// Package sysinfo stores information about which features a kernel supports.
package sysinfo // import "github.com/docker/docker/pkg/sysinfo"

import "github.com/docker/docker/pkg/parsers"

// Opt for New().
type Opt func(info *SysInfo)

// SysInfo stores information about which features a kernel supports.
// TODO Windows: Factor out platform specific capabilities.
type SysInfo struct {
	// Whether the kernel supports AppArmor or not
	AppArmor bool
	// Whether the kernel supports Seccomp or not
	Seccomp bool

	cgroupMemInfo
	cgroupCPUInfo
	cgroupBlkioInfo
	cgroupCpusetInfo
	cgroupPids

	// Whether the kernel supports cgroup namespaces or not
	CgroupNamespaces bool

	// Whether IPv4 forwarding is supported or not, if this was disabled, networking will not work
	IPv4ForwardingDisabled bool

	// Whether bridge-nf-call-iptables is supported or not
	BridgeNFCallIPTablesDisabled bool

	// Whether bridge-nf-call-ip6tables is supported or not
	BridgeNFCallIP6TablesDisabled bool

	// Whether the cgroup has the mountpoint of "devices" or not
	CgroupDevicesEnabled bool

	// Whether the cgroup is in unified mode (v2).
	CgroupUnified bool

	// Warnings contains a slice of warnings that occurred  while collecting
	// system information. These warnings are intended to be informational
	// messages for the user, and can either be logged or returned to the
	// client; they are not intended to be parsed / used for other purposes,
	// and do not have a fixed format.
	Warnings []string

	// cgMounts is the list of cgroup v1 mount paths, indexed by subsystem, to
	// inspect availability of subsystems.
	cgMounts map[string]string

	// cg2GroupPath is the cgroup v2 group path to inspect availability of the controllers.
	cg2GroupPath string

	// cg2Controllers is an index of available cgroup v2 controllers.
	cg2Controllers map[string]struct{}
}

type cgroupMemInfo struct {
	// Whether memory limit is supported or not
	MemoryLimit bool

	// Whether swap limit is supported or not
	SwapLimit bool

	// Whether soft limit is supported or not
	MemoryReservation bool

	// Whether OOM killer disable is supported or not
	OomKillDisable bool

	// Whether memory swappiness is supported or not
	MemorySwappiness bool

	// Whether kernel memory limit is supported or not. This option is used to
	// detect support for kernel-memory limits on API < v1.42. Kernel memory
	// limit (`kmem.limit_in_bytes`) is not supported on cgroups v2, and has been
	// removed in kernel 5.4.
	KernelMemory bool

	// Whether kernel memory TCP limit is supported or not. Kernel memory TCP
	// limit (`memory.kmem.tcp.limit_in_bytes`) is not supported on cgroups v2.
	KernelMemoryTCP bool
}

type cgroupCPUInfo struct {
	// Whether CPU shares is supported or not
	CPUShares bool

	// Whether CPU CFS (Completely Fair Scheduler) is supported
	CPUCfs bool

	// Whether CPU real-time scheduler is supported
	CPURealtime bool
}

type cgroupBlkioInfo struct {
	// Whether Block IO weight is supported or not
	BlkioWeight bool

	// Whether Block IO weight_device is supported or not
	BlkioWeightDevice bool

	// Whether Block IO read limit in bytes per second is supported or not
	BlkioReadBpsDevice bool

	// Whether Block IO write limit in bytes per second is supported or not
	BlkioWriteBpsDevice bool

	// Whether Block IO read limit in IO per second is supported or not
	BlkioReadIOpsDevice bool

	// Whether Block IO write limit in IO per second is supported or not
	BlkioWriteIOpsDevice bool
}

type cgroupCpusetInfo struct {
	// Whether Cpuset is supported or not
	Cpuset bool

	// Available Cpuset's cpus
	Cpus string

	// Available Cpuset's memory nodes
	Mems string
}

type cgroupPids struct {
	// Whether Pids Limit is supported or not
	PidsLimit bool
}

// IsCpusetCpusAvailable returns `true` if the provided string set is contained
// in cgroup's cpuset.cpus set, `false` otherwise.
// If error is not nil a parsing error occurred.
func (c cgroupCpusetInfo) IsCpusetCpusAvailable(provided string) (bool, error) {
	return isCpusetListAvailable(provided, c.Cpus)
}

// IsCpusetMemsAvailable returns `true` if the provided string set is contained
// in cgroup's cpuset.mems set, `false` otherwise.
// If error is not nil a parsing error occurred.
func (c cgroupCpusetInfo) IsCpusetMemsAvailable(provided string) (bool, error) {
	return isCpusetListAvailable(provided, c.Mems)
}

func isCpusetListAvailable(provided, available string) (bool, error) {
	parsedAvailable, err := parsers.ParseUintList(available)
	if err != nil {
		return false, err
	}
	// 8192 is the normal maximum number of CPUs in Linux, so accept numbers up to this
	// or more if we actually have more CPUs.
	max := 8192
	for m := range parsedAvailable {
		if m > max {
			max = m
		}
	}
	parsedProvided, err := parsers.ParseUintListMaximum(provided, max)
	if err != nil {
		return false, err
	}
	for k := range parsedProvided {
		if !parsedAvailable[k] {
			return false, nil
		}
	}
	return true, nil
}