1// SPDX-License-Identifier: GPL-2.0
 2
 3//! Seq file bindings.
 4//!
 5//! C header: [`include/linux/seq_file.h`](srctree/include/linux/seq_file.h)
 6
 7use crate::{bindings, c_str, types::NotThreadSafe, types::Opaque};
 8
 9/// A utility for generating the contents of a seq file.
10#[repr(transparent)]
11pub struct SeqFile {
12    inner: Opaque<bindings::seq_file>,
13    _not_send: NotThreadSafe,
14}
15
16impl SeqFile {
17    /// Creates a new [`SeqFile`] from a raw pointer.
18    ///
19    /// # Safety
20    ///
21    /// The caller must ensure that for the duration of 'a the following is satisfied:
22    /// * The pointer points at a valid `struct seq_file`.
23    /// * The `struct seq_file` is not accessed from any other thread.
24    pub unsafe fn from_raw<'a>(ptr: *mut bindings::seq_file) -> &'a SeqFile {
25        // SAFETY: The caller ensures that the reference is valid for 'a. There's no way to trigger
26        // a data race by using the `&SeqFile` since this is the only thread accessing the seq_file.
27        //
28        // CAST: The layout of `struct seq_file` and `SeqFile` is compatible.
29        unsafe { &*ptr.cast() }
30    }
31
32    /// Used by the [`seq_print`] macro.
33    pub fn call_printf(&self, args: core::fmt::Arguments<'_>) {
34        // SAFETY: Passing a void pointer to `Arguments` is valid for `%pA`.
35        unsafe {
36            bindings::seq_printf(
37                self.inner.get(),
38                c_str!("%pA").as_char_ptr(),
39                &args as *const _ as *const crate::ffi::c_void,
40            );
41        }
42    }
43}
44
45/// Write to a [`SeqFile`] with the ordinary Rust formatting syntax.
46#[macro_export]
47macro_rules! seq_print {
48    ($m:expr, $($arg:tt)+) => (
49        $m.call_printf(format_args!($($arg)+))
50    );
51}
52pub use seq_print;