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daemon: Refactor bind-mount code.

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This is just code motion.
This commit is contained in:
Richard W.M. Jones
2013-10-07 19:53:54 +01:00
parent 93793db049
commit b8b1b0296b
1 changed files with 79 additions and 33 deletions
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112
daemon/command.c
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@@ -20,6 +20,7 @@
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include "guestfs_protocol.h"
@@ -31,21 +32,94 @@
GUESTFSD_EXT_CMD(str_mount, mount);
GUESTFSD_EXT_CMD(str_umount, umount);
#ifdef HAVE_ATTRIBUTE_CLEANUP
#define CLEANUP_BIND_STATE __attribute__((cleanup(free_bind_state)))
#else
#define CLEANUP_BIND_STATE
#endif
struct bind_state {
bool mounted;
char *sysroot_dev;
char *sysroot_dev_pts;
char *sysroot_proc;
char *sysroot_sys;
bool dev_ok, dev_pts_ok, proc_ok, sys_ok;
};
/* While running the command, bind-mount /dev, /proc, /sys
* into the chroot. However we must be careful to unmount them
* afterwards because otherwise they would interfere with
* future mount and unmount operations.
*
* We deliberately allow these commands to fail silently, BUT
* if a mount fails, don't unmount the corresponding mount.
*/
static int
bind_mount (struct bind_state *bs)
{
int r;
memset (bs, 0, sizeof *bs);
bs->sysroot_dev = sysroot_path ("/dev");
bs->sysroot_dev_pts = sysroot_path ("/dev/pts");
bs->sysroot_proc = sysroot_path ("/proc");
bs->sysroot_sys = sysroot_path ("/sys");
if (bs->sysroot_dev == NULL || bs->sysroot_dev_pts == NULL ||
bs->sysroot_proc == NULL || bs->sysroot_sys == NULL) {
reply_with_perror ("malloc");
free (bs->sysroot_dev);
free (bs->sysroot_dev_pts);
free (bs->sysroot_proc);
free (bs->sysroot_sys);
return -1;
}
r = command (NULL, NULL, str_mount, "--bind", "/dev", bs->sysroot_dev, NULL);
bs->dev_ok = r != -1;
r = command (NULL, NULL, str_mount, "--bind", "/dev/pts", bs->sysroot_dev_pts, NULL);
bs->dev_pts_ok = r != -1;
r = command (NULL, NULL, str_mount, "--bind", "/proc", bs->sysroot_proc, NULL);
bs->proc_ok = r != -1;
r = command (NULL, NULL, str_mount, "--bind", "/sys", bs->sysroot_sys, NULL);
bs->sys_ok = r != -1;
bs->mounted = true;
return 0;
}
static inline void
umount_ignore_fail (const char *path)
{
ignore_value (command (NULL, NULL, str_umount, path, NULL));
}
static void
free_bind_state (struct bind_state *bs)
{
if (bs->mounted) {
if (bs->sys_ok) umount_ignore_fail (bs->sysroot_sys);
free (bs->sysroot_sys);
if (bs->proc_ok) umount_ignore_fail (bs->sysroot_proc);
free (bs->sysroot_proc);
if (bs->dev_pts_ok) umount_ignore_fail (bs->sysroot_dev_pts);
free (bs->sysroot_dev_pts);
if (bs->dev_ok) umount_ignore_fail (bs->sysroot_dev);
free (bs->sysroot_dev);
bs->mounted = false;
}
}
char *
do_command (char *const *argv)
{
char *out;
CLEANUP_FREE char *err = NULL;
int r;
CLEANUP_FREE char *sysroot_dev = NULL, *sysroot_dev_pts = NULL,
*sysroot_proc = NULL, *sysroot_sys = NULL;
int dev_ok, dev_pts_ok, proc_ok, sys_ok;
CLEANUP_BIND_STATE struct bind_state bind_state = { .mounted = false };
/* We need a root filesystem mounted to do this. */
NEED_ROOT (, return NULL);
@@ -59,42 +133,14 @@ do_command (char *const *argv)
return NULL;
}
/* While running the command, bind-mount /dev, /proc, /sys
* into the chroot. However we must be careful to unmount them
* afterwards because otherwise they would interfere with
* future mount and unmount operations.
*
* We deliberately allow these commands to fail silently, BUT
* if a mount fails, don't unmount the corresponding mount.
*/
sysroot_dev = sysroot_path ("/dev");
sysroot_dev_pts = sysroot_path ("/dev/pts");
sysroot_proc = sysroot_path ("/proc");
sysroot_sys = sysroot_path ("/sys");
if (sysroot_dev == NULL || sysroot_dev_pts == NULL ||
sysroot_proc == NULL || sysroot_sys == NULL) {
reply_with_perror ("malloc");
if (bind_mount (&bind_state) == -1)
return NULL;
}
r = command (NULL, NULL, str_mount, "--bind", "/dev", sysroot_dev, NULL);
dev_ok = r != -1;
r = command (NULL, NULL, str_mount, "--bind", "/dev/pts", sysroot_dev_pts, NULL);
dev_pts_ok = r != -1;
r = command (NULL, NULL, str_mount, "--bind", "/proc", sysroot_proc, NULL);
proc_ok = r != -1;
r = command (NULL, NULL, str_mount, "--bind", "/sys", sysroot_sys, NULL);
sys_ok = r != -1;
CHROOT_IN;
r = commandv (&out, &err, (const char * const *) argv);
CHROOT_OUT;
if (sys_ok) umount_ignore_fail (sysroot_sys);
if (proc_ok) umount_ignore_fail (sysroot_proc);
if (dev_pts_ok) umount_ignore_fail (sysroot_dev_pts);
if (dev_ok) umount_ignore_fail (sysroot_dev);
free_bind_state (&bind_state);
if (r == -1) {
reply_with_error ("%s", err);