Andrew's git / gitweb.git / refs.c
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refs.con commit SubmittingPatches: The download location of External Editor has moved (ff62b7f)
   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                        memcpy(path + baselen, de->d_name, namelen+1);
 146                        if (stat(git_path("%s", path), &st) < 0)
 147                                continue;
 148                        if (S_ISDIR(st.st_mode)) {
 149                                retval = do_for_each_ref(path, fn, trim);
 150                                if (retval)
 151                                        break;
 152                                continue;
 153                        }
 154                        if (read_ref(git_path("%s", path), sha1) < 0) {
 155                                error("%s points nowhere!", path);
 156                                continue;
 157                        }
 158                        if (!has_sha1_file(sha1)) {
 159                                error("%s does not point to a valid "
 160                                      "commit object!", path);
 161                                continue;
 162                        }
 163                        retval = fn(path + trim, sha1);
 164                        if (retval)
 165                                break;
 166                }
 167                free(path);
 168                closedir(dir);
 169        }
 170        return retval;
 171}
 172
 173int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
 174{
 175        unsigned char sha1[20];
 176        if (!read_ref(git_path("HEAD"), sha1))
 177                return fn("HEAD", sha1);
 178        return 0;
 179}
 180
 181int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
 182{
 183        return do_for_each_ref("refs", fn, 0);
 184}
 185
 186int for_each_tag_ref(int (*fn)(const char *path, const unsigned char *sha1))
 187{
 188        return do_for_each_ref("refs/tags", fn, 10);
 189}
 190
 191int for_each_branch_ref(int (*fn)(const char *path, const unsigned char *sha1))
 192{
 193        return do_for_each_ref("refs/heads", fn, 11);
 194}
 195
 196int for_each_remote_ref(int (*fn)(const char *path, const unsigned char *sha1))
 197{
 198        return do_for_each_ref("refs/remotes", fn, 13);
 199}
 200
 201static char *ref_file_name(const char *ref)
 202{
 203        char *base = get_refs_directory();
 204        int baselen = strlen(base);
 205        int reflen = strlen(ref);
 206        char *ret = xmalloc(baselen + 2 + reflen);
 207        sprintf(ret, "%s/%s", base, ref);
 208        return ret;
 209}
 210
 211static char *ref_lock_file_name(const char *ref)
 212{
 213        char *base = get_refs_directory();
 214        int baselen = strlen(base);
 215        int reflen = strlen(ref);
 216        char *ret = xmalloc(baselen + 7 + reflen);
 217        sprintf(ret, "%s/%s.lock", base, ref);
 218        return ret;
 219}
 220
 221int get_ref_sha1(const char *ref, unsigned char *sha1)
 222{
 223        const char *filename;
 224
 225        if (check_ref_format(ref))
 226                return -1;
 227        filename = git_path("refs/%s", ref);
 228        return read_ref(filename, sha1);
 229}
 230
 231static int lock_ref_file(const char *filename, const char *lock_filename,
 232                         const unsigned char *old_sha1)
 233{
 234        int fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 235        unsigned char current_sha1[20];
 236        int retval;
 237        if (fd < 0) {
 238                return error("Couldn't open lock file for %s: %s",
 239                             filename, strerror(errno));
 240        }
 241        retval = read_ref(filename, current_sha1);
 242        if (old_sha1) {
 243                if (retval) {
 244                        close(fd);
 245                        unlink(lock_filename);
 246                        return error("Could not read the current value of %s",
 247                                     filename);
 248                }
 249                if (memcmp(current_sha1, old_sha1, 20)) {
 250                        close(fd);
 251                        unlink(lock_filename);
 252                        error("The current value of %s is %s",
 253                              filename, sha1_to_hex(current_sha1));
 254                        return error("Expected %s",
 255                                     sha1_to_hex(old_sha1));
 256                }
 257        } else {
 258                if (!retval) {
 259                        close(fd);
 260                        unlink(lock_filename);
 261                        return error("Unexpectedly found a value of %s for %s",
 262                                     sha1_to_hex(current_sha1), filename);
 263                }
 264        }
 265        return fd;
 266}
 267
 268int lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
 269{
 270        char *filename;
 271        char *lock_filename;
 272        int retval;
 273        if (check_ref_format(ref))
 274                return -1;
 275        filename = ref_file_name(ref);
 276        lock_filename = ref_lock_file_name(ref);
 277        retval = lock_ref_file(filename, lock_filename, old_sha1);
 278        free(filename);
 279        free(lock_filename);
 280        return retval;
 281}
 282
 283static int write_ref_file(const char *filename,
 284                          const char *lock_filename, int fd,
 285                          const unsigned char *sha1)
 286{
 287        char *hex = sha1_to_hex(sha1);
 288        char term = '\n';
 289        if (write(fd, hex, 40) < 40 ||
 290            write(fd, &term, 1) < 1) {
 291                error("Couldn't write %s", filename);
 292                close(fd);
 293                return -1;
 294        }
 295        close(fd);
 296        rename(lock_filename, filename);
 297        return 0;
 298}
 299
 300int write_ref_sha1(const char *ref, int fd, const unsigned char *sha1)
 301{
 302        char *filename;
 303        char *lock_filename;
 304        int retval;
 305        if (fd < 0)
 306                return -1;
 307        if (check_ref_format(ref))
 308                return -1;
 309        filename = ref_file_name(ref);
 310        lock_filename = ref_lock_file_name(ref);
 311        if (safe_create_leading_directories(filename))
 312                die("unable to create leading directory for %s", filename);
 313        retval = write_ref_file(filename, lock_filename, fd, sha1);
 314        free(filename);
 315        free(lock_filename);
 316        return retval;
 317}
 318
 319/*
 320 * Make sure "ref" is something reasonable to have under ".git/refs/";
 321 * We do not like it if:
 322 *
 323 * - any path component of it begins with ".", or
 324 * - it has double dots "..", or
 325 * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 326 * - it ends with a "/".
 327 */
 328
 329static inline int bad_ref_char(int ch)
 330{
 331        return (((unsigned) ch) <= ' ' ||
 332                ch == '~' || ch == '^' || ch == ':' ||
 333                /* 2.13 Pattern Matching Notation */
 334                ch == '?' || ch == '*' || ch == '[');
 335}
 336
 337int check_ref_format(const char *ref)
 338{
 339        int ch, level;
 340        const char *cp = ref;
 341
 342        level = 0;
 343        while (1) {
 344                while ((ch = *cp++) == '/')
 345                        ; /* tolerate duplicated slashes */
 346                if (!ch)
 347                        return -1; /* should not end with slashes */
 348
 349                /* we are at the beginning of the path component */
 350                if (ch == '.' || bad_ref_char(ch))
 351                        return -1;
 352
 353                /* scan the rest of the path component */
 354                while ((ch = *cp++) != 0) {
 355                        if (bad_ref_char(ch))
 356                                return -1;
 357                        if (ch == '/')
 358                                break;
 359                        if (ch == '.' && *cp == '.')
 360                                return -1;
 361                }
 362                level++;
 363                if (!ch) {
 364                        if (level < 2)
 365                                return -1; /* at least of form "heads/blah" */
 366                        return 0;
 367                }
 368        }
 369}
 370
 371int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1)
 372{
 373        char *filename;
 374        char *lock_filename;
 375        int fd;
 376        int retval;
 377        if (check_ref_format(ref))
 378                return -1;
 379        filename = ref_file_name(ref);
 380        lock_filename = ref_lock_file_name(ref);
 381        if (safe_create_leading_directories(filename))
 382                die("unable to create leading directory for %s", filename);
 383        fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 384        if (fd < 0) {
 385                error("Writing %s", lock_filename);
 386                perror("Open");
 387        }
 388        retval = write_ref_file(filename, lock_filename, fd, sha1);
 389        free(filename);
 390        free(lock_filename);
 391        return retval;
 392}