dotcloud/docker

package seccomp

import (
    "fmt"
    "sync"

    "golang.org/x/sys/unix"
)

var (
    currentKernelVersion *KernelVersion
    kernelVersionError   error
    once                 sync.Once
)

// getKernelVersion gets the current kernel version.
func getKernelVersion() (*KernelVersion, error) {
    once.Do(func() {
        var uts unix.Utsname
        if err := unix.Uname(&uts); err != nil {
            return
        }
        // Remove the \x00 from the release for Atoi to parse correctly
        currentKernelVersion, kernelVersionError = parseRelease(unix.ByteSliceToString(uts.Release[:]))
    })
    return currentKernelVersion, kernelVersionError
}

// parseRelease parses a string and creates a KernelVersion based on it.
func parseRelease(release string) (*KernelVersion, error) {
    version := KernelVersion{}

    // We're only make sure we get the "kernel" and "major revision". Sometimes we have
    // 3.12.25-gentoo, but sometimes we just have 3.12-1-amd64.
    _, err := fmt.Sscanf(release, "%d.%d", &version.Kernel, &version.Major)
    if err != nil {
        return nil, fmt.Errorf("failed to parse kernel version %q: %w", release, err)
    }
    return &version, nil
}

// kernelGreaterEqualThan checks if the host's kernel version is greater than, or
// equal to the given kernel version v. Only "kernel version" and "major revision"
// can be specified (e.g., "3.12") and will be taken into account, which means
// that 3.12.25-gentoo and 3.12-1-amd64 are considered equal (kernel: 3, major: 12).
func kernelGreaterEqualThan(minVersion KernelVersion) (bool, error) {
    kv, err := getKernelVersion()
    if err != nil {
        return false, err
    }
    if kv.Kernel > minVersion.Kernel {
        return true, nil
    }
    if kv.Kernel == minVersion.Kernel && kv.Major >= minVersion.Major {
        return true, nil
    }
    return false, nil
}