From b8b1b0296b0af8d072f329828ecf004116bfc7d3 Mon Sep 17 00:00:00 2001
From: "Richard W.M. Jones" <rjones@redhat.com>
Date: Mon, 7 Oct 2013 19:53:54 +0100
Subject: [PATCH] daemon: Refactor bind-mount code.

This is just code motion.
---
 daemon/command.c | 112 +++++++++++++++++++++++++++++++++--------------
 1 file changed, 79 insertions(+), 33 deletions(-)

diff --git a/daemon/command.c b/daemon/command.c
index 99a58c199..b100b145c 100644
--- a/daemon/command.c
+++ b/daemon/command.c
@@ -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);