Andrew's git - gitweb.git/blob

   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#ifdef USE_SYMLINK_HEAD
  80        if (!only_use_symrefs) {
  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))
 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);
 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, 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);
 184}
 185
 186static char *ref_file_name(const char *ref)
 187{
 188        char *base = get_refs_directory();
 189        int baselen = strlen(base);
 190        int reflen = strlen(ref);
 191        char *ret = xmalloc(baselen + 2 + reflen);
 192        sprintf(ret, "%s/%s", base, ref);
 193        return ret;
 194}
 195
 196static char *ref_lock_file_name(const char *ref)
 197{
 198        char *base = get_refs_directory();
 199        int baselen = strlen(base);
 200        int reflen = strlen(ref);
 201        char *ret = xmalloc(baselen + 7 + reflen);
 202        sprintf(ret, "%s/%s.lock", base, ref);
 203        return ret;
 204}
 205
 206int get_ref_sha1(const char *ref, unsigned char *sha1)
 207{
 208        const char *filename;
 209
 210        if (check_ref_format(ref))
 211                return -1;
 212        filename = git_path("refs/%s", ref);
 213        return read_ref(filename, sha1);
 214}
 215
 216static int lock_ref_file(const char *filename, const char *lock_filename,
 217                         const unsigned char *old_sha1)
 218{
 219        int fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 220        unsigned char current_sha1[20];
 221        int retval;
 222        if (fd < 0) {
 223                return error("Couldn't open lock file for %s: %s",
 224                             filename, strerror(errno));
 225        }
 226        retval = read_ref(filename, current_sha1);
 227        if (old_sha1) {
 228                if (retval) {
 229                        close(fd);
 230                        unlink(lock_filename);
 231                        return error("Could not read the current value of %s",
 232                                     filename);
 233                }
 234                if (memcmp(current_sha1, old_sha1, 20)) {
 235                        close(fd);
 236                        unlink(lock_filename);
 237                        error("The current value of %s is %s",
 238                              filename, sha1_to_hex(current_sha1));
 239                        return error("Expected %s",
 240                                     sha1_to_hex(old_sha1));
 241                }
 242        } else {
 243                if (!retval) {
 244                        close(fd);
 245                        unlink(lock_filename);
 246                        return error("Unexpectedly found a value of %s for %s",
 247                                     sha1_to_hex(current_sha1), filename);
 248                }
 249        }
 250        return fd;
 251}
 252
 253int lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
 254{
 255        char *filename;
 256        char *lock_filename;
 257        int retval;
 258        if (check_ref_format(ref))
 259                return -1;
 260        filename = ref_file_name(ref);
 261        lock_filename = ref_lock_file_name(ref);
 262        retval = lock_ref_file(filename, lock_filename, old_sha1);
 263        free(filename);
 264        free(lock_filename);
 265        return retval;
 266}
 267
 268static int write_ref_file(const char *filename,
 269                          const char *lock_filename, int fd,
 270                          const unsigned char *sha1)
 271{
 272        char *hex = sha1_to_hex(sha1);
 273        char term = '\n';
 274        if (write(fd, hex, 40) < 40 ||
 275            write(fd, &term, 1) < 1) {
 276                error("Couldn't write %s", filename);
 277                close(fd);
 278                return -1;
 279        }
 280        close(fd);
 281        rename(lock_filename, filename);
 282        return 0;
 283}
 284
 285int write_ref_sha1(const char *ref, int fd, const unsigned char *sha1)
 286{
 287        char *filename;
 288        char *lock_filename;
 289        int retval;
 290        if (fd < 0)
 291                return -1;
 292        if (check_ref_format(ref))
 293                return -1;
 294        filename = ref_file_name(ref);
 295        lock_filename = ref_lock_file_name(ref);
 296        if (safe_create_leading_directories(filename))
 297                die("unable to create leading directory for %s", filename);
 298        retval = write_ref_file(filename, lock_filename, fd, sha1);
 299        free(filename);
 300        free(lock_filename);
 301        return retval;
 302}
 303
 304/*
 305 * Make sure "ref" is something reasonable to have under ".git/refs/";
 306 * We do not like it if:
 307 *
 308 * - any path component of it begins with ".", or
 309 * - it has double dots "..", or
 310 * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 311 * - it ends with a "/".
 312 */
 313
 314static inline int bad_ref_char(int ch)
 315{
 316        return (((unsigned) ch) <= ' ' ||
 317                ch == '~' || ch == '^' || ch == ':' ||
 318                /* 2.13 Pattern Matching Notation */
 319                ch == '?' || ch == '*' || ch == '[');
 320}
 321
 322int check_ref_format(const char *ref)
 323{
 324        int ch, level;
 325        const char *cp = ref;
 326
 327        level = 0;
 328        while (1) {
 329                while ((ch = *cp++) == '/')
 330                        ; /* tolerate duplicated slashes */
 331                if (!ch)
 332                        return -1; /* should not end with slashes */
 333
 334                /* we are at the beginning of the path component */
 335                if (ch == '.' || bad_ref_char(ch))
 336                        return -1;
 337
 338                /* scan the rest of the path component */
 339                while ((ch = *cp++) != 0) {
 340                        if (bad_ref_char(ch))
 341                                return -1;
 342                        if (ch == '/')
 343                                break;
 344                        if (ch == '.' && *cp == '.')
 345                                return -1;
 346                }
 347                level++;
 348                if (!ch) {
 349                        if (level < 2)
 350                                return -1; /* at least of form "heads/blah" */
 351                        return 0;
 352                }
 353        }
 354}
 355
 356int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1)
 357{
 358        char *filename;
 359        char *lock_filename;
 360        int fd;
 361        int retval;
 362        if (check_ref_format(ref))
 363                return -1;
 364        filename = ref_file_name(ref);
 365        lock_filename = ref_lock_file_name(ref);
 366        if (safe_create_leading_directories(filename))
 367                die("unable to create leading directory for %s", filename);
 368        fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 369        if (fd < 0) {
 370                error("Writing %s", lock_filename);
 371                perror("Open");
 372        }
 373        retval = write_ref_file(filename, lock_filename, fd, sha1);
 374        free(filename);
 375        free(lock_filename);
 376        return retval;
 377}