dotcloud/docker

package oci // import "github.com/docker/docker/oci"

import (
    "fmt"
    "os"
    "path/filepath"
    "strings"

    coci "github.com/containerd/containerd/oci"
    specs "github.com/opencontainers/runtime-spec/specs-go"
)

func deviceCgroup(d *specs.LinuxDevice, permissions string) specs.LinuxDeviceCgroup {
    return specs.LinuxDeviceCgroup{
        Allow:  true,
        Type:   d.Type,
        Major:  &d.Major,
        Minor:  &d.Minor,
        Access: permissions,
    }
}

// DevicesFromPath computes a list of devices and device permissions from paths (pathOnHost and pathInContainer) and cgroup permissions.
func DevicesFromPath(pathOnHost, pathInContainer, cgroupPermissions string) (devs []specs.LinuxDevice, devPermissions []specs.LinuxDeviceCgroup, err error) {
    resolvedPathOnHost := pathOnHost

    // check if it is a symbolic link
    if src, e := os.Lstat(pathOnHost); e == nil && src.Mode()&os.ModeSymlink == os.ModeSymlink {
        if linkedPathOnHost, e := filepath.EvalSymlinks(pathOnHost); e == nil {
            resolvedPathOnHost = linkedPathOnHost
        }
    }

    device, err := coci.DeviceFromPath(resolvedPathOnHost)
    // if there was no error, return the device
    if err == nil {
        device.Path = pathInContainer
        return append(devs, *device), append(devPermissions, deviceCgroup(device, cgroupPermissions)), nil
    }

    // if the device is not a device node
    // try to see if it's a directory holding many devices
    if err == coci.ErrNotADevice {
        // check if it is a directory
        if src, e := os.Stat(resolvedPathOnHost); e == nil && src.IsDir() {
            // mount the internal devices recursively
            // TODO check if additional errors should be handled or logged
            _ = filepath.WalkDir(resolvedPathOnHost, func(dpath string, f os.DirEntry, _ error) error {
                childDevice, e := coci.DeviceFromPath(dpath)
                if e != nil {
                    // ignore the device
                    return nil
                }

                // add the device to userSpecified devices
                childDevice.Path = strings.Replace(dpath, resolvedPathOnHost, pathInContainer, 1)
                devs = append(devs, *childDevice)
                devPermissions = append(devPermissions, deviceCgroup(childDevice, cgroupPermissions))

                return nil
            })
        }
    }

    if len(devs) > 0 {
        return devs, devPermissions, nil
    }

    return devs, devPermissions, fmt.Errorf("error gathering device information while adding custom device %q: %s", pathOnHost, err)
}