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termenv_unix.go
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termenv_unix.go
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// +build darwin dragonfly freebsd linux netbsd openbsd solaris
package termenv
import (
"fmt"
"os"
"strconv"
"strings"
"golang.org/x/sys/unix"
)
func colorProfile() Profile {
term := os.Getenv("TERM")
colorTerm := os.Getenv("COLORTERM")
switch strings.ToLower(colorTerm) {
case "24bit":
fallthrough
case "truecolor":
if term == "screen" || !strings.HasPrefix(term, "screen") {
// enable TrueColor in tmux, but not for old-school screen
return TrueColor
}
case "yes":
fallthrough
case "true":
return ANSI256
}
if strings.Contains(term, "256color") {
return ANSI256
}
if strings.Contains(term, "color") {
return ANSI
}
return Ascii
}
func foregroundColor() Color {
s, err := termStatusReport(10)
if err == nil {
c, err := xTermColor(s)
if err == nil {
return c
}
}
colorFGBG := os.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 backgroundColor() Color {
s, err := termStatusReport(11)
if err == nil {
c, err := xTermColor(s)
if err == nil {
return c
}
}
colorFGBG := os.Getenv("COLORFGBG")
if strings.Contains(colorFGBG, ";") {
c := strings.Split(colorFGBG, ";")
i, err := strconv.Atoi(c[1])
if err == nil {
return ANSIColor(i)
}
}
// default black
return ANSIColor(0)
}
func readNextByte(f *os.File) (byte, error) {
var b [1]byte
n, err := f.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 readNextResponse(fd *os.File) (response string, isOSC bool, err error) {
start, err := readNextByte(fd)
if err != nil {
return "", false, err
}
// if we encounter a backslash, this is a left-over from the previous OSC
// response, which can be terminated by an optional backslash
if start == '\\' {
start, err = readNextByte(fd)
if err != nil {
return "", false, err
}
}
// first byte must be ESC
if start != '\033' {
return "", false, ErrStatusReport
}
response += string(start)
// next byte is either '[' (cursor position response) or ']' (OSC response)
tpe, err := readNextByte(fd)
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 := readNextByte(os.Stdout)
if err != nil {
return "", false, err
}
response += string(b)
if oscResponse {
// OSC can be terminated by BEL (\a) or ST (ESC)
if b == '\a' || strings.HasSuffix(response, "\033") {
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 termStatusReport(sequence int) (string, error) {
// screen/tmux can't support OSC, because they can be connected to multiple
// terminals concurrently.
term := os.Getenv("TERM")
if strings.HasPrefix(term, "screen") {
return "", ErrStatusReport
}
t, err := unix.IoctlGetTermios(unix.Stdout, tcgetattr)
if err != nil {
return "", ErrStatusReport
}
defer unix.IoctlSetTermios(unix.Stdout, tcsetattr, t)
noecho := *t
noecho.Lflag = noecho.Lflag &^ unix.ECHO
noecho.Lflag = noecho.Lflag &^ unix.ICANON
if err := unix.IoctlSetTermios(unix.Stdout, tcsetattr, &noecho); err != nil {
return "", ErrStatusReport
}
// first, send OSC query, which is ignored by terminal which do not support it
fmt.Printf("\033]%d;?\033\\", sequence)
// then, query cursor position, should be supported by all terminals
fmt.Printf("\033[6n")
// read the next response
res, isOSC, err := readNextResponse(os.Stdout)
if err != nil {
return "", 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 = readNextResponse(os.Stdout)
if err != nil {
return "", err
}
// fmt.Println("Rcvd", res[1:])
return res, nil
}