question: idiomatic/safe method to detect nanos & klibs at runtime

[rinor]

1. what would be an alternate idiomatic/safe method for an app (process) to detect at runtime if it's running on nanos, without making use of the environment variable(s) injected by ops/manually? - not a feature request and not important

2. what would be an alternate idiomatic/safe method for an app (process) to detect at runtime the enabled klibs with the respective features, without making use of the environment variable(s) injected by ops/manually? - not a feature request and not important

[francescolavra]

1. A process can detect whether it's running on Nanos via the uname() syscall; more specifically, the sysname field of struct utsname will contain the string "Nanos". Example:

$ ops run /bin/uname -a "-s"
running local instance
booting /home/francesco/.ops/images/uname ...
en1: assigned 10.0.2.15
Nanos

2. Currenly the kernel does not expose information about enabled klibs to the process

[rinor]

thank you

[rinor]

running local instance
...
en1: assigned 10.0.2.15
Nanos version: "Nanos 5.0-0.1.45 888809a7a8f0003b66a8ec2af2f5e8dd749866d0 x86_64"

• sample code - go

package main

import (
	"fmt"
	"syscall"
)

func main() {
	fmt.Printf("Nanos version: %q\n", Version())
}

func Version() string {
	var uts syscall.Utsname
	if err := syscall.Uname(&uts); err != nil {
		return ""
	}

	sysname := int8ToString(uts.Sysname[:])
	release := int8ToString(uts.Release[:])
	version := int8ToString(uts.Version[:])
	machine := int8ToString(uts.Machine[:])

	return sysname + " " + release + " " + version + " " + machine
}

func int8ToString(s []int8) string {
	b := make([]byte, 0, len(s))
	for _, v := range s {
		if v == 0x00 {
			break
		}
		b = append(b, byte(v))
	}
	return string(b)
}