adelolmo · adelolmo · Aug 29, 2019 · Aug 16, 2019 · Aug 27, 2019 · Aug 29, 2019
diff --git a/README.md b/README.md
@@ -50,7 +50,7 @@ There are various ways of installing `hd-idle`
 ### Precompiled binaries
 
 Precompiled binaries for released versions are available in the 
-[*releases* section](https://github.com/adelolmo/hd-idle/releases).
+[*releases*](https://github.com/adelolmo/hd-idle/releases) section.
 
 ### Building from source
 
@@ -69,14 +69,11 @@ On Debian you can also clone the repository yourself and build using `dpkg-build
     $ cd $GOPATH/src/github.com/adelolmo
     $ git clone https://github.com/adelolmo/hd-idle.git
     $ cd hd-idle
-    $ dpkg-buildpackage -a armhf -us -uc -b
-
-In the example above, the package is built for `armhf`, but you can build it also for the platforms `i386`, `amd64`, and `arm64` 
-by substituting the parameter `-a`.
+    $ dpkg-buildpackage -us -uc -b
 
 Then install the package:
 
-    # dpkg -i ../hd-idle_1.5_armhf.deb
+    # dpkg -i ../hd-idle*.deb
 
 ## Running hd-idle
 
@@ -118,7 +115,15 @@ Command line options:
 + -c *command_type*       
                         Api call to stop the device. Possible values are `scsi`
                         (default value) and `ata`.
-
+
++ -s *symlink_policy*   
+                        Set the policy to resolve symlinks for devices. If set 
+                        to `0`, symlinks are resolve only on start. If set to `1`,
+                        symlinks are also resolved on runtime until success.
+                        By default symlinks are only resolve on start. If the 
+                        symlink doesn't resolve to a device, the default
+                        configuration will be applied.
+
 + -l *logfile*            
                         Name of logfile (written only after a disk has spun
                         up). Please note that this option might cause the
@@ -142,8 +147,8 @@ Miscellaneous options:
 
 Regarding the parameter *-a*:
 
-The parameter *-a* can be used to set a filter on
-the disk's device name (omit /dev/) for subsequent idle-time settings.
+The parameter *-a* can be used to set a filter on the disk's device name (omit /dev/) 
+for subsequent idle-time settings.
 
 1) 
     A *-i* option before the first *-a* option will set the default idle time.

diff --git a/debian/changelog b/debian/changelog
@@ -1,3 +1,13 @@
+hd-idle (1.6) unstable; urgency=low
+
+  * The parameter "-s" allows to resolve symlinks for disk names also in runtime.
+    It is disable by default, because resolving symlinks causes an overhead.
+    That means that disk symlinks only get resolved on start up by default.
+    If the parameter "-s" is set to 1, disk symlinks will be also resolve during
+    execution until the symlink is resolved.
+
+ -- Andoni del Olmo <[email protected]>  Wed, 28 Aug 2019 19:33:00 +0100
+
 hd-idle (1.5) unstable; urgency=low
 
   * Monitor the skew between monitoring cycles, on discovery of clock skew

diff --git a/device/disk.go b/device/disk.go
diff --git a/device/disk_test.go b/device/disk_test.go
diff --git a/hd-idle.1 b/hd-idle.1
@@ -57,6 +57,13 @@ all disks.
 Api call to stop the device. Possible values are "scsi" (default value)
 and "ata".
 .TP
+.B \-s symlink_policy
+Set the policy to resolve symlinks for devices. If set to "0", symlinks
+are resolve only on start. If set to "1", symlinks are also resolved on
+runtime until success. By default symlinks are only resolve on start.
+If the symlink doesn't resolve to a device, the default configuration
+will be applied.
+.TP
 .B \-l logfile
 Name of logfile (written only after a disk has spun up). Please note that
 this option might cause the disk which holds the logfile to spin up just

diff --git a/hd-idle.conf b/hd-idle.conf
@@ -14,6 +14,12 @@ START_HD_IDLE=false
 #  -i <idle_time>          Idle time in seconds.
 #  -c <command_type>       Api call to stop the device. Possible values are "scsi"
 #                          (default value) and "ata".
+#  -s symlink_policy       Set the policy to resolve symlinks for devices.
+#                          If set to "0", symlinks are resolve only on start.
+#                          If set to "1", symlinks are also resolved on runtime
+#                          until success. By default symlinks are only resolve on start.
+#                          If the symlink doesn't resolve to a device, the default
+#                          configuration will be applied.
 #  -l <logfile>            Name of logfile (written only after a disk has spun
 #                          up). Please note that this option might cause the
 #                          disk which holds the logfile to spin up just because

diff --git a/hdidle.go b/hdidle.go
@@ -3,6 +3,7 @@ package main
 import (
 	"fmt"
 	"github.com/adelolmo/hd-idle/diskstats"
+	"github.com/adelolmo/hd-idle/io"
 	"github.com/adelolmo/hd-idle/sgio"
 	"log"
 	"os"
@@ -16,14 +17,16 @@ const (
 )
 
 type DefaultConf struct {
-	Idle        int
-	CommandType string
-	Debug       bool
-	LogFile     string
+	Idle          int
+	CommandType   string
+	Debug         bool
+	LogFile       string
+	SymlinkPolicy int
 }
 
 type DeviceConf struct {
 	Name        string
+	GivenName   string
 	Idle        int
 	CommandType string
 }
@@ -42,12 +45,33 @@ func ObserveDiskActivity(config *Config) {
 	actualSnapshot := diskstats.Snapshot()
 
 	now = time.Now()
+	resolveSymlinks(config)
 	for _, stats := range actualSnapshot {
 		updateState(stats, config)
 	}
 	lastNow = now
 }
 
+func resolveSymlinks(config *Config) {
+	if config.Defaults.SymlinkPolicy == 0 {
+		return
+	}
+	for i := range config.Devices {
+		device := config.Devices[i]
+		if len(device.Name) == 0 {
+			realPath, err := io.RealPath(device.GivenName)
+			if err == nil {
+				config.Devices[i].Name = realPath
+				logToFile(config.Defaults.LogFile,
+					fmt.Sprintf("symlink %s resolved to %s", device.GivenName, realPath))
+			}
+			if err != nil && config.Defaults.Debug {
+				fmt.Printf("Cannot resolve sysmlink %s\n", device.GivenName)
+			}
+		}
+	}
+}
+
 func updateState(tmp diskstats.DiskStats, config *Config) {
 	dsi := previousDiskStatsIndex(tmp.Name)
 	if dsi < 0 {
@@ -81,9 +105,7 @@ func updateState(tmp diskstats.DiskStats, config *Config) {
 		if ds.SpunDown {
 			/* disk was spun down, thus it has just spun up */
 			fmt.Printf("%s spinup\n", ds.Name)
-			if len(config.Defaults.LogFile) > 0 {
-				logSpinup(ds, config.Defaults.LogFile)
-			}
+			logSpinup(ds, config.Defaults.LogFile)
 			previousSnapshots[dsi].SpinUpAt = now
 		}
 		previousSnapshots[dsi].Reads = tmp.Reads
@@ -162,33 +184,35 @@ func spindownDisk(deviceName, command string) {
 
 func logSpinup(ds diskstats.DiskStats, file string) {
 	now := time.Now()
-	text := fmt.Sprintf("date: %s, time: %s, disk: %s, running: %d, stopped: %d\n",
+	text := fmt.Sprintf("date: %s, time: %s, disk: %s, running: %d, stopped: %d",
 		now.Format("2006-01-02"), now.Format("15:04:05"), ds.Name,
 		int(ds.SpinDownAt.Sub(ds.SpinUpAt).Seconds()), int(now.Sub(ds.SpinDownAt).Seconds()))
 	logToFile(file, text)
 }
 
 func logSpinupAfterSleep(name string, file string) {
-	text := fmt.Sprintf("date: %s, time: %s, disk: %s, assuming disk spun up after long sleep\n",
+	text := fmt.Sprintf("date: %s, time: %s, disk: %s, assuming disk spun up after long sleep",
 		now.Format("2006-01-02"), now.Format("15:04:05"), name)
 	logToFile(file, text)
 }
 
 func logToFile(file string, text string) {
-	cacheFile, err := os.OpenFile(file, os.O_APPEND|os.O_WRONLY, 0600)
-	if err != nil {
-		log.Fatalf("Cannot open file %s. Error: %s", file, err)
-	}
-	if _, err = cacheFile.WriteString(text); err != nil {
-		log.Fatalf("Cannot write into file %s. Error: %s", file, err)
-	}
-	err = cacheFile.Close()
-	if err != nil {
-		log.Fatalf("Cannot close file %s. Error: %s", file, err)
+	if len(file) > 0 {
+		cacheFile, err := os.OpenFile(file, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0600)
+		if err != nil {
+			log.Fatalf("Cannot open file %s. Error: %s", file, err)
+		}
+		if _, err = cacheFile.WriteString(text + "\n"); err != nil {
+			log.Fatalf("Cannot write into file %s. Error: %s", file, err)
+		}
+		err = cacheFile.Close()
+		if err != nil {
+			log.Fatalf("Cannot close file %s. Error: %s", file, err)
+		}
 	}
 }
 
 func (c *Config) String() string {
-	return fmt.Sprintf("defaultIdle=%d, defaultCommand=%s, debug=%t, devices=%v, logFile=%s",
-		c.Defaults.Idle, c.Defaults.CommandType, c.Defaults.Debug, c.Devices, c.Defaults.LogFile)
+	return fmt.Sprintf("symlinkPolicy=%d, defaultIdle=%d, defaultCommand=%s, debug=%t, devices=%v, logFile=%s",
+		c.Defaults.SymlinkPolicy, c.Defaults.Idle, c.Defaults.CommandType, c.Defaults.Debug, c.Devices, c.Defaults.LogFile)
 }
diff --git a/io/disk.go b/io/disk.go
@@ -0,0 +1,23 @@
+package io
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+func RealPath(path string) (string, error) {
+	if path[0] != '/' {
+		return path, nil
+	}
+	if !strings.Contains(path, "by-") {
+		return filepath.Base(path), nil
+	}
+	s, err := os.Readlink(path)
+	if err == nil {
+		return filepath.Base(s), nil
+	}
+
+	return "", fmt.Errorf("cannot find device for %s", path)
+}