[RFC] Teaching mount(8) to use nmount()
Craig Rodrigues
rodrigc at crodrigues.org
Fri Oct 7 19:46:20 PDT 2005
Hi,
The mount(8) command-line program that is used in FreeBSD behaves more
or less as follows:
The mount program will process the command-line arguments,
and then fork() and do one of the following:
-> The filesystem to mount is UFS, either by specifying "-t ufs" or
omitting the -t flag entirely.
An internal function
mount_ufs() which in turn calls the "old-style" mount() syscall
to actually mount the filesystem
-> If you specify some other filesystem, "-t myfoofs", then
the mount program will exec() a copy of "mount_myfoofs", passing
the command-line parameters that are necessary to mount the FS.
If someone comes along with a new filesystem, they then need
to create a new mount_mynewfs binary, in order to mount
the filesystem with mount -t mynewfs.
This is OK, but leads to a plethora of mount_* binaries which
are probably unnecessary. I think that the mount program
should eventually do the following:
-> for most filesystems (including UFS), the
mount program should parse command-line arguments, and invoke
the new nmount() syscall
-> for very exceptional cases (not to be encouraged), like NFS, SMBFS, etc.,
instead of calling nmount() directly, we can fork() a new
mount_nfs, mount_smbfs, etc. binary and do the mount
Since I don't know how all the existing mount programs work, and I
don't know the dependencies on how UFS mounting works, I propose
an interim behavior for mount:
if (filesystem_to_mount == "ufs" ) {
call special mount_ufs() function
} else if (filesystem_to_mount == something that needs an external binary) {
fork() and exec("mount_somefoofs");
} else {
call nmount()
}
When things get cleaned up, we can eliminate the special mount_ufs()
function, and just have everything call nmount(), except for
the special cases which need their own mount program.
In the list of filesystems which need an external binary, I put all
the mount_* binaries I could find on my FreeBSD box except the ones for
mount_std, mount_devfs, mount_fdescfs, mount_linprocfs, mount_procfs because:
-> all these binaries are copies of mount_std, mount_std checks
argv[0] to see how it was invoked.
if argv[0] == "mount_std" it is an error
else { strip out the mount_ part of argv[0], and nmount() that
filesystem }
-> so mount_std and friends are basically thin wrappers around nmount
I would appreciate any comments on the attached patch.
--
Craig Rodrigues
rodrigc at crodrigues.org
-------------- next part --------------
? ktrace.out
? mount
? mount.8.gz
Index: Makefile
===================================================================
RCS file: /home/ncvs/src/sbin/mount/Makefile,v
retrieving revision 1.16
diff -u -u -r1.16 Makefile
--- Makefile 7 Oct 2005 02:22:48 -0000 1.16
+++ Makefile 8 Oct 2005 02:23:29 -0000
@@ -2,7 +2,7 @@
# $FreeBSD: src/sbin/mount/Makefile,v 1.16 2005/10/07 02:22:48 rodrigc Exp $
PROG= mount
-SRCS= mount.c mount_ufs.c getmntopts.c vfslist.c
+SRCS= mount.c mount_fs.c mount_ufs.c getmntopts.c vfslist.c
WARNS?= 3
MAN= mount.8
# We do NOT install the getmntopts.3 man page.
Index: extern.h
===================================================================
RCS file: /home/ncvs/src/sbin/mount/extern.h,v
retrieving revision 1.5
diff -u -u -r1.5 extern.h
--- extern.h 7 Oct 2005 02:18:20 -0000 1.5
+++ extern.h 8 Oct 2005 02:23:29 -0000
@@ -32,3 +32,4 @@
/* mount_ufs.c */
int mount_ufs(int, char * const []);
+int mount_fs(const char *, int, char * const []);
Index: mount.c
===================================================================
RCS file: /home/ncvs/src/sbin/mount/mount.c,v
retrieving revision 1.71
diff -u -u -r1.71 mount.c
--- mount.c 7 Oct 2005 02:22:04 -0000 1.71
+++ mount.c 8 Oct 2005 02:23:29 -0000
@@ -120,6 +120,67 @@
0
};
+static int
+use_mountprog(const char *vfstype)
+{
+ /* XXX: We need to get away from implementing external mount
+ * programs for every filesystem, and move towards having
+ * each filesystem properly implement the nmount() system call.
+ */
+ unsigned int i;
+ const char *fs[] = {
+ "cd9660", "ext2fs", "mfs", "msdosfs", "nfs", "nfs4", "ntfs",
+ "nwfs", "nullfs", "portalfs", "reiserfs", "smbfs", "udf", "umapfs",
+ "unionfs",
+ NULL
+ };
+
+ for (i=0; fs[i] != NULL; ++i) {
+ if (strcmp(vfstype, fs[i]) == 0)
+ return 1;
+ }
+
+ return 0;
+}
+
+static int
+exec_mountprog(const char *vfstype, const char *name, const char *execname,
+ char *const argv[])
+{
+ pid_t pid;
+ int status;
+
+ switch (pid = fork()) {
+ case -1: /* Error. */
+ warn("fork");
+ exit (1);
+ case 0: /* Child. */
+ /* Go find an executable. */
+ execvP(execname, _PATH_SYSPATH, argv);
+ if (errno == ENOENT) {
+ warn("exec %s not found in %s", execname,
+ _PATH_SYSPATH);
+ }
+ exit(1);
+ default: /* Parent. */
+ if (waitpid(pid, &status, 0) < 0) {
+ warn("waitpid");
+ return (1);
+ }
+
+ if (WIFEXITED(status)) {
+ if (WEXITSTATUS(status) != 0)
+ return (WEXITSTATUS(status));
+ } else if (WIFSIGNALED(status)) {
+ warnx("%s: %s", name, sys_siglist[WTERMSIG(status)]);
+ return (1);
+ }
+ break;
+ }
+
+ return (0);
+}
+
int
main(int argc, char *argv[])
{
@@ -385,8 +446,7 @@
{
const char *argv[100];
struct statfs sf;
- pid_t pid;
- int argc, i, status;
+ int argc, i, ret;
char *optbuf, execname[PATH_MAX], mntpath[PATH_MAX];
#if __GNUC__
@@ -447,50 +507,26 @@
return (0);
}
- switch (pid = fork()) {
- case -1: /* Error. */
- warn("fork");
- free(optbuf);
- return (1);
- case 0: /* Child. */
- if (strcmp(vfstype, "ufs") == 0)
- exit(mount_ufs(argc, (char * const *) argv));
-
- /* Go find an executable. */
- execvP(execname, _PATH_SYSPATH, (char * const *)argv);
- if (errno == ENOENT) {
- warn("exec mount_%s not found in %s", vfstype,
- _PATH_SYSPATH);
- }
- exit(1);
- /* NOTREACHED */
- default: /* Parent. */
- free(optbuf);
+ if (strcmp(vfstype, "ufs")==0) {
+ ret = mount_ufs(argc, (char * const *) argv);
+ } else if (use_mountprog(vfstype)) {
+ ret = exec_mountprog(vfstype, name, execname,
+ (char * const *)argv);
+ } else {
+ ret = mount_fs(vfstype, argc,(char * const *)argv);
+ }
- if (waitpid(pid, &status, 0) < 0) {
- warn("waitpid");
- return (1);
- }
+ free(optbuf);
- if (WIFEXITED(status)) {
- if (WEXITSTATUS(status) != 0)
- return (WEXITSTATUS(status));
- } else if (WIFSIGNALED(status)) {
- warnx("%s: %s", name, sys_siglist[WTERMSIG(status)]);
+ if (verbose) {
+ if (statfs(name, &sf) < 0) {
+ warn("statfs %s", name);
return (1);
}
-
- if (verbose) {
- if (statfs(name, &sf) < 0) {
- warn("statfs %s", name);
- return (1);
- }
- if (fstab_style)
- putfsent(&sf);
- else
- prmount(&sf);
- }
- break;
+ if (fstab_style)
+ putfsent(&sf);
+ else
+ prmount(&sf);
}
return (0);
Index: mount_fs.c
===================================================================
RCS file: mount_fs.c
diff -N mount_fs.c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ mount_fs.c 8 Oct 2005 02:23:29 -0000
@@ -0,0 +1,139 @@
+/*
+ * Copyright (c) 1992, 1993, 1994
+ * The Regents of the University of California. All rights reserved.
+ *
+ * This code is derived from software donated to Berkeley by
+ * Jan-Simon Pendry.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the University of
+ * California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef lint
+static const char copyright[] =
+"@(#) Copyright (c) 1992, 1993, 1994\n\
+ The Regents of the University of California. All rights reserved.\n";
+#endif /* not lint */
+
+#ifndef lint
+#if 0
+static char sccsid[] = "@(#)mount_fs.c 8.6 (Berkeley) 4/26/95";
+#endif
+static const char rcsid[] =
+ "$Id$";
+#endif /* not lint */
+
+#include <sys/param.h>
+#include <sys/mount.h>
+
+#include <err.h>
+#include <getopt.h>
+#include <libgen.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "extern.h"
+#include "mntopts.h"
+
+struct mntopt mopts[] = {
+ MOPT_STDOPTS,
+ MOPT_END
+};
+
+extern int getmnt_silent;
+
+static void
+usage(void)
+{
+ (void)fprintf(stderr,
+ "usage: mount_xfs [-t fstype] [-o options] target_fs mount_point\n");
+ exit(1);
+}
+
+int
+mount_fs(const char *vfstype, int argc, char * const argv[])
+{
+ struct iovec *iov;
+ int iovlen;
+ int mntflags = 0;
+ int ch;
+ char *dev, *dir, mntpath[MAXPATHLEN];
+ char fstype[32];
+ char *p, *val;
+ int ret;
+ int i;
+ printf("argc is: %d\n", argc); for (i=0; i < argc; ++i) { printf("%d: %s\n", argc, argv[i]); }
+ strncpy(fstype, vfstype, sizeof(fstype));
+
+ getmnt_silent = 1;
+ iov = NULL;
+ iovlen = 0;
+
+ optind = optreset = 1; /* Reset for parse of new argv. */
+ while ((ch = getopt(argc, argv, "o:")) != -1) {
+ switch(ch) {
+ case 'o':
+ getmntopts(optarg, mopts, &mntflags, 0);
+ p = strchr(optarg, '=');
+ val = "";
+ if (p != NULL) {
+ *p = '\0';
+ val = p + 1;
+ }
+ build_iovec(&iov, &iovlen, optarg, val, -1);
+ break;
+ case '?':
+ default:
+ usage();
+ }
+ }
+
+ argc -= optind;
+ argv += optind;
+ printf("argc is: %d\n", argc);
+ if (argc != 2)
+ usage();
+
+ dev = argv[0];
+ dir = argv[1];
+
+ (void)checkpath(dir, mntpath);
+ (void)rmslashes(dev, dev);
+
+ build_iovec(&iov, &iovlen, "fstype", fstype, -1);
+ build_iovec(&iov, &iovlen, "fspath", mntpath, -1);
+ build_iovec(&iov, &iovlen, "from", dev, -1);
+
+ ret = nmount(iov, iovlen, mntflags);
+ if (ret < 0)
+ err(1, "%s", dev);
+
+ return (ret);
+}
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