X-Git-Url: https://ruderich.org/simon/gitweb/?a=blobdiff_plain;f=frontend%2Fterm.go;fp=frontend%2Fterm.go;h=f50f16264cdcae8590278e67e1f8208772b97fd1;hb=ecbcb0132728cc18016819a214378b642d92278e;hp=0000000000000000000000000000000000000000;hpb=b0f49e5d47786984e24731b200d3d3d7d6add263;p=safcm%2Fsafcm.git

diff --git a/frontend/term.go b/frontend/term.go
new file mode 100644
index 0000000..f50f162
--- /dev/null
+++ b/frontend/term.go
@@ -0,0 +1,77 @@
+// Frontend: Functions for terminal output
+
+// Copyright (C) 2021  Simon Ruderich
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package frontend
+
+import (
+	"fmt"
+	"regexp"
+)
+
+type Color int
+
+const (
+	_ Color = iota
+	ColorRed
+	ColorGreen
+	ColorCyan
+	ColorMagenta
+)
+
+func ColorString(isTTY bool, color Color, x string) string {
+	if !isTTY {
+		return x
+	}
+
+	var code string
+	switch color {
+	case ColorRed:
+		code = "31"
+	case ColorGreen:
+		code = "32"
+	case ColorMagenta:
+		code = "35"
+	case ColorCyan:
+		code = "36"
+	default:
+		panic(fmt.Sprintf("invalid color %v", color))
+	}
+	// TODO: check terminal support
+	return "\033[" + code + "m" + x + "\033[0m"
+}
+
+var escapeRegexp = regexp.MustCompile(`[\x00-\x08\x0B-\x1F\x7F]`)
+
+// EscapeControlCharacters escapes all ASCII control characters (except
+// newline and tab) by replacing them with their hex value. If the output is
+// to a TTY then the escaped characters are colored.
+//
+// This function must be used when displaying any input from remote hosts to
+// prevent terminal escape code injections.
+func EscapeControlCharacters(isTTY bool, x string) string {
+	return escapeRegexp.ReplaceAllStringFunc(x, func(x string) string {
+		if len(x) != 1 {
+			panic("invalid escapeRegexp")
+		}
+		if x == "\r" {
+			x = "\\r" // occurs often and more readable than \x0D
+		} else {
+			x = fmt.Sprintf("\\x%02X", x[0])
+		}
+		return ColorString(isTTY, ColorMagenta, x)
+	})
+}