[Libguestfs] [PATCH 1/5] daemon: Replace root_mounted global with intelligence.
Richard W.M. Jones
rjones at redhat.com
Thu Jan 27 18:02:51 UTC 2011
This is a good general patch -- we should apply it anyway
regardless of the rest.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
libguestfs lets you edit virtual machines. Supports shell scripting,
bindings from many languages. http://libguestfs.org
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>From 701ba942339ab3c56b361891496cda6bd2fdbd71 Mon Sep 17 00:00:00 2001
From: Richard W.M. Jones <rjones at redhat.com>
Date: Thu, 27 Jan 2011 17:27:41 +0000
Subject: [PATCH 1/5] daemon: Replace root_mounted global with intelligence.
We used to maintain a global flag 'root_mounted' which tells us if the
user has mounted something on root (ie. on the sysroot directory).
This flag caused a lot of trouble (eg. RHBZ#599503) because it's hard
to keep the flag updated correctly when the user can do arbitrary
mounts and also use mkmountpoint.
Remove this flag and replace it with a test to see if something is
mounted on *or under* the sysroot. (It has to be *or under* because
of mkmountpoint and friends).
This also replaces a rather convoluted "have we mounted root yet"
check in the mount* APIs with a simpler check to see if the mountpoint
exists and is an ordinary directory.
---
daemon/daemon.h | 4 +-
daemon/mount.c | 74 ++++++++++++++++++++++++++++++++++++------------------
2 files changed, 51 insertions(+), 27 deletions(-)
diff --git a/daemon/daemon.h b/daemon/daemon.h
index 6845e1b..da991b1 100644
--- a/daemon/daemon.h
+++ b/daemon/daemon.h
@@ -107,7 +107,7 @@ extern uint64_t progress_hint;
extern uint64_t optargs_bitmask;
/*-- in mount.c --*/
-extern int root_mounted;
+extern int is_root_mounted (void);
/*-- in stubs.c (auto-generated) --*/
extern void dispatch_incoming_message (XDR *);
@@ -178,7 +178,7 @@ extern void notify_progress (uint64_t position, uint64_t total);
*/
#define NEED_ROOT(cancel_stmt,fail_stmt) \
do { \
- if (!root_mounted) { \
+ if (!is_root_mounted ()) { \
if ((cancel_stmt) != -2) \
reply_with_error ("%s: you must call 'mount' first to mount the root filesystem", __func__); \
fail_stmt; \
diff --git a/daemon/mount.c b/daemon/mount.c
index ccd07c6..c584f81 100644
--- a/daemon/mount.c
+++ b/daemon/mount.c
@@ -24,12 +24,43 @@
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
+#include <mntent.h>
#include "daemon.h"
#include "actions.h"
-/* You must mount something on "/" first, hence: */
-int root_mounted = 0;
+/* You must mount something on "/" first before many operations.
+ * Hence we have an internal function which can test if something is
+ * mounted on *or under* the sysroot directory. (It has to be *or
+ * under* because of mkmountpoint and friends).
+ */
+int
+is_root_mounted (void)
+{
+ FILE *fp;
+ struct mntent *m;
+
+ fp = setmntent ("/etc/mtab", "r");
+ if (fp == NULL) {
+ perror ("/etc/mtab");
+ exit (EXIT_FAILURE);
+ }
+
+ while ((m = getmntent (fp)) != NULL) {
+ /* Allow a mount directory like "/sysroot". */
+ if (sysroot_len > 0 && STREQ (m->mnt_dir, sysroot)) {
+ gotit:
+ endmntent (fp);
+ return 1;
+ }
+ /* Or allow a mount directory like "/sysroot/...". */
+ if (STRPREFIX (m->mnt_dir, sysroot) && m->mnt_dir[sysroot_len] == '/')
+ goto gotit;
+ }
+
+ endmntent (fp);
+ return 0;
+}
/* The "simple mount" call offers no complex options, you can just
* mount a device on a mountpoint. The variations like mount_ro,
@@ -44,25 +75,31 @@ int
do_mount_vfs (const char *options, const char *vfstype,
const char *device, const char *mountpoint)
{
- int r, is_root;
+ int r;
char *mp;
char *error;
+ struct stat statbuf;
ABS_PATH (mountpoint, 0, return -1);
- is_root = STREQ (mountpoint, "/");
-
- if (!root_mounted && !is_root) {
- reply_with_error ("you must mount something on / first");
- return -1;
- }
-
mp = sysroot_path (mountpoint);
if (!mp) {
reply_with_perror ("malloc");
return -1;
}
+ /* Check the mountpoint exists and is a directory. */
+ if (stat (mp, &statbuf) == -1) {
+ reply_with_perror ("mount: %s", mountpoint);
+ free (mp);
+ return -1;
+ }
+ if (!S_ISDIR (statbuf.st_mode)) {
+ reply_with_perror ("mount: %s: mount point is not a directory", mountpoint);
+ free (mp);
+ return -1;
+ }
+
if (vfstype)
r = command (NULL, &error,
"mount", "-o", options, "-t", vfstype, device, mp, NULL);
@@ -76,9 +113,6 @@ do_mount_vfs (const char *options, const char *vfstype,
return -1;
}
- if (is_root)
- root_mounted = 1;
-
return 0;
}
@@ -134,8 +168,6 @@ do_umount (const char *pathordevice)
free (err);
- /* update root_mounted? */
-
return 0;
}
@@ -324,9 +356,6 @@ do_umount_all (void)
free_stringslen (mounts, size);
- /* We've unmounted root now, so ... */
- root_mounted = 0;
-
return 0;
}
@@ -368,8 +397,8 @@ do_mount_loop (const char *file, const char *mountpoint)
}
/* Specialized calls mkmountpoint and rmmountpoint are really
- * variations on mkdir and rmdir which do no checking and (in the
- * mkmountpoint case) set the root_mounted flag.
+ * variations on mkdir and rmdir which do no checking of the
+ * is_root_mounted() flag.
*/
int
do_mkmountpoint (const char *path)
@@ -388,11 +417,6 @@ do_mkmountpoint (const char *path)
return -1;
}
- /* Set the flag so that filesystems can be mounted here,
- * not just on /sysroot.
- */
- root_mounted = 1;
-
return 0;
}
--
1.7.3.5
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