safcm: move sync_changes.go and term.go to frontend package

[safcm/safcm.git] / frontend / term.go

diff --git a/frontend/term.go b/frontend/term.go
new file mode 100644 (file)
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)
+       })
+}