| Todd Wang | 092395e | 2014-10-29 16:15:27 -0700 | [diff] [blame] | 1 | package textutil |
| 2 | |
| 3 | import ( |
| 4 | "syscall" |
| 5 | "unsafe" |
| 6 | ) |
| 7 | |
| 8 | // TerminalSize returns the dimensions of the terminal, if it's available from |
| 9 | // the OS, otherwise returns an error. |
| 10 | func TerminalSize() (row, col int, _ error) { |
| 11 | // Try getting the terminal size from stdout, stderr and stdin respectively. |
| 12 | // We try each of these in turn because the mechanism we're using fails if any |
| 13 | // of the fds is redirected on the command line. E.g. "tool | less" redirects |
| 14 | // the stdout of tool to the stdin of less, and will mean tool cannot retrieve |
| 15 | // the terminal size from stdout. |
| 16 | // |
| 17 | // TODO(toddw): This probably only works on some linux / unix variants; add |
| 18 | // build tags and support different platforms. |
| 19 | if row, col, err := terminalSize(syscall.Stdout); err == nil { |
| 20 | return row, col, err |
| 21 | } |
| 22 | if row, col, err := terminalSize(syscall.Stderr); err == nil { |
| 23 | return row, col, err |
| 24 | } |
| 25 | return terminalSize(syscall.Stdin) |
| 26 | } |
| 27 | |
| 28 | func terminalSize(fd int) (int, int, error) { |
| 29 | var ws winsize |
| 30 | if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, uintptr(fd), uintptr(syscall.TIOCGWINSZ), uintptr(unsafe.Pointer(&ws))); err != 0 { |
| 31 | return 0, 0, err |
| 32 | } |
| 33 | return int(ws.row), int(ws.col), nil |
| 34 | } |
| 35 | |
| 36 | // winsize must correspond to the struct defined in "sys/ioctl.h". Do not |
| 37 | // export this struct; it's a platform-specific implementation detail. |
| 38 | type winsize struct { |
| 39 | row, col, xpixel, ypixel uint16 |
| 40 | } |
