go lint and documentation tweaks for the sysfs package

sysfs/digital_pin.go

@@ -8,18 +8,29 @@ import (
 )
 
 const (
+	// IN gpio direction
 	IN = "in"
+	// OUT gpio direction
 	OUT = "out"
+	// HIGH gpio level
 	HIGH = 1
+	// LOW gpio level
 	LOW = 0
+	// GPIOPATH default linux gpio path
 	GPIOPATH = "/sys/class/gpio"
 )
 
+// DigitalPin is the interface for sysfs gpio interactions
 type DigitalPin interface {
+	// Unexport unexports the pin and releases the pin from the operating system
 	Unexport() error
+	// Export exports the pin for use by the operating system
 	Export() error
+	// Read reads the current value of the pin
 	Read() (int, error)
+	// Direction sets the direction for the pin
 	Direction(string) error
+	// Write writes to the pin
 	Write(int) error
 }
 
@@ -42,19 +53,16 @@ func NewDigitalPin(pin int, v ...string) DigitalPin {
 	return d
 }
 
-// Direction sets the direction for the pin
 func (d *digitalPin) Direction(dir string) error {
 	_, err := writeFile(fmt.Sprintf("%v/%v/direction", GPIOPATH, d.label), []byte(dir))
 	return err
 }
 
-// Write writes to the pin
 func (d *digitalPin) Write(b int) error {
 	_, err := writeFile(fmt.Sprintf("%v/%v/value", GPIOPATH, d.label), []byte(strconv.Itoa(b)))
 	return err
 }
 
-// Read reads the current value of the pin
 func (d *digitalPin) Read() (n int, err error) {
 	buf, err := readFile(fmt.Sprintf("%v/%v/value", GPIOPATH, d.label))
 	if err != nil {
@@ -63,7 +71,6 @@ func (d *digitalPin) Read() (n int, err error) {
 	return strconv.Atoi(string(buf[0]))
 }
 
-// Export exports the pin for use by the operating system
 func (d *digitalPin) Export() error {
 	if _, err := writeFile(GPIOPATH+"/export", []byte(d.pin)); err != nil {
 		// If EBUSY then the pin has already been exported
@@ -74,7 +81,6 @@ func (d *digitalPin) Export() error {
 	return nil
 }
 
-// Unexport unexports the pin and releases the pin from the operating system
 func (d *digitalPin) Unexport() error {
 	if _, err := writeFile(GPIOPATH+"/unexport", []byte(d.pin)); err != nil {
 		// If EINVAL then the pin is reserved in the system and can't be unexported

sysfs/fs.go

@@ -4,6 +4,7 @@ import (
 	"os"
 )
 
+// A File represents basic IO interactions with the underlying file system
 type File interface {
 	Write(b []byte) (n int, err error)
 	WriteString(s string) (ret int, err error)
@@ -14,26 +15,28 @@ type File interface {
 	Close() error
 }
 
+// Filesystem opens files and returns either a native file system or user defined
 type Filesystem interface {
 	OpenFile(name string, flag int, perm os.FileMode) (file File, err error)
 }
 
-// Filesystem that opens real files on the host.
+// NativeFilesystem represents the native file system implementation
 type NativeFilesystem struct{}
 
 // Default to the host filesystem.
 var fs Filesystem = &NativeFilesystem{}
 
-// Override the default filesystem.
+// SetFilesystem sets the filesystem implementation.
 func SetFilesystem(f Filesystem) {
 	fs = f
 }
 
+// OpenFile calls os.OpenFile().
 func (fs *NativeFilesystem) OpenFile(name string, flag int, perm os.FileMode) (file File, err error) {
 	return os.OpenFile(name, flag, perm)
 }
 
-// Open a file the same as os.OpenFile().
+// OpenFile calls either the NativeFilesystem or user defined OpenFile
 func OpenFile(name string, flag int, perm os.FileMode) (file File, err error) {
 	return fs.OpenFile(name, flag, perm)
 }

sysfs/fs_mock.go

@@ -6,13 +6,16 @@ import (
 	"time"
 )
 
-// A mock filesystem of simple files.
+var _ File = (*MockFile)(nil)
+var _ Filesystem = (*MockFilesystem)(nil)
+
+// MockFilesystem represents  a filesystem of mock files.
 type MockFilesystem struct {
 	Seq   int // Increases with each write or read.
 	Files map[string]*MockFile
 }
 
-// A simple mock file that contains a single string.  Any write
+// A MockFile represents a mock file that contains a single string.  Any write
 // overwrites, and any read returns from the start.
 type MockFile struct {
 	Contents string
@@ -24,23 +27,24 @@ type MockFile struct {
 	fs *MockFilesystem
 }
 
-var _ File = (*MockFile)(nil)
-var _ Filesystem = (*MockFilesystem)(nil)
-
+// Write writes string(b) to f.Contents
 func (f *MockFile) Write(b []byte) (n int, err error) {
 	return f.WriteString(string(b))
 }
 
+// WriteString writes s to f.Contents
 func (f *MockFile) WriteString(s string) (ret int, err error) {
 	f.Contents = s
 	f.Seq = f.fs.next()
 	return len(s), nil
 }
 
+// Sync implements the File interface Sync function
 func (f *MockFile) Sync() (err error) {
 	return nil
 }
 
+// Read copies b bytes from f.Contents
 func (f *MockFile) Read(b []byte) (n int, err error) {
 	count := len(b)
 	if len(f.Contents) < count {
@@ -52,18 +56,22 @@ func (f *MockFile) Read(b []byte) (n int, err error) {
 	return count, nil
 }
 
+// ReadAt calls MockFile.Read
 func (f *MockFile) ReadAt(b []byte, off int64) (n int, err error) {
 	return f.Read(b)
 }
 
+// Fd returns a random uintprt based on the time of the MockFile creation
 func (f *MockFile) Fd() uintptr {
 	return f.fd
 }
 
+// Close implements the File interface Close function
 func (f *MockFile) Close() error {
 	return nil
 }
 
+// NewMockFilesystem returns a new MockFilesystem given a list of file paths
 func NewMockFilesystem(files []string) *MockFilesystem {
 	m := &MockFilesystem{
 		Files: make(map[string]*MockFile),
@@ -76,17 +84,18 @@ func NewMockFilesystem(files []string) *MockFilesystem {
 	return m
 }
 
+// OpenFile opens file name from fs.Files, if the file does not exist it returns an os.PathError
 func (fs *MockFilesystem) OpenFile(name string, flag int, perm os.FileMode) (file File, err error) {
 	f, ok := fs.Files[name]
 	if ok {
 		f.Opened = true
 		f.Closed = false
 		return f, nil
-	} else {
+	}
 	return (*MockFile)(nil), &os.PathError{Err: errors.New(name + ": No such file.")}
 }
-}
 
+// Add adds a new file to fs.Files given a name, and returns the newly created file
 func (fs *MockFilesystem) Add(name string) *MockFile {
 	f := &MockFile{
 		Seq: -1,

sysfs/fs_mock_test.go

@@ -1,8 +1,9 @@
 package sysfs
 
 import (
-	"github.com/hybridgroup/gobot"
 	"testing"
+
+	"github.com/hybridgroup/gobot"
 )
 
 func TestMockFilesystemOpen(t *testing.T) {

sysfs/fs_test.go

@@ -1,9 +1,10 @@
 package sysfs
 
 import (
-	"github.com/hybridgroup/gobot"
 	"os"
 	"testing"
+
+	"github.com/hybridgroup/gobot"
 )
 
 func TestFilesystemOpen(t *testing.T) {

sysfs/i2c_device.go

@@ -1,16 +1,17 @@
 package sysfs
 
 import (
-	"errors"
 	"fmt"
 	"io"
 	"os"
 	"syscall"
 )
 
+// I2CSlave is the linux default ioctrl request code
 const I2CSlave = 0x0703
 
-// NewI2cDevice creates a new io.ReadWriteCloser with the proper ioctrl given an i2c bus location and device address
+// NewI2cDevice returns an io.ReadWriteCloser with the proper ioctrl given
+// an i2c bus location and device address
 func NewI2cDevice(location string, address byte) (io.ReadWriteCloser, error) {
 	file, err := OpenFile(location, os.O_RDWR, os.ModeExclusive)
 
@@ -26,7 +27,7 @@ func NewI2cDevice(location string, address byte) (io.ReadWriteCloser, error) {
 	)
 
 	if errno != 0 {
-		return nil, errors.New(fmt.Sprintf("Failed with syscall.Errno %v", errno))
+		return nil, fmt.Errorf("Failed with syscall.Errno %v", errno)
 	}
 
 	return file, nil

sysfs/i2c_device_test.go

@@ -1,10 +1,11 @@
 package sysfs
 
 import (
-	"github.com/hybridgroup/gobot"
 	"io"
 	"os"
 	"testing"
+
+	"github.com/hybridgroup/gobot"
 )
 
 func TestNewI2cDevice(t *testing.T) {

sysfs/syscall.go

@@ -4,27 +4,35 @@ import (
 	"syscall"
 )
 
+// SystemCaller represents a Syscall
 type SystemCaller interface {
 	Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err syscall.Errno)
 }
 
+// NativeSyscall represents the native Syscall
 type NativeSyscall struct{}
+
+// MockSyscall represents the mock Syscall
 type MockSyscall struct{}
 
 var sys SystemCaller = &NativeSyscall{}
 
+// SetSyscall sets the Syscall implementation
 func SetSyscall(s SystemCaller) {
 	sys = s
 }
 
+// Syscall calls either the NativeSyscall or user defined Syscall
 func Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err syscall.Errno) {
 	return sys.Syscall(trap, a1, a2, a3)
 }
 
+// Syscall calls syscall.Syscall
 func (sys *NativeSyscall) Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err syscall.Errno) {
 	return syscall.Syscall(trap, a1, a2, a3)
 }
 
+// Syscall implements the SystemCaller interface
 func (sys *MockSyscall) Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err syscall.Errno) {
 	return 0, 0, 0
 }