1 files changed, 110 insertions, 0 deletions
diff --git a/nexgb/auth.go b/nexgb/auth.go
new file mode 100644
index 0000000..ec51d10
--- /dev/null
+++ b/nexgb/auth.go
@@ -0,0 +1,110 @@
+package xgb
+
+/*
+auth.go contains functions to facilitate the parsing of .Xauthority files.
+
+It is largely unmodified from the original XGB package that I forked.
+*/
+
+import (
+	"encoding/binary"
+	"errors"
+	"io"
+	"os"
+)
+
+// readAuthority reads the X authority file for the DISPLAY.
+// If hostname == "" or hostname == "localhost",
+// then use the system's hostname (as returned by os.Hostname) instead.
+func readAuthority(hostname, display string) (
+	name string, data []byte, err error) {
+
+	// b is a scratch buffer to use and should be at least 256 bytes long
+	// (i.e. it should be able to hold a hostname).
+	b := make([]byte, 256)
+
+	// As per /usr/include/X11/Xauth.h.
+	const familyLocal = 256
+	const familyWild = 65535
+
+	if len(hostname) == 0 || hostname == "localhost" {
+		hostname, err = os.Hostname()
+		if err != nil {
+			return "", nil, err
+		}
+	}
+
+	fname := os.Getenv("XAUTHORITY")
+	if len(fname) == 0 {
+		home := os.Getenv("HOME")
+		if len(home) == 0 {
+			err = errors.New("Xauthority not found: $XAUTHORITY, $HOME not set")
+			return "", nil, err
+		}
+		fname = home + "/.Xauthority"
+	}
+
+	r, err := os.Open(fname)
+	if err != nil {
+		return "", nil, err
+	}
+	defer r.Close()
+
+	for {
+		var family uint16
+		if err := binary.Read(r, binary.BigEndian, &family); err != nil {
+			return "", nil, err
+		}
+
+		addr, err := getString(r, b)
+		if err != nil {
+			return "", nil, err
+		}
+
+		disp, err := getString(r, b)
+		if err != nil {
+			return "", nil, err
+		}
+
+		name0, err := getString(r, b)
+		if err != nil {
+			return "", nil, err
+		}
+
+		data0, err := getBytes(r, b)
+		if err != nil {
+			return "", nil, err
+		}
+
+		addrmatch := (family == familyWild) ||
+			(family == familyLocal && addr == hostname)
+		dispmatch := (disp == "") || (disp == display)
+
+		if addrmatch && dispmatch {
+			return name0, data0, nil
+		}
+	}
+	panic("unreachable")
+}
+
+func getBytes(r io.Reader, b []byte) ([]byte, error) {
+	var n uint16
+	if err := binary.Read(r, binary.BigEndian, &n); err != nil {
+		return nil, err
+	} else if n > uint16(len(b)) {
+		return nil, errors.New("bytes too long for buffer")
+	}
+
+	if _, err := io.ReadFull(r, b[0:n]); err != nil {
+		return nil, err
+	}
+	return b[0:n], nil
+}
+
+func getString(r io.Reader, b []byte) (string, error) {
+	b, err := getBytes(r, b)
+	if err != nil {
+		return "", err
+	}
+	return string(b), nil
+}