ll-merge.con commit Merge branch 'jk/maint-reflog-bottom' (9f5074e)
   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
  13struct ll_merge_driver;
  14
  15typedef 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
  24struct 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 */
  36static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
  37                           mmbuffer_t *result,
  38                           const char *path_unused,
  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 "ours" for the final round,
  50         * or common ancestor for an internal merge.  Still return
  51         * "conflicted merge" status.
  52         */
  53        stolen = opts->virtual_ancestor ? orig : src1;
  54
  55        result->ptr = stolen->ptr;
  56        result->size = stolen->size;
  57        stolen->ptr = NULL;
  58        return 1;
  59}
  60
  61static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
  62                        mmbuffer_t *result,
  63                        const char *path,
  64                        mmfile_t *orig, const char *orig_name,
  65                        mmfile_t *src1, const char *name1,
  66                        mmfile_t *src2, const char *name2,
  67                        const struct ll_merge_options *opts,
  68                        int marker_size)
  69{
  70        xmparam_t xmp;
  71        assert(opts);
  72
  73        if (buffer_is_binary(orig->ptr, orig->size) ||
  74            buffer_is_binary(src1->ptr, src1->size) ||
  75            buffer_is_binary(src2->ptr, src2->size)) {
  76                warning("Cannot merge binary files: %s (%s vs. %s)\n",
  77                        path, name1, name2);
  78                return ll_binary_merge(drv_unused, result,
  79                                       path,
  80                                       orig, orig_name,
  81                                       src1, name1,
  82                                       src2, name2,
  83                                       opts, marker_size);
  84        }
  85
  86        memset(&xmp, 0, sizeof(xmp));
  87        xmp.level = XDL_MERGE_ZEALOUS;
  88        xmp.favor = opts->variant;
  89        xmp.xpp.flags = opts->xdl_opts;
  90        if (git_xmerge_style >= 0)
  91                xmp.style = git_xmerge_style;
  92        if (marker_size > 0)
  93                xmp.marker_size = marker_size;
  94        xmp.ancestor = orig_name;
  95        xmp.file1 = name1;
  96        xmp.file2 = name2;
  97        return xdl_merge(orig, src1, src2, &xmp, result);
  98}
  99
 100static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 101                          mmbuffer_t *result,
 102                          const char *path_unused,
 103                          mmfile_t *orig, const char *orig_name,
 104                          mmfile_t *src1, const char *name1,
 105                          mmfile_t *src2, const char *name2,
 106                          const struct ll_merge_options *opts,
 107                          int marker_size)
 108{
 109        /* Use union favor */
 110        struct ll_merge_options o;
 111        assert(opts);
 112        o = *opts;
 113        o.variant = XDL_MERGE_FAVOR_UNION;
 114        return ll_xdl_merge(drv_unused, result, path_unused,
 115                            orig, NULL, src1, NULL, src2, NULL,
 116                            &o, marker_size);
 117}
 118
 119#define LL_BINARY_MERGE 0
 120#define LL_TEXT_MERGE 1
 121#define LL_UNION_MERGE 2
 122static struct ll_merge_driver ll_merge_drv[] = {
 123        { "binary", "built-in binary merge", ll_binary_merge },
 124        { "text", "built-in 3-way text merge", ll_xdl_merge },
 125        { "union", "built-in union merge", ll_union_merge },
 126};
 127
 128static void create_temp(mmfile_t *src, char *path)
 129{
 130        int fd;
 131
 132        strcpy(path, ".merge_file_XXXXXX");
 133        fd = xmkstemp(path);
 134        if (write_in_full(fd, src->ptr, src->size) != src->size)
 135                die_errno("unable to write temp-file");
 136        close(fd);
 137}
 138
 139/*
 140 * User defined low-level merge driver support.
 141 */
 142static int ll_ext_merge(const struct ll_merge_driver *fn,
 143                        mmbuffer_t *result,
 144                        const char *path,
 145                        mmfile_t *orig, const char *orig_name,
 146                        mmfile_t *src1, const char *name1,
 147                        mmfile_t *src2, const char *name2,
 148                        const struct ll_merge_options *opts,
 149                        int marker_size)
 150{
 151        char temp[4][50];
 152        struct strbuf cmd = STRBUF_INIT;
 153        struct strbuf_expand_dict_entry dict[5];
 154        const char *args[] = { NULL, NULL };
 155        int status, fd, i;
 156        struct stat st;
 157        assert(opts);
 158
 159        dict[0].placeholder = "O"; dict[0].value = temp[0];
 160        dict[1].placeholder = "A"; dict[1].value = temp[1];
 161        dict[2].placeholder = "B"; dict[2].value = temp[2];
 162        dict[3].placeholder = "L"; dict[3].value = temp[3];
 163        dict[4].placeholder = NULL; dict[4].value = NULL;
 164
 165        if (fn->cmdline == NULL)
 166                die("custom merge driver %s lacks command line.", fn->name);
 167
 168        result->ptr = NULL;
 169        result->size = 0;
 170        create_temp(orig, temp[0]);
 171        create_temp(src1, temp[1]);
 172        create_temp(src2, temp[2]);
 173        sprintf(temp[3], "%d", marker_size);
 174
 175        strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
 176
 177        args[0] = cmd.buf;
 178        status = run_command_v_opt(args, RUN_USING_SHELL);
 179        fd = open(temp[1], O_RDONLY);
 180        if (fd < 0)
 181                goto bad;
 182        if (fstat(fd, &st))
 183                goto close_bad;
 184        result->size = st.st_size;
 185        result->ptr = xmalloc(result->size + 1);
 186        if (read_in_full(fd, result->ptr, result->size) != result->size) {
 187                free(result->ptr);
 188                result->ptr = NULL;
 189                result->size = 0;
 190        }
 191 close_bad:
 192        close(fd);
 193 bad:
 194        for (i = 0; i < 3; i++)
 195                unlink_or_warn(temp[i]);
 196        strbuf_release(&cmd);
 197        return status;
 198}
 199
 200/*
 201 * merge.default and merge.driver configuration items
 202 */
 203static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 204static const char *default_ll_merge;
 205
 206static int read_merge_config(const char *var, const char *value, void *cb)
 207{
 208        struct ll_merge_driver *fn;
 209        const char *ep, *name;
 210        int namelen;
 211
 212        if (!strcmp(var, "merge.default")) {
 213                if (value)
 214                        default_ll_merge = xstrdup(value);
 215                return 0;
 216        }
 217
 218        /*
 219         * We are not interested in anything but "merge.<name>.variable";
 220         * especially, we do not want to look at variables such as
 221         * "merge.summary", "merge.tool", and "merge.verbosity".
 222         */
 223        if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
 224                return 0;
 225
 226        /*
 227         * Find existing one as we might be processing merge.<name>.var2
 228         * after seeing merge.<name>.var1.
 229         */
 230        name = var + 6;
 231        namelen = ep - name;
 232        for (fn = ll_user_merge; fn; fn = fn->next)
 233                if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 234                        break;
 235        if (!fn) {
 236                fn = xcalloc(1, sizeof(struct ll_merge_driver));
 237                fn->name = xmemdupz(name, namelen);
 238                fn->fn = ll_ext_merge;
 239                *ll_user_merge_tail = fn;
 240                ll_user_merge_tail = &(fn->next);
 241        }
 242
 243        ep++;
 244
 245        if (!strcmp("name", ep)) {
 246                if (!value)
 247                        return error("%s: lacks value", var);
 248                fn->description = xstrdup(value);
 249                return 0;
 250        }
 251
 252        if (!strcmp("driver", ep)) {
 253                if (!value)
 254                        return error("%s: lacks value", var);
 255                /*
 256                 * merge.<name>.driver specifies the command line:
 257                 *
 258                 *      command-line
 259                 *
 260                 * The command-line will be interpolated with the following
 261                 * tokens and is given to the shell:
 262                 *
 263                 *    %O - temporary file name for the merge base.
 264                 *    %A - temporary file name for our version.
 265                 *    %B - temporary file name for the other branches' version.
 266                 *    %L - conflict marker length
 267                 *
 268                 * The external merge driver should write the results in the
 269                 * file named by %A, and signal that it has done with zero exit
 270                 * status.
 271                 */
 272                fn->cmdline = xstrdup(value);
 273                return 0;
 274        }
 275
 276        if (!strcmp("recursive", ep)) {
 277                if (!value)
 278                        return error("%s: lacks value", var);
 279                fn->recursive = xstrdup(value);
 280                return 0;
 281        }
 282
 283        return 0;
 284}
 285
 286static void initialize_ll_merge(void)
 287{
 288        if (ll_user_merge_tail)
 289                return;
 290        ll_user_merge_tail = &ll_user_merge;
 291        git_config(read_merge_config, NULL);
 292}
 293
 294static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 295{
 296        struct ll_merge_driver *fn;
 297        const char *name;
 298        int i;
 299
 300        initialize_ll_merge();
 301
 302        if (ATTR_TRUE(merge_attr))
 303                return &ll_merge_drv[LL_TEXT_MERGE];
 304        else if (ATTR_FALSE(merge_attr))
 305                return &ll_merge_drv[LL_BINARY_MERGE];
 306        else if (ATTR_UNSET(merge_attr)) {
 307                if (!default_ll_merge)
 308                        return &ll_merge_drv[LL_TEXT_MERGE];
 309                else
 310                        name = default_ll_merge;
 311        }
 312        else
 313                name = merge_attr;
 314
 315        for (fn = ll_user_merge; fn; fn = fn->next)
 316                if (!strcmp(fn->name, name))
 317                        return fn;
 318
 319        for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 320                if (!strcmp(ll_merge_drv[i].name, name))
 321                        return &ll_merge_drv[i];
 322
 323        /* default to the 3-way */
 324        return &ll_merge_drv[LL_TEXT_MERGE];
 325}
 326
 327static int git_path_check_merge(const char *path, struct git_attr_check check[2])
 328{
 329        if (!check[0].attr) {
 330                check[0].attr = git_attr("merge");
 331                check[1].attr = git_attr("conflict-marker-size");
 332        }
 333        return git_checkattr(path, 2, check);
 334}
 335
 336static void normalize_file(mmfile_t *mm, const char *path)
 337{
 338        struct strbuf strbuf = STRBUF_INIT;
 339        if (renormalize_buffer(path, mm->ptr, mm->size, &strbuf)) {
 340                free(mm->ptr);
 341                mm->size = strbuf.len;
 342                mm->ptr = strbuf_detach(&strbuf, NULL);
 343        }
 344}
 345
 346int ll_merge(mmbuffer_t *result_buf,
 347             const char *path,
 348             mmfile_t *ancestor, const char *ancestor_label,
 349             mmfile_t *ours, const char *our_label,
 350             mmfile_t *theirs, const char *their_label,
 351             const struct ll_merge_options *opts)
 352{
 353        static struct git_attr_check check[2];
 354        const char *ll_driver_name = NULL;
 355        int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 356        const struct ll_merge_driver *driver;
 357
 358        if (!opts) {
 359                struct ll_merge_options default_opts = {0};
 360                return ll_merge(result_buf, path, ancestor, ancestor_label,
 361                                ours, our_label, theirs, their_label,
 362                                &default_opts);
 363        }
 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        if (opts->virtual_ancestor && driver->recursive)
 380                driver = find_ll_merge_driver(driver->recursive);
 381        return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
 382                          ours, our_label, theirs, their_label,
 383                          opts, marker_size);
 384}
 385
 386int ll_merge_marker_size(const char *path)
 387{
 388        static struct git_attr_check check;
 389        int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 390
 391        if (!check.attr)
 392                check.attr = git_attr("conflict-marker-size");
 393        if (!git_checkattr(path, 1, &check) && check.value) {
 394                marker_size = atoi(check.value);
 395                if (marker_size <= 0)
 396                        marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 397        }
 398        return marker_size;
 399}