some quotactl preparation

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

src/main.rs

@@ -15,6 +15,7 @@ pub mod pidfd;
 pub mod seccomp;
 pub mod socket;
 pub mod sys_mknod;
+pub mod sys_quotactl;
 pub mod syscall;
 pub mod tools;
 

src/sys_quotactl.rs

@@ -0,0 +1,47 @@
+use failure::Error;
+use nix::errno::Errno;
+
+use crate::lxcseccomp::ProxyMessageBuffer;
+use crate::syscall::SyscallStatus;
+
+/*
+ * int quotactl(int cmd, const char *special, int id, caddr_t addr);
+ *
+ * `special` is a path to the mount point, so we need to be in the process' file system view
+ * `addr` will point to a datastructure, so we should read a reasonable amount (a 4k page?) of
+ *  memory from there, but only if the sub command type makes use of it.
+ *
+ *  Actually the libc crate contains most of the structures anyway!
+ *
+ * Cmd:
+ *  QCMD(SubCmd, Type)
+ *      Type: USRQUOTA | GRPQUOTA | PRJQUOTA (but we don't need to care)
+ * SubCmd:
+ *  |          name           addr meaning|
+ *        Q_QUOTAON     path to quota file
+ *       Q_QUOTAOFF                ignored
+ *       Q_GETQUOTA        struct dqblk {}       a page should be sufficient
+ *   Q_GETNEXTQUOTA    struct nextdqblk {}       a page should be sufficient
+ *       Q_SETQUOTA        struct dqblk {}       a page should be sufficient
+ *       Q_SETQUOTA        struct dqblk {}       a page should be sufficient
+ *        Q_SETQLIM                              -EOPNOTSUPP: not documented anymore
+ *         Q_SETUSE                              -EOPNOTSUPP: not documented anymore
+ *        Q_GETINFO       struct dqinfo {}
+ *        Q_SETINFO       struct dqinfo {}
+ *         Q_GETFMT                [u8; 4]
+ *           Q_SYNC                ignored       -EOPNOTSUPP if `special` is NULL!
+ *       Q_GETSTATS      struct dqstats {}       -EOPNOTSUPP: obsolete, removed since 2.4.22!
+ *
+ * xfs stuff:
+ *       Q_XQUOTAON           unsigned int
+ *      Q_XQUOTAOFF           unsigned int
+ *      ...
+ *      (we don't actually have xfs containers atm...)
+ */
+pub async fn quotactl(msg: &ProxyMessageBuffer) -> Result<SyscallStatus, Error> {
+    let _cmd = msg.arg_int(0)?;
+    let _special = msg.arg_opt_c_string(1)?;
+    let _id = msg.arg_int(2)?;
+    let _addr = msg.arg_caddr_t(3)?;
+    Ok(Errno::ENOSYS.into())
+}