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