summaryrefslogtreecommitdiff
path: root/source4/ntvfs/common/brlock.c
diff options
context:
space:
mode:
Diffstat (limited to 'source4/ntvfs/common/brlock.c')
-rw-r--r--source4/ntvfs/common/brlock.c418
1 files changed, 418 insertions, 0 deletions
diff --git a/source4/ntvfs/common/brlock.c b/source4/ntvfs/common/brlock.c
new file mode 100644
index 0000000000..0eb644e943
--- /dev/null
+++ b/source4/ntvfs/common/brlock.c
@@ -0,0 +1,418 @@
+/*
+ Unix SMB/CIFS implementation.
+
+ generic byte range locking code
+
+ Copyright (C) Andrew Tridgell 1992-2004
+ 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.
+*/
+
+/* This module implements a tdb based byte range locking service,
+ replacing the fcntl() based byte range locking previously
+ used. This allows us to provide the same semantics as NT */
+
+#include "includes.h"
+
+struct brl_context {
+ struct tdb_wrap *w;
+ servid_t server;
+ uint16_t tid;
+};
+
+/*
+ in this module a "DATA_BLOB *file_key" is a blob that uniquely identifies
+ a file. For a local posix filesystem this will usually be a combination
+ of the device and inode numbers of the file, but it can be anything
+ that uniquely idetifies a file for locking purposes, as long
+ as it is applied consistently.
+*/
+
+/*
+ the lock context contains the elements that define whether one
+ lock is the same as another lock
+*/
+struct lock_context {
+ servid_t server;
+ uint16_t smbpid;
+ uint16_t tid;
+};
+
+/* The data in brlock 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 lock_struct {
+ struct lock_context context;
+ uint64_t start;
+ uint64_t size;
+ uint16_t fnum;
+ enum brl_type lock_type;
+};
+
+/*
+ Open up the brlock.tdb database. Close it down using
+ talloc_free()
+*/
+void *brl_init(TALLOC_CTX *mem_ctx, servid_t server, uint16_t tid)
+{
+ char *path;
+ struct brl_context *brl;
+
+ brl = talloc_p(mem_ctx, struct brl_context);
+ if (brl == NULL) {
+ return NULL;
+ }
+
+ path = lock_path(brl, "brlock.tdb");
+ brl->w = tdb_wrap_open(brl, path, 0,
+ TDB_DEFAULT|TDB_CLEAR_IF_FIRST,
+ O_RDWR|O_CREAT, 0600);
+ talloc_free(path);
+ if (brl->w == NULL) {
+ talloc_free(brl);
+ return NULL;
+ }
+
+ brl->server = server;
+ brl->tid = tid;
+
+ return (void *)brl;
+}
+
+
+/*
+ see if two locking contexts are equal
+*/
+static BOOL brl_same_context(struct lock_context *ctx1, struct lock_context *ctx2)
+{
+ return (ctx1->server == ctx2->server &&
+ ctx1->smbpid == ctx2->smbpid &&
+ ctx1->tid == ctx2->tid);
+}
+
+/*
+ See if lock2 can be added when lock1 is in place.
+*/
+static BOOL brl_conflict(struct lock_struct *lck1,
+ struct lock_struct *lck2)
+{
+ if (lck1->lock_type == READ_LOCK && lck2->lock_type == READ_LOCK) {
+ return False;
+ }
+
+ if (brl_same_context(&lck1->context, &lck2->context) &&
+ lck2->lock_type == READ_LOCK && lck1->fnum == lck2->fnum) {
+ return False;
+ }
+
+ if (lck1->start >= (lck2->start + lck2->size) ||
+ lck2->start >= (lck1->start + lck1->size)) {
+ return False;
+ }
+
+ return True;
+}
+
+
+/*
+ Check to see if this lock conflicts, but ignore our own locks on the
+ same fnum only.
+*/
+static BOOL brl_conflict_other(struct lock_struct *lck1, struct lock_struct *lck2)
+{
+ if (lck1->lock_type == READ_LOCK && lck2->lock_type == READ_LOCK)
+ return False;
+
+ if (brl_same_context(&lck1->context, &lck2->context) &&
+ lck1->fnum == lck2->fnum) {
+ return False;
+ }
+
+ if (lck1->start >= (lck2->start + lck2->size) ||
+ lck2->start >= (lck1->start + lck1->size))
+ return False;
+
+ return True;
+}
+
+
+
+/*
+ Lock a range of bytes.
+*/
+NTSTATUS brl_lock(void *brl_ctx,
+ DATA_BLOB *file_key,
+ uint16_t smbpid,
+ uint16_t fnum,
+ uint64_t start, uint64_t size,
+ enum brl_type lock_type)
+{
+ struct brl_context *brl = brl_ctx;
+ TDB_DATA kbuf, dbuf;
+ int count, i;
+ struct lock_struct lock, *locks;
+ char *tp;
+ NTSTATUS status;
+
+ kbuf.dptr = file_key->data;
+ kbuf.dsize = file_key->length;
+
+ if (tdb_chainlock(brl->w->tdb, kbuf) != 0) {
+ return NT_STATUS_INTERNAL_DB_CORRUPTION;
+ }
+
+ dbuf = tdb_fetch(brl->w->tdb, kbuf);
+
+ lock.context.smbpid = smbpid;
+ lock.context.server = brl->server;
+ lock.context.tid = brl->tid;
+ lock.start = start;
+ lock.size = size;
+ lock.fnum = fnum;
+ lock.lock_type = lock_type;
+
+ if (dbuf.dptr) {
+ /* there are existing locks - make sure they don't conflict */
+ locks = (struct lock_struct *)dbuf.dptr;
+ count = dbuf.dsize / sizeof(*locks);
+ for (i=0; i<count; i++) {
+ if (brl_conflict(&locks[i], &lock)) {
+ status = NT_STATUS_LOCK_NOT_GRANTED;
+ goto fail;
+ }
+ }
+ }
+
+ /* no conflicts - add it to the list of locks */
+ tp = Realloc(dbuf.dptr, dbuf.dsize + sizeof(*locks));
+ if (!tp) {
+ status = NT_STATUS_NO_MEMORY;
+ goto fail;
+ } else {
+ dbuf.dptr = tp;
+ }
+ memcpy(dbuf.dptr + dbuf.dsize, &lock, sizeof(lock));
+ dbuf.dsize += sizeof(lock);
+
+ if (tdb_store(brl->w->tdb, kbuf, dbuf, TDB_REPLACE) != 0) {
+ status = NT_STATUS_INTERNAL_DB_CORRUPTION;
+ goto fail;
+ }
+
+ free(dbuf.dptr);
+ tdb_chainunlock(brl->w->tdb, kbuf);
+ return NT_STATUS_OK;
+
+ fail:
+
+ free(dbuf.dptr);
+ tdb_chainunlock(brl->w->tdb, kbuf);
+ return status;
+}
+
+
+/*
+ Unlock a range of bytes.
+*/
+NTSTATUS brl_unlock(void *brl_ctx,
+ DATA_BLOB *file_key,
+ uint16_t smbpid,
+ uint16_t fnum,
+ uint64_t start, uint64_t size)
+{
+ struct brl_context *brl = brl_ctx;
+ TDB_DATA kbuf, dbuf;
+ int count, i;
+ struct lock_struct *locks;
+ struct lock_context context;
+ NTSTATUS status;
+
+ kbuf.dptr = file_key->data;
+ kbuf.dsize = file_key->length;
+
+ if (tdb_chainlock(brl->w->tdb, kbuf) != 0) {
+ return NT_STATUS_INTERNAL_DB_CORRUPTION;
+ }
+
+ dbuf = tdb_fetch(brl->w->tdb, kbuf);
+ if (!dbuf.dptr) {
+ tdb_chainunlock(brl->w->tdb, kbuf);
+ return NT_STATUS_RANGE_NOT_LOCKED;
+ }
+
+ context.smbpid = smbpid;
+ context.server = brl->server;
+ context.tid = brl->tid;
+
+ /* there are existing locks - find a match */
+ locks = (struct lock_struct *)dbuf.dptr;
+ count = dbuf.dsize / sizeof(*locks);
+
+ locks = (struct lock_struct *)dbuf.dptr;
+ count = dbuf.dsize / sizeof(*locks);
+ for (i=0; i<count; i++) {
+ struct lock_struct *lock = &locks[i];
+
+ if (brl_same_context(&lock->context, &context) &&
+ lock->fnum == fnum &&
+ lock->start == start &&
+ lock->size == size) {
+ /* found it - delete it */
+ if (count == 1) {
+ if (tdb_delete(brl->w->tdb, kbuf) != 0) {
+ status = NT_STATUS_INTERNAL_DB_CORRUPTION;
+ goto fail;
+ }
+ } else {
+ if (i < count-1) {
+ memmove(&locks[i], &locks[i+1],
+ sizeof(*locks)*((count-1) - i));
+ }
+ dbuf.dsize -= sizeof(*locks);
+ if (tdb_store(brl->w->tdb, kbuf, dbuf, TDB_REPLACE) != 0) {
+ status = NT_STATUS_INTERNAL_DB_CORRUPTION;
+ goto fail;
+ }
+ }
+
+ free(dbuf.dptr);
+ tdb_chainunlock(brl->w->tdb, kbuf);
+ return NT_STATUS_OK;
+ }
+ }
+
+ /* we didn't find it */
+ status = NT_STATUS_RANGE_NOT_LOCKED;
+
+ fail:
+ free(dbuf.dptr);
+ tdb_chainunlock(brl->w->tdb, kbuf);
+ return status;
+}
+
+
+/*
+ Test if we are allowed to perform IO on a region of an open file
+*/
+NTSTATUS brl_locktest(void *brl_ctx,
+ DATA_BLOB *file_key,
+ uint16_t fnum,
+ uint16 smbpid,
+ uint64_t start, uint64_t size,
+ enum brl_type lock_type)
+{
+ struct brl_context *brl = brl_ctx;
+ TDB_DATA kbuf, dbuf;
+ int count, i;
+ struct lock_struct lock, *locks;
+
+ kbuf.dptr = file_key->data;
+ kbuf.dsize = file_key->length;
+
+ dbuf = tdb_fetch(brl->w->tdb, kbuf);
+ if (dbuf.dptr == NULL) {
+ return NT_STATUS_OK;
+ }
+
+ lock.context.smbpid = smbpid;
+ lock.context.server = brl->server;
+ lock.context.tid = brl->tid;
+ lock.start = start;
+ lock.size = size;
+ lock.fnum = fnum;
+ lock.lock_type = lock_type;
+
+ /* there are existing locks - make sure they don't conflict */
+ locks = (struct lock_struct *)dbuf.dptr;
+ count = dbuf.dsize / sizeof(*locks);
+
+ for (i=0; i<count; i++) {
+ if (brl_conflict_other(&locks[i], &lock)) {
+ free(dbuf.dptr);
+ return NT_STATUS_FILE_LOCK_CONFLICT;
+ }
+ }
+
+ free(dbuf.dptr);
+ return NT_STATUS_OK;
+}
+
+
+/*
+ Remove any locks associated with a open file.
+*/
+NTSTATUS brl_close(void *brl_ctx,
+ DATA_BLOB *file_key, int fnum)
+{
+ struct brl_context *brl = brl_ctx;
+ TDB_DATA kbuf, dbuf;
+ int count, i, dcount=0;
+ struct lock_struct *locks;
+ NTSTATUS status;
+
+ kbuf.dptr = file_key->data;
+ kbuf.dsize = file_key->length;
+
+ if (tdb_chainlock(brl->w->tdb, kbuf) != 0) {
+ return NT_STATUS_INTERNAL_DB_CORRUPTION;
+ }
+
+ dbuf = tdb_fetch(brl->w->tdb, kbuf);
+ if (!dbuf.dptr) {
+ tdb_chainunlock(brl->w->tdb, kbuf);
+ return NT_STATUS_OK;
+ }
+
+ /* there are existing locks - remove any for this fnum */
+ locks = (struct lock_struct *)dbuf.dptr;
+ count = dbuf.dsize / sizeof(*locks);
+
+ for (i=0; i<count; i++) {
+ struct lock_struct *lock = &locks[i];
+
+ if (lock->context.tid == brl->tid &&
+ lock->context.server == brl->server &&
+ lock->fnum == fnum) {
+ /* found it - delete it */
+ if (count > 1 && i < count-1) {
+ memmove(&locks[i], &locks[i+1],
+ sizeof(*locks)*((count-1) - i));
+ }
+ count--;
+ i--;
+ dcount++;
+ }
+ }
+
+ status = NT_STATUS_OK;
+
+ if (count == 0) {
+ if (tdb_delete(brl->w->tdb, kbuf) != 0) {
+ status = NT_STATUS_INTERNAL_DB_CORRUPTION;
+ }
+ } else if (dcount != 0) {
+ dbuf.dsize -= dcount * sizeof(*locks);
+ if (tdb_store(brl->w->tdb, kbuf, dbuf, TDB_REPLACE) != 0) {
+ status = NT_STATUS_INTERNAL_DB_CORRUPTION;
+ }
+ }
+
+ free(dbuf.dptr);
+ tdb_chainunlock(brl->w->tdb, kbuf);
+
+ return status;
+}
+
generated by cgit (git 2.34.1) at 2025-03-09 11:47:58 +0000