ll-merge.con commit Fourth batch (bc12974)
   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 "config.h"
   9#include "attr.h"
  10#include "xdiff-interface.h"
  11#include "run-command.h"
  12#include "ll-merge.h"
  13#include "quote.h"
  14
  15struct ll_merge_driver;
  16
  17typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
  18                           mmbuffer_t *result,
  19                           const char *path,
  20                           mmfile_t *orig, const char *orig_name,
  21                           mmfile_t *src1, const char *name1,
  22                           mmfile_t *src2, const char *name2,
  23                           const struct ll_merge_options *opts,
  24                           int marker_size);
  25
  26struct ll_merge_driver {
  27        const char *name;
  28        const char *description;
  29        ll_merge_fn fn;
  30        const char *recursive;
  31        struct ll_merge_driver *next;
  32        char *cmdline;
  33};
  34
  35static struct attr_check *merge_attributes;
  36static struct attr_check *load_merge_attributes(void)
  37{
  38        if (!merge_attributes)
  39                merge_attributes = attr_check_initl("merge", "conflict-marker-size", NULL);
  40        return merge_attributes;
  41}
  42
  43void reset_merge_attributes(void)
  44{
  45        attr_check_free(merge_attributes);
  46        merge_attributes = NULL;
  47}
  48
  49/*
  50 * Built-in low-levels
  51 */
  52static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
  53                           mmbuffer_t *result,
  54                           const char *path,
  55                           mmfile_t *orig, const char *orig_name,
  56                           mmfile_t *src1, const char *name1,
  57                           mmfile_t *src2, const char *name2,
  58                           const struct ll_merge_options *opts,
  59                           int marker_size)
  60{
  61        mmfile_t *stolen;
  62        assert(opts);
  63
  64        /*
  65         * The tentative merge result is the common ancestor for an
  66         * internal merge.  For the final merge, it is "ours" by
  67         * default but -Xours/-Xtheirs can tweak the choice.
  68         */
  69        if (opts->virtual_ancestor) {
  70                stolen = orig;
  71        } else {
  72                switch (opts->variant) {
  73                default:
  74                        warning("Cannot merge binary files: %s (%s vs. %s)",
  75                                path, name1, name2);
  76                        /* fallthru */
  77                case XDL_MERGE_FAVOR_OURS:
  78                        stolen = src1;
  79                        break;
  80                case XDL_MERGE_FAVOR_THEIRS:
  81                        stolen = src2;
  82                        break;
  83                }
  84        }
  85
  86        result->ptr = stolen->ptr;
  87        result->size = stolen->size;
  88        stolen->ptr = NULL;
  89
  90        /*
  91         * With -Xtheirs or -Xours, we have cleanly merged;
  92         * otherwise we got a conflict.
  93         */
  94        return (opts->variant ? 0 : 1);
  95}
  96
  97static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
  98                        mmbuffer_t *result,
  99                        const char *path,
 100                        mmfile_t *orig, const char *orig_name,
 101                        mmfile_t *src1, const char *name1,
 102                        mmfile_t *src2, const char *name2,
 103                        const struct ll_merge_options *opts,
 104                        int marker_size)
 105{
 106        xmparam_t xmp;
 107        assert(opts);
 108
 109        if (orig->size > MAX_XDIFF_SIZE ||
 110            src1->size > MAX_XDIFF_SIZE ||
 111            src2->size > MAX_XDIFF_SIZE ||
 112            buffer_is_binary(orig->ptr, orig->size) ||
 113            buffer_is_binary(src1->ptr, src1->size) ||
 114            buffer_is_binary(src2->ptr, src2->size)) {
 115                return ll_binary_merge(drv_unused, result,
 116                                       path,
 117                                       orig, orig_name,
 118                                       src1, name1,
 119                                       src2, name2,
 120                                       opts, marker_size);
 121        }
 122
 123        memset(&xmp, 0, sizeof(xmp));
 124        xmp.level = XDL_MERGE_ZEALOUS;
 125        xmp.favor = opts->variant;
 126        xmp.xpp.flags = opts->xdl_opts;
 127        if (git_xmerge_style >= 0)
 128                xmp.style = git_xmerge_style;
 129        if (marker_size > 0)
 130                xmp.marker_size = marker_size;
 131        xmp.ancestor = orig_name;
 132        xmp.file1 = name1;
 133        xmp.file2 = name2;
 134        return xdl_merge(orig, src1, src2, &xmp, result);
 135}
 136
 137static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 138                          mmbuffer_t *result,
 139                          const char *path_unused,
 140                          mmfile_t *orig, const char *orig_name,
 141                          mmfile_t *src1, const char *name1,
 142                          mmfile_t *src2, const char *name2,
 143                          const struct ll_merge_options *opts,
 144                          int marker_size)
 145{
 146        /* Use union favor */
 147        struct ll_merge_options o;
 148        assert(opts);
 149        o = *opts;
 150        o.variant = XDL_MERGE_FAVOR_UNION;
 151        return ll_xdl_merge(drv_unused, result, path_unused,
 152                            orig, NULL, src1, NULL, src2, NULL,
 153                            &o, marker_size);
 154}
 155
 156#define LL_BINARY_MERGE 0
 157#define LL_TEXT_MERGE 1
 158#define LL_UNION_MERGE 2
 159static struct ll_merge_driver ll_merge_drv[] = {
 160        { "binary", "built-in binary merge", ll_binary_merge },
 161        { "text", "built-in 3-way text merge", ll_xdl_merge },
 162        { "union", "built-in union merge", ll_union_merge },
 163};
 164
 165static void create_temp(mmfile_t *src, char *path, size_t len)
 166{
 167        int fd;
 168
 169        xsnprintf(path, len, ".merge_file_XXXXXX");
 170        fd = xmkstemp(path);
 171        if (write_in_full(fd, src->ptr, src->size) < 0)
 172                die_errno("unable to write temp-file");
 173        close(fd);
 174}
 175
 176/*
 177 * User defined low-level merge driver support.
 178 */
 179static int ll_ext_merge(const struct ll_merge_driver *fn,
 180                        mmbuffer_t *result,
 181                        const char *path,
 182                        mmfile_t *orig, const char *orig_name,
 183                        mmfile_t *src1, const char *name1,
 184                        mmfile_t *src2, const char *name2,
 185                        const struct ll_merge_options *opts,
 186                        int marker_size)
 187{
 188        char temp[4][50];
 189        struct strbuf cmd = STRBUF_INIT;
 190        struct strbuf_expand_dict_entry dict[6];
 191        struct strbuf path_sq = STRBUF_INIT;
 192        const char *args[] = { NULL, NULL };
 193        int status, fd, i;
 194        struct stat st;
 195        assert(opts);
 196
 197        sq_quote_buf(&path_sq, path);
 198        dict[0].placeholder = "O"; dict[0].value = temp[0];
 199        dict[1].placeholder = "A"; dict[1].value = temp[1];
 200        dict[2].placeholder = "B"; dict[2].value = temp[2];
 201        dict[3].placeholder = "L"; dict[3].value = temp[3];
 202        dict[4].placeholder = "P"; dict[4].value = path_sq.buf;
 203        dict[5].placeholder = NULL; dict[5].value = NULL;
 204
 205        if (fn->cmdline == NULL)
 206                die("custom merge driver %s lacks command line.", fn->name);
 207
 208        result->ptr = NULL;
 209        result->size = 0;
 210        create_temp(orig, temp[0], sizeof(temp[0]));
 211        create_temp(src1, temp[1], sizeof(temp[1]));
 212        create_temp(src2, temp[2], sizeof(temp[2]));
 213        xsnprintf(temp[3], sizeof(temp[3]), "%d", marker_size);
 214
 215        strbuf_expand(&cmd, fn->cmdline, strbuf_expand_dict_cb, &dict);
 216
 217        args[0] = cmd.buf;
 218        status = run_command_v_opt(args, RUN_USING_SHELL);
 219        fd = open(temp[1], O_RDONLY);
 220        if (fd < 0)
 221                goto bad;
 222        if (fstat(fd, &st))
 223                goto close_bad;
 224        result->size = st.st_size;
 225        result->ptr = xmallocz(result->size);
 226        if (read_in_full(fd, result->ptr, result->size) != result->size) {
 227                FREE_AND_NULL(result->ptr);
 228                result->size = 0;
 229        }
 230 close_bad:
 231        close(fd);
 232 bad:
 233        for (i = 0; i < 3; i++)
 234                unlink_or_warn(temp[i]);
 235        strbuf_release(&cmd);
 236        strbuf_release(&path_sq);
 237        return status;
 238}
 239
 240/*
 241 * merge.default and merge.driver configuration items
 242 */
 243static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 244static const char *default_ll_merge;
 245
 246static int read_merge_config(const char *var, const char *value, void *cb)
 247{
 248        struct ll_merge_driver *fn;
 249        const char *key, *name;
 250        int namelen;
 251
 252        if (!strcmp(var, "merge.default"))
 253                return git_config_string(&default_ll_merge, var, value);
 254
 255        /*
 256         * We are not interested in anything but "merge.<name>.variable";
 257         * especially, we do not want to look at variables such as
 258         * "merge.summary", "merge.tool", and "merge.verbosity".
 259         */
 260        if (parse_config_key(var, "merge", &name, &namelen, &key) < 0 || !name)
 261                return 0;
 262
 263        /*
 264         * Find existing one as we might be processing merge.<name>.var2
 265         * after seeing merge.<name>.var1.
 266         */
 267        for (fn = ll_user_merge; fn; fn = fn->next)
 268                if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 269                        break;
 270        if (!fn) {
 271                fn = xcalloc(1, sizeof(struct ll_merge_driver));
 272                fn->name = xmemdupz(name, namelen);
 273                fn->fn = ll_ext_merge;
 274                *ll_user_merge_tail = fn;
 275                ll_user_merge_tail = &(fn->next);
 276        }
 277
 278        if (!strcmp("name", key))
 279                return git_config_string(&fn->description, var, value);
 280
 281        if (!strcmp("driver", key)) {
 282                if (!value)
 283                        return error("%s: lacks value", var);
 284                /*
 285                 * merge.<name>.driver specifies the command line:
 286                 *
 287                 *      command-line
 288                 *
 289                 * The command-line will be interpolated with the following
 290                 * tokens and is given to the shell:
 291                 *
 292                 *    %O - temporary file name for the merge base.
 293                 *    %A - temporary file name for our version.
 294                 *    %B - temporary file name for the other branches' version.
 295                 *    %L - conflict marker length
 296                 *    %P - the original path (safely quoted for the shell)
 297                 *
 298                 * The external merge driver should write the results in the
 299                 * file named by %A, and signal that it has done with zero exit
 300                 * status.
 301                 */
 302                fn->cmdline = xstrdup(value);
 303                return 0;
 304        }
 305
 306        if (!strcmp("recursive", key))
 307                return git_config_string(&fn->recursive, var, value);
 308
 309        return 0;
 310}
 311
 312static void initialize_ll_merge(void)
 313{
 314        if (ll_user_merge_tail)
 315                return;
 316        ll_user_merge_tail = &ll_user_merge;
 317        git_config(read_merge_config, NULL);
 318}
 319
 320static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 321{
 322        struct ll_merge_driver *fn;
 323        const char *name;
 324        int i;
 325
 326        initialize_ll_merge();
 327
 328        if (ATTR_TRUE(merge_attr))
 329                return &ll_merge_drv[LL_TEXT_MERGE];
 330        else if (ATTR_FALSE(merge_attr))
 331                return &ll_merge_drv[LL_BINARY_MERGE];
 332        else if (ATTR_UNSET(merge_attr)) {
 333                if (!default_ll_merge)
 334                        return &ll_merge_drv[LL_TEXT_MERGE];
 335                else
 336                        name = default_ll_merge;
 337        }
 338        else
 339                name = merge_attr;
 340
 341        for (fn = ll_user_merge; fn; fn = fn->next)
 342                if (!strcmp(fn->name, name))
 343                        return fn;
 344
 345        for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 346                if (!strcmp(ll_merge_drv[i].name, name))
 347                        return &ll_merge_drv[i];
 348
 349        /* default to the 3-way */
 350        return &ll_merge_drv[LL_TEXT_MERGE];
 351}
 352
 353static void normalize_file(mmfile_t *mm, const char *path, struct index_state *istate)
 354{
 355        struct strbuf strbuf = STRBUF_INIT;
 356        if (renormalize_buffer(istate, path, mm->ptr, mm->size, &strbuf)) {
 357                free(mm->ptr);
 358                mm->size = strbuf.len;
 359                mm->ptr = strbuf_detach(&strbuf, NULL);
 360        }
 361}
 362
 363int ll_merge(mmbuffer_t *result_buf,
 364             const char *path,
 365             mmfile_t *ancestor, const char *ancestor_label,
 366             mmfile_t *ours, const char *our_label,
 367             mmfile_t *theirs, const char *their_label,
 368             struct index_state *istate,
 369             const struct ll_merge_options *opts)
 370{
 371        struct attr_check *check = load_merge_attributes();
 372        static const struct ll_merge_options default_opts;
 373        const char *ll_driver_name = NULL;
 374        int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 375        const struct ll_merge_driver *driver;
 376
 377        if (!opts)
 378                opts = &default_opts;
 379
 380        if (opts->renormalize) {
 381                normalize_file(ancestor, path, istate);
 382                normalize_file(ours, path, istate);
 383                normalize_file(theirs, path, istate);
 384        }
 385
 386        git_check_attr(istate, path, check);
 387        ll_driver_name = check->items[0].value;
 388        if (check->items[1].value) {
 389                marker_size = atoi(check->items[1].value);
 390                if (marker_size <= 0)
 391                        marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 392        }
 393        driver = find_ll_merge_driver(ll_driver_name);
 394
 395        if (opts->virtual_ancestor) {
 396                if (driver->recursive)
 397                        driver = find_ll_merge_driver(driver->recursive);
 398        }
 399        if (opts->extra_marker_size) {
 400                marker_size += opts->extra_marker_size;
 401        }
 402        return driver->fn(driver, result_buf, path, ancestor, ancestor_label,
 403                          ours, our_label, theirs, their_label,
 404                          opts, marker_size);
 405}
 406
 407int ll_merge_marker_size(struct index_state *istate, const char *path)
 408{
 409        static struct attr_check *check;
 410        int marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 411
 412        if (!check)
 413                check = attr_check_initl("conflict-marker-size", NULL);
 414        git_check_attr(istate, path, check);
 415        if (check->items[0].value) {
 416                marker_size = atoi(check->items[0].value);
 417                if (marker_size <= 0)
 418                        marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 419        }
 420        return marker_size;
 421}