WIP: json-sysctl

Depends on a byteorder crate locally patched to make std not a default
feature, see #121 for why.

Author: geofft

tests/json-sysctl/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "json-sysctl"
+version = "0.1.0"
+authors = ["Alex Gaynor <alex.gaynor@gmail.com", "Geoffrey Thomas <geofft@ldpreload.com>"]
+edition = "2018"
+
+[lib]
+crate-type = ["staticlib"]
+
+[dependencies]
+linux-kernel-module = { path = "../.." }
+serde = { version = "*", default-features = false , features = ["derive"] }
+serde-json-core = { git = "https://github.com/japaric/serde-json-core" }
+typenum = "*"
+
+[patch.crates-io]
+byteorder = { path = "/root/byteorder" }

tests/json-sysctl/src/lib.rs

@@ -0,0 +1,67 @@
+#![no_std]
+#![feature(const_str_as_bytes)]
+
+use core::sync::atomic::{AtomicBool, Ordering};
+
+use serde::Serialize;
+use serde_json_core;
+
+use linux_kernel_module::sysctl::Sysctl;
+use linux_kernel_module::Mode;
+use linux_kernel_module::println;
+
+struct JsonSysctlModule {
+    a: Sysctl<AtomicBool>,
+    b: Sysctl<AtomicBool>,
+    c: Sysctl<AtomicBool>,
+}
+
+#[derive(Serialize)]
+struct Output {
+    a: bool,
+    b: bool,
+    c: bool,
+}
+
+impl linux_kernel_module::KernelModule for JsonSysctlModule {
+    fn init() -> linux_kernel_module::KernelResult<Self> {
+        Ok(JsonSysctlModule {
+            a: Sysctl::register(
+                "json-sysctl\x00",
+                "a\x00",
+                AtomicBool::new(false),
+                Mode::from_int(0o666),
+            )?,
+            b: Sysctl::register(
+                "json-sysctl\x00",
+                "b\x00",
+                AtomicBool::new(false),
+                Mode::from_int(0o666),
+            )?,
+            c: Sysctl::register(
+                "json-sysctl\x00",
+                "c\x00",
+                AtomicBool::new(false),
+                Mode::from_int(0o666),
+            )?,
+        })
+    }
+}
+
+impl Drop for JsonSysctlModule {
+    fn drop(&mut self) {
+        let o = Output {
+            a: self.a.get().load(Ordering::Relaxed),
+            b: self.b.get().load(Ordering::Relaxed),
+            c: self.c.get().load(Ordering::Relaxed),
+        };
+        println!("{}", serde_json_core::to_string::<typenum::U32, _>(&o).unwrap());
+    }
+}
+
+linux_kernel_module::kernel_module!(
+    JsonSysctlModule,
+    author: "Alex Gaynor and Geoffrey Thomas",
+    description: "Use JSON serialization in kernelspace",
+    license: "GPL"
+);