btrfsutil 0.2.0

Safe wrappers for libbtrfsutil.
Documentation 
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//! Btrfs quota groups

use crate::Result;

use btrfsutil_sys::btrfs_util_create_qgroup_inherit;
use btrfsutil_sys::btrfs_util_destroy_qgroup_inherit;
use btrfsutil_sys::btrfs_util_qgroup_inherit;
use btrfsutil_sys::btrfs_util_qgroup_inherit_add_group;
use btrfsutil_sys::btrfs_util_qgroup_inherit_get_groups;

use libc::c_void;
use libc::free;

/// Qgroup inheritance specifier.
///
/// Wrapper around [btrfs_util_qgroup_inherit].
///
/// [btrfs_util_qgroup_inherit]: ../bindings/struct.btrfs_util_qgroup_inherit.html
#[derive(Clone, Debug)]
pub struct QgroupInherit(*mut btrfs_util_qgroup_inherit);

impl QgroupInherit {
    /// Create a quota group inheritance specifier.
    pub fn create() -> Result<Self> {
        let mut qgroup_ptr: *mut btrfs_util_qgroup_inherit = std::ptr::null_mut();

        unsafe_wrapper!({ btrfs_util_create_qgroup_inherit(0, &mut qgroup_ptr) })?;

        Ok(Self(qgroup_ptr))
    }

    /// Add inheritance from a qgroup to a qgroup inheritance specifier.
    pub fn add<U>(&mut self, qgroup_id: U) -> Result<()>
    where
        U: Into<u64>,
    {
        self.add_impl(qgroup_id.into())
    }

    fn add_impl(&mut self, qgroup_id: u64) -> Result<()> {
        let qgroup_ptr_initial: *mut btrfs_util_qgroup_inherit = self.as_ptr();
        let mut qgroup_ptr: *mut btrfs_util_qgroup_inherit = self.as_ptr();

        unsafe_wrapper!({ btrfs_util_qgroup_inherit_add_group(&mut qgroup_ptr, qgroup_id) })?;

        if qgroup_ptr != qgroup_ptr_initial {
            self.0 = qgroup_ptr;
        }

        Ok(())
    }

    /// Get the qgroup ids contained by this inheritance specifier.
    pub fn get_groups(&self) -> Result<Vec<u64>> {
        let qgroup_ptr: *const btrfs_util_qgroup_inherit = self.as_ptr();
        let mut qgroup_ids_ptr: *const u64 = std::ptr::null();
        let mut qgroup_ids_count: usize = 0;

        unsafe {
            btrfs_util_qgroup_inherit_get_groups(
                qgroup_ptr,
                &mut qgroup_ids_ptr,
                &mut qgroup_ids_count,
            );
        }

        if qgroup_ids_count == 0 {
            return Ok(Vec::new());
        }

        let ids: Vec<u64> = {
            let slice = unsafe { std::slice::from_raw_parts(qgroup_ids_ptr, qgroup_ids_count) };
            let vec = slice.to_vec();
            unsafe { free(qgroup_ids_ptr as *mut c_void) };
            vec
        };
        Ok(ids)
    }

    #[inline]
    pub(crate) fn as_ptr(&self) -> *mut btrfs_util_qgroup_inherit {
        self.0
    }
}

impl Drop for QgroupInherit {
    fn drop(&mut self) {
        unsafe {
            btrfs_util_destroy_qgroup_inherit(self.0);
        }
    }
}