libdiskfs: 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(diskfs_S_file_record_lock):
          Don't set rendezvous to MACH_PORT_NULL.

2018-12-07  Svante Signell <svante.signell@gmail.com>

        * Update copyright years.
        * dir-lookup.c(diskfs_S_dir_lookup): Call fshelp_rlock_tweak()
          with new last argument rendezvous = MACH_PORT_NULL.
        * file-lock.c(diskfs_S_file_lock): Likewise.
        * file-record-lock.c(diskfs_S_file_record_lock): Likewise.
        (diskfs_S_file_record_lock): Add new argument mach_port_t rendezvous.

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

        * Update copyright years and headers.

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

        * file-lock-stat.c: Port from cthreads to libpthread.
        * file-lock.c: Likewise.
        * file-record-lock: Likewise.

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

        * Makefile (FSSRCS): Add file-record-lock.c.
        * diskfs.h (struct peropen): Change the type of lock_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 (diskfs_S_dir_lookup): Use fshelp_rlock_tweak
        as fshelp_acquire_lock is now depreciated.
        * file-lock-stat.c (diskfs_S_file_lock_stat): Total rewrite
        around the new record locking functions.
        * file-lock.c (diskfs_S_file_lock): Total rewrite around the
        new record locking functions.
        * file-record-lock.c: New file.  Implement
        diskfs_S_file_record_lock.
        * node-make.c (diskfs_make_node):  Initialize userbox with
        fshelp_rlock_init.
        * peropen-make.c (diskfs_make_peropen): Initialize lock_status
        using fshelp_rlock_po_init.
        * peropen-rele.c (diskfs_release_peropen): Release lock_status
        using fshelp_rlock_drop_peropen.

1 files changed, 48 insertions, 20 deletions

diff --git a/libdiskfs/file-lock.c b/libdiskfs/file-lock.c
index ab536e86..b95c3f0c 100644
--- a/libdiskfs/file-lock.c
+++ b/libdiskfs/file-lock.c
@@ -1,36 +1,64 @@
-/*
-   Copyright (C) 1993, 1994 Free Software Foundation
+/* Copyright (C) 1993-1994, 2001, 2014-2019 Free Software Foundation, Inc.
 
-   This file is part of the GNU Hurd.
+   Written by Neal H Walfield <neal@cs.uml.edu>
 
-   The GNU Hurd 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, or (at your option)
-   any later version.
+   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, or (at
+   your option) any later version.
 
-   The GNU Hurd 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.
+   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 the GNU Hurd; see the file COPYING.  If not, write to
-   the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
-
-/* Written by Michael I. Bushnell.  */
+   along with the GNU Hurd.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include "priv.h"
 #include "fs_S.h"
 
+#include <fcntl.h>
+#include <sys/file.h>
+
 kern_return_t
 diskfs_S_file_lock (struct protid *cred, int flags)
 {
   error_t err;
-  if (!cred)
+  struct flock64 lock;
+  struct node *node;
+  int openstat = cred->po->openstat;
+  mach_port_t rendezvous = MACH_PORT_NULL;
+
+  if (! cred)
     return EOPNOTSUPP;
-  pthread_mutex_lock (&cred->po->np->lock);
-  err = fshelp_acquire_lock (&cred->po->np->userlock, &cred->po->lock_status,
-			     &cred->po->np->lock, flags);
-  pthread_mutex_unlock (&cred->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 = cred->po->np;
+  pthread_mutex_lock (&node->lock);
+  err = fshelp_rlock_tweak (&node->userlock, &node->lock,
+			    &cred->po->lock_status, openstat,
+			    0, 0, flags & LOCK_NB ? F_SETLK64 : F_SETLKW64,
+			    &lock, rendezvous);
+  pthread_mutex_unlock (&node->lock);
   return err;
 }