Filter kati output to collapse verbose messages

1. Collapses the "including .../Android.mk ..." lines like ninja does,
so that we overwrite the last line if there wasn't anything else to
print.
2. Strips ansi control codes so that log files don't include unreadable
characters.

Test: m -j
Test: m -j | tee output.log   (with colored output)
Change-Id: Ib18437f6f9d37084360097a9d586800c833072c5

ui/build/util.go

@@ -15,9 +15,13 @@
 package build
 
 import (
+	"bytes"
+	"io"
 	"os"
 	"path/filepath"
 	"strings"
+	"syscall"
+	"unsafe"
 )
 
 // indexList finds the index of a string in a []string
@@ -77,3 +81,81 @@ func decodeKeyValue(str string) (string, string, bool) {
 	}
 	return str[:idx], str[idx+1:], true
 }
+
+func isTerminal(w io.Writer) bool {
+	if f, ok := w.(*os.File); ok {
+		var termios syscall.Termios
+		_, _, err := syscall.Syscall6(syscall.SYS_IOCTL, f.Fd(),
+			ioctlGetTermios, uintptr(unsafe.Pointer(&termios)),
+			0, 0, 0)
+		return err == 0
+	}
+	return false
+}
+
+func termWidth(w io.Writer) (int, bool) {
+	if f, ok := w.(*os.File); ok {
+		var winsize struct {
+			ws_row, ws_column    uint16
+			ws_xpixel, ws_ypixel uint16
+		}
+		_, _, err := syscall.Syscall6(syscall.SYS_IOCTL, f.Fd(),
+			syscall.TIOCGWINSZ, uintptr(unsafe.Pointer(&winsize)),
+			0, 0, 0)
+		return int(winsize.ws_column), err == 0
+	}
+	return 0, false
+}
+
+// stripAnsiEscapes strips ANSI control codes from a byte array in place.
+func stripAnsiEscapes(input []byte) []byte {
+	// read represents the remaining part of input that needs to be processed.
+	read := input
+	// write represents where we should be writing in input.
+	// It will share the same backing store as input so that we make our modifications
+	// in place.
+	write := input
+
+	// advance will copy count bytes from read to write and advance those slices
+	advance := func(write, read []byte, count int) ([]byte, []byte) {
+		copy(write, read[:count])
+		return write[count:], read[count:]
+	}
+
+	for {
+		// Find the next escape sequence
+		i := bytes.IndexByte(read, 0x1b)
+		// If it isn't found, or if there isn't room for <ESC>[, finish
+		if i == -1 || i+1 >= len(read) {
+			copy(write, read)
+			break
+		}
+
+		// Not a CSI code, continue searching
+		if read[i+1] != '[' {
+			write, read = advance(write, read, i+1)
+			continue
+		}
+
+		// Found a CSI code, advance up to the <ESC>
+		write, read = advance(write, read, i)
+
+		// Find the end of the CSI code
+		i = bytes.IndexFunc(read, func(r rune) bool {
+			return (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z')
+		})
+		if i == -1 {
+			// We didn't find the end of the code, just remove the rest
+			i = len(read) - 1
+		}
+
+		// Strip off the end marker too
+		i = i + 1
+
+		// Skip the reader forward and reduce final length by that amount
+		read = read[i:]
+		input = input[:len(input)-i]
+	}
+
+	return input
+}