//! Process execution domains

use crate::errno::Errno;

use crate::Result;

use libc::{self, c_int, c_ulong};

libc_bitflags! {

    /// Flags used and returned by [`get()`](fn.get.html) and

    /// [`set()`](fn.set.html).

    pub struct Persona: c_int {

        /// Provide the legacy virtual address space layout.

        ADDR_COMPAT_LAYOUT;

        /// Disable address-space-layout randomization.

        ADDR_NO_RANDOMIZE;

        /// Limit the address space to 32 bits.

        ADDR_LIMIT_32BIT;

        /// Use `0xc0000000` as the offset at which to search a virtual memory

        /// chunk on [`mmap(2)`], otherwise use `0xffffe000`.

        ///

        /// [`mmap(2)`]: https://man7.org/linux/man-pages/man2/mmap.2.html

        ADDR_LIMIT_3GB;

        /// User-space function pointers to signal handlers point to descriptors.

        #[cfg(not(any(target_env = "musl", target_env = "uclibc")))]

        #[cfg_attr(docsrs, doc(cfg(all())))]

        FDPIC_FUNCPTRS;

        /// Map page 0 as read-only.

        MMAP_PAGE_ZERO;

        /// `PROT_READ` implies `PROT_EXEC` for [`mmap(2)`].

        ///

        /// [`mmap(2)`]: https://man7.org/linux/man-pages/man2/mmap.2.html

        READ_IMPLIES_EXEC;

        /// No effects.

        SHORT_INODE;

        /// [`select(2)`], [`pselect(2)`], and [`ppoll(2)`] do not modify the

        /// returned timeout argument when interrupted by a signal handler.

        ///

        /// [`select(2)`]: https://man7.org/linux/man-pages/man2/select.2.html

        /// [`pselect(2)`]: https://man7.org/linux/man-pages/man2/pselect.2.html

        /// [`ppoll(2)`]: https://man7.org/linux/man-pages/man2/ppoll.2.html

        STICKY_TIMEOUTS;

        /// Have [`uname(2)`] report a 2.6.40+ version number rather than a 3.x

        /// version number.

        ///

        /// [`uname(2)`]: https://man7.org/linux/man-pages/man2/uname.2.html

        #[cfg(not(any(target_env = "musl", target_env = "uclibc")))]

        #[cfg_attr(docsrs, doc(cfg(all())))]

        UNAME26;

        /// No effects.

        WHOLE_SECONDS;

    }

}

/// Retrieve the current process personality.

///

/// Returns a Result containing a Persona instance.

///

/// Example:

///

/// ```

/// # use nix::sys::personality::{self, Persona};

/// let pers = personality::get().unwrap();

/// assert!(!pers.contains(Persona::WHOLE_SECONDS));

/// ```

pub fn get() -> Result<Persona> {

    let res = unsafe { libc::personality(0xFFFFFFFF) };

    Errno::result(res).map(Persona::from_bits_truncate)

}

/// Set the current process personality.

///

/// Returns a Result containing the *previous* personality for the

/// process, as a Persona.

///

/// For more information, see [personality(2)](https://man7.org/linux/man-pages/man2/personality.2.html)

///

/// **NOTE**: This call **replaces** the current personality entirely.

/// To **update** the personality, first call `get()` and then `set()`

/// with the modified persona.

///

/// Example:

///

/// ```

/// # use nix::sys::personality::{self, Persona};

/// let mut pers = personality::get().unwrap();

/// assert!(!pers.contains(Persona::ADDR_NO_RANDOMIZE));

/// personality::set(pers | Persona::ADDR_NO_RANDOMIZE).unwrap();

/// ```

pub fn set(persona: Persona) -> Result<Persona> {

    let res = unsafe { libc::personality(persona.bits() as c_ulong) };

    Errno::result(res).map(Persona::from_bits_truncate)

}