source: code/trunk/vendor/github.com/prometheus/procfs/kernel_random.go@ 823

// Copyright 2020 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//go:build !windows
// +build !windows

package procfs

import (
        "os"

        "github.com/prometheus/procfs/internal/util"
)

// KernelRandom contains information about to the kernel's random number generator.
type KernelRandom struct {
        // EntropyAvaliable gives the available entropy, in bits.
        EntropyAvaliable *uint64
        // PoolSize gives the size of the entropy pool, in bits.
        PoolSize *uint64
        // URandomMinReseedSeconds is the number of seconds after which the DRNG will be reseeded.
        URandomMinReseedSeconds *uint64
        // WriteWakeupThreshold the number of bits of entropy below which we wake up processes
        // that do a select(2) or poll(2) for write access to /dev/random.
        WriteWakeupThreshold *uint64
        // ReadWakeupThreshold is the number of bits of entropy required for waking up processes that sleep
        // waiting for entropy from /dev/random.
        ReadWakeupThreshold *uint64
}

// KernelRandom returns values from /proc/sys/kernel/random.
func (fs FS) KernelRandom() (KernelRandom, error) {
        random := KernelRandom{}

        for file, p := range map[string]**uint64{
                "entropy_avail":           &random.EntropyAvaliable,
                "poolsize":                &random.PoolSize,
                "urandom_min_reseed_secs": &random.URandomMinReseedSeconds,
                "write_wakeup_threshold":  &random.WriteWakeupThreshold,
                "read_wakeup_threshold":   &random.ReadWakeupThreshold,
        } {
                val, err := util.ReadUintFromFile(fs.proc.Path("sys", "kernel", "random", file))
                if os.IsNotExist(err) {
                        continue
                }
                if err != nil {
                        return random, err
                }
                *p = &val
        }

        return random, nil
}