diff options
Diffstat (limited to 'source4/locking/posix.c')
| -rw-r--r-- | source4/locking/posix.c | 1313 |
1 files changed, 1313 insertions, 0 deletions
diff --git a/source4/locking/posix.c b/source4/locking/posix.c new file mode 100644 index 0000000000..81690bace9 --- /dev/null +++ b/source4/locking/posix.c @@ -0,0 +1,1313 @@ +/* + Unix SMB/CIFS implementation. + Locking functions + Copyright (C) Jeremy Allison 1992-2000 + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + + Revision History: + + POSIX locking support. Jeremy Allison (jeremy@valinux.com), Apr. 2000. +*/ + +#include "includes.h" + +/* + * The POSIX locking database handle. + */ + +static TDB_CONTEXT *posix_lock_tdb; + +/* + * The pending close database handle. + */ + +static TDB_CONTEXT *posix_pending_close_tdb; + +/* + * The data in POSIX lock records is an unsorted linear array of these + * records. It is unnecessary to store the count as tdb provides the + * size of the record. + */ + +struct posix_lock { + int fd; + SMB_OFF_T start; + SMB_OFF_T size; + int lock_type; +}; + +/* + * The data in POSIX pending close records is an unsorted linear array of int + * records. It is unnecessary to store the count as tdb provides the + * size of the record. + */ + +/* The key used in both the POSIX databases. */ + +struct posix_lock_key { + SMB_DEV_T device; + SMB_INO_T inode; +}; + +/******************************************************************* + Form a static locking key for a dev/inode pair. +******************************************************************/ + +static TDB_DATA locking_key(SMB_DEV_T dev, SMB_INO_T inode) +{ + static struct posix_lock_key key; + TDB_DATA kbuf; + + memset(&key, '\0', sizeof(key)); + key.device = dev; + key.inode = inode; + kbuf.dptr = (char *)&key; + kbuf.dsize = sizeof(key); + return kbuf; +} + +/******************************************************************* + Convenience function to get a key from an fsp. +******************************************************************/ + +static TDB_DATA locking_key_fsp(files_struct *fsp) +{ + return locking_key(fsp->dev, fsp->inode); +} + +/**************************************************************************** + Add an fd to the pending close tdb. +****************************************************************************/ + +static BOOL add_fd_to_close_entry(files_struct *fsp) +{ + TDB_DATA kbuf = locking_key_fsp(fsp); + TDB_DATA dbuf; + char *tp; + + dbuf.dptr = NULL; + + dbuf = tdb_fetch(posix_pending_close_tdb, kbuf); + + tp = Realloc(dbuf.dptr, dbuf.dsize + sizeof(int)); + if (!tp) { + DEBUG(0,("add_fd_to_close_entry: Realloc fail !\n")); + SAFE_FREE(dbuf.dptr); + return False; + } else + dbuf.dptr = tp; + + memcpy(dbuf.dptr + dbuf.dsize, &fsp->fd, sizeof(int)); + dbuf.dsize += sizeof(int); + + if (tdb_store(posix_pending_close_tdb, kbuf, dbuf, TDB_REPLACE) == -1) { + DEBUG(0,("add_fd_to_close_entry: tdb_store fail !\n")); + } + + SAFE_FREE(dbuf.dptr); + return True; +} + +/**************************************************************************** + Remove all fd entries for a specific dev/inode pair from the tdb. +****************************************************************************/ + +static void delete_close_entries(files_struct *fsp) +{ + TDB_DATA kbuf = locking_key_fsp(fsp); + + if (tdb_delete(posix_pending_close_tdb, kbuf) == -1) + DEBUG(0,("delete_close_entries: tdb_delete fail !\n")); +} + +/**************************************************************************** + Get the array of POSIX pending close records for an open fsp. Caller must + free. Returns number of entries. +****************************************************************************/ + +static size_t get_posix_pending_close_entries(files_struct *fsp, int **entries) +{ + TDB_DATA kbuf = locking_key_fsp(fsp); + TDB_DATA dbuf; + size_t count = 0; + + *entries = NULL; + dbuf.dptr = NULL; + + dbuf = tdb_fetch(posix_pending_close_tdb, kbuf); + + if (!dbuf.dptr) { + return 0; + } + + *entries = (int *)dbuf.dptr; + count = (size_t)(dbuf.dsize / sizeof(int)); + + return count; +} + +/**************************************************************************** + Get the array of POSIX locks for an fsp. Caller must free. Returns + number of entries. +****************************************************************************/ + +static size_t get_posix_lock_entries(files_struct *fsp, struct posix_lock **entries) +{ + TDB_DATA kbuf = locking_key_fsp(fsp); + TDB_DATA dbuf; + size_t count = 0; + + *entries = NULL; + + dbuf.dptr = NULL; + + dbuf = tdb_fetch(posix_lock_tdb, kbuf); + + if (!dbuf.dptr) { + return 0; + } + + *entries = (struct posix_lock *)dbuf.dptr; + count = (size_t)(dbuf.dsize / sizeof(struct posix_lock)); + + return count; +} + +/**************************************************************************** + Deal with pending closes needed by POSIX locking support. + Note that posix_locking_close_file() is expected to have been called + to delete all locks on this fsp before this function is called. +****************************************************************************/ + +int fd_close_posix(struct tcon_context *conn, files_struct *fsp) +{ + int saved_errno = 0; + int ret; + size_t count, i; + struct posix_lock *entries = NULL; + int *fd_array = NULL; + BOOL locks_on_other_fds = False; + + if (!lp_posix_locking(SNUM(conn))) { + /* + * No POSIX to worry about, just close. + */ + ret = conn->vfs_ops.close(fsp,fsp->fd); + fsp->fd = -1; + return ret; + } + + /* + * Get the number of outstanding POSIX locks on this dev/inode pair. + */ + + count = get_posix_lock_entries(fsp, &entries); + + /* + * Check if there are any outstanding locks belonging to + * other fd's. This should never be the case if posix_locking_close_file() + * has been called first, but it never hurts to be *sure*. + */ + + for (i = 0; i < count; i++) { + if (entries[i].fd != fsp->fd) { + locks_on_other_fds = True; + break; + } + } + + if (locks_on_other_fds) { + + /* + * There are outstanding locks on this dev/inode pair on other fds. + * Add our fd to the pending close tdb and set fsp->fd to -1. + */ + + if (!add_fd_to_close_entry(fsp)) { + SAFE_FREE(entries); + return False; + } + + SAFE_FREE(entries); + fsp->fd = -1; + return 0; + } + + SAFE_FREE(entries); + + /* + * No outstanding POSIX locks. Get the pending close fd's + * from the tdb and close them all. + */ + + count = get_posix_pending_close_entries(fsp, &fd_array); + + if (count) { + DEBUG(10,("fd_close_posix: doing close on %u fd's.\n", (unsigned int)count )); + + for(i = 0; i < count; i++) { + if (conn->vfs_ops.close(fsp,fd_array[i]) == -1) { + saved_errno = errno; + } + } + + /* + * Delete all fd's stored in the tdb + * for this dev/inode pair. + */ + + delete_close_entries(fsp); + } + + SAFE_FREE(fd_array); + + /* + * Finally close the fd associated with this fsp. + */ + + ret = conn->vfs_ops.close(fsp,fsp->fd); + + if (saved_errno != 0) { + errno = saved_errno; + ret = -1; + } + + fsp->fd = -1; + + return ret; +} + +/**************************************************************************** + Debugging aid :-). +****************************************************************************/ + +static const char *posix_lock_type_name(int lock_type) +{ + return (lock_type == F_RDLCK) ? "READ" : "WRITE"; +} + +/**************************************************************************** + Delete a POSIX lock entry by index number. Used if the tdb add succeeds, but + then the POSIX fcntl lock fails. +****************************************************************************/ + +static BOOL delete_posix_lock_entry_by_index(files_struct *fsp, size_t entry) +{ + TDB_DATA kbuf = locking_key_fsp(fsp); + TDB_DATA dbuf; + struct posix_lock *locks; + size_t count; + + dbuf.dptr = NULL; + + dbuf = tdb_fetch(posix_lock_tdb, kbuf); + + if (!dbuf.dptr) { + DEBUG(10,("delete_posix_lock_entry_by_index: tdb_fetch failed !\n")); + goto fail; + } + + count = (size_t)(dbuf.dsize / sizeof(struct posix_lock)); + locks = (struct posix_lock *)dbuf.dptr; + + if (count == 1) { + tdb_delete(posix_lock_tdb, kbuf); + } else { + if (entry < count-1) { + memmove(&locks[entry], &locks[entry+1], sizeof(*locks)*((count-1) - entry)); + } + dbuf.dsize -= sizeof(*locks); + tdb_store(posix_lock_tdb, kbuf, dbuf, TDB_REPLACE); + } + + SAFE_FREE(dbuf.dptr); + + return True; + + fail: + + SAFE_FREE(dbuf.dptr); + return False; +} + +/**************************************************************************** + Add an entry into the POSIX locking tdb. We return the index number of the + added lock (used in case we need to delete *exactly* this entry). Returns + False on fail, True on success. +****************************************************************************/ + +static BOOL add_posix_lock_entry(files_struct *fsp, SMB_OFF_T start, SMB_OFF_T size, int lock_type, size_t *pentry_num) +{ + TDB_DATA kbuf = locking_key_fsp(fsp); + TDB_DATA dbuf; + struct posix_lock pl; + char *tp; + + dbuf.dptr = NULL; + + dbuf = tdb_fetch(posix_lock_tdb, kbuf); + + *pentry_num = (size_t)(dbuf.dsize / sizeof(pl)); + + /* + * Add new record. + */ + + pl.fd = fsp->fd; + pl.start = start; + pl.size = size; + pl.lock_type = lock_type; + + tp = Realloc(dbuf.dptr, dbuf.dsize + sizeof(pl)); + if (!tp) { + DEBUG(0,("add_posix_lock_entry: Realloc fail !\n")); + goto fail; + } else + dbuf.dptr = tp; + + memcpy(dbuf.dptr + dbuf.dsize, &pl, sizeof(pl)); + dbuf.dsize += sizeof(pl); + + if (tdb_store(posix_lock_tdb, kbuf, dbuf, TDB_REPLACE) == -1) { + DEBUG(0,("add_posix_lock: Failed to add lock entry on file %s\n", fsp->fsp_name)); + goto fail; + } + + SAFE_FREE(dbuf.dptr); + + DEBUG(10,("add_posix_lock: File %s: type = %s: start=%.0f size=%.0f: dev=%.0f inode=%.0f\n", + fsp->fsp_name, posix_lock_type_name(lock_type), (double)start, (double)size, + (double)fsp->dev, (double)fsp->inode )); + + return True; + + fail: + + SAFE_FREE(dbuf.dptr); + return False; +} + +/**************************************************************************** + Calculate if locks have any overlap at all. +****************************************************************************/ + +static BOOL does_lock_overlap(SMB_OFF_T start1, SMB_OFF_T size1, SMB_OFF_T start2, SMB_OFF_T size2) +{ + if (start1 >= start2 && start1 <= start2 + size2) + return True; + + if (start1 < start2 && start1 + size1 > start2) + return True; + + return False; +} + +/**************************************************************************** + Delete an entry from the POSIX locking tdb. Returns a copy of the entry being + deleted and the number of records that are overlapped by this one, or -1 on error. +****************************************************************************/ + +static int delete_posix_lock_entry(files_struct *fsp, SMB_OFF_T start, SMB_OFF_T size, struct posix_lock *pl) +{ + TDB_DATA kbuf = locking_key_fsp(fsp); + TDB_DATA dbuf; + struct posix_lock *locks; + size_t i, count; + BOOL found = False; + int num_overlapping_records = 0; + + dbuf.dptr = NULL; + + dbuf = tdb_fetch(posix_lock_tdb, kbuf); + + if (!dbuf.dptr) { + DEBUG(10,("delete_posix_lock_entry: tdb_fetch failed !\n")); + goto fail; + } + + /* There are existing locks - find a match. */ + locks = (struct posix_lock *)dbuf.dptr; + count = (size_t)(dbuf.dsize / sizeof(*locks)); + + /* + * Search for and delete the first record that matches the + * unlock criteria. + */ + + for (i=0; i<count; i++) { + struct posix_lock *entry = &locks[i]; + + if (entry->fd == fsp->fd && + entry->start == start && + entry->size == size) { + + /* Make a copy if requested. */ + if (pl) + *pl = *entry; + + /* Found it - delete it. */ + if (count == 1) { + tdb_delete(posix_lock_tdb, kbuf); + } else { + if (i < count-1) { + memmove(&locks[i], &locks[i+1], sizeof(*locks)*((count-1) - i)); + } + dbuf.dsize -= sizeof(*locks); + tdb_store(posix_lock_tdb, kbuf, dbuf, TDB_REPLACE); + } + count--; + found = True; + break; + } + } + + if (!found) + goto fail; + + /* + * Count the number of entries that are + * overlapped by this unlock request. + */ + + for (i = 0; i < count; i++) { + struct posix_lock *entry = &locks[i]; + + if (fsp->fd == entry->fd && + does_lock_overlap( start, size, entry->start, entry->size)) + num_overlapping_records++; + } + + DEBUG(10,("delete_posix_lock_entry: type = %s: start=%.0f size=%.0f, num_records = %d\n", + posix_lock_type_name(pl->lock_type), (double)pl->start, (double)pl->size, + (unsigned int)num_overlapping_records )); + + SAFE_FREE(dbuf.dptr); + + return num_overlapping_records; + + fail: + + SAFE_FREE(dbuf.dptr); + return -1; +} + +/**************************************************************************** + Utility function to map a lock type correctly depending on the open + mode of a file. +****************************************************************************/ + +static int map_posix_lock_type( files_struct *fsp, enum brl_type lock_type) +{ + if((lock_type == WRITE_LOCK) && !fsp->can_write) { + /* + * Many UNIX's cannot get a write lock on a file opened read-only. + * Win32 locking semantics allow this. + * Do the best we can and attempt a read-only lock. + */ + DEBUG(10,("map_posix_lock_type: Downgrading write lock to read due to read-only file.\n")); + return F_RDLCK; + } else if((lock_type == READ_LOCK) && !fsp->can_read) { + /* + * Ditto for read locks on write only files. + */ + DEBUG(10,("map_posix_lock_type: Changing read lock to write due to write-only file.\n")); + return F_WRLCK; + } + + /* + * This return should be the most normal, as we attempt + * to always open files read/write. + */ + + return (lock_type == READ_LOCK) ? F_RDLCK : F_WRLCK; +} + +/**************************************************************************** + Check to see if the given unsigned lock range is within the possible POSIX + range. Modifies the given args to be in range if possible, just returns + False if not. +****************************************************************************/ + +static BOOL posix_lock_in_range(SMB_OFF_T *offset_out, SMB_OFF_T *count_out, + SMB_BIG_UINT u_offset, SMB_BIG_UINT u_count) +{ + SMB_OFF_T offset = (SMB_OFF_T)u_offset; + SMB_OFF_T count = (SMB_OFF_T)u_count; + + /* + * For the type of system we are, attempt to + * find the maximum positive lock offset as an SMB_OFF_T. + */ + +#if defined(MAX_POSITIVE_LOCK_OFFSET) /* Some systems have arbitrary limits. */ + + SMB_OFF_T max_positive_lock_offset = (MAX_POSITIVE_LOCK_OFFSET); + +#elif defined(LARGE_SMB_OFF_T) && !defined(HAVE_BROKEN_FCNTL64_LOCKS) + + /* + * In this case SMB_OFF_T is 64 bits, + * and the underlying system can handle 64 bit signed locks. + */ + + SMB_OFF_T mask2 = ((SMB_OFF_T)0x4) << (SMB_OFF_T_BITS-4); + SMB_OFF_T mask = (mask2<<1); + SMB_OFF_T max_positive_lock_offset = ~mask; + +#else /* !LARGE_SMB_OFF_T || HAVE_BROKEN_FCNTL64_LOCKS */ + + /* + * In this case either SMB_OFF_T is 32 bits, + * or the underlying system cannot handle 64 bit signed locks. + * All offsets & counts must be 2^31 or less. + */ + + SMB_OFF_T max_positive_lock_offset = 0x7FFFFFFF; + +#endif /* !LARGE_SMB_OFF_T || HAVE_BROKEN_FCNTL64_LOCKS */ + + /* + * POSIX locks of length zero mean lock to end-of-file. + * Win32 locks of length zero are point probes. Ignore + * any Win32 locks of length zero. JRA. + */ + + if (count == (SMB_OFF_T)0) { + DEBUG(10,("posix_lock_in_range: count = 0, ignoring.\n")); + return False; + } + + /* + * If the given offset was > max_positive_lock_offset then we cannot map this at all + * ignore this lock. + */ + + if (u_offset & ~((SMB_BIG_UINT)max_positive_lock_offset)) { + DEBUG(10,("posix_lock_in_range: (offset = %.0f) offset > %.0f and we cannot handle this. Ignoring lock.\n", + (double)u_offset, (double)((SMB_BIG_UINT)max_positive_lock_offset) )); + return False; + } + + /* + * We must truncate the count to less than max_positive_lock_offset. + */ + + if (u_count & ~((SMB_BIG_UINT)max_positive_lock_offset)) + count = max_positive_lock_offset; + + /* + * Truncate count to end at max lock offset. + */ + + if (offset + count < 0 || offset + count > max_positive_lock_offset) + count = max_positive_lock_offset - offset; + + /* + * If we ate all the count, ignore this lock. + */ + + if (count == 0) { + DEBUG(10,("posix_lock_in_range: Count = 0. Ignoring lock u_offset = %.0f, u_count = %.0f\n", + (double)u_offset, (double)u_count )); + return False; + } + + /* + * The mapping was successful. + */ + + DEBUG(10,("posix_lock_in_range: offset_out = %.0f, count_out = %.0f\n", + (double)offset, (double)count )); + + *offset_out = offset; + *count_out = count; + + return True; +} + +/**************************************************************************** + Actual function that does POSIX locks. Copes with 64 -> 32 bit cruft and + broken NFS implementations. +****************************************************************************/ + +static BOOL posix_fcntl_lock(files_struct *fsp, int op, SMB_OFF_T offset, SMB_OFF_T count, int type) +{ + int ret; + struct tcon_context *conn = fsp->conn; + + DEBUG(8,("posix_fcntl_lock %d %d %.0f %.0f %d\n",fsp->fd,op,(double)offset,(double)count,type)); + + ret = conn->vfs_ops.lock(fsp,fsp->fd,op,offset,count,type); + + if (!ret && ((errno == EFBIG) || (errno == ENOLCK) || (errno == EINVAL))) { + + DEBUG(0,("posix_fcntl_lock: WARNING: lock request at offset %.0f, length %.0f returned\n", + (double)offset,(double)count)); + DEBUG(0,("an %s error. This can happen when using 64 bit lock offsets\n", strerror(errno))); + DEBUG(0,("on 32 bit NFS mounted file systems.\n")); + + /* + * If the offset is > 0x7FFFFFFF then this will cause problems on + * 32 bit NFS mounted filesystems. Just ignore it. + */ + + if (offset & ~((SMB_OFF_T)0x7fffffff)) { + DEBUG(0,("Offset greater than 31 bits. Returning success.\n")); + return True; + } + + if (count & ~((SMB_OFF_T)0x7fffffff)) { + /* 32 bit NFS file system, retry with smaller offset */ + DEBUG(0,("Count greater than 31 bits - retrying with 31 bit truncated length.\n")); + errno = 0; + count &= 0x7fffffff; + ret = conn->vfs_ops.lock(fsp,fsp->fd,op,offset,count,type); + } + } + + DEBUG(8,("posix_fcntl_lock: Lock call %s\n", ret ? "successful" : "failed")); + + return ret; +} + +/**************************************************************************** + POSIX function to see if a file region is locked. Returns True if the + region is locked, False otherwise. +****************************************************************************/ + +BOOL is_posix_locked(files_struct *fsp, SMB_BIG_UINT u_offset, SMB_BIG_UINT u_count, enum brl_type lock_type) +{ + SMB_OFF_T offset; + SMB_OFF_T count; + int posix_lock_type = map_posix_lock_type(fsp,lock_type); + + DEBUG(10,("is_posix_locked: File %s, offset = %.0f, count = %.0f, type = %s\n", + fsp->fsp_name, (double)u_offset, (double)u_count, posix_lock_type_name(lock_type) )); + + /* + * If the requested lock won't fit in the POSIX range, we will + * never set it, so presume it is not locked. + */ + + if(!posix_lock_in_range(&offset, &count, u_offset, u_count)) + return False; + + /* + * Note that most UNIX's can *test* for a write lock on + * a read-only fd, just not *set* a write lock on a read-only + * fd. So we don't need to use map_lock_type here. + */ + + return posix_fcntl_lock(fsp,SMB_F_GETLK,offset,count,posix_lock_type); +} + +/* + * Structure used when splitting a lock range + * into a POSIX lock range. Doubly linked list. + */ + +struct lock_list { + struct lock_list *next; + struct lock_list *prev; + SMB_OFF_T start; + SMB_OFF_T size; +}; + +/**************************************************************************** + Create a list of lock ranges that don't overlap a given range. Used in calculating + POSIX locks and unlocks. This is a difficult function that requires ASCII art to + understand it :-). +****************************************************************************/ + +static struct lock_list *posix_lock_list(TALLOC_CTX *ctx, struct lock_list *lhead, files_struct *fsp) +{ + TDB_DATA kbuf = locking_key_fsp(fsp); + TDB_DATA dbuf; + struct posix_lock *locks; + size_t num_locks, i; + + dbuf.dptr = NULL; + + dbuf = tdb_fetch(posix_lock_tdb, kbuf); + + if (!dbuf.dptr) + return lhead; + + locks = (struct posix_lock *)dbuf.dptr; + num_locks = (size_t)(dbuf.dsize / sizeof(*locks)); + + /* + * Check the current lock list on this dev/inode pair. + * Quit if the list is deleted. + */ + + DEBUG(10,("posix_lock_list: curr: start=%.0f,size=%.0f\n", + (double)lhead->start, (double)lhead->size )); + + for (i=0; i<num_locks && lhead; i++) { + + struct posix_lock *lock = &locks[i]; + struct lock_list *l_curr; + + /* + * Walk the lock list, checking for overlaps. Note that + * the lock list can expand within this loop if the current + * range being examined needs to be split. + */ + + for (l_curr = lhead; l_curr;) { + + DEBUG(10,("posix_lock_list: lock: fd=%d: start=%.0f,size=%.0f:type=%s", lock->fd, + (double)lock->start, (double)lock->size, posix_lock_type_name(lock->lock_type) )); + + if ( (l_curr->start >= (lock->start + lock->size)) || + (lock->start >= (l_curr->start + l_curr->size))) { + + /* No overlap with this lock - leave this range alone. */ +/********************************************* + +---------+ + | l_curr | + +---------+ + +-------+ + | lock | + +-------+ +OR.... + +---------+ + | l_curr | + +---------+ +**********************************************/ + + DEBUG(10,("no overlap case.\n" )); + + l_curr = l_curr->next; + + } else if ( (l_curr->start >= lock->start) && + (l_curr->start + l_curr->size <= lock->start + lock->size) ) { + + /* + * This unlock is completely overlapped by this existing lock range + * and thus should have no effect (not be unlocked). Delete it from the list. + */ +/********************************************* + +---------+ + | l_curr | + +---------+ + +---------------------------+ + | lock | + +---------------------------+ +**********************************************/ + /* Save the next pointer */ + struct lock_list *ul_next = l_curr->next; + + DEBUG(10,("delete case.\n" )); + + DLIST_REMOVE(lhead, l_curr); + if(lhead == NULL) + break; /* No more list... */ + + l_curr = ul_next; + + } else if ( (l_curr->start >= lock->start) && + (l_curr->start < lock->start + lock->size) && + (l_curr->start + l_curr->size > lock->start + lock->size) ) { + + /* + * This unlock overlaps the existing lock range at the high end. + * Truncate by moving start to existing range end and reducing size. + */ +/********************************************* + +---------------+ + | l_curr | + +---------------+ + +---------------+ + | lock | + +---------------+ +BECOMES.... + +-------+ + | l_curr| + +-------+ +**********************************************/ + + l_curr->size = (l_curr->start + l_curr->size) - (lock->start + lock->size); + l_curr->start = lock->start + lock->size; + + DEBUG(10,("truncate high case: start=%.0f,size=%.0f\n", + (double)l_curr->start, (double)l_curr->size )); + + l_curr = l_curr->next; + + } else if ( (l_curr->start < lock->start) && + (l_curr->start + l_curr->size > lock->start) && + (l_curr->start + l_curr->size <= lock->start + lock->size) ) { + + /* + * This unlock overlaps the existing lock range at the low end. + * Truncate by reducing size. + */ +/********************************************* + +---------------+ + | l_curr | + +---------------+ + +---------------+ + | lock | + +---------------+ +BECOMES.... + +-------+ + | l_curr| + +-------+ +**********************************************/ + + l_curr->size = lock->start - l_curr->start; + + DEBUG(10,("truncate low case: start=%.0f,size=%.0f\n", + (double)l_curr->start, (double)l_curr->size )); + + l_curr = l_curr->next; + + } else if ( (l_curr->start < lock->start) && + (l_curr->start + l_curr->size > lock->start + lock->size) ) { + /* + * Worst case scenario. Unlock request completely overlaps an existing + * lock range. Split the request into two, push the new (upper) request + * into the dlink list, and continue with the entry after ul_new (as we + * know that ul_new will not overlap with this lock). + */ +/********************************************* + +---------------------------+ + | l_curr | + +---------------------------+ + +---------+ + | lock | + +---------+ +BECOMES..... + +-------+ +---------+ + | l_curr| | l_new | + +-------+ +---------+ +**********************************************/ + struct lock_list *l_new = (struct lock_list *)talloc(ctx, + sizeof(struct lock_list)); + + if(l_new == NULL) { + DEBUG(0,("posix_lock_list: talloc fail.\n")); + return NULL; /* The talloc_destroy takes care of cleanup. */ + } + + ZERO_STRUCTP(l_new); + l_new->start = lock->start + lock->size; + l_new->size = l_curr->start + l_curr->size - l_new->start; + + /* Truncate the l_curr. */ + l_curr->size = lock->start - l_curr->start; + + DEBUG(10,("split case: curr: start=%.0f,size=%.0f \ +new: start=%.0f,size=%.0f\n", (double)l_curr->start, (double)l_curr->size, + (double)l_new->start, (double)l_new->size )); + + /* + * Add into the dlink list after the l_curr point - NOT at lhead. + * Note we can't use DLINK_ADD here as this inserts at the head of the given list. + */ + + l_new->prev = l_curr; + l_new->next = l_curr->next; + l_curr->next = l_new; + + /* And move after the link we added. */ + l_curr = l_new->next; + + } else { + + /* + * This logic case should never happen. Ensure this is the + * case by forcing an abort.... Remove in production. + */ + pstring msg; + + slprintf(msg, sizeof(msg)-1, "logic flaw in cases: l_curr: start = %.0f, size = %.0f : \ +lock: start = %.0f, size = %.0f\n", (double)l_curr->start, (double)l_curr->size, (double)lock->start, (double)lock->size ); + + smb_panic(msg); + } + } /* end for ( l_curr = lhead; l_curr;) */ + } /* end for (i=0; i<num_locks && ul_head; i++) */ + + SAFE_FREE(dbuf.dptr); + + return lhead; +} + +/**************************************************************************** + POSIX function to acquire a lock. Returns True if the + lock could be granted, False if not. +****************************************************************************/ + +BOOL set_posix_lock(files_struct *fsp, SMB_BIG_UINT u_offset, SMB_BIG_UINT u_count, enum brl_type lock_type) +{ + SMB_OFF_T offset; + SMB_OFF_T count; + BOOL ret = True; + size_t entry_num = 0; + size_t lock_count; + TALLOC_CTX *l_ctx = NULL; + struct lock_list *llist = NULL; + struct lock_list *ll = NULL; + int posix_lock_type = map_posix_lock_type(fsp,lock_type); + + DEBUG(5,("set_posix_lock: File %s, offset = %.0f, count = %.0f, type = %s\n", + fsp->fsp_name, (double)u_offset, (double)u_count, posix_lock_type_name(lock_type) )); + + /* + * If the requested lock won't fit in the POSIX range, we will + * pretend it was successful. + */ + + if(!posix_lock_in_range(&offset, &count, u_offset, u_count)) + return True; + + /* + * Windows is very strange. It allows read locks to be overlayed + * (even over a write lock), but leaves the write lock in force until the first + * unlock. It also reference counts the locks. This means the following sequence : + * + * process1 process2 + * ------------------------------------------------------------------------ + * WRITE LOCK : start = 2, len = 10 + * READ LOCK: start =0, len = 10 - FAIL + * READ LOCK : start = 0, len = 14 + * READ LOCK: start =0, len = 10 - FAIL + * UNLOCK : start = 2, len = 10 + * READ LOCK: start =0, len = 10 - OK + * + * Under POSIX, the same sequence in steps 1 and 2 would not be reference counted, but + * would leave a single read lock over the 0-14 region. In order to + * re-create Windows semantics mapped to POSIX locks, we create multiple TDB + * entries, one for each overlayed lock request. We are guarenteed by the brlock + * semantics that if a write lock is added, then it will be first in the array. + */ + + if ((l_ctx = talloc_init("set_posix_lock")) == NULL) { + DEBUG(0,("set_posix_lock: unable to init talloc context.\n")); + return True; /* Not a fatal error. */ + } + + if ((ll = (struct lock_list *)talloc(l_ctx, sizeof(struct lock_list))) == NULL) { + DEBUG(0,("set_posix_lock: unable to talloc unlock list.\n")); + talloc_destroy(l_ctx); + return True; /* Not a fatal error. */ + } + + /* + * Create the initial list entry containing the + * lock we want to add. + */ + + ZERO_STRUCTP(ll); + ll->start = offset; + ll->size = count; + + DLIST_ADD(llist, ll); + + /* + * The following call calculates if there are any + * overlapping locks held by this process on + * fd's open on the same file and splits this list + * into a list of lock ranges that do not overlap with existing + * POSIX locks. + */ + + llist = posix_lock_list(l_ctx, llist, fsp); + + /* + * Now we have the list of ranges to lock it is safe to add the + * entry into the POSIX lock tdb. We take note of the entry we + * added here in case we have to remove it on POSIX lock fail. + */ + + if (!add_posix_lock_entry(fsp,offset,count,posix_lock_type,&entry_num)) { + DEBUG(0,("set_posix_lock: Unable to create posix lock entry !\n")); + talloc_destroy(l_ctx); + return False; + } + + /* + * Add the POSIX locks on the list of ranges returned. + * As the lock is supposed to be added atomically, we need to + * back out all the locks if any one of these calls fail. + */ + + for (lock_count = 0, ll = llist; ll; ll = ll->next, lock_count++) { + offset = ll->start; + count = ll->size; + + DEBUG(5,("set_posix_lock: Real lock: Type = %s: offset = %.0f, count = %.0f\n", + posix_lock_type_name(posix_lock_type), (double)offset, (double)count )); + + if (!posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,posix_lock_type)) { + DEBUG(5,("set_posix_lock: Lock fail !: Type = %s: offset = %.0f, count = %.0f. Errno = %s\n", + posix_lock_type_name(posix_lock_type), (double)offset, (double)count, strerror(errno) )); + ret = False; + break; + } + } + + if (!ret) { + + /* + * Back out all the POSIX locks we have on fail. + */ + + for (ll = llist; lock_count; ll = ll->next, lock_count--) { + offset = ll->start; + count = ll->size; + + DEBUG(5,("set_posix_lock: Backing out locks: Type = %s: offset = %.0f, count = %.0f\n", + posix_lock_type_name(posix_lock_type), (double)offset, (double)count )); + + posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,F_UNLCK); + } + + /* + * Remove the tdb entry for this lock. + */ + + delete_posix_lock_entry_by_index(fsp,entry_num); + } + + talloc_destroy(l_ctx); + return ret; +} + +/**************************************************************************** + POSIX function to release a lock. Returns True if the + lock could be released, False if not. +****************************************************************************/ + +BOOL release_posix_lock(files_struct *fsp, SMB_BIG_UINT u_offset, SMB_BIG_UINT u_count) +{ + SMB_OFF_T offset; + SMB_OFF_T count; + BOOL ret = True; + TALLOC_CTX *ul_ctx = NULL; + struct lock_list *ulist = NULL; + struct lock_list *ul = NULL; + struct posix_lock deleted_lock; + int num_overlapped_entries; + + DEBUG(5,("release_posix_lock: File %s, offset = %.0f, count = %.0f\n", + fsp->fsp_name, (double)u_offset, (double)u_count )); + + /* + * If the requested lock won't fit in the POSIX range, we will + * pretend it was successful. + */ + + if(!posix_lock_in_range(&offset, &count, u_offset, u_count)) + return True; + + /* + * We treat this as one unlock request for POSIX accounting purposes even + * if it may later be split into multiple smaller POSIX unlock ranges. + * num_overlapped_entries is the number of existing locks that have any + * overlap with this unlock request. + */ + + num_overlapped_entries = delete_posix_lock_entry(fsp, offset, count, &deleted_lock); + + if (num_overlapped_entries == -1) { + smb_panic("release_posix_lock: unable find entry to delete !\n"); + } + + /* + * If num_overlapped_entries is > 0, and the lock_type we just deleted from the tdb was + * a POSIX write lock, then before doing the unlock we need to downgrade + * the POSIX lock to a read lock. This allows any overlapping read locks + * to be atomically maintained. + */ + + if (num_overlapped_entries > 0 && deleted_lock.lock_type == F_WRLCK) { + if (!posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,F_RDLCK)) { + DEBUG(0,("release_posix_lock: downgrade of lock failed with error %s !\n", strerror(errno) )); + return False; + } + } + + if ((ul_ctx = talloc_init("release_posix_lock")) == NULL) { + DEBUG(0,("release_posix_lock: unable to init talloc context.\n")); + return True; /* Not a fatal error. */ + } + + if ((ul = (struct lock_list *)talloc(ul_ctx, sizeof(struct lock_list))) == NULL) { + DEBUG(0,("release_posix_lock: unable to talloc unlock list.\n")); + talloc_destroy(ul_ctx); + return True; /* Not a fatal error. */ + } + + /* + * Create the initial list entry containing the + * lock we want to remove. + */ + + ZERO_STRUCTP(ul); + ul->start = offset; + ul->size = count; + + DLIST_ADD(ulist, ul); + + /* + * The following call calculates if there are any + * overlapping locks held by this process on + * fd's open on the same file and creates a + * list of unlock ranges that will allow + * POSIX lock ranges to remain on the file whilst the + * unlocks are performed. + */ + + ulist = posix_lock_list(ul_ctx, ulist, fsp); + + /* + * Release the POSIX locks on the list of ranges returned. + */ + + for(; ulist; ulist = ulist->next) { + offset = ulist->start; + count = ulist->size; + + DEBUG(5,("release_posix_lock: Real unlock: offset = %.0f, count = %.0f\n", + (double)offset, (double)count )); + + if (!posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,F_UNLCK)) + ret = False; + } + + talloc_destroy(ul_ctx); + + return ret; +} + +/**************************************************************************** + Remove all lock entries for a specific dev/inode pair from the tdb. +****************************************************************************/ + +static void delete_posix_lock_entries(files_struct *fsp) +{ + TDB_DATA kbuf = locking_key_fsp(fsp); + + if (tdb_delete(posix_lock_tdb, kbuf) == -1) + DEBUG(0,("delete_close_entries: tdb_delete fail !\n")); +} + +/**************************************************************************** + Debug function. +****************************************************************************/ + +static void dump_entry(struct posix_lock *pl) +{ + DEBUG(10,("entry: start=%.0f, size=%.0f, type=%d, fd=%i\n", + (double)pl->start, (double)pl->size, (int)pl->lock_type, pl->fd )); +} + +/**************************************************************************** + Remove any locks on this fd. Called from file_close(). +****************************************************************************/ + +void posix_locking_close_file(files_struct *fsp) +{ + struct posix_lock *entries = NULL; + size_t count, i; + + /* + * Optimization for the common case where we are the only + * opener of a file. If all fd entries are our own, we don't + * need to explicitly release all the locks via the POSIX functions, + * we can just remove all the entries in the tdb and allow the + * close to remove the real locks. + */ + + count = get_posix_lock_entries(fsp, &entries); + + if (count == 0) { + DEBUG(10,("posix_locking_close_file: file %s has no outstanding locks.\n", fsp->fsp_name )); + return; + } + + for (i = 0; i < count; i++) { + if (entries[i].fd != fsp->fd ) + break; + + dump_entry(&entries[i]); + } + + if (i == count) { + /* All locks are ours. */ + DEBUG(10,("posix_locking_close_file: file %s has %u outstanding locks, but all on one fd.\n", + fsp->fsp_name, (unsigned int)count )); + SAFE_FREE(entries); + delete_posix_lock_entries(fsp); + return; + } + + /* + * Difficult case. We need to delete all our locks, whilst leaving + * all other POSIX locks in place. + */ + + for (i = 0; i < count; i++) { + struct posix_lock *pl = &entries[i]; + if (pl->fd == fsp->fd) + release_posix_lock(fsp, (SMB_BIG_UINT)pl->start, (SMB_BIG_UINT)pl->size ); + } + SAFE_FREE(entries); +} + +/******************************************************************* + Create the in-memory POSIX lock databases. +********************************************************************/ + +BOOL posix_locking_init(int read_only) +{ + if (posix_lock_tdb && posix_pending_close_tdb) + return True; + + if (!posix_lock_tdb) + posix_lock_tdb = tdb_open_log(NULL, 0, TDB_INTERNAL, + read_only?O_RDONLY:(O_RDWR|O_CREAT), 0644); + if (!posix_lock_tdb) { + DEBUG(0,("Failed to open POSIX byte range locking database.\n")); + return False; + } + if (!posix_pending_close_tdb) + posix_pending_close_tdb = tdb_open_log(NULL, 0, TDB_INTERNAL, + read_only?O_RDONLY:(O_RDWR|O_CREAT), 0644); + if (!posix_pending_close_tdb) { + DEBUG(0,("Failed to open POSIX pending close database.\n")); + return False; + } + + return True; +} + +/******************************************************************* + Delete the in-memory POSIX lock databases. +********************************************************************/ + +BOOL posix_locking_end(void) +{ + if (posix_lock_tdb && tdb_close(posix_lock_tdb) != 0) + return False; + if (posix_pending_close_tdb && tdb_close(posix_pending_close_tdb) != 0) + return False; + return True; +} |