feat: ✨ implement serde for KernelVersion

Author: dergecko

procfs-core/Cargo.toml

@@ -14,14 +14,20 @@ rust-version.workspace = true
 
 [features]
 default = ["chrono"]
-serde1 = ["serde", "bitflags/serde"]
+serde1 = ["serde", "bitflags/serde", "serde_with"]
 
 [dependencies]
 backtrace = { version = "0.3", optional = true }
 bitflags = { version = "2" }
-chrono = { version = "0.4.20", optional = true, features = ["clock"], default-features = false }
+chrono = { version = "0.4.20", optional = true, features = [
+    "clock",
+], default-features = false }
 hex = "0.4"
 serde = { version = "1.0", features = ["derive"], optional = true }
+serde_with = { version = "3.11", optional = true }
+
+[dev-dependencies]
+serde_json = { version = "1.0" }
 
 [package.metadata.docs.rs]
 all-features = true

procfs-core/src/lib.rs

@@ -278,7 +278,6 @@ pub struct ExplicitSystemInfo {
     pub ticks_per_second: u64,
     pub page_size: u64,
     pub is_little_endian: bool,
-    #[cfg_attr(feature = "serde1", serde(skip))]
     pub kernel_version: KernelVersion,
 }
 

procfs-core/src/sys/kernel/mod.rs

@@ -3,20 +3,20 @@
 //! The files in this directory can be used to tune and monitor miscellaneous
 //! and general things in the operation of the Linux kernel.
 
-use std::cmp;
 use std::collections::HashSet;
 use std::str::FromStr;
+use std::{cmp, fmt::Display};
 
 #[cfg(feature = "serde1")]
-use serde::{Deserialize, Serialize};
+use serde_with::{DeserializeFromStr, SerializeDisplay};
 
 use bitflags::bitflags;
 
 use crate::{ProcError, ProcResult};
 
 /// Represents a kernel version, in major.minor.release version.
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Hash, Default)]
-#[cfg_attr(feature = "serde1", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "serde1", derive(SerializeDisplay, DeserializeFromStr))]
 pub struct Version {
     pub major: u8,
     pub minor: u8,
@@ -103,6 +103,12 @@ impl cmp::PartialOrd for Version {
     }
 }
 
+impl Display for Version {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}.{}.{}", self.major, self.minor, self.patch)
+    }
+}
+
 /// Represents a kernel type
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub struct Type {
@@ -429,4 +435,33 @@ mod tests {
         let a = SemaphoreLimits::from_str("1 string 500 3200");
         assert!(a.is_err() && a.err().unwrap() == "Failed to parse SEMMNS");
     }
+
+    #[cfg(feature = "serde1")]
+    mod serde_kernel_version {
+        #[test]
+        fn should_serialize_kernel_version() {
+            let version = Version {
+                major: 42,
+                minor: 0,
+                patch: 1,
+            };
+            let version = serde_json::to_string(&version).unwrap();
+
+            // NOTE: The double quote is necessary because of the JSON format.
+            assert_eq!(r#""42.0.1""#, &version);
+        }
+
+        #[test]
+        fn should_deserialize_kernel_version() {
+            let expected = Version {
+                major: 21,
+                minor: 0,
+                patch: 2,
+            };
+            // NOTE: The double quote is necessary because of the JSON format.
+            let version: Version = serde_json::from_str(r#""21.0.2""#).unwrap();
+
+            assert_eq!(version, expected);
+        }
+    }
 }