extend stdlib to allow import of more packages (#1099)

* stdlib: extend stdlib to allow import of more packages

src/os/env.go

@@ -0,0 +1,5 @@
+package os
+
+func Getenv(key string) string {
+	return ""
+}

src/os/errors.go

@@ -0,0 +1,39 @@
+package os
+
+import (
+	"errors"
+)
+
+var (
+	ErrInvalid    = errors.New("invalid argument")
+	ErrPermission = errors.New("permission denied")
+	ErrClosed     = errors.New("file already closed")
+
+	// Portable analogs of some common system call errors.
+	// Note that these are exported for use in the Filesystem interface.
+	ErrUnsupported    = errors.New("operation not supported")
+	ErrNotImplemented = errors.New("operation not implemented")
+	ErrNotExist       = errors.New("file not found")
+	ErrExist          = errors.New("file exists")
+)
+
+func IsPermission(err error) bool {
+	return err == ErrPermission
+}
+
+func NewSyscallError(syscall string, err error) error {
+	if err == nil {
+		return nil
+	}
+	return &SyscallError{syscall, err}
+}
+
+// SyscallError records an error from a specific system call.
+type SyscallError struct {
+	Syscall string
+	Err     error
+}
+
+func (e *SyscallError) Error() string { return e.Syscall + ": " + e.Err.Error() }
+
+func (e *SyscallError) Unwrap() error { return e.Err }

src/os/exec.go

@@ -0,0 +1,6 @@
+package os
+
+type Signal interface {
+	String() string
+	Signal() // to distinguish from other Stringers
+}

src/os/file.go

@@ -6,16 +6,7 @@
 package os
 
 import (
-	"errors"
-)
-
-// Portable analogs of some common system call errors.
-// Note that these are exported for use in the Filesystem interface.
-var (
-	ErrUnsupported    = errors.New("operation not supported")
-	ErrNotImplemented = errors.New("operation not implemented")
-	ErrNotExist       = errors.New("file not found")
-	ErrExist          = errors.New("file exists")
+	"syscall"
 )
 
 // Mkdir creates a directory. If the operation fails, it will return an error of
@@ -91,6 +82,10 @@ func (f *File) Read(b []byte) (n int, err error) {
 	return
 }
 
+func (f *File) ReadAt(b []byte, off int64) (n int, err error) {
+	return 0, ErrNotImplemented
+}
+
 // Write writes len(b) bytes to the File. It returns the number of bytes written
 // and an error, if any. Write returns a non-nil error when n != len(b).
 func (f *File) Write(b []byte) (n int, err error) {
@@ -125,6 +120,20 @@ func (f *File) Stat() (FileInfo, error) {
 	return nil, &PathError{"stat", f.name, ErrNotImplemented}
 }
 
+// Sync is a stub, not yet implemented
+func (f *File) Sync() error {
+	return ErrNotImplemented
+}
+
+func (f *File) SyscallConn() (syscall.RawConn, error) {
+	return nil, ErrNotImplemented
+}
+
+// Fd returns the file handle referencing the open file.
+func (f *File) Fd() uintptr {
+	panic("unimplemented: os.file.Fd()")
+}
+
 const (
 	PathSeparator     = '/' // OS-specific path separator
 	PathListSeparator = ':' // OS-specific path list separator
@@ -194,7 +203,7 @@ type FileInfo interface {
 	Name() string   // base name of the file
 	Size() int64    // length in bytes for regular files; system-dependent for others
 	Mode() FileMode // file mode bits
-	// ModTime() time.Time // modification time
+	// TODO ModTime() time.Time // modification time
 	IsDir() bool      // abbreviation for Mode().IsDir()
 	Sys() interface{} // underlying data source (can return nil)
 }

src/os/sys.go

@@ -0,0 +1,5 @@
+package os
+
+func Hostname() (name string, err error) {
+	return "", ErrNotImplemented
+}