libnetfs: Support for file record locking

2019-03-04  Svante Signell <svante.signell@gmail.com>

	* file-lock.c: Make flock work regardless of the
          mode in which the file was opened.

2019-02-12  Svante Signell <svante.signell@gmail.com>

	* file-lock.c: Comment out "Make flock work without R or W mode"

2019-02-01  Svante Signell <svante.signell@gmail.com>

       * Update copyright years.
       * file-record-lock.c(netfs_S_file_record_lock):
         Don't set rendezvous to MACH_PORT_NULL.

2017-01-05  Svante Signell <svante.signell@gmail.com>

	* Update copyright years and headers.
	* dir-lookup.c(netfs_S_dir_lookup): Call fshelp_rlock_tweak()
          with new last argument rendezvous = MACH_PORT_NULL.
	* file-lock.c(netfs_S_file_lock): Likewise.
	* file-record-lock.c(netfs_S_file_record_lock): Likewise.
	(netfs_S_file_record_lock): Add new argument mach_port_t rendezvous.

2016-05-23  Svante Signell <svante.signell@gmail.com>

	* netfs.h (struct peropen): Change the type of rlock_status from
	an int to a struct rlock_peropen.
	(struct node): Change the type of userbox from a struct lock_box
	to a struct rlock_box.
	* dir-lookup.c (netfs_S_dir_lookup): Use fshelp_rlock_tweak.
	* file-lock-stat.c (netfs_S_file_lock_stat): Total rewrite
	around the new record locking functions.
	* file-lock.c (netfs_S_file_lock): Likewise.
	* file-record-lock.c (netfs_S_file_record_lock): Likewise.
	* make-node.c (netfs_make_node): Initialize userbox with
	fshelp_rlock_init.
	* make-peropen.c (netfs_make_peropen): Initialize lock_status
	using fshelp_rlock_po_init.
	(netfs_make_peropen): Add a comment that po->refcnt starts at zero.
	* relese-peropen.c (netfs_release_peropen): Release lock_status
	using fshelp_rlock_drop_peropen.

2001-04-11  Neal H Walfield  <neal@cs.uml.edu>

	* file-record-lock.c: New file.  Implement
	netfs_S_file_record_lock.
	* Makefile (SRCS): Add file-record-lock.c

1 files changed, 40 insertions, 8 deletions

diff --git a/libnetfs/file-lock.c b/libnetfs/file-lock.c
index 0010d4be..7bb81d43 100644
--- a/libnetfs/file-lock.c
+++ b/libnetfs/file-lock.c
@@ -1,5 +1,5 @@
-/* 
-   Copyright (C) 1995 Free Software Foundation, Inc.
+/*
+   Copyright (C) 1995, 2015-2019 Free Software Foundation, Inc.
    Written by Michael I. Bushnell, p/BSG.
 
    This file is part of the GNU Hurd.
@@ -15,22 +15,54 @@
    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., 59 Temple Place - Suite 330, Boston, MA  02111, USA. */
+   along with the GNU Hurd.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include "netfs.h"
 #include "fs_S.h"
 
+#include <fcntl.h>
+#include <sys/file.h>
+
 error_t
 netfs_S_file_lock (struct protid *user,
 		   int flags)
 {
   error_t err;
+  struct flock64 lock;
+  struct node *node;
+  int openstat = user->po->openstat;
+  mach_port_t rendezvous = MACH_PORT_NULL;
+
   if (!user)
     return EOPNOTSUPP;
-  pthread_mutex_lock (&user->po->np->lock);
-  err = fshelp_acquire_lock (&user->po->np->userlock, &user->po->lock_status,
-			     &user->po->np->lock, flags);
-  pthread_mutex_unlock (&user->po->np->lock);
+
+  lock.l_whence = SEEK_SET;
+  lock.l_start = 0;
+  lock.l_len = 0;
+
+  if (flags & LOCK_UN)
+    lock.l_type = F_UNLCK;
+  else if (flags & LOCK_SH)
+    lock.l_type = F_RDLCK;
+  else if (flags & LOCK_EX)
+    lock.l_type = F_WRLCK;
+  else
+    return EINVAL;
+
+  /*
+    XXX: Fix for flock(2) calling fcntl(2)
+    From flock(2): A shared or exclusive lock can be placed on a file
+    regardless of the mode in which the file was opened.
+  */
+  if (openstat & (O_RDONLY|O_WRONLY|O_EXEC)) openstat |= O_RDONLY|O_WRONLY;
+
+  node = user->po->np;
+  pthread_mutex_lock (&node->lock);
+  err = fshelp_rlock_tweak (&node->userlock, &node->lock,
+			    &user->po->lock_status, openstat,
+			    0, 0, flags & LOCK_NB ? F_SETLK64 : F_SETLKW64,
+			    &lock, rendezvous);
+  pthread_mutex_unlock (&node->lock);
+
   return err;
 }