1
0
mirror of https://github.com/samba-team/samba.git synced 2024-12-25 23:21:54 +03:00
samba-mirror/source3/locking/posix.c
Jeremy Allison 5b69009b25 Fixed the nastiest locking bug to track down.... smb_pids are sent in the
lockingX calls - use that instead of smb_pid in the packet.
Jeremy.
(This used to be commit a3925cb9c6)
2001-07-02 02:42:41 +00:00

1381 lines
39 KiB
C

/*
Unix SMB/Netbios implementation.
Version 3.0
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"
extern int DEBUGLEVEL;
/*
* 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;
dbuf.dptr = NULL;
dbuf = tdb_fetch(posix_pending_close_tdb, kbuf);
dbuf.dptr = Realloc(dbuf.dptr, dbuf.dsize + sizeof(int));
if (!dbuf.dptr) {
DEBUG(0,("add_fd_to_close_entry: Realloc fail !\n"));
return False;
}
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"));
}
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 connection_struct *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)) {
free((char *)entries);
return False;
}
free((char *)entries);
fsp->fd = -1;
return 0;
}
if(entries)
free((char *)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);
}
if (fd_array)
free((char *)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);
}
free(dbuf.dptr);
return True;
fail:
if (dbuf.dptr)
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;
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;
dbuf.dptr = Realloc(dbuf.dptr, dbuf.dsize + sizeof(pl));
if (!dbuf.dptr) {
DEBUG(0,("add_posix_lock_entry: Realloc fail !\n"));
goto fail;
}
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;
}
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:
if (dbuf.dptr)
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 ));
if (dbuf.dptr)
free(dbuf.dptr);
return num_overlapping_records;
fail:
if (dbuf.dptr)
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(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 */
/*
* 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 offset and count to less than max_positive_lock_offset.
*/
offset &= max_positive_lock_offset;
count &= max_positive_lock_offset;
/*
* Deal with a very common case of count of all ones.
* (lock entire file).
*/
if(count == (SMB_OFF_T)-1)
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;
}
/****************************************************************************
Pathetically try and map a 64 bit lock offset into 31 bits. I hate Windows :-).
****************************************************************************/
uint32 map_lock_offset(uint32 high, uint32 low)
{
unsigned int i;
uint32 mask = 0;
uint32 highcopy = high;
/*
* Try and find out how many significant bits there are in high.
*/
for(i = 0; highcopy; i++)
highcopy >>= 1;
/*
* We use 31 bits not 32 here as POSIX
* lock offsets may not be negative.
*/
mask = (~0) << (31 - i);
if(low & mask)
return 0; /* Fail. */
high <<= (31 - i);
return (high|low);
}
/****************************************************************************
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 connection_struct *conn = fsp->conn;
#if defined(LARGE_SMB_OFF_T)
/*
* In the 64 bit locking case we store the original
* values in case we have to map to a 32 bit lock on
* a filesystem that doesn't support 64 bit locks.
*/
SMB_OFF_T orig_offset = offset;
SMB_OFF_T orig_count = count;
#endif /* LARGE_SMB_OFF_T */
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)) {
if( DEBUGLVL( 0 )) {
dbgtext("posix_fcntl_lock: WARNING: lock request at offset %.0f, length %.0f returned\n", (double)offset,(double)count);
dbgtext("a 'file too large' error. This can happen when using 64 bit lock offsets\n");
dbgtext("on 32 bit NFS mounted file systems. Retrying with 32 bit truncated length.\n");
}
/* 32 bit NFS file system, retry with smaller offset */
errno = 0;
count &= 0x7fffffff;
ret = conn->vfs_ops.lock(fsp,fsp->fd,op,offset,count,type);
}
/* A lock query - just return. */
if (op == SMB_F_GETLK)
return ret;
/* A lock set or unset. */
if (!ret) {
DEBUG(3,("posix_fcntl_lock: lock failed at offset %.0f count %.0f op %d type %d (%s)\n",
(double)offset,(double)count,op,type,strerror(errno)));
/* Perhaps it doesn't support this sort of locking ? */
if (errno == EINVAL) {
#if defined(LARGE_SMB_OFF_T)
{
/*
* Ok - if we get here then we have a 64 bit lock request
* that has returned EINVAL. Try and map to 31 bits for offset
* and length and try again. This may happen if a filesystem
* doesn't support 64 bit offsets (efs/ufs) although the underlying
* OS does.
*/
uint32 off_low = (orig_offset & 0xFFFFFFFF);
uint32 off_high = ((orig_offset >> 32) & 0xFFFFFFFF);
count = (orig_count & 0x7FFFFFFF);
offset = (SMB_OFF_T)map_lock_offset(off_high, off_low);
ret = conn->vfs_ops.lock(fsp,fsp->fd,op,offset,count,type);
if (!ret) {
if (errno == EINVAL) {
DEBUG(3,("posix_fcntl_lock: locking not supported? returning True\n"));
return(True);
}
return False;
}
DEBUG(3,("posix_fcntl_lock: 64 -> 32 bit modified lock call successful\n"));
return True;
}
#else /* LARGE_SMB_OFF_T */
DEBUG(3,("locking not supported? returning True\n"));
return(True);
#endif /* LARGE_SMB_OFF_T */
}
return(False);
}
DEBUG(8,("posix_fcntl_lock: Lock call successful\n"));
return(True);
}
/****************************************************************************
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++) */
if (dbuf.dptr)
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()) == 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\n",
posix_lock_type_name(posix_lock_type), (double)offset, (double)count ));
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 !\n"));
return False;
}
}
if ((ul_ctx = talloc_init()) == 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 ));
free((char *)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 );
}
free((char *)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;
}