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termenv_unix.go
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termenv_unix.go
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//go:build darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
// +build darwin dragonfly freebsd linux netbsd openbsd solaris
package termenv
import (
"fmt"
"io"
"strconv"
"strings"
"time"
"golang.org/x/sys/unix"
)
const (
// timeout for OSC queries
OSCTimeout = 5 * time.Second
)
// ColorProfile returns the supported color profile:
// Ascii, ANSI, ANSI256, or TrueColor.
func (o *Output) ColorProfile() Profile {
if !o.isTTY() {
return Ascii
}
if o.environ.Getenv("GOOGLE_CLOUD_SHELL") == "true" {
return TrueColor
}
term := o.environ.Getenv("TERM")
colorTerm := o.environ.Getenv("COLORTERM")
switch strings.ToLower(colorTerm) {
case "24bit":
fallthrough
case "truecolor":
if strings.HasPrefix(term, "screen") {
// tmux supports TrueColor, screen only ANSI256
if o.environ.Getenv("TERM_PROGRAM") != "tmux" {
return ANSI256
}
}
return TrueColor
case "yes":
fallthrough
case "true":
return ANSI256
}
switch term {
case "xterm-kitty", "wezterm":
return TrueColor
case "linux":
return ANSI
}
if strings.Contains(term, "256color") {
return ANSI256
}
if strings.Contains(term, "color") {
return ANSI
}
if strings.Contains(term, "ansi") {
return ANSI
}
return Ascii
}
func (o Output) foregroundColor() Color {
s, err := o.termStatusReport(10)
if err == nil {
c, err := xTermColor(s)
if err == nil {
return c
}
}
colorFGBG := o.environ.Getenv("COLORFGBG")
if strings.Contains(colorFGBG, ";") {
c := strings.Split(colorFGBG, ";")
i, err := strconv.Atoi(c[0])
if err == nil {
return ANSIColor(i)
}
}
// default gray
return ANSIColor(7)
}
func (o Output) backgroundColor() Color {
s, err := o.termStatusReport(11)
if err == nil {
c, err := xTermColor(s)
if err == nil {
return c
}
}
colorFGBG := o.environ.Getenv("COLORFGBG")
if strings.Contains(colorFGBG, ";") {
c := strings.Split(colorFGBG, ";")
i, err := strconv.Atoi(c[len(c)-1])
if err == nil {
return ANSIColor(i)
}
}
// default black
return ANSIColor(0)
}
func (o *Output) waitForData(timeout time.Duration) error {
fd := o.TTY().Fd()
tv := unix.NsecToTimeval(int64(timeout))
var readfds unix.FdSet
readfds.Set(int(fd))
for {
n, err := unix.Select(int(fd)+1, &readfds, nil, nil, &tv)
if err == unix.EINTR {
continue
}
if err != nil {
return err
}
if n == 0 {
return fmt.Errorf("timeout")
}
break
}
return nil
}
func (o *Output) readNextByte() (byte, error) {
if !o.unsafe {
if err := o.waitForData(OSCTimeout); err != nil {
return 0, err
}
}
var b [1]byte
n, err := o.TTY().Read(b[:])
if err != nil {
return 0, err
}
if n == 0 {
panic("read returned no data")
}
return b[0], nil
}
// readNextResponse reads either an OSC response or a cursor position response:
// - OSC response: "\x1b]11;rgb:1111/1111/1111\x1b\\"
// - cursor position response: "\x1b[42;1R"
func (o *Output) readNextResponse() (response string, isOSC bool, err error) {
start, err := o.readNextByte()
if err != nil {
return "", false, err
}
// first byte must be ESC
for start != ESC {
start, err = o.readNextByte()
if err != nil {
return "", false, err
}
}
response += string(start)
// next byte is either '[' (cursor position response) or ']' (OSC response)
tpe, err := o.readNextByte()
if err != nil {
return "", false, err
}
response += string(tpe)
var oscResponse bool
switch tpe {
case '[':
oscResponse = false
case ']':
oscResponse = true
default:
return "", false, ErrStatusReport
}
for {
b, err := o.readNextByte()
if err != nil {
return "", false, err
}
response += string(b)
if oscResponse {
// OSC can be terminated by BEL (\a) or ST (ESC)
if b == BEL || strings.HasSuffix(response, string(ESC)) {
return response, true, nil
}
} else {
// cursor position response is terminated by 'R'
if b == 'R' {
return response, false, nil
}
}
// both responses have less than 25 bytes, so if we read more, that's an error
if len(response) > 25 {
break
}
}
return "", false, ErrStatusReport
}
func (o Output) termStatusReport(sequence int) (string, error) {
// screen/tmux can't support OSC, because they can be connected to multiple
// terminals concurrently.
term := o.environ.Getenv("TERM")
if strings.HasPrefix(term, "screen") || strings.HasPrefix(term, "tmux") {
return "", ErrStatusReport
}
tty := o.TTY()
if tty == nil {
return "", ErrStatusReport
}
if !o.unsafe {
fd := int(tty.Fd())
// if in background, we can't control the terminal
if !isForeground(fd) {
return "", ErrStatusReport
}
t, err := unix.IoctlGetTermios(fd, tcgetattr)
if err != nil {
return "", fmt.Errorf("%s: %s", ErrStatusReport, err)
}
defer unix.IoctlSetTermios(fd, tcsetattr, t) //nolint:errcheck
noecho := *t
noecho.Lflag = noecho.Lflag &^ unix.ECHO
noecho.Lflag = noecho.Lflag &^ unix.ICANON
if err := unix.IoctlSetTermios(fd, tcsetattr, &noecho); err != nil {
return "", fmt.Errorf("%s: %s", ErrStatusReport, err)
}
}
// first, send OSC query, which is ignored by terminal which do not support it
fmt.Fprintf(tty, OSC+"%d;?"+ST, sequence)
// then, query cursor position, should be supported by all terminals
fmt.Fprintf(tty, CSI+"6n")
// read the next response
res, isOSC, err := o.readNextResponse()
if err != nil {
return "", fmt.Errorf("%s: %s", ErrStatusReport, err)
}
// if this is not OSC response, then the terminal does not support it
if !isOSC {
return "", ErrStatusReport
}
// read the cursor query response next and discard the result
_, _, err = o.readNextResponse()
if err != nil {
return "", err
}
// fmt.Println("Rcvd", res[1:])
return res, nil
}
// EnableVirtualTerminalProcessing enables virtual terminal processing on
// Windows for w and returns a function that restores w to its previous state.
// On non-Windows platforms, or if w does not refer to a terminal, then it
// returns a non-nil no-op function and no error.
func EnableVirtualTerminalProcessing(_ io.Writer) (func() error, error) {
return func() error { return nil }, nil
}