// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package os

import syscall "syscall"

// An Error can represent any printable error condition.
type Error interface {
	String() string
}

// A helper type that can be embedded or wrapped to simplify satisfying
// Error.
type ErrorString string

func (e ErrorString) String() string  { return string(e) }
func (e ErrorString) Temporary() bool { return false }
func (e ErrorString) Timeout() bool   { return false }

// Note: If the name of the function NewError changes,
// pkg/go/doc/doc.go should be adjusted since it hardwires
// this name in a heuristic.

// NewError converts s to an ErrorString, which satisfies the Error interface.
func NewError(s string) Error { return ErrorString(s) }

// Errno is the Unix error number.  Names such as EINVAL are simple
// wrappers to convert the error number into an Error.
type Errno int64

func (e Errno) String() string { return syscall.Errstr(int(e)) }

func (e Errno) Temporary() bool {
	return e == Errno(syscall.EINTR) || e.Timeout()
}

func (e Errno) Timeout() bool {
	return e == Errno(syscall.EAGAIN) || e == Errno(syscall.EWOULDBLOCK) || e == Errno(syscall.ETIMEDOUT)
}

// Commonly known Unix errors.
var (
	EPERM        Error = Errno(syscall.EPERM)
	ENOENT       Error = Errno(syscall.ENOENT)
	ESRCH        Error = Errno(syscall.ESRCH)
	EINTR        Error = Errno(syscall.EINTR)
	EIO          Error = Errno(syscall.EIO)
	ENXIO        Error = Errno(syscall.ENXIO)
	E2BIG        Error = Errno(syscall.E2BIG)
	ENOEXEC      Error = Errno(syscall.ENOEXEC)
	EBADF        Error = Errno(syscall.EBADF)
	ECHILD       Error = Errno(syscall.ECHILD)
	EDEADLK      Error = Errno(syscall.EDEADLK)
	ENOMEM       Error = Errno(syscall.ENOMEM)
	EACCES       Error = Errno(syscall.EACCES)
	EFAULT       Error = Errno(syscall.EFAULT)
	EBUSY        Error = Errno(syscall.EBUSY)
	EEXIST       Error = Errno(syscall.EEXIST)
	EXDEV        Error = Errno(syscall.EXDEV)
	ENODEV       Error = Errno(syscall.ENODEV)
	ENOTDIR      Error = Errno(syscall.ENOTDIR)
	EISDIR       Error = Errno(syscall.EISDIR)
	EINVAL       Error = Errno(syscall.EINVAL)
	ENFILE       Error = Errno(syscall.ENFILE)
	EMFILE       Error = Errno(syscall.EMFILE)
	ENOTTY       Error = Errno(syscall.ENOTTY)
	EFBIG        Error = Errno(syscall.EFBIG)
	ENOSPC       Error = Errno(syscall.ENOSPC)
	ESPIPE       Error = Errno(syscall.ESPIPE)
	EROFS        Error = Errno(syscall.EROFS)
	EMLINK       Error = Errno(syscall.EMLINK)
	EPIPE        Error = Errno(syscall.EPIPE)
	EAGAIN       Error = Errno(syscall.EAGAIN)
	EDOM         Error = Errno(syscall.EDOM)
	ERANGE       Error = Errno(syscall.ERANGE)
	EADDRINUSE   Error = Errno(syscall.EADDRINUSE)
	ECONNREFUSED Error = Errno(syscall.ECONNREFUSED)
	ENAMETOOLONG Error = Errno(syscall.ENAMETOOLONG)
	EAFNOSUPPORT Error = Errno(syscall.EAFNOSUPPORT)
	ETIMEDOUT    Error = Errno(syscall.ETIMEDOUT)
	ENOTCONN     Error = Errno(syscall.ENOTCONN)
)

// PathError records an error and the operation and file path that caused it.
type PathError struct {
	Op    string
	Path  string
	Error Error
}

func (e *PathError) String() string { return e.Op + " " + e.Path + ": " + e.Error.String() }

// SyscallError records an error from a specific system call.
type SyscallError struct {
	Syscall string
	Errno   Errno
}

func (e *SyscallError) String() string { return e.Syscall + ": " + e.Errno.String() }

// Note: If the name of the function NewSyscallError changes,
// pkg/go/doc/doc.go should be adjusted since it hardwires
// this name in a heuristic.

// NewSyscallError returns, as an Error, a new SyscallError
// with the given system call name and error number.
// As a convenience, if errno is 0, NewSyscallError returns nil.
func NewSyscallError(syscall string, errno int) Error {
	if errno == 0 {
		return nil
	}
	return &SyscallError{syscall, Errno(errno)}
}