fstat(fd, &st))
 206                 goto close_bad;
 207         result->size = st.st_size;
 208         result->ptr = xmallocz(result->size);
 209         if (read_in_full(fd, result->ptr, result->size) != result->size) {
 210                 free(result->ptr);
 211                 result->ptr = NULL;
 212                 result->size = 0;
 213         }
 214  close_bad:
 215         close(fd);
 216  bad:
 217         for (i = 0; i < 3; i++)
 218                 unlink_or_warn(temp[i]);
 219         strbuf_release(&cmd);
 220         strbuf_release(&path_sq);
 221         return status;
 222 }
 223
 224 /*
 225  * merge.default and merge.driver configuration items
 226  */
 227 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 228 static const char *default_ll_merge;
 229
 230 static int read_merge_config(const char *var, const char *value, void *cb)
 231 {
 232         struct ll_merge_driver *fn;
 233         const char *key, *name;
 234         int namelen;
 235
 236         if (!strcmp(var, "merge.default"))
 237                 return git_config_string(&default_ll_merge, var, value);
 238
 239         /*
 240          * We are not interested in anything but "merge.<name>.variable";
 241          * especially, we do not want to look at variables such as
 242          * "merge.summary", "merge.tool", and "merge.verbosity".
 243          */
 244         if (parse_config_key(var, "merge", &name, &namelen, &key) < 0 || !name)
 245                 return 0;
 246
 247         /*
 248          * Find existing one as we might be processing merge.<name>.var2
 249          * after seeing merge.<name>.var1.
 250          */
 251         for (fn = ll_user_merge; fn; fn = fn->next)
 252                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 253                         break;
 254         if (!fn) {
 255                 fn = xcalloc(1, sizeof(struct ll_merge_driver));
 256                 fn->name = xmemdupz(name, namelen);
 257                 fn->fn = ll_ext_merge;
 258                 *ll_user_merge_tail = fn;
 259                 ll_user_merge_tail = &(fn->next);
 260         }
 261
 262         if (!strcmp("name", key))
 263                 return git_config_string(&fn->description, var, value);
 264
 265         if (!strcmp("driver", key)) {
 266                 if (!value)
 267                         return error("%s: lacks value", var);
 268                 /*
 269                  * merge.<name>.driver specifies the command line:
 270                  *
 271                  *      command-line
 272                  *
 273                  * The command-line will be interpolated with the following
 274                  * tokens and is given to the shell:
 275                  *
 276                  *    %O - temporary file name for the merge base.
 277                  *    %A - temporary file name for our version.
 278                  *    %B - temporary file name for the other branches' version.
 279                  *    %L - conflict marker length
 280                  *    %P - the original path (safely quoted for the shell)
 281                  *
 282                  * The external merge driver should write the results in the
 283                  * file named by %A, and signal that it has done with zero exit
 284                  * status.
 285                  */
 286                 fn->cmdline = xstrdup(value);
 287                 return 0;
 288         }
 289
 290         if (!strcmp("recursive", key))
 291                 return git_config_string(&fn->recursive, var, value);
 292
 293         return 0;
 294 }
 295
 296 static void initialize_ll_merge(void)
 297 {
 298         if (ll_user_merge_tail)
 299                 return;
 300         ll_user_merge_tail = &ll_user_merge;
 301         git_config(read_merge_config, NULL);
 302 }
 303
 304 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 305 {
 306         struct ll_merge_driver *fn;
 307         const char *name;
 308         int i;
 309
 310         initialize_ll_merge();
 311
 312         if (ATTR_TRUE(merge_attr))
 313                 return &ll_merge_drv[LL_TEXT_MERGE];
 314         else if (ATTR_FALSE(merge_attr))
 315                 return &ll_merge_drv[LL_BINARY_MERGE];
 316         else if (ATTR_UNSET(merge_attr)) {
 317                 if (!default_ll_merge)
 318                         return &ll_merge_drv[LL_TEXT_MERGE];
 319                 else
 320                         name = default_ll_merge;
 321         }
 322         else
 323                 name = merge_attr;
 324
 325         for (fn = ll_user_merge; fn; fn = fn->next)
 326                 if (!strcmp(fn->name, name))
 327                         return fn;
 328
 329         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 330                 if (!strcmp(ll_merge_drv[i].name, name))
 331                         return &ll_merge_drv[i];
 332
 333         /* default to the 3-way */
 334         return &ll_merge_drv[LL_TEXT_MERGE];
 335 }
 336
 337 static int git_path_check_merge(const char *path, struct git_attr_check check[2])
 338 {
 339         if (!check[0].attr) {
 340                 check[0].attr = git_attr("merge");
 341                 check[1].attr = git_attr("conflict-marker-size");
 342         }
 343         return git_check_attr(path, 2, check);
 344 }
 345
 346 static void normalize_file(mmfile_t *mm, const char *path)
 347 {
 348         struct strbuf strbuf = STRBUF_INIT;
 349         if (renormalize_buffer(path, mm->ptr, mm->size, &strbuf)) {
 350                 free(mm->ptr);
 351                 mm->size = strbuf.len;
 352                 mm->ptr = strbuf_detach(&strbuf, NULL);
 353         }
 354 }
 355
 356 int ll_merge(mmbuffer_t *result_buf,
 357              const char *path,
 358              mmfile_t *ancestor, const char *ancestor_label,
 359              mmfile_t *ours, const char *our_label,
 360              mmfile_t *theirs, const char *their_label,
 361              const struct ll_merge_options *opts)
 362 {
 363         static struct git_attr_check check[2];
 364         static const struct ll_merge_options default_opts;
 365         const char *ll_driver_name = NULL;
 366         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 367         const struct ll_merge_driver *driver;
 368
 369         if (!opts)
 370                 opts = &default_opts;
 371
 372         if (opts->renormalize) {
 373                 normalize_file(ancestor, path);
 374                 normalize_file(ours, path);
 375                 normalize_file(theirs, path);
 376         }
 377         if (!git_path_check_merge(path, check)) {
 378                 ll_driver_name = check[0].value;
 379                 if (check[1].value) {
 380                         marker_size = atoi(check[1].value);
 381                         if (marker_size <= 0)
 382                                 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 383                 }
 384         }
 385         driver = find_ll_merge_driver(ll_driver_name);
 386         if (opts->virtual_ancestor && driver->recursive)
 387                 driver = find_ll_merge_driver(driver->recursive);
 388         return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
 389                           ours, our_label, theirs, their_label,
 390                           opts, marker_size);
 391 }
 392
 393 int ll_merge_marker_size(const char *path)
 394 {
 395         static struct git_attr_check check;
 396         int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 397
 398         if (!check.attr)
 399                 check.attr = git_attr("conflict-marker-size");
 400         if (!git_check_attr(path, 1, &check) && check.value) {
 401                 marker_size = atoi(check.value);
 402                 if (marker_size <= 0)
 403                         marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 404         }
 405         return marker_size;
 406 }