Refs #55 -- added API for allocating character device numbers (#59)

Author: alex

build.rs

@@ -19,6 +19,8 @@ const INCLUDED_FUNCTIONS: &[&str] = &[
     "access_ok",
     "_copy_to_user",
     "_copy_from_user",
+    "alloc_chrdev_region",
+    "unregister_chrdev_region",
 ];
 const INCLUDED_VARS: &[&str] = &[
     "EINVAL",

src/chrdev.rs

@@ -0,0 +1,44 @@
+use core::ops::Range;
+
+use bindings;
+use c_types;
+use error;
+
+pub struct DeviceNumberRegion {
+    dev: bindings::dev_t,
+    count: usize,
+}
+
+impl DeviceNumberRegion {
+    pub fn allocate(
+        minors: Range<usize>,
+        name: &'static str,
+    ) -> error::KernelResult<DeviceNumberRegion> {
+        if !name.ends_with('\x00') {
+            return Err(error::Error::EINVAL);
+        }
+
+        let count = minors.end - minors.start;
+        let mut dev: bindings::dev_t = 0;
+        let res = unsafe {
+            bindings::alloc_chrdev_region(
+                &mut dev,
+                minors.start as bindings::dev_t,
+                count as bindings::dev_t,
+                name.as_ptr() as *const c_types::c_char,
+            )
+        };
+        if res != 0 {
+            return Err(error::Error::from_kernel_errno(res));
+        }
+        return Ok(DeviceNumberRegion { dev, count });
+    }
+}
+
+impl Drop for DeviceNumberRegion {
+    fn drop(&mut self) {
+        unsafe {
+            bindings::unregister_chrdev_region(self.dev, self.count as bindings::dev_t);
+        }
+    }
+}

src/lib.rs

@@ -11,6 +11,7 @@ use core::panic::PanicInfo;
 mod allocator;
 pub mod bindings;
 mod c_types;
+pub mod chrdev;
 mod error;
 pub mod filesystem;
 #[macro_use]

tests/chrdev/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "chrdev-tests"
+version = "0.1.0"
+authors = ["Alex Gaynor <alex.gaynor@gmail.com>", "Geoffrey Thomas <geofft@ldpreload.com>"]
+
+[lib]
+crate-type = ["staticlib"]
+
+[dependencies]
+linux-kernel-module = { path = "../.." }

tests/chrdev/src/lib.rs

@@ -0,0 +1,27 @@
+#![no_std]
+#![feature(const_str_as_bytes)]
+
+#[macro_use]
+extern crate linux_kernel_module;
+
+struct ChrdevTestModule {
+    _dev: linux_kernel_module::chrdev::DeviceNumberRegion,
+}
+
+impl linux_kernel_module::KernelModule for ChrdevTestModule {
+    fn init() -> linux_kernel_module::KernelResult<Self> {
+        Ok(ChrdevTestModule {
+            _dev: linux_kernel_module::chrdev::DeviceNumberRegion::allocate(
+                0..1,
+                "chrdev-tests\x00",
+            )?,
+        })
+    }
+}
+
+kernel_module!(
+    ChrdevTestModule,
+    author: "Alex Gaynor and Geoffrey Thomas",
+    description: "A module for testing character devices",
+    license: "GPL"
+);

tests/chrdev/tests.rs

@@ -0,0 +1,27 @@
+extern crate kernel_module_tests;
+
+use kernel_module_tests::with_kernel_module;
+use std::fs;
+
+#[test]
+fn test_proc_devices() {
+    with_kernel_module(|| {
+        let devices = fs::read_to_string("/proc/devices").unwrap();
+        let dev_no_line = devices
+            .lines()
+            .find(|l| l.ends_with("chrdev-tests"))
+            .unwrap();
+        let elements = dev_no_line.rsplitn(2, " ").collect::<Vec<_>>();
+        assert_eq!(elements.len(), 2);
+        assert_eq!(elements[0], "chrdev-tests");
+        assert!(elements[1].trim().parse::<u32>().is_ok());
+    });
+
+    let devices = fs::read_to_string("/proc/devices").unwrap();
+    assert!(
+        devices
+            .lines()
+            .find(|l| l.ends_with("chrdev-tests"))
+            .is_none()
+    );
+}