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vis: make all logic byte-native

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The mixing of "byte" and "rune" usage made the code a little more
complicated than necessary. The benchmarks seem to indicate that this
bumps the speed of most operations up by ~3% but I would just chalk that
up to noise.

Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
This commit is contained in:
Aleksa Sarai 2025-09-23 16:53:47 +10:00
parent 38fd14f297
commit 7e2695a1be
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GPG key ID: 2897FAD2B7E9446F
1 changed files with 24 additions and 22 deletions
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46
pkg/govis/vis.go
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@ -24,24 +24,25 @@ import (
"unicode"
)
func isunsafe(ch rune) bool {
var maxAscii byte = unicode.MaxASCII // 0x7f
func isunsafe(ch byte) bool {
return ch == '\b' || ch == '\007' || ch == '\r'
}
func isglob(ch rune) bool {
func isglob(ch byte) bool {
return ch == '*' || ch == '?' || ch == '[' || ch == '#'
}
// ishttp is defined by RFC 1808.
func ishttp(ch rune) bool {
func ishttp(ch byte) bool {
// RFC1808 does not really consider characters outside of ASCII, so just to
// be safe always treat characters outside the ASCII character set as "not
// HTTP".
if ch > unicode.MaxASCII {
if ch > maxAscii {
return false
}
return unicode.IsDigit(ch) || unicode.IsLetter(ch) ||
return unicode.IsDigit(rune(ch)) || unicode.IsLetter(rune(ch)) ||
// Safe characters.
ch == '$' || ch == '-' || ch == '_' || ch == '.' || ch == '+' ||
// Extra characters.
@ -49,8 +50,13 @@ func ishttp(ch rune) bool {
ch == ')' || ch == ','
}
func isgraph(ch rune) bool {
return unicode.IsGraphic(ch) && !unicode.IsSpace(ch) && ch <= unicode.MaxASCII
func isgraph(ch byte) bool {
return ch <= maxAscii &&
unicode.IsGraphic(rune(ch)) && !unicode.IsSpace(rune(ch))
}
func isctrl(ch byte) bool {
return unicode.IsControl(rune(ch))
}
// vis converts a single *byte* into its encoding. While Go supports the
@ -60,10 +66,7 @@ func isgraph(ch rune) bool {
// the plus side this is actually a benefit on the encoding side (it will
// always work with the simple unvis(3) implementation). It also means that we
// don't have to worry about different multi-byte encodings.
func vis(output *strings.Builder, b byte, flag VisFlag) {
// Treat the single-byte character as a rune.
ch := rune(b)
func vis(output *strings.Builder, ch byte, flag VisFlag) {
// XXX: This is quite a horrible thing to support.
if flag&VisHTTPStyle == VisHTTPStyle && !ishttp(ch) {
_, _ = fmt.Fprintf(output, "%%%.2X", ch)
@ -74,7 +77,7 @@ func vis(output *strings.Builder, b byte, flag VisFlag) {
// encode most "normal" (graphical) characters as themselves unless we have
// been specifically asked not to.
switch {
case ch > unicode.MaxASCII:
case ch > maxAscii:
// We must *always* encode stuff characters not in ASCII.
case flag&VisGlob == VisGlob && isglob(ch):
// Glob characters are graphical but can be forced to be encoded.
@ -87,7 +90,7 @@ func vis(output *strings.Builder, b byte, flag VisFlag) {
flag&VisTab != VisTab && ch == '\t',
flag&VisNewline != VisNewline && ch == '\n',
flag&VisSafe != 0 && isunsafe(ch):
_ = output.WriteByte(b)
_ = output.WriteByte(ch)
return
}
@ -127,7 +130,7 @@ func vis(output *strings.Builder, b byte, flag VisFlag) {
// For graphical characters we generate octal output (and also if it's
// being forced by the caller's flags). Also spaces should always be
// encoded as octal.
// encoded as octal (note that ' '|0x80 == '\xa0' is a non-breaking space).
if flag&VisOctal == VisOctal || isgraph(ch) || ch&0x7f == ' ' {
// Always output three-character octal just to be safe.
_, _ = fmt.Fprintf(output, "\\%.3o", ch)
@ -145,21 +148,20 @@ func vis(output *strings.Builder, b byte, flag VisFlag) {
// Meta characters have 0x80 set, but are otherwise identical to control
// characters.
if b&0x80 != 0 {
b &= 0x7f
if ch&0x80 != 0 {
ch &= 0x7f
_ = output.WriteByte('M')
}
if unicode.IsControl(rune(b)) {
if isctrl(ch) {
_ = output.WriteByte('^')
if b == 0x7f {
if ch == 0x7f {
_ = output.WriteByte('?')
} else {
_ = output.WriteByte(b + '@')
_ = output.WriteByte(ch + '@')
}
} else {
_ = output.WriteByte('-')
_ = output.WriteByte(b)
_ = output.WriteByte(ch)
}
}