libgo: Update to current sources.

[thirdparty/gcc.git] / libgo / go / unicode / utf8 / utf8.go

diff --git a/libgo/go/unicode/utf8/utf8.go b/libgo/go/unicode/utf8/utf8.go
index 57ea19e96d4e0b2f9b7b9c112aae6d4efa3bab77..ad2357774069a6dedd623946f263874264416db0 100644 (file)
--- a/libgo/go/unicode/utf8/utf8.go
+++ b/libgo/go/unicode/utf8/utf8.go
@@ -18,6 +18,12 @@ const (
        UTFMax    = 4            // maximum number of bytes of a UTF-8 encoded Unicode character.
 )
 
+// Code points in the surrogate range are not valid for UTF-8.
+const (
+       surrogateMin = 0xD800
+       surrogateMax = 0xDFFF
+)
+
 const (
        t1 = 0x00 // 0000 0000
        tx = 0x80 // 1000 0000
@@ -34,7 +40,6 @@ const (
        rune1Max = 1<<7 - 1
        rune2Max = 1<<11 - 1
        rune3Max = 1<<16 - 1
-       rune4Max = 1<<21 - 1
 )
 
 func decodeRuneInternal(p []byte) (r rune, size int, short bool) {
@@ -87,6 +92,9 @@ func decodeRuneInternal(p []byte) (r rune, size int, short bool) {
                if r <= rune2Max {
                        return RuneError, 1, false
                }
+               if surrogateMin <= r && r <= surrogateMax {
+                       return RuneError, 1, false
+               }
                return r, 3, false
        }
 
@@ -102,7 +110,7 @@ func decodeRuneInternal(p []byte) (r rune, size int, short bool) {
        // 4-byte, 21-bit sequence?
        if c0 < t5 {
                r = rune(c0&mask4)<<18 | rune(c1&maskx)<<12 | rune(c2&maskx)<<6 | rune(c3&maskx)
-               if r <= rune3Max {
+               if r <= rune3Max || MaxRune < r {
                        return RuneError, 1, false
                }
                return r, 4, false
@@ -162,6 +170,9 @@ func decodeRuneInStringInternal(s string) (r rune, size int, short bool) {
                if r <= rune2Max {
                        return RuneError, 1, false
                }
+               if surrogateMin <= r && r <= surrogateMax {
+                       return RuneError, 1, false
+               }
                return r, 3, false
        }
 
@@ -177,7 +188,7 @@ func decodeRuneInStringInternal(s string) (r rune, size int, short bool) {
        // 4-byte, 21-bit sequence?
        if c0 < t5 {
                r = rune(c0&mask4)<<18 | rune(c1&maskx)<<12 | rune(c2&maskx)<<6 | rune(c3&maskx)
-               if r <= rune3Max {
+               if r <= rune3Max || MaxRune < r {
                        return RuneError, 1, false
                }
                return r, 4, false
@@ -202,6 +213,9 @@ func FullRuneInString(s string) bool {
 
 // DecodeRune unpacks the first UTF-8 encoding in p and returns the rune and its width in bytes.
 // If the encoding is invalid, it returns (RuneError, 1), an impossible result for correct UTF-8.
+// An encoding is invalid if it is incorrect UTF-8, encodes a rune that is
+// out of range, or is not the shortest possible UTF-8 encoding for the
+// value. No other validation is performed.
 func DecodeRune(p []byte) (r rune, size int) {
        r, size, _ = decodeRuneInternal(p)
        return
@@ -209,6 +223,9 @@ func DecodeRune(p []byte) (r rune, size int) {
 
 // DecodeRuneInString is like DecodeRune but its input is a string.
 // If the encoding is invalid, it returns (RuneError, 1), an impossible result for correct UTF-8.
+// An encoding is invalid if it is incorrect UTF-8, encodes a rune that is
+// out of range, or is not the shortest possible UTF-8 encoding for the
+// value. No other validation is performed.
 func DecodeRuneInString(s string) (r rune, size int) {
        r, size, _ = decodeRuneInStringInternal(s)
        return
@@ -216,6 +233,9 @@ func DecodeRuneInString(s string) (r rune, size int) {
 
 // DecodeLastRune unpacks the last UTF-8 encoding in p and returns the rune and its width in bytes.
 // If the encoding is invalid, it returns (RuneError, 1), an impossible result for correct UTF-8.
+// An encoding is invalid if it is incorrect UTF-8, encodes a rune that is
+// out of range, or is not the shortest possible UTF-8 encoding for the
+// value. No other validation is performed.
 func DecodeLastRune(p []byte) (r rune, size int) {
        end := len(p)
        if end == 0 {
@@ -250,6 +270,9 @@ func DecodeLastRune(p []byte) (r rune, size int) {
 
 // DecodeLastRuneInString is like DecodeLastRune but its input is a string.
 // If the encoding is invalid, it returns (RuneError, 1), an impossible result for correct UTF-8.
+// An encoding is invalid if it is incorrect UTF-8, encodes a rune that is
+// out of range, or is not the shortest possible UTF-8 encoding for the
+// value. No other validation is performed.
 func DecodeLastRuneInString(s string) (r rune, size int) {
        end := len(s)
        if end == 0 {
@@ -283,15 +306,20 @@ func DecodeLastRuneInString(s string) (r rune, size int) {
 }
 
 // RuneLen returns the number of bytes required to encode the rune.
+// It returns -1 if the rune is not a valid value to encode in UTF-8.
 func RuneLen(r rune) int {
        switch {
+       case r < 0:
+               return -1
        case r <= rune1Max:
                return 1
        case r <= rune2Max:
                return 2
+       case surrogateMin <= r && r <= surrogateMax:
+               return -1
        case r <= rune3Max:
                return 3
-       case r <= rune4Max:
+       case r <= MaxRune:
                return 4
        }
        return -1
@@ -316,6 +344,10 @@ func EncodeRune(p []byte, r rune) int {
                r = RuneError
        }
 
+       if surrogateMin <= r && r <= surrogateMax {
+               r = RuneError
+       }
+
        if uint32(r) <= rune3Max {
                p[0] = t3 | byte(r>>12)
                p[1] = tx | byte(r>>6)&maskx
@@ -395,3 +427,17 @@ func ValidString(s string) bool {
        }
        return true
 }
+
+// ValidRune reports whether r can be legally encoded as UTF-8.
+// Code points that are out of range or a surrogate half are illegal.
+func ValidRune(r rune) bool {
+       switch {
+       case r < 0:
+               return false
+       case surrogateMin <= r && r <= surrogateMax:
+               return false
+       case r > MaxRune:
+               return false
+       }
+       return true
+}