parse /proc/sys/kernel/random (prometheus#305)

Signed-off-by: binjip978 <[email protected]>

Author: Sergei Semenchuk

fixtures.ttar

@@ -2346,6 +2346,32 @@ Mode: 644
 Directory: fixtures/proc/sys
 Mode: 775
 # ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Directory: fixtures/proc/sys/kernel
+Mode: 775
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Directory: fixtures/proc/sys/kernel/random
+Mode: 755
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Path: fixtures/proc/sys/kernel/random/entropy_avail
+Lines: 1
+3943
+Mode: 644
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Path: fixtures/proc/sys/kernel/random/poolsize
+Lines: 1
+4096
+Mode: 644
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Path: fixtures/proc/sys/kernel/random/urandom_min_reseed_secs
+Lines: 1
+60
+Mode: 644
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+Path: fixtures/proc/sys/kernel/random/write_wakeup_threshold
+Lines: 1
+3072
+Mode: 644
+# ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 Directory: fixtures/proc/sys/vm
 Mode: 775
 # ttar - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

kernel_random.go

@@ -0,0 +1,62 @@
+// 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.
+
+// +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 bytes.
+	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
+}

kernel_random_test.go

@@ -0,0 +1,50 @@
+// 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.
+
+// +build !windows
+
+package procfs
+
+import (
+	"testing"
+)
+
+const procfsFixtures = "fixtures/proc"
+
+func TestKernelRandom(t *testing.T) {
+	fs, err := NewFS(procfsFixtures)
+	if err != nil {
+		t.Fatalf("failed to access %s: %v", procfsFixtures, err)
+	}
+
+	random, err := fs.KernelRandom()
+	if err != nil {
+		t.Fatalf("failed to collect %s/sys/kernel/random: %v", procfsFixtures, err)
+	}
+
+	if *random.EntropyAvaliable != 3943 {
+		t.Errorf("entropy_avail, want %d got %d", 3943, *random.EntropyAvaliable)
+	}
+	if *random.PoolSize != 4096 {
+		t.Errorf("poolsize, want %d got %d", 4096, *random.PoolSize)
+	}
+	if *random.URandomMinReseedSeconds != 60 {
+		t.Errorf("urandom_min_reseed_secs, want %d got %d", 60, *random.URandomMinReseedSeconds)
+	}
+	if *random.WriteWakeupThreshold != 3072 {
+		t.Errorf("write_wakeup_threshold, want %d got %d", 3072, *random.WriteWakeupThreshold)
+	}
+	if random.ReadWakeupThreshold != nil {
+		t.Errorf("read_wakeup_threshold, want %v got %d", nil, *random.ReadWakeupThreshold)
+	}
+}