Use accurate build time only when publishing

.github/workflows/publish_aster_nixos.yml

@@ -98,6 +98,7 @@ jobs:
           image: asterinas/asterinas:0.17.0-20251228
           options: --privileged -v /dev:/dev -v ${{ github.workspace }}:/root/asterinas
           run: |
+            export ASTER_BUILD_TIMESTAMP=`date '+%a %b %e %H:%M:%S %Z %Y'`
             make iso RELEASE=1 AUTO_INSTALL=false ARCH=${{ matrix.arch }}
             iso_path=$(realpath ./target/nixos/iso_image/iso/*.iso)
             echo "iso_path=$iso_path"

Cargo.lock

@@ -191,6 +191,7 @@ dependencies = [
  "bitvec",
  "cfg-if",
  "component",
+ "const_format",
  "controlled",
  "core2",
  "cpio-decoder",
@@ -522,6 +523,26 @@ dependencies = [
  "toml",
 ]
 
+[[package]]
+name = "const_format"
+version = "0.2.35"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7faa7469a93a566e9ccc1c73fe783b4a65c274c5ace346038dca9c39fe0030ad"
+dependencies = [
+ "const_format_proc_macros",
+]
+
+[[package]]
+name = "const_format_proc_macros"
+version = "0.2.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1d57c2eccfb16dbac1f4e61e206105db5820c9d26c3c472bc17c774259ef7744"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-xid",
+]
+
 [[package]]
 name = "controlled"
 version = "0.1.0"
@@ -1926,6 +1947,12 @@ version = "1.0.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5a5f39404a5da50712a4c1eecf25e90dd62b613502b7e925fd4e4d19b5c96512"
 
+[[package]]
+name = "unicode-xid"
+version = "0.2.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ebc1c04c71510c7f702b52b7c350734c9ff1295c464a03335b00bb84fc54f853"
+
 [[package]]
 name = "universal-hash"
 version = "0.4.1"

Cargo.toml

@@ -150,6 +150,7 @@ volatile = "0.6.1"
 # a capability it currently lacks.
 aes-gcm = { version = "0.9.4", features = ["force-soft"] }
 bittle = "0.5.6"
+const_format = "0.2.35"
 ctr = "0.8.0"
 font8x8 = { version = "0.2.5", default-features = false, features = [ "unicode" ] }
 getset = "0.1.2"

kernel/Cargo.toml

@@ -29,6 +29,7 @@ bitflags.workspace = true
 bitvec.workspace = true
 cfg-if.workspace = true
 component.workspace = true
+const_format.workspace = true
 controlled.workspace = true
 core2.workspace = true
 cpio-decoder.workspace = true

kernel/src/net/uts_ns.rs

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: MPL-2.0
 
-use ostd::sync::RwMutexReadGuard;
+use ostd::{const_assert, sync::RwMutexReadGuard};
 use spin::Once;
 
 use crate::{
@@ -153,11 +153,29 @@ impl UtsName {
 
     /// The version name.
     pub const VERSION: &str = {
-        if let Some(version) = option_env!("OSDK_BUILD_TIMESTAMP") {
-            version
+        const BUILD_TIMESTAMP: &str = if let Some(timestamp) = option_env!("ASTER_BUILD_TIMESTAMP")
+        {
+            timestamp
         } else {
-            "unknown"
-        }
+            const UNIX_EPOCH: &str = "Thu Jan  1 00:00:00 UTC 1970";
+            UNIX_EPOCH
+        };
+
+        // The definition of Linux's UTS_VERSION can be found at:
+        // <https://elixir.bootlin.com/linux/v6.18/source/init/Makefile#L37>.
+        // Linux specifies that the total length of this string must not exceed 64 bytes.
+
+        // In Linux, the BUILD_VERSION represents the compilation count, which
+        // increments each time the kernel is built within the same source tree.
+        // We use a fixed value of '1' here to ensure build determinism.
+        // Reference: <https://elixir.bootlin.com/linux/v6.18/source/scripts/build-version>.
+        const BUILD_VERSION: usize = 1;
+        const SMP_FLAGS: &str = "SMP ";
+        const PREEMPT_FLAGS: &str = "";
+        const VERSION: &str =
+            const_format::formatcp!("#{BUILD_VERSION} {SMP_FLAGS}{PREEMPT_FLAGS}{BUILD_TIMESTAMP}");
+        const_assert!(VERSION.len() <= 64);
+        VERSION
     };
 
     /// The machine name.

osdk/src/commands/build/mod.rs

@@ -250,19 +250,7 @@ fn build_kernel_elf(
                 .unwrap_or_else(|_| "unknown".to_string())
         ),
     );
-    // Use system date command to get the formatted time string
-    let date_output = std::process::Command::new("date")
-        // Reference: <https://man7.org/linux/man-pages/man1/date.1.html>
-        .arg("+%a %b %e %H:%M:%S %Z %Y")
-        .output()
-        .ok()
-        .and_then(|output| {
-            String::from_utf8(output.stdout)
-                .ok()
-                .map(|s| s.trim().to_string())
-        })
-        .unwrap_or_else(|| "Thu Jan  1 00:00:00 UTC 1970".to_string());
-    command.env("OSDK_BUILD_TIMESTAMP", format!("#1 {}", date_output));
+
     command.env("RUSTFLAGS", rustflags.join(" "));
     command.arg("build");
     command.arg("--features").arg(features.join(" "));