builtin / merge-tree.con commit fetch-pack.c: use oidset to check existence of loose object (024aa46)
   1#include "builtin.h"
   2#include "tree-walk.h"
   3#include "xdiff-interface.h"
   4#include "blob.h"
   5#include "exec_cmd.h"
   6#include "merge-blobs.h"
   7
   8static const char merge_tree_usage[] = "git merge-tree <base-tree> <branch1> <branch2>";
   9
  10struct merge_list {
  11        struct merge_list *next;
  12        struct merge_list *link;        /* other stages for this object */
  13
  14        unsigned int stage : 2;
  15        unsigned int mode;
  16        const char *path;
  17        struct blob *blob;
  18};
  19
  20static struct merge_list *merge_result, **merge_result_end = &merge_result;
  21
  22static void add_merge_entry(struct merge_list *entry)
  23{
  24        *merge_result_end = entry;
  25        merge_result_end = &entry->next;
  26}
  27
  28static void merge_trees(struct tree_desc t[3], const char *base);
  29
  30static const char *explanation(struct merge_list *entry)
  31{
  32        switch (entry->stage) {
  33        case 0:
  34                return "merged";
  35        case 3:
  36                return "added in remote";
  37        case 2:
  38                if (entry->link)
  39                        return "added in both";
  40                return "added in local";
  41        }
  42
  43        /* Existed in base */
  44        entry = entry->link;
  45        if (!entry)
  46                return "removed in both";
  47
  48        if (entry->link)
  49                return "changed in both";
  50
  51        if (entry->stage == 3)
  52                return "removed in local";
  53        return "removed in remote";
  54}
  55
  56static void *result(struct merge_list *entry, unsigned long *size)
  57{
  58        enum object_type type;
  59        struct blob *base, *our, *their;
  60        const char *path = entry->path;
  61
  62        if (!entry->stage)
  63                return read_sha1_file(entry->blob->object.oid.hash, &type, size);
  64        base = NULL;
  65        if (entry->stage == 1) {
  66                base = entry->blob;
  67                entry = entry->link;
  68        }
  69        our = NULL;
  70        if (entry && entry->stage == 2) {
  71                our = entry->blob;
  72                entry = entry->link;
  73        }
  74        their = NULL;
  75        if (entry)
  76                their = entry->blob;
  77        return merge_blobs(path, base, our, their, size);
  78}
  79
  80static void *origin(struct merge_list *entry, unsigned long *size)
  81{
  82        enum object_type type;
  83        while (entry) {
  84                if (entry->stage == 2)
  85                        return read_sha1_file(entry->blob->object.oid.hash, &type, size);
  86                entry = entry->link;
  87        }
  88        return NULL;
  89}
  90
  91static int show_outf(void *priv_, mmbuffer_t *mb, int nbuf)
  92{
  93        int i;
  94        for (i = 0; i < nbuf; i++)
  95                printf("%.*s", (int) mb[i].size, mb[i].ptr);
  96        return 0;
  97}
  98
  99static void show_diff(struct merge_list *entry)
 100{
 101        unsigned long size;
 102        mmfile_t src, dst;
 103        xpparam_t xpp;
 104        xdemitconf_t xecfg;
 105        xdemitcb_t ecb;
 106
 107        xpp.flags = 0;
 108        memset(&xecfg, 0, sizeof(xecfg));
 109        xecfg.ctxlen = 3;
 110        ecb.outf = show_outf;
 111        ecb.priv = NULL;
 112
 113        src.ptr = origin(entry, &size);
 114        if (!src.ptr)
 115                size = 0;
 116        src.size = size;
 117        dst.ptr = result(entry, &size);
 118        if (!dst.ptr)
 119                size = 0;
 120        dst.size = size;
 121        if (xdi_diff(&src, &dst, &xpp, &xecfg, &ecb))
 122                die("unable to generate diff");
 123        free(src.ptr);
 124        free(dst.ptr);
 125}
 126
 127static void show_result_list(struct merge_list *entry)
 128{
 129        printf("%s\n", explanation(entry));
 130        do {
 131                struct merge_list *link = entry->link;
 132                static const char *desc[4] = { "result", "base", "our", "their" };
 133                printf("  %-6s %o %s %s\n", desc[entry->stage], entry->mode, oid_to_hex(&entry->blob->object.oid), entry->path);
 134                entry = link;
 135        } while (entry);
 136}
 137
 138static void show_result(void)
 139{
 140        struct merge_list *walk;
 141
 142        walk = merge_result;
 143        while (walk) {
 144                show_result_list(walk);
 145                show_diff(walk);
 146                walk = walk->next;
 147        }
 148}
 149
 150/* An empty entry never compares same, not even to another empty entry */
 151static int same_entry(struct name_entry *a, struct name_entry *b)
 152{
 153        return  a->oid &&
 154                b->oid &&
 155                !oidcmp(a->oid, b->oid) &&
 156                a->mode == b->mode;
 157}
 158
 159static int both_empty(struct name_entry *a, struct name_entry *b)
 160{
 161        return !(a->oid || b->oid);
 162}
 163
 164static struct merge_list *create_entry(unsigned stage, unsigned mode, const struct object_id *oid, const char *path)
 165{
 166        struct merge_list *res = xcalloc(1, sizeof(*res));
 167
 168        res->stage = stage;
 169        res->path = path;
 170        res->mode = mode;
 171        res->blob = lookup_blob(oid);
 172        return res;
 173}
 174
 175static char *traverse_path(const struct traverse_info *info, const struct name_entry *n)
 176{
 177        char *path = xmallocz(traverse_path_len(info, n));
 178        return make_traverse_path(path, info, n);
 179}
 180
 181static void resolve(const struct traverse_info *info, struct name_entry *ours, struct name_entry *result)
 182{
 183        struct merge_list *orig, *final;
 184        const char *path;
 185
 186        /* If it's already ours, don't bother showing it */
 187        if (!ours)
 188                return;
 189
 190        path = traverse_path(info, result);
 191        orig = create_entry(2, ours->mode, ours->oid, path);
 192        final = create_entry(0, result->mode, result->oid, path);
 193
 194        final->link = orig;
 195
 196        add_merge_entry(final);
 197}
 198
 199static void unresolved_directory(const struct traverse_info *info,
 200                                 struct name_entry n[3])
 201{
 202        char *newbase;
 203        struct name_entry *p;
 204        struct tree_desc t[3];
 205        void *buf0, *buf1, *buf2;
 206
 207        for (p = n; p < n + 3; p++) {
 208                if (p->mode && S_ISDIR(p->mode))
 209                        break;
 210        }
 211        if (n + 3 <= p)
 212                return; /* there is no tree here */
 213
 214        newbase = traverse_path(info, p);
 215
 216#define ENTRY_OID(e) (((e)->mode && S_ISDIR((e)->mode)) ? (e)->oid : NULL)
 217        buf0 = fill_tree_descriptor(t + 0, ENTRY_OID(n + 0));
 218        buf1 = fill_tree_descriptor(t + 1, ENTRY_OID(n + 1));
 219        buf2 = fill_tree_descriptor(t + 2, ENTRY_OID(n + 2));
 220#undef ENTRY_OID
 221
 222        merge_trees(t, newbase);
 223
 224        free(buf0);
 225        free(buf1);
 226        free(buf2);
 227        free(newbase);
 228}
 229
 230
 231static struct merge_list *link_entry(unsigned stage, const struct traverse_info *info, struct name_entry *n, struct merge_list *entry)
 232{
 233        const char *path;
 234        struct merge_list *link;
 235
 236        if (!n->mode)
 237                return entry;
 238        if (entry)
 239                path = entry->path;
 240        else
 241                path = traverse_path(info, n);
 242        link = create_entry(stage, n->mode, n->oid, path);
 243        link->link = entry;
 244        return link;
 245}
 246
 247static void unresolved(const struct traverse_info *info, struct name_entry n[3])
 248{
 249        struct merge_list *entry = NULL;
 250        int i;
 251        unsigned dirmask = 0, mask = 0;
 252
 253        for (i = 0; i < 3; i++) {
 254                mask |= (1 << i);
 255                /*
 256                 * Treat missing entries as directories so that we return
 257                 * after unresolved_directory has handled this.
 258                 */
 259                if (!n[i].mode || S_ISDIR(n[i].mode))
 260                        dirmask |= (1 << i);
 261        }
 262
 263        unresolved_directory(info, n);
 264
 265        if (dirmask == mask)
 266                return;
 267
 268        if (n[2].mode && !S_ISDIR(n[2].mode))
 269                entry = link_entry(3, info, n + 2, entry);
 270        if (n[1].mode && !S_ISDIR(n[1].mode))
 271                entry = link_entry(2, info, n + 1, entry);
 272        if (n[0].mode && !S_ISDIR(n[0].mode))
 273                entry = link_entry(1, info, n + 0, entry);
 274
 275        add_merge_entry(entry);
 276}
 277
 278/*
 279 * Merge two trees together (t[1] and t[2]), using a common base (t[0])
 280 * as the origin.
 281 *
 282 * This walks the (sorted) trees in lock-step, checking every possible
 283 * name. Note that directories automatically sort differently from other
 284 * files (see "base_name_compare"), so you'll never see file/directory
 285 * conflicts, because they won't ever compare the same.
 286 *
 287 * IOW, if a directory changes to a filename, it will automatically be
 288 * seen as the directory going away, and the filename being created.
 289 *
 290 * Think of this as a three-way diff.
 291 *
 292 * The output will be either:
 293 *  - successful merge
 294 *       "0 mode sha1 filename"
 295 *    NOTE NOTE NOTE! FIXME! We really really need to walk the index
 296 *    in parallel with this too!
 297 *
 298 *  - conflict:
 299 *      "1 mode sha1 filename"
 300 *      "2 mode sha1 filename"
 301 *      "3 mode sha1 filename"
 302 *    where not all of the 1/2/3 lines may exist, of course.
 303 *
 304 * The successful merge rules are the same as for the three-way merge
 305 * in git-read-tree.
 306 */
 307static int threeway_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *entry, struct traverse_info *info)
 308{
 309        /* Same in both? */
 310        if (same_entry(entry+1, entry+2) || both_empty(entry+1, entry+2)) {
 311                /* Modified, added or removed identically */
 312                resolve(info, NULL, entry+1);
 313                return mask;
 314        }
 315
 316        if (same_entry(entry+0, entry+1)) {
 317                if (entry[2].oid && !S_ISDIR(entry[2].mode)) {
 318                        /* We did not touch, they modified -- take theirs */
 319                        resolve(info, entry+1, entry+2);
 320                        return mask;
 321                }
 322                /*
 323                 * If we did not touch a directory but they made it
 324                 * into a file, we fall through and unresolved()
 325                 * recurses down.  Likewise for the opposite case.
 326                 */
 327        }
 328
 329        if (same_entry(entry+0, entry+2) || both_empty(entry+0, entry+2)) {
 330                /* We added, modified or removed, they did not touch -- take ours */
 331                resolve(info, NULL, entry+1);
 332                return mask;
 333        }
 334
 335        unresolved(info, entry);
 336        return mask;
 337}
 338
 339static void merge_trees(struct tree_desc t[3], const char *base)
 340{
 341        struct traverse_info info;
 342
 343        setup_traverse_info(&info, base);
 344        info.fn = threeway_callback;
 345        traverse_trees(3, t, &info);
 346}
 347
 348static void *get_tree_descriptor(struct tree_desc *desc, const char *rev)
 349{
 350        struct object_id oid;
 351        void *buf;
 352
 353        if (get_oid(rev, &oid))
 354                die("unknown rev %s", rev);
 355        buf = fill_tree_descriptor(desc, &oid);
 356        if (!buf)
 357                die("%s is not a tree", rev);
 358        return buf;
 359}
 360
 361int cmd_merge_tree(int argc, const char **argv, const char *prefix)
 362{
 363        struct tree_desc t[3];
 364        void *buf1, *buf2, *buf3;
 365
 366        if (argc != 4)
 367                usage(merge_tree_usage);
 368
 369        buf1 = get_tree_descriptor(t+0, argv[1]);
 370        buf2 = get_tree_descriptor(t+1, argv[2]);
 371        buf3 = get_tree_descriptor(t+2, argv[3]);
 372        merge_trees(t, "");
 373        free(buf1);
 374        free(buf2);
 375        free(buf3);
 376
 377        show_result();
 378        return 0;
 379}