Change the read-only property to a attribute of the structure.

Properties were intended to be things that does not apply to all disks.
The example was 'ephemeral'. On amazon, we would correctly identify
ephemeral disks, but on other platforms they *may* be ephemeral.

All disks are either writable or not, so lets just put this on the
structure.

demo/disk.go

@@ -100,24 +100,29 @@ func diskShow(c *cli.Context) error {
 }
 
 func getDiskSet(mysys disko.System, paths ...string) (disko.DiskSet, error) {
-	matchAllSkipReadOnly := func(d disko.Disk) bool {
-		if _, ok := d.Properties[disko.ReadOnly]; ok == true {
-			return false
-		}
+	matchAll := func(d disko.Disk) bool {
 		return true
 	}
 
+	return getDiskSetFilter(mysys, matchAll, paths...)
+}
+
+func getDiskSetFilter(mysys disko.System, matcher disko.DiskFilter, paths ...string) (disko.DiskSet, error) {
 	if len(paths) == 0 || (len(paths) == 1 && paths[0] == "all") {
-		return mysys.ScanAllDisks(matchAllSkipReadOnly)
+		return mysys.ScanAllDisks(matcher)
 	}
 
-	return mysys.ScanDisks(matchAllSkipReadOnly, paths...)
+	return mysys.ScanDisks(matcher, paths...)
 }
 
 func diskWipe(c *cli.Context) error {
 	mysys := linux.System()
 
-	disks, err := getDiskSet(mysys, c.Args().Slice()...)
+	// only match read-write disks here.
+	disks, err := getDiskSetFilter(
+		mysys,
+		func(d disko.Disk) bool { return !d.ReadOnly },
+		c.Args().Slice()...)
 
 	if err != nil {
 		return err

disk.go

@@ -240,8 +240,6 @@ type Property string
 const (
 	// Ephemeral - A cloud ephemeral disk.
 	Ephemeral Property = "EPHEMERAL"
-	// ReadOnly  - A disk that cannot be modified, writes fail
-	ReadOnly Property = "READ-ONLY"
 )
 
 // PropertySet - a group of properties of a disk
@@ -324,6 +322,9 @@ type Disk struct {
 	// applicable it will return 0.
 	SectorSize uint `json:"sectorSize"`
 
+	// ReadOnly - cannot be written to.
+	ReadOnly bool `json:"read-only"`
+
 	// Type is the DiskType indicating the type of this disk. This value
 	// can be used to determine if the disk is of a particular media type like
 	// HDD, SSD or NVMe.

go.mod

@@ -3,7 +3,6 @@ module github.com/anuvu/disko
 go 1.13
 
 require (
-	github.com/Jeffail/gabs v1.4.0 // indirect
 	github.com/patrickmn/go-cache v2.1.0+incompatible
 	github.com/pkg/errors v0.9.1
 	github.com/rekby/gpt v0.0.0-20200219180433-a930afbc6edc

go.sum

@@ -1,6 +1,4 @@
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
-github.com/Jeffail/gabs v1.4.0 h1://5fYRRTq1edjfIrQGvdkcd22pkYUrHZ5YC/H2GJVAo=
-github.com/Jeffail/gabs v1.4.0/go.mod h1:6xMvQMK4k33lb7GUUpaAPh6nKMmemQeg5d4gn7/bOXc=
 github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d h1:U+s90UTSYgptZMwQh2aRr3LuazLJIa+Pg3Kc1ylSYVY=
 github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
 github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=

linux/system.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"path"
 	"regexp"
+	"strings"
 	"syscall"
 
 	"github.com/anuvu/disko"
@@ -83,23 +84,28 @@ func (ls *linuxSystem) ScanDisks(filter disko.DiskFilter,
 	return disks, nil
 }
 
-func getDiskReadOnlyProperty(d disko.UdevInfo) (bool, error) {
-	syspath, err := getSysPathForBlockDevicePath(d.Name)
+func getDiskReadOnly(kname string) (bool, error) {
+	syspath, err := getSysPathForBlockDevicePath(kname)
 	if err != nil {
 		return false, err
 	}
 
 	syspathReadOnly := syspath + "/ro"
-	if disko.PathExists(syspathReadOnly) {
-		content, err := ioutil.ReadFile(syspathReadOnly)
-		if err != nil {
-			return false, fmt.Errorf("failed to read %s for %s", syspathReadOnly, d.Name)
-		}
-		if string(content) == "1\n" {
-			return true, nil
-		}
+	content, err := ioutil.ReadFile(syspathReadOnly)
+
+	if err != nil {
+		return false, err
+	}
+
+	val := strings.TrimRight(string(content), "\n")
+
+	if val == "1" {
+		return true, nil
+	} else if val == "0" {
+		return false, nil
 	}
-	return false, nil
+
+	return false, fmt.Errorf("unexpected value '%s' found in %s", syspathReadOnly, val)
 }
 
 func getDiskProperties(d disko.UdevInfo) disko.PropertySet {
@@ -113,15 +119,10 @@ func getDiskProperties(d disko.UdevInfo) disko.PropertySet {
 		props[disko.Ephemeral] = true
 	}
 
-	readOnly, err := getDiskReadOnlyProperty(d)
-	// only mark read-only prop if set
-	if err == nil && readOnly {
-		props[disko.ReadOnly] = readOnly
-	}
-
 	return props
 }
 
+// nolint: funlen
 func (ls *linuxSystem) ScanDisk(devicePath string) (disko.Disk, error) {
 	var err error
 	var blockdev = true
@@ -167,6 +168,13 @@ func (ls *linuxSystem) ScanDisk(devicePath string) (disko.Disk, error) {
 		Properties: properties,
 	}
 
+	ro, err := getDiskReadOnly(disk.Name)
+	if err != nil {
+		return disk, err
+	}
+
+	disk.ReadOnly = ro
+
 	fh, err := os.Open(devicePath)
 	if err != nil {
 		return disk, err

util.go

@@ -2,7 +2,6 @@ package disko
 
 import (
 	"fmt"
-	"os"
 	"sort"
 )
 
@@ -62,11 +61,3 @@ func findRangeGaps(ranges uRanges, min, max uint64) uRanges {
 
 	return ret
 }
-
-func PathExists(d string) bool {
-	_, err := os.Stat(d)
-	if err != nil && os.IsNotExist(err) {
-		return false
-	}
-	return true
-}