zfs/lib/libshare/nfs.c

160 lines
3.6 KiB
C

/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <fcntl.h>
#include <stdio.h>
#include <errno.h>
#include <libshare.h>
#include "nfs.h"
static int nfs_lock_fd = -1;
/*
* nfs_exports_[lock|unlock] are used to guard against conconcurrent
* updates to the exports file. Each protocol is responsible for
* providing the necessary locking to ensure consistency.
*/
static int
nfs_exports_lock(const char *name)
{
int err;
nfs_lock_fd = open(name, O_RDWR | O_CREAT | O_CLOEXEC, 0600);
if (nfs_lock_fd == -1) {
err = errno;
fprintf(stderr, "failed to lock %s: %s\n", name, strerror(err));
return (err);
}
while ((err = flock(nfs_lock_fd, LOCK_EX)) != 0 && errno == EINTR)
;
if (err != 0) {
err = errno;
fprintf(stderr, "failed to lock %s: %s\n", name, strerror(err));
(void) close(nfs_lock_fd);
nfs_lock_fd = -1;
return (err);
}
return (0);
}
static void
nfs_exports_unlock(const char *name)
{
verify(nfs_lock_fd > 0);
if (flock(nfs_lock_fd, LOCK_UN) != 0) {
fprintf(stderr, "failed to unlock %s: %s\n",
name, strerror(errno));
}
(void) close(nfs_lock_fd);
nfs_lock_fd = -1;
}
static char *
nfs_init_tmpfile(const char *prefix, const char *mdir)
{
char *tmpfile = NULL;
struct stat sb;
if (mdir != NULL &&
stat(mdir, &sb) < 0 &&
mkdir(mdir, 0755) < 0) {
fprintf(stderr, "failed to create %s: %s\n",
mdir, strerror(errno));
return (NULL);
}
if (asprintf(&tmpfile, "%s.XXXXXXXX", prefix) == -1) {
fprintf(stderr, "Unable to allocate temporary file\n");
return (NULL);
}
int fd = mkostemp(tmpfile, O_CLOEXEC);
if (fd == -1) {
fprintf(stderr, "Unable to create temporary file: %s",
strerror(errno));
free(tmpfile);
return (NULL);
}
close(fd);
return (tmpfile);
}
static int
nfs_fini_tmpfile(const char *exports, char *tmpfile)
{
if (rename(tmpfile, exports) == -1) {
fprintf(stderr, "Unable to rename %s: %s\n", tmpfile,
strerror(errno));
unlink(tmpfile);
free(tmpfile);
return (SA_SYSTEM_ERR);
}
free(tmpfile);
return (SA_OK);
}
int
nfs_toggle_share(const char *lockfile, const char *exports,
const char *expdir, sa_share_impl_t impl_share,
int(*cbk)(sa_share_impl_t impl_share, char *filename))
{
int error;
char *filename;
if ((filename = nfs_init_tmpfile(exports, expdir)) == NULL)
return (SA_SYSTEM_ERR);
error = nfs_exports_lock(lockfile);
if (error != 0) {
unlink(filename);
free(filename);
return (error);
}
error = nfs_copy_entries(filename, impl_share->sa_mountpoint);
if (error != SA_OK)
goto fullerr;
error = cbk(impl_share, filename);
if (error != SA_OK)
goto fullerr;
error = nfs_fini_tmpfile(exports, filename);
nfs_exports_unlock(lockfile);
return (error);
fullerr:
unlink(filename);
free(filename);
nfs_exports_unlock(lockfile);
return (error);
}