Andrew's git / gitweb.git / refs.c
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refs.con commit Enable ref log creation in git checkout -b. (969d326)
   1#include "refs.h"
   2#include "cache.h"
   3
   4#include <errno.h>
   5
   6/* We allow "recursive" symbolic refs. Only within reason, though */
   7#define MAXDEPTH 5
   8
   9const char *resolve_ref(const char *path, unsigned char *sha1, int reading)
  10{
  11        int depth = MAXDEPTH, len;
  12        char buffer[256];
  13
  14        for (;;) {
  15                struct stat st;
  16                char *buf;
  17                int fd;
  18
  19                if (--depth < 0)
  20                        return NULL;
  21
  22                /* Special case: non-existing file.
  23                 * Not having the refs/heads/new-branch is OK
  24                 * if we are writing into it, so is .git/HEAD
  25                 * that points at refs/heads/master still to be
  26                 * born.  It is NOT OK if we are resolving for
  27                 * reading.
  28                 */
  29                if (lstat(path, &st) < 0) {
  30                        if (reading || errno != ENOENT)
  31                                return NULL;
  32                        memset(sha1, 0, 20);
  33                        return path;
  34                }
  35
  36                /* Follow "normalized" - ie "refs/.." symlinks by hand */
  37                if (S_ISLNK(st.st_mode)) {
  38                        len = readlink(path, buffer, sizeof(buffer)-1);
  39                        if (len >= 5 && !memcmp("refs/", buffer, 5)) {
  40                                path = git_path("%.*s", len, buffer);
  41                                continue;
  42                        }
  43                }
  44
  45                /*
  46                 * Anything else, just open it and try to use it as
  47                 * a ref
  48                 */
  49                fd = open(path, O_RDONLY);
  50                if (fd < 0)
  51                        return NULL;
  52                len = read(fd, buffer, sizeof(buffer)-1);
  53                close(fd);
  54
  55                /*
  56                 * Is it a symbolic ref?
  57                 */
  58                if (len < 4 || memcmp("ref:", buffer, 4))
  59                        break;
  60                buf = buffer + 4;
  61                len -= 4;
  62                while (len && isspace(*buf))
  63                        buf++, len--;
  64                while (len && isspace(buf[len-1]))
  65                        buf[--len] = 0;
  66                path = git_path("%.*s", len, buf);
  67        }
  68        if (len < 40 || get_sha1_hex(buffer, sha1))
  69                return NULL;
  70        return path;
  71}
  72
  73int create_symref(const char *git_HEAD, const char *refs_heads_master)
  74{
  75        const char *lockpath;
  76        char ref[1000];
  77        int fd, len, written;
  78
  79#ifndef NO_SYMLINK_HEAD
  80        if (prefer_symlink_refs) {
  81                unlink(git_HEAD);
  82                if (!symlink(refs_heads_master, git_HEAD))
  83                        return 0;
  84                fprintf(stderr, "no symlink - falling back to symbolic ref\n");
  85        }
  86#endif
  87
  88        len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
  89        if (sizeof(ref) <= len) {
  90                error("refname too long: %s", refs_heads_master);
  91                return -1;
  92        }
  93        lockpath = mkpath("%s.lock", git_HEAD);
  94        fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666); 
  95        written = write(fd, ref, len);
  96        close(fd);
  97        if (written != len) {
  98                unlink(lockpath);
  99                error("Unable to write to %s", lockpath);
 100                return -2;
 101        }
 102        if (rename(lockpath, git_HEAD) < 0) {
 103                unlink(lockpath);
 104                error("Unable to create %s", git_HEAD);
 105                return -3;
 106        }
 107        return 0;
 108}
 109
 110int read_ref(const char *filename, unsigned char *sha1)
 111{
 112        if (resolve_ref(filename, sha1, 1))
 113                return 0;
 114        return -1;
 115}
 116
 117static int do_for_each_ref(const char *base, int (*fn)(const char *path, const unsigned char *sha1), int trim)
 118{
 119        int retval = 0;
 120        DIR *dir = opendir(git_path("%s", base));
 121
 122        if (dir) {
 123                struct dirent *de;
 124                int baselen = strlen(base);
 125                char *path = xmalloc(baselen + 257);
 126
 127                if (!strncmp(base, "./", 2)) {
 128                        base += 2;
 129                        baselen -= 2;
 130                }
 131                memcpy(path, base, baselen);
 132                if (baselen && base[baselen-1] != '/')
 133                        path[baselen++] = '/';
 134
 135                while ((de = readdir(dir)) != NULL) {
 136                        unsigned char sha1[20];
 137                        struct stat st;
 138                        int namelen;
 139
 140                        if (de->d_name[0] == '.')
 141                                continue;
 142                        namelen = strlen(de->d_name);
 143                        if (namelen > 255)
 144                                continue;
 145                        if (namelen>5 && !strcmp(de->d_name+namelen-5,".lock"))
 146                                continue;
 147                        memcpy(path + baselen, de->d_name, namelen+1);
 148                        if (stat(git_path("%s", path), &st) < 0)
 149                                continue;
 150                        if (S_ISDIR(st.st_mode)) {
 151                                retval = do_for_each_ref(path, fn, trim);
 152                                if (retval)
 153                                        break;
 154                                continue;
 155                        }
 156                        if (read_ref(git_path("%s", path), sha1) < 0) {
 157                                error("%s points nowhere!", path);
 158                                continue;
 159                        }
 160                        if (!has_sha1_file(sha1)) {
 161                                error("%s does not point to a valid "
 162                                      "commit object!", path);
 163                                continue;
 164                        }
 165                        retval = fn(path + trim, sha1);
 166                        if (retval)
 167                                break;
 168                }
 169                free(path);
 170                closedir(dir);
 171        }
 172        return retval;
 173}
 174
 175int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
 176{
 177        unsigned char sha1[20];
 178        if (!read_ref(git_path("HEAD"), sha1))
 179                return fn("HEAD", sha1);
 180        return 0;
 181}
 182
 183int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
 184{
 185        return do_for_each_ref("refs", fn, 0);
 186}
 187
 188int for_each_tag_ref(int (*fn)(const char *path, const unsigned char *sha1))
 189{
 190        return do_for_each_ref("refs/tags", fn, 10);
 191}
 192
 193int for_each_branch_ref(int (*fn)(const char *path, const unsigned char *sha1))
 194{
 195        return do_for_each_ref("refs/heads", fn, 11);
 196}
 197
 198int for_each_remote_ref(int (*fn)(const char *path, const unsigned char *sha1))
 199{
 200        return do_for_each_ref("refs/remotes", fn, 13);
 201}
 202
 203int get_ref_sha1(const char *ref, unsigned char *sha1)
 204{
 205        if (check_ref_format(ref))
 206                return -1;
 207        return read_ref(git_path("refs/%s", ref), sha1);
 208}
 209
 210/*
 211 * Make sure "ref" is something reasonable to have under ".git/refs/";
 212 * We do not like it if:
 213 *
 214 * - any path component of it begins with ".", or
 215 * - it has double dots "..", or
 216 * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 217 * - it ends with a "/".
 218 */
 219
 220static inline int bad_ref_char(int ch)
 221{
 222        return (((unsigned) ch) <= ' ' ||
 223                ch == '~' || ch == '^' || ch == ':' ||
 224                /* 2.13 Pattern Matching Notation */
 225                ch == '?' || ch == '*' || ch == '[');
 226}
 227
 228int check_ref_format(const char *ref)
 229{
 230        int ch, level;
 231        const char *cp = ref;
 232
 233        level = 0;
 234        while (1) {
 235                while ((ch = *cp++) == '/')
 236                        ; /* tolerate duplicated slashes */
 237                if (!ch)
 238                        return -1; /* should not end with slashes */
 239
 240                /* we are at the beginning of the path component */
 241                if (ch == '.' || bad_ref_char(ch))
 242                        return -1;
 243
 244                /* scan the rest of the path component */
 245                while ((ch = *cp++) != 0) {
 246                        if (bad_ref_char(ch))
 247                                return -1;
 248                        if (ch == '/')
 249                                break;
 250                        if (ch == '.' && *cp == '.')
 251                                return -1;
 252                }
 253                level++;
 254                if (!ch) {
 255                        if (level < 2)
 256                                return -1; /* at least of form "heads/blah" */
 257                        return 0;
 258                }
 259        }
 260}
 261
 262static struct ref_lock* verify_lock(struct ref_lock *lock,
 263        const unsigned char *old_sha1, int mustexist)
 264{
 265        char buf[40];
 266        int nr, fd = open(lock->ref_file, O_RDONLY);
 267        if (fd < 0 && (mustexist || errno != ENOENT)) {
 268                error("Can't verify ref %s", lock->ref_file);
 269                unlock_ref(lock);
 270                return NULL;
 271        }
 272        nr = read(fd, buf, 40);
 273        close(fd);
 274        if (nr != 40 || get_sha1_hex(buf, lock->old_sha1) < 0) {
 275                error("Can't verify ref %s", lock->ref_file);
 276                unlock_ref(lock);
 277                return NULL;
 278        }
 279        if (memcmp(lock->old_sha1, old_sha1, 20)) {
 280                error("Ref %s is at %s but expected %s", lock->ref_file,
 281                        sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 282                unlock_ref(lock);
 283                return NULL;
 284        }
 285        return lock;
 286}
 287
 288static struct ref_lock* lock_ref_sha1_basic(const char *path,
 289        int plen,
 290        const unsigned char *old_sha1, int mustexist)
 291{
 292        struct ref_lock *lock;
 293        struct stat st;
 294
 295        lock = xcalloc(1, sizeof(struct ref_lock));
 296        lock->lock_fd = -1;
 297
 298        plen = strlen(path) - plen;
 299        path = resolve_ref(path, lock->old_sha1, mustexist);
 300        if (!path) {
 301                unlock_ref(lock);
 302                return NULL;
 303        }
 304
 305        lock->ref_file = strdup(path);
 306        lock->lock_file = strdup(mkpath("%s.lock", lock->ref_file));
 307        lock->log_file = strdup(git_path("logs/%s", lock->ref_file + plen));
 308        lock->force_write = lstat(lock->ref_file, &st) && errno == ENOENT;
 309
 310        if (safe_create_leading_directories(lock->lock_file))
 311                die("unable to create directory for %s", lock->lock_file);
 312        lock->lock_fd = open(lock->lock_file,
 313                O_WRONLY | O_CREAT | O_EXCL, 0666);
 314        if (lock->lock_fd < 0) {
 315                error("Couldn't open lock file %s: %s",
 316                        lock->lock_file, strerror(errno));
 317                unlock_ref(lock);
 318                return NULL;
 319        }
 320
 321        return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 322}
 323
 324struct ref_lock* lock_ref_sha1(const char *ref,
 325        const unsigned char *old_sha1, int mustexist)
 326{
 327        if (check_ref_format(ref))
 328                return NULL;
 329        return lock_ref_sha1_basic(git_path("refs/%s", ref),
 330                5 + strlen(ref), old_sha1, mustexist);
 331}
 332
 333struct ref_lock* lock_any_ref_for_update(const char *ref,
 334        const unsigned char *old_sha1, int mustexist)
 335{
 336        return lock_ref_sha1_basic(git_path("%s", ref),
 337                strlen(ref), old_sha1, mustexist);
 338}
 339
 340void unlock_ref (struct ref_lock *lock)
 341{
 342        if (lock->lock_fd >= 0) {
 343                close(lock->lock_fd);
 344                unlink(lock->lock_file);
 345        }
 346        if (lock->ref_file)
 347                free(lock->ref_file);
 348        if (lock->lock_file)
 349                free(lock->lock_file);
 350        if (lock->log_file)
 351                free(lock->log_file);
 352        free(lock);
 353}
 354
 355static int log_ref_write(struct ref_lock *lock,
 356        const unsigned char *sha1, const char *msg)
 357{
 358        int logfd, written, oflags = O_APPEND | O_WRONLY;
 359        unsigned maxlen, len;
 360        char *logrec;
 361        const char *comitter;
 362
 363        if (log_all_ref_updates) {
 364                if (safe_create_leading_directories(lock->log_file) < 0)
 365                        return error("unable to create directory for %s",
 366                                lock->log_file);
 367                oflags |= O_CREAT;
 368        }
 369
 370        logfd = open(lock->log_file, oflags, 0666);
 371        if (logfd < 0) {
 372                if (!log_all_ref_updates && errno == ENOENT)
 373                        return 0;
 374                return error("Unable to append to %s: %s",
 375                        lock->log_file, strerror(errno));
 376        }
 377
 378        setup_ident();
 379        comitter = git_committer_info(1);
 380        if (msg) {
 381                maxlen = strlen(comitter) + strlen(msg) + 2*40 + 5;
 382                logrec = xmalloc(maxlen);
 383                len = snprintf(logrec, maxlen, "%s %s %s\t%s\n",
 384                        sha1_to_hex(lock->old_sha1),
 385                        sha1_to_hex(sha1),
 386                        comitter,
 387                        msg);
 388        } else {
 389                maxlen = strlen(comitter) + 2*40 + 4;
 390                logrec = xmalloc(maxlen);
 391                len = snprintf(logrec, maxlen, "%s %s %s\n",
 392                        sha1_to_hex(lock->old_sha1),
 393                        sha1_to_hex(sha1),
 394                        comitter);
 395        }
 396        written = len <= maxlen ? write(logfd, logrec, len) : -1;
 397        free(logrec);
 398        close(logfd);
 399        if (written != len)
 400                return error("Unable to append to %s", lock->log_file);
 401        return 0;
 402}
 403
 404int write_ref_sha1(struct ref_lock *lock,
 405        const unsigned char *sha1, const char *logmsg)
 406{
 407        static char term = '\n';
 408
 409        if (!lock)
 410                return -1;
 411        if (!lock->force_write && !memcmp(lock->old_sha1, sha1, 20)) {
 412                unlock_ref(lock);
 413                return 0;
 414        }
 415        if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
 416            write(lock->lock_fd, &term, 1) != 1
 417                || close(lock->lock_fd) < 0) {
 418                error("Couldn't write %s", lock->lock_file);
 419                unlock_ref(lock);
 420                return -1;
 421        }
 422        if (log_ref_write(lock, sha1, logmsg) < 0) {
 423                unlock_ref(lock);
 424                return -1;
 425        }
 426        if (rename(lock->lock_file, lock->ref_file) < 0) {
 427                error("Couldn't set %s", lock->ref_file);
 428                unlock_ref(lock);
 429                return -1;
 430        }
 431        lock->lock_fd = -1;
 432        unlock_ref(lock);
 433        return 0;
 434}
 435
 436int read_ref_at(const char *ref, unsigned long at_time, unsigned char *sha1)
 437{
 438        const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
 439        char *tz_c;
 440        int logfd, tz;
 441        struct stat st;
 442        unsigned long date;
 443        unsigned char logged_sha1[20];
 444
 445        logfile = git_path("logs/%s", ref);
 446        logfd = open(logfile, O_RDONLY, 0);
 447        if (logfd < 0)
 448                die("Unable to read log %s: %s", logfile, strerror(errno));
 449        fstat(logfd, &st);
 450        if (!st.st_size)
 451                die("Log %s is empty.", logfile);
 452        logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
 453        close(logfd);
 454
 455        lastrec = NULL;
 456        rec = logend = logdata + st.st_size;
 457        while (logdata < rec) {
 458                if (logdata < rec && *(rec-1) == '\n')
 459                        rec--;
 460                lastgt = NULL;
 461                while (logdata < rec && *(rec-1) != '\n') {
 462                        rec--;
 463                        if (*rec == '>')
 464                                lastgt = rec;
 465                }
 466                if (!lastgt)
 467                        die("Log %s is corrupt.", logfile);
 468                date = strtoul(lastgt + 1, &tz_c, 10);
 469                if (date <= at_time) {
 470                        if (lastrec) {
 471                                if (get_sha1_hex(lastrec, logged_sha1))
 472                                        die("Log %s is corrupt.", logfile);
 473                                if (get_sha1_hex(rec + 41, sha1))
 474                                        die("Log %s is corrupt.", logfile);
 475                                if (memcmp(logged_sha1, sha1, 20)) {
 476                                        tz = strtoul(tz_c, NULL, 10);
 477                                        fprintf(stderr,
 478                                                "warning: Log %s has gap after %s.\n",
 479                                                logfile, show_rfc2822_date(date, tz));
 480                                }
 481                        } else if (date == at_time) {
 482                                if (get_sha1_hex(rec + 41, sha1))
 483                                        die("Log %s is corrupt.", logfile);
 484                        } else {
 485                                if (get_sha1_hex(rec + 41, logged_sha1))
 486                                        die("Log %s is corrupt.", logfile);
 487                                if (memcmp(logged_sha1, sha1, 20)) {
 488                                        tz = strtoul(tz_c, NULL, 10);
 489                                        fprintf(stderr,
 490                                                "warning: Log %s unexpectedly ended on %s.\n",
 491                                                logfile, show_rfc2822_date(date, tz));
 492                                }
 493                        }
 494                        munmap((void*)logdata, st.st_size);
 495                        return 0;
 496                }
 497                lastrec = rec;
 498        }
 499
 500        rec = logdata;
 501        while (rec < logend && *rec != '>' && *rec != '\n')
 502                rec++;
 503        if (rec == logend || *rec == '\n')
 504                die("Log %s is corrupt.", logfile);
 505        date = strtoul(rec + 1, &tz_c, 10);
 506        tz = strtoul(tz_c, NULL, 10);
 507        if (get_sha1_hex(logdata, sha1))
 508                die("Log %s is corrupt.", logfile);
 509        munmap((void*)logdata, st.st_size);
 510        fprintf(stderr, "warning: Log %s only goes back to %s.\n",
 511                logfile, show_rfc2822_date(date, tz));
 512        return 0;
 513}