Andrew's git / gitweb.git / refs.c
?
refs.con commit Merge http://www.kernel.org/pub/scm/gitk/gitk (8fc66df)
   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
   9#ifndef USE_SYMLINK_HEAD
  10#define USE_SYMLINK_HEAD 1
  11#endif
  12
  13const char *resolve_ref(const char *path, unsigned char *sha1, int reading)
  14{
  15        int depth = MAXDEPTH, len;
  16        char buffer[256];
  17
  18        for (;;) {
  19                struct stat st;
  20                char *buf;
  21                int fd;
  22
  23                if (--depth < 0)
  24                        return NULL;
  25
  26                /* Special case: non-existing file.
  27                 * Not having the refs/heads/new-branch is OK
  28                 * if we are writing into it, so is .git/HEAD
  29                 * that points at refs/heads/master still to be
  30                 * born.  It is NOT OK if we are resolving for
  31                 * reading.
  32                 */
  33                if (lstat(path, &st) < 0) {
  34                        if (reading || errno != ENOENT)
  35                                return NULL;
  36                        memset(sha1, 0, 20);
  37                        return path;
  38                }
  39
  40                /* Follow "normalized" - ie "refs/.." symlinks by hand */
  41                if (S_ISLNK(st.st_mode)) {
  42                        len = readlink(path, buffer, sizeof(buffer)-1);
  43                        if (len >= 5 && !memcmp("refs/", buffer, 5)) {
  44                                path = git_path("%.*s", len, buffer);
  45                                continue;
  46                        }
  47                }
  48
  49                /*
  50                 * Anything else, just open it and try to use it as
  51                 * a ref
  52                 */
  53                fd = open(path, O_RDONLY);
  54                if (fd < 0)
  55                        return NULL;
  56                len = read(fd, buffer, sizeof(buffer)-1);
  57                close(fd);
  58
  59                /*
  60                 * Is it a symbolic ref?
  61                 */
  62                if (len < 4 || memcmp("ref:", buffer, 4))
  63                        break;
  64                buf = buffer + 4;
  65                len -= 4;
  66                while (len && isspace(*buf))
  67                        buf++, len--;
  68                while (len && isspace(buf[len-1]))
  69                        buf[--len] = 0;
  70                path = git_path("%.*s", len, buf);
  71        }
  72        if (len < 40 || get_sha1_hex(buffer, sha1))
  73                return NULL;
  74        return path;
  75}
  76
  77int create_symref(const char *git_HEAD, const char *refs_heads_master)
  78{
  79        const char *lockpath;
  80        char ref[1000];
  81        int fd, len, written;
  82
  83#if USE_SYMLINK_HEAD
  84        if (!only_use_symrefs) {
  85                unlink(git_HEAD);
  86                if (!symlink(refs_heads_master, git_HEAD))
  87                        return 0;
  88                fprintf(stderr, "no symlink - falling back to symbolic ref\n");
  89        }
  90#endif
  91
  92        len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
  93        if (sizeof(ref) <= len) {
  94                error("refname too long: %s", refs_heads_master);
  95                return -1;
  96        }
  97        lockpath = mkpath("%s.lock", git_HEAD);
  98        fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666); 
  99        written = write(fd, ref, len);
 100        close(fd);
 101        if (written != len) {
 102                unlink(lockpath);
 103                error("Unable to write to %s", lockpath);
 104                return -2;
 105        }
 106        if (rename(lockpath, git_HEAD) < 0) {
 107                unlink(lockpath);
 108                error("Unable to create %s", git_HEAD);
 109                return -3;
 110        }
 111        return 0;
 112}
 113
 114int read_ref(const char *filename, unsigned char *sha1)
 115{
 116        if (resolve_ref(filename, sha1, 1))
 117                return 0;
 118        return -1;
 119}
 120
 121static int do_for_each_ref(const char *base, int (*fn)(const char *path, const unsigned char *sha1))
 122{
 123        int retval = 0;
 124        DIR *dir = opendir(git_path("%s", base));
 125
 126        if (dir) {
 127                struct dirent *de;
 128                int baselen = strlen(base);
 129                char *path = xmalloc(baselen + 257);
 130
 131                if (!strncmp(base, "./", 2)) {
 132                        base += 2;
 133                        baselen -= 2;
 134                }
 135                memcpy(path, base, baselen);
 136                if (baselen && base[baselen-1] != '/')
 137                        path[baselen++] = '/';
 138
 139                while ((de = readdir(dir)) != NULL) {
 140                        unsigned char sha1[20];
 141                        struct stat st;
 142                        int namelen;
 143
 144                        if (de->d_name[0] == '.')
 145                                continue;
 146                        namelen = strlen(de->d_name);
 147                        if (namelen > 255)
 148                                continue;
 149                        memcpy(path + baselen, de->d_name, namelen+1);
 150                        if (stat(git_path("%s", path), &st) < 0)
 151                                continue;
 152                        if (S_ISDIR(st.st_mode)) {
 153                                retval = do_for_each_ref(path, fn);
 154                                if (retval)
 155                                        break;
 156                                continue;
 157                        }
 158                        if (read_ref(git_path("%s", path), sha1) < 0)
 159                                continue;
 160                        if (!has_sha1_file(sha1))
 161                                continue;
 162                        retval = fn(path, sha1);
 163                        if (retval)
 164                                break;
 165                }
 166                free(path);
 167                closedir(dir);
 168        }
 169        return retval;
 170}
 171
 172int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
 173{
 174        unsigned char sha1[20];
 175        if (!read_ref(git_path("HEAD"), sha1))
 176                return fn("HEAD", sha1);
 177        return 0;
 178}
 179
 180int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
 181{
 182        return do_for_each_ref("refs", fn);
 183}
 184
 185static char *ref_file_name(const char *ref)
 186{
 187        char *base = get_refs_directory();
 188        int baselen = strlen(base);
 189        int reflen = strlen(ref);
 190        char *ret = xmalloc(baselen + 2 + reflen);
 191        sprintf(ret, "%s/%s", base, ref);
 192        return ret;
 193}
 194
 195static char *ref_lock_file_name(const char *ref)
 196{
 197        char *base = get_refs_directory();
 198        int baselen = strlen(base);
 199        int reflen = strlen(ref);
 200        char *ret = xmalloc(baselen + 7 + reflen);
 201        sprintf(ret, "%s/%s.lock", base, ref);
 202        return ret;
 203}
 204
 205int get_ref_sha1(const char *ref, unsigned char *sha1)
 206{
 207        const char *filename;
 208
 209        if (check_ref_format(ref))
 210                return -1;
 211        filename = git_path("refs/%s", ref);
 212        return read_ref(filename, sha1);
 213}
 214
 215static int lock_ref_file(const char *filename, const char *lock_filename,
 216                         const unsigned char *old_sha1)
 217{
 218        int fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 219        unsigned char current_sha1[20];
 220        int retval;
 221        if (fd < 0) {
 222                return error("Couldn't open lock file for %s: %s",
 223                             filename, strerror(errno));
 224        }
 225        retval = read_ref(filename, current_sha1);
 226        if (old_sha1) {
 227                if (retval) {
 228                        close(fd);
 229                        unlink(lock_filename);
 230                        return error("Could not read the current value of %s",
 231                                     filename);
 232                }
 233                if (memcmp(current_sha1, old_sha1, 20)) {
 234                        close(fd);
 235                        unlink(lock_filename);
 236                        error("The current value of %s is %s",
 237                              filename, sha1_to_hex(current_sha1));
 238                        return error("Expected %s",
 239                                     sha1_to_hex(old_sha1));
 240                }
 241        } else {
 242                if (!retval) {
 243                        close(fd);
 244                        unlink(lock_filename);
 245                        return error("Unexpectedly found a value of %s for %s",
 246                                     sha1_to_hex(current_sha1), filename);
 247                }
 248        }
 249        return fd;
 250}
 251
 252int lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
 253{
 254        char *filename;
 255        char *lock_filename;
 256        int retval;
 257        if (check_ref_format(ref))
 258                return -1;
 259        filename = ref_file_name(ref);
 260        lock_filename = ref_lock_file_name(ref);
 261        retval = lock_ref_file(filename, lock_filename, old_sha1);
 262        free(filename);
 263        free(lock_filename);
 264        return retval;
 265}
 266
 267static int write_ref_file(const char *filename,
 268                          const char *lock_filename, int fd,
 269                          const unsigned char *sha1)
 270{
 271        char *hex = sha1_to_hex(sha1);
 272        char term = '\n';
 273        if (write(fd, hex, 40) < 40 ||
 274            write(fd, &term, 1) < 1) {
 275                error("Couldn't write %s\n", filename);
 276                close(fd);
 277                return -1;
 278        }
 279        close(fd);
 280        rename(lock_filename, filename);
 281        return 0;
 282}
 283
 284int write_ref_sha1(const char *ref, int fd, const unsigned char *sha1)
 285{
 286        char *filename;
 287        char *lock_filename;
 288        int retval;
 289        if (fd < 0)
 290                return -1;
 291        if (check_ref_format(ref))
 292                return -1;
 293        filename = ref_file_name(ref);
 294        lock_filename = ref_lock_file_name(ref);
 295        retval = write_ref_file(filename, lock_filename, fd, sha1);
 296        free(filename);
 297        free(lock_filename);
 298        return retval;
 299}
 300
 301/*
 302 * Make sure "ref" is something reasonable to have under ".git/refs/";
 303 * We do not like it if:
 304 *
 305 * - any path component of it begins with ".", or
 306 * - it has double dots "..", or
 307 * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 308 * - it ends with a "/".
 309 */
 310
 311static inline int bad_ref_char(int ch)
 312{
 313        return (((unsigned) ch) <= ' ' ||
 314                ch == '~' || ch == '^' || ch == ':');
 315}
 316
 317int check_ref_format(const char *ref)
 318{
 319        int ch, level;
 320        const char *cp = ref;
 321
 322        level = 0;
 323        while (1) {
 324                while ((ch = *cp++) == '/')
 325                        ; /* tolerate duplicated slashes */
 326                if (!ch)
 327                        return -1; /* should not end with slashes */
 328
 329                /* we are at the beginning of the path component */
 330                if (ch == '.' || bad_ref_char(ch))
 331                        return -1;
 332
 333                /* scan the rest of the path component */
 334                while ((ch = *cp++) != 0) {
 335                        if (bad_ref_char(ch))
 336                                return -1;
 337                        if (ch == '/')
 338                                break;
 339                        if (ch == '.' && *cp == '.')
 340                                return -1;
 341                }
 342                level++;
 343                if (!ch) {
 344                        if (level < 2)
 345                                return -1; /* at least of form "heads/blah" */
 346                        return 0;
 347                }
 348        }
 349}
 350
 351int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1)
 352{
 353        char *filename;
 354        char *lock_filename;
 355        int fd;
 356        int retval;
 357        if (check_ref_format(ref))
 358                return -1;
 359        filename = ref_file_name(ref);
 360        lock_filename = ref_lock_file_name(ref);
 361        fd = open(lock_filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
 362        if (fd < 0) {
 363                error("Writing %s", lock_filename);
 364                perror("Open");
 365        }
 366        retval = write_ref_file(filename, lock_filename, fd, sha1);
 367        free(filename);
 368        free(lock_filename);
 369        return retval;
 370}