lib/tdb_compat/tdb_compat.c

   1 #include <tdb_compat.h>
   2
   3 /* Note: for the moment, we only need this file for TDB2, so we can
   4  * assume waf. */
   5 #if BUILD_TDB2
   6 TDB_DATA tdb_null = { NULL, 0 };
   7
   8 /* Proxy which sets waitflag to false so we never block. */
   9 static int lock_nonblock(int fd, int rw, off_t off, off_t len, bool waitflag,
  10                          void *_orig)
  11 {
  12         struct tdb_attribute_flock *orig = _orig;
  13
  14         return orig->lock(fd, rw, off, len, false, orig->data);
  15 }
  16
  17 enum TDB_ERROR tdb_transaction_start_nonblock(struct tdb_context *tdb)
  18 {
  19         union tdb_attribute locking, orig;
  20         enum TDB_ERROR ecode;
  21
  22         orig.base.attr = TDB_ATTRIBUTE_FLOCK;
  23         ecode = tdb_get_attribute(tdb, &orig);
  24         if (ecode != TDB_SUCCESS)
  25                 return ecode;
  26
  27         /* Replace locking function with our own. */
  28         locking = orig;
  29         locking.flock.data = &orig;
  30         locking.flock.lock = lock_nonblock;
  31
  32         ecode = tdb_set_attribute(tdb, &locking);
  33         if (ecode != TDB_SUCCESS)
  34                 return ecode;
  35
  36         ecode = tdb_transaction_start(tdb);
  37         tdb_unset_attribute(tdb, TDB_ATTRIBUTE_FLOCK);
  38         return ecode;
  39 }
  40
  41 /* For TDB1 tdbs, read traverse vs normal matters: write traverse
  42    locks the entire thing! */
  43 int64_t tdb_traverse_read_(struct tdb_context *tdb,
  44                            int (*fn)(struct tdb_context *,
  45                                                        TDB_DATA, TDB_DATA,
  46                                                        void *),
  47                            void *p)
  48 {
  49         int64_t ret;
  50
  51         if (tdb_get_flags(tdb) & TDB_RDONLY) {
  52                 return tdb_traverse(tdb, fn, p);
  53         }
  54
  55         tdb_add_flag(tdb, TDB_RDONLY);
  56         ret = tdb_traverse(tdb, fn, p);
  57         tdb_remove_flag(tdb, TDB_RDONLY);
  58         return ret;
  59 }
  60
  61 /*
  62  * This handles TDB_CLEAR_IF_FIRST.
  63  */
  64 static enum TDB_ERROR clear_if_first(int fd, void *unused)
  65 {
  66         /* We hold a lock offset 4 always, so we can tell if anyone else is. */
  67         struct flock fl;
  68
  69         fl.l_type = F_WRLCK;
  70         fl.l_whence = SEEK_SET;
  71         fl.l_start = 4; /* ACTIVE_LOCK */
  72         fl.l_len = 1;
  73
  74         if (fcntl(fd, F_SETLK, &fl) == 0) {
  75                 /* We must be first ones to open it w/ TDB_CLEAR_IF_FIRST! */
  76                 if (ftruncate(fd, 0) != 0) {
  77                         return TDB_ERR_IO;
  78                 }
  79         }
  80         fl.l_type = F_RDLCK;
  81         if (fcntl(fd, F_SETLKW, &fl) != 0) {
  82                 return TDB_ERR_IO;
  83         }
  84         return TDB_SUCCESS;
  85 }
  86
  87 struct tdb_context *
  88 tdb_open_compat_(const char *name, int hash_size,
  89                  int tdb_flags, int open_flags, mode_t mode,
  90                  void (*log_fn)(struct tdb_context *,
  91                                 enum tdb_log_level,
  92                                 enum TDB_ERROR,
  93                                 const char *message,
  94                                 void *data),
  95                  void *log_data)
  96 {
  97         union tdb_attribute cif, log, hash, max_dead, hsize, *attr = NULL;
  98
  99         if (!getenv("TDB_COMPAT_USE_TDB2")) {
 100                 tdb_flags |= TDB_VERSION1;
 101         }
 102
 103         if (log_fn) {
 104                 log.log.base.attr = TDB_ATTRIBUTE_LOG;
 105                 log.log.base.next = NULL;
 106                 log.log.fn = log_fn;
 107                 log.log.data = log_data;
 108                 attr = &log;
 109         }
 110
 111         if (tdb_flags & TDB_CLEAR_IF_FIRST) {
 112                 cif.openhook.base.attr = TDB_ATTRIBUTE_OPENHOOK;
 113                 cif.openhook.base.next = attr;
 114                 cif.openhook.fn = clear_if_first;
 115                 attr = &cif;
 116                 tdb_flags &= ~TDB_CLEAR_IF_FIRST;
 117         }
 118
 119         if (tdb_flags & TDB_INCOMPATIBLE_HASH) {
 120                 if (tdb_flags & TDB_VERSION1) {
 121                         hash.hash.base.attr = TDB_ATTRIBUTE_HASH;
 122                         hash.hash.base.next = attr;
 123                         hash.hash.fn = tdb1_incompatible_hash;
 124                         attr = &hash;
 125                 }
 126                 tdb_flags &= ~TDB_INCOMPATIBLE_HASH;
 127         }
 128
 129         if (tdb_flags & TDB_VOLATILE) {
 130                 if (tdb_flags & TDB_VERSION1) {
 131                         max_dead.base.attr = TDB_ATTRIBUTE_TDB1_MAX_DEAD;
 132                         max_dead.base.next = attr;
 133                         max_dead.tdb1_max_dead.max_dead = 5;
 134                         attr = &max_dead;
 135                 }
 136                 tdb_flags &= ~TDB_VOLATILE;
 137         }
 138
 139         if (hash_size && (tdb_flags & TDB_VERSION1) && (open_flags & O_CREAT)) {
 140                 hsize.base.attr = TDB_ATTRIBUTE_TDB1_HASHSIZE;
 141                 hsize.base.next = attr;
 142                 hsize.tdb1_hashsize.hsize = hash_size;
 143                 attr = &hsize;
 144         }
 145
 146         /* Testsuite uses this to speed things up. */
 147         if (getenv("TDB_NO_FSYNC")) {
 148                 tdb_flags |= TDB_NOSYNC;
 149         }
 150
 151         return tdb_open(name, tdb_flags|TDB_ALLOW_NESTING, open_flags, mode,
 152                         attr);
 153 }
 154
 155 /* We only need these for the CLEAR_IF_FIRST lock. */
 156 static int reacquire_cif_lock(struct tdb_context *tdb, bool *fail)
 157 {
 158         struct flock fl;
 159         union tdb_attribute cif;
 160
 161         cif.openhook.base.attr = TDB_ATTRIBUTE_OPENHOOK;
 162         cif.openhook.base.next = NULL;
 163
 164         if (tdb_get_attribute(tdb, &cif) != TDB_SUCCESS
 165             || cif.openhook.fn != clear_if_first) {
 166                 return 0;
 167         }
 168
 169         /* We hold a lock offset 4 always, so we can tell if anyone else is. */
 170         fl.l_type = F_RDLCK;
 171         fl.l_whence = SEEK_SET;
 172         fl.l_start = 4; /* ACTIVE_LOCK */
 173         fl.l_len = 1;
 174         if (fcntl(tdb_fd(tdb), F_SETLKW, &fl) != 0) {
 175                 *fail = true;
 176                 return -1;
 177         }
 178         return 0;
 179 }
 180
 181 int tdb_reopen(struct tdb_context *tdb)
 182 {
 183         bool unused;
 184         return reacquire_cif_lock(tdb, &unused);
 185 }
 186
 187 int tdb_reopen_all(int parent_longlived)
 188 {
 189         bool fail = false;
 190
 191         if (parent_longlived) {
 192                 return 0;
 193         }
 194
 195         tdb_foreach(reacquire_cif_lock, &fail);
 196         if (fail)
 197                 return -1;
 198         return 0;
 199 }
 200 #endif