From 3e16b523619a75ee8b8a90eeb3f2a57ed4fe9c28 Mon Sep 17 00:00:00 2001
From: Preetha Appan <preetha@hashicorp.com>
Date: Wed, 16 Jan 2019 11:04:11 -0600
Subject: [PATCH] clean up read access

---
 drivers/docker/driver.go      |  2 +-
 drivers/docker/fingerprint.go | 14 +++++++++++---
 drivers/exec/driver.go        | 10 +++++++++-
 drivers/rkt/driver.go         | 12 ++++++++++--
 4 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/drivers/docker/driver.go b/drivers/docker/driver.go
index 0de93aba7..3467338c5 100644
--- a/drivers/docker/driver.go
+++ b/drivers/docker/driver.go
@@ -92,7 +92,7 @@ type Driver struct {
 	// A tri-state boolean to know if the fingerprinting has happened and
 	// whether it has been successful
 	fingerprintSuccess *bool
-	fingerprintLock    sync.Mutex
+	fingerprintLock    sync.RWMutex
 }
 
 // NewDockerDriver returns a docker implementation of a driver plugin
diff --git a/drivers/docker/fingerprint.go b/drivers/docker/fingerprint.go
index 50d64374c..a84bafd90 100644
--- a/drivers/docker/fingerprint.go
+++ b/drivers/docker/fingerprint.go
@@ -31,6 +31,14 @@ func (d *Driver) setFingerprintFailure() {
 	d.fingerprintLock.Unlock()
 }
 
+// fingerprintSuccessful returns true if the driver has
+// never fingerprinted or has successfully fingerprinted
+func (d *Driver) fingerprintSuccessful() bool {
+	d.fingerprintLock.Lock()
+	defer d.fingerprintLock.Unlock()
+	return d.fingerprintSuccess == nil || *d.fingerprintSuccess
+}
+
 func (d *Driver) handleFingerprint(ctx context.Context, ch chan *drivers.Fingerprint) {
 	defer close(ch)
 	ticker := time.NewTimer(0)
@@ -55,7 +63,7 @@ func (d *Driver) buildFingerprint() *drivers.Fingerprint {
 	}
 	client, _, err := d.dockerClients()
 	if err != nil {
-		if d.fingerprintSuccess == nil || *d.fingerprintSuccess {
+		if d.fingerprintSuccessful() {
 			d.logger.Info("failed to initialize client", "error", err)
 		}
 		d.setFingerprintFailure()
@@ -67,7 +75,7 @@ func (d *Driver) buildFingerprint() *drivers.Fingerprint {
 
 	env, err := client.Version()
 	if err != nil {
-		if d.fingerprintSuccess == nil || *d.fingerprintSuccess {
+		if d.fingerprintSuccessful() {
 			d.logger.Debug("could not connect to docker daemon", "endpoint", client.Endpoint(), "error", err)
 		}
 		d.setFingerprintFailure()
@@ -105,7 +113,7 @@ func (d *Driver) buildFingerprint() *drivers.Fingerprint {
 			} else {
 				// Docker 17.09.0-ce dropped the Gateway IP from the bridge network
 				// See https://github.com/moby/moby/issues/32648
-				if d.fingerprintSuccess == nil || *d.fingerprintSuccess {
+				if d.fingerprintSuccessful() {
 					d.logger.Debug("bridge_ip could not be discovered")
 				}
 			}
diff --git a/drivers/exec/driver.go b/drivers/exec/driver.go
index 8aab879ed..d8250d873 100644
--- a/drivers/exec/driver.go
+++ b/drivers/exec/driver.go
@@ -147,6 +147,14 @@ func (d *Driver) setFingerprintFailure() {
 	d.fingerprintLock.Unlock()
 }
 
+// fingerprintSuccessful returns true if the driver has
+// never fingerprinted or has successfully fingerprinted
+func (d *Driver) fingerprintSuccessful() bool {
+	d.fingerprintLock.Lock()
+	defer d.fingerprintLock.Unlock()
+	return d.fingerprintSuccess == nil || *d.fingerprintSuccess
+}
+
 func (d *Driver) PluginInfo() (*base.PluginInfoResponse, error) {
 	return pluginInfo, nil
 }
@@ -222,7 +230,7 @@ func (d *Driver) buildFingerprint() *drivers.Fingerprint {
 	if err != nil {
 		fp.Health = drivers.HealthStateUnhealthy
 		fp.HealthDescription = drivers.NoCgroupMountMessage
-		if d.fingerprintSuccess == nil || *d.fingerprintSuccess {
+		if d.fingerprintSuccessful() {
 			d.logger.Warn(fp.HealthDescription, "error", err)
 		}
 		d.setFingerprintFailure()
diff --git a/drivers/rkt/driver.go b/drivers/rkt/driver.go
index 2035327d0..54f0510c1 100644
--- a/drivers/rkt/driver.go
+++ b/drivers/rkt/driver.go
@@ -280,6 +280,14 @@ func (d *Driver) setFingerprintFailure() {
 	d.fingerprintLock.Unlock()
 }
 
+// fingerprintSuccessful returns true if the driver has
+// never fingerprinted or has successfully fingerprinted
+func (d *Driver) fingerprintSuccessful() bool {
+	d.fingerprintLock.Lock()
+	defer d.fingerprintLock.Unlock()
+	return d.fingerprintSuccess == nil || *d.fingerprintSuccess
+}
+
 func (d *Driver) buildFingerprint() *drivers.Fingerprint {
 	fingerprint := &drivers.Fingerprint{
 		Attributes:        map[string]*pstructs.Attribute{},
@@ -289,7 +297,7 @@ func (d *Driver) buildFingerprint() *drivers.Fingerprint {
 
 	// Only enable if we are root
 	if syscall.Geteuid() != 0 {
-		if d.fingerprintSuccess == nil || *d.fingerprintSuccess {
+		if d.fingerprintSuccessful() {
 			d.logger.Debug("must run as root user, disabling")
 		}
 		d.setFingerprintFailure()
@@ -322,7 +330,7 @@ func (d *Driver) buildFingerprint() *drivers.Fingerprint {
 		// Do not allow ancient rkt versions
 		fingerprint.Health = drivers.HealthStateUndetected
 		fingerprint.HealthDescription = fmt.Sprintf("Unsuported rkt version %s", currentVersion)
-		if d.fingerprintSuccess == nil || *d.fingerprintSuccess {
+		if d.fingerprintSuccessful() {
 			d.logger.Warn("unsupported rkt version please upgrade to >= "+minVersion.String(),
 				"rkt_version", currentVersion)
 		}