Add shared subtree support, suggested by Vladimir Dronnikov. Also break out a

few new (unfinished) config options, which I intend to make hidden (but
enabled) when CONFIG_NITPICK is disabled.  Getting the .config infrastructure
to do that is non-obvious, it seems...

1 files changed, 57 insertions, 50 deletions

diff --git a/util-linux/mount.c b/util-linux/mount.c
index d5d3eae17..5d5f487c2 100644
--- a/util-linux/mount.c
+++ b/util-linux/mount.c
@@ -25,17 +25,6 @@
 #include "busybox.h"
 #include <mntent.h>
 
-// These two aren't always defined in old headers
-#ifndef MS_BIND
-#define MS_BIND         4096
-#endif
-#ifndef MS_MOVE
-#define MS_MOVE         8192
-#endif
-#ifndef MS_SILENT
-#define MS_SILENT       32768
-#endif
-
 // Not real flags, but we want to be able to check for this.
 #define MOUNT_NOAUTO    (1<<29)
 #define MOUNT_SWAP      (1<<30)
@@ -43,40 +32,59 @@
  * flags */
 
 struct {
-        const char *name;
+        char *name;
         long flags;
-} static const mount_options[] = {
-        // NOP flags.
-
-        {"loop", 0},
-        {"defaults", 0},
-        {"quiet", 0},
-
-        // vfs flags
-
-        {"ro", MS_RDONLY},
-        {"rw", ~MS_RDONLY},
-        {"nosuid", MS_NOSUID},
-        {"suid", ~MS_NOSUID},
-        {"dev", ~MS_NODEV},
-        {"nodev", MS_NODEV},
-        {"exec", ~MS_NOEXEC},
-        {"noexec", MS_NOEXEC},
-        {"sync", MS_SYNCHRONOUS},
-        {"async", ~MS_SYNCHRONOUS},
-        {"atime", ~MS_NOATIME},
-        {"noatime", MS_NOATIME},
-        {"diratime", ~MS_NODIRATIME},
-        {"nodiratime", MS_NODIRATIME},
-        {"loud", ~MS_SILENT},
-
-        // action flags
-
-        {"remount", MS_REMOUNT},
-        {"bind", MS_BIND},
-        {"move", MS_MOVE},
-        {"noauto",MOUNT_NOAUTO},
-        {"swap",MOUNT_SWAP}
+} static mount_options[] = {
+        // MS_FLAGS set a bit.  ~MS_FLAGS disable that bit.  0 flags are NOPs.
+
+        USE_FEATURE_MOUNT_LOOP(
+                {"loop", 0},
+        )
+
+        USE_FEATURE_MOUNT_FSTAB(
+                {"defaults", 0},
+                {"quiet", 0},
+                {"noauto",MOUNT_NOAUTO},
+                {"swap",MOUNT_SWAP},
+        )
+
+        USE_FEATURE_MOUNT_FLAGS(
+                // vfs flags
+                {"nosuid", MS_NOSUID},
+                {"suid", ~MS_NOSUID},
+                {"dev", ~MS_NODEV},
+                {"nodev", MS_NODEV},
+                {"exec", ~MS_NOEXEC},
+                {"noexec", MS_NOEXEC},
+                {"sync", MS_SYNCHRONOUS},
+                {"async", ~MS_SYNCHRONOUS},
+                {"atime", ~MS_NOATIME},
+                {"noatime", MS_NOATIME},
+                {"diratime", ~MS_NODIRATIME},
+                {"nodiratime", MS_NODIRATIME},
+                {"loud", ~MS_SILENT},
+
+                // action flags
+
+                {"bind", MS_BIND},
+                {"move", MS_MOVE},
+                {"shared", MS_SHARED},
+                {"slave", MS_SLAVE},
+                {"private", MS_PRIVATE},
+                {"unbindable", MS_UNBINDABLE},
+                {"rshared", MS_SHARED|MS_RECURSIVE},
+                {"rslave", MS_SLAVE|MS_RECURSIVE},
+                {"rprivate", MS_SLAVE|MS_RECURSIVE},
+                {"runbindable", MS_UNBINDABLE|MS_RECURSIVE},
+        )
+
+        // Always understood.
+
+        {"ro", MS_RDONLY},        // vfs flag
+        {"rw", ~MS_RDONLY},       // vfs flag
+        {"remount", MS_REMOUNT},  // action flag
+
+
 };
 
 /* Append mount options to string */
@@ -225,9 +233,8 @@ static int mount_it_now(struct mntent *mp, int vfsflags, char *filteropts)
 
                 for(i=0; mount_options[i].flags != MS_REMOUNT; i++)
                         if (mount_options[i].flags > 0)
-                                append_mount_options(&(mp->mnt_opts),
-// Shut up about the darn const.  It's not important.  I don't care.
-                                                (char *)mount_options[i].name);
+// Shut up about the darn const.  It's not important.  I don't care.  (char *)
+                                append_mount_options(&(mp->mnt_opts), mount_options[i].name);
 
                 // Remove trailing / (if any) from directory we mounted on
 
@@ -285,8 +292,8 @@ static int singlemount(struct mntent *mp, int ignore_busy)
         // Look at the file.  (Not found isn't a failure for remount, or for
         // a synthetic filesystem like proc or sysfs.)
 
-        if (stat(mp->mnt_fsname, &st));
-        else if (!(vfsflags & (MS_REMOUNT | MS_BIND | MS_MOVE))) {
+        if (!lstat(mp->mnt_fsname, &st) && !(vfsflags & (MS_REMOUNT | MS_BIND | MS_MOVE | MS_SHARED | MS_PRIVATE || MS_SLAVE | MS_UNBINDABLE)))
+        {
                 // Do we need to allocate a loopback device for it?
 
                 if (ENABLE_FEATURE_MOUNT_LOOP && S_ISREG(st.st_mode)) {
@@ -456,7 +463,7 @@ int mount_main(int argc, char **argv)
         // Open either fstab or mtab
 
         if (parse_mount_options(cmdopts,0) & MS_REMOUNT)
-                fstabname = (char *)bb_path_mtab_file;  // Again with the evil const.
+                fstabname = bb_path_mtab_file;  // Again with the evil const (char *).
         else fstabname="/etc/fstab";
 
         if (!(fstab=setmntent(fstabname,"r")))