From e69aea92564da0e608a21871f0c2138cf64d8b39 Mon Sep 17 00:00:00 2001
From: Alexander Potapenko <glider@google.com>
Date: Wed, 29 Sep 2021 12:14:35 +0000
Subject: [PATCH] init: introduce ro.kernel.version property

This property will hold the major.minor part of the kernel version (e.g. "5.4"), allowing init scripts to act depending on that version, enabling and disabling certain features.

Bug: 194156700
Test: manual on a Pixel device
Signed-off-by: Alexander Potapenko <glider@google.com>
Merged-In: Icec640b8a7150b344d9aa3bc0bdbcdae050c7c45
Change-Id: I5af411e39da600e5e0f6703f3a2a4930d509e29d
---
 init/init.cpp | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/init/init.cpp b/init/init.cpp
index a7325cad9..942feb939 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -27,6 +27,7 @@
 #include <sys/mount.h>
 #include <sys/signalfd.h>
 #include <sys/types.h>
+#include <sys/utsname.h>
 #include <unistd.h>
 
 #define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
@@ -554,6 +555,19 @@ static void SetUsbController() {
     }
 }
 
+/// Set ro.kernel.version property to contain the major.minor pair as returned
+/// by uname(2).
+static void SetKernelVersion() {
+    struct utsname uts;
+    unsigned int major, minor;
+
+    if ((uname(&uts) != 0) || (sscanf(uts.release, "%u.%u", &major, &minor) != 2)) {
+        LOG(ERROR) << "Could not parse the kernel version from uname";
+        return;
+    }
+    SetProperty("ro.kernel.version", android::base::StringPrintf("%u.%u", major, minor));
+}
+
 static void HandleSigtermSignal(const signalfd_siginfo& siginfo) {
     if (siginfo.ssi_pid != 0) {
         // Drop any userspace SIGTERM requests.
@@ -824,6 +838,7 @@ int SecondStageMain(int argc, char** argv) {
     export_oem_lock_status();
     MountHandler mount_handler(&epoll);
     SetUsbController();
+    SetKernelVersion();
 
     const BuiltinFunctionMap& function_map = GetBuiltinFunctionMap();
     Action::set_function_map(&function_map);