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path: root/src/pkg/bufio/bufio.go
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Diffstat (limited to 'src/pkg/bufio/bufio.go')
-rw-r--r--src/pkg/bufio/bufio.go147
1 files changed, 95 insertions, 52 deletions
diff --git a/src/pkg/bufio/bufio.go b/src/pkg/bufio/bufio.go
index d1ff3c9ed..61ef26191 100644
--- a/src/pkg/bufio/bufio.go
+++ b/src/pkg/bufio/bufio.go
@@ -38,6 +38,7 @@ type Reader struct {
}
const minReadBufferSize = 16
+const maxConsecutiveEmptyReads = 100
// NewReaderSize returns a new Reader whose buffer has at least the specified
// size. If the argument io.Reader is already a Reader with large enough
@@ -87,15 +88,26 @@ func (b *Reader) fill() {
b.r = 0
}
- // Read new data.
- n, err := b.rd.Read(b.buf[b.w:])
- if n < 0 {
- panic(errNegativeRead)
+ if b.w >= len(b.buf) {
+ panic("bufio: tried to fill full buffer")
}
- b.w += n
- if err != nil {
- b.err = err
+
+ // Read new data: try a limited number of times.
+ for i := maxConsecutiveEmptyReads; i > 0; i-- {
+ n, err := b.rd.Read(b.buf[b.w:])
+ if n < 0 {
+ panic(errNegativeRead)
+ }
+ b.w += n
+ if err != nil {
+ b.err = err
+ return
+ }
+ if n > 0 {
+ return
+ }
}
+ b.err = io.ErrNoProgress
}
func (b *Reader) readErr() error {
@@ -115,8 +127,9 @@ func (b *Reader) Peek(n int) ([]byte, error) {
if n > len(b.buf) {
return nil, ErrBufferFull
}
+ // 0 <= n <= len(b.buf)
for b.w-b.r < n && b.err == nil {
- b.fill()
+ b.fill() // b.w-b.r < len(b.buf) => buffer is not full
}
m := b.w - b.r
if m > n {
@@ -142,7 +155,7 @@ func (b *Reader) Read(p []byte) (n int, err error) {
if n == 0 {
return 0, b.readErr()
}
- if b.w == b.r {
+ if b.r == b.w {
if b.err != nil {
return 0, b.readErr()
}
@@ -150,13 +163,16 @@ func (b *Reader) Read(p []byte) (n int, err error) {
// Large read, empty buffer.
// Read directly into p to avoid copy.
n, b.err = b.rd.Read(p)
+ if n < 0 {
+ panic(errNegativeRead)
+ }
if n > 0 {
b.lastByte = int(p[n-1])
b.lastRuneSize = -1
}
return n, b.readErr()
}
- b.fill()
+ b.fill() // buffer is empty
if b.w == b.r {
return 0, b.readErr()
}
@@ -176,11 +192,11 @@ func (b *Reader) Read(p []byte) (n int, err error) {
// If no byte is available, returns an error.
func (b *Reader) ReadByte() (c byte, err error) {
b.lastRuneSize = -1
- for b.w == b.r {
+ for b.r == b.w {
if b.err != nil {
return 0, b.readErr()
}
- b.fill()
+ b.fill() // buffer is empty
}
c = b.buf[b.r]
b.r++
@@ -190,19 +206,19 @@ func (b *Reader) ReadByte() (c byte, err error) {
// UnreadByte unreads the last byte. Only the most recently read byte can be unread.
func (b *Reader) UnreadByte() error {
- b.lastRuneSize = -1
- if b.r == b.w && b.lastByte >= 0 {
- b.w = 1
- b.r = 0
- b.buf[0] = byte(b.lastByte)
- b.lastByte = -1
- return nil
- }
- if b.r <= 0 {
+ if b.lastByte < 0 || b.r == 0 && b.w > 0 {
return ErrInvalidUnreadByte
}
- b.r--
+ // b.r > 0 || b.w == 0
+ if b.r > 0 {
+ b.r--
+ } else {
+ // b.r == 0 && b.w == 0
+ b.w = 1
+ }
+ b.buf[b.r] = byte(b.lastByte)
b.lastByte = -1
+ b.lastRuneSize = -1
return nil
}
@@ -210,8 +226,8 @@ func (b *Reader) UnreadByte() error {
// rune and its size in bytes. If the encoded rune is invalid, it consumes one byte
// and returns unicode.ReplacementChar (U+FFFD) with a size of 1.
func (b *Reader) ReadRune() (r rune, size int, err error) {
- for b.r+utf8.UTFMax > b.w && !utf8.FullRune(b.buf[b.r:b.w]) && b.err == nil {
- b.fill()
+ for b.r+utf8.UTFMax > b.w && !utf8.FullRune(b.buf[b.r:b.w]) && b.err == nil && b.w-b.r < len(b.buf) {
+ b.fill() // b.w-b.r < len(buf) => buffer is not full
}
b.lastRuneSize = -1
if b.r == b.w {
@@ -232,7 +248,7 @@ func (b *Reader) ReadRune() (r rune, size int, err error) {
// regard it is stricter than UnreadByte, which will unread the last byte
// from any read operation.)
func (b *Reader) UnreadRune() error {
- if b.lastRuneSize < 0 || b.r == 0 {
+ if b.lastRuneSize < 0 || b.r < b.lastRuneSize {
return ErrInvalidUnreadRune
}
b.r -= b.lastRuneSize
@@ -255,37 +271,39 @@ func (b *Reader) Buffered() int { return b.w - b.r }
// ReadBytes or ReadString instead.
// ReadSlice returns err != nil if and only if line does not end in delim.
func (b *Reader) ReadSlice(delim byte) (line []byte, err error) {
- // Look in buffer.
- if i := bytes.IndexByte(b.buf[b.r:b.w], delim); i >= 0 {
- line1 := b.buf[b.r : b.r+i+1]
- b.r += i + 1
- return line1, nil
- }
-
- // Read more into buffer, until buffer fills or we find delim.
for {
- if b.err != nil {
- line := b.buf[b.r:b.w]
- b.r = b.w
- return line, b.readErr()
+ // Search buffer.
+ if i := bytes.IndexByte(b.buf[b.r:b.w], delim); i >= 0 {
+ line = b.buf[b.r : b.r+i+1]
+ b.r += i + 1
+ break
}
- n := b.Buffered()
- b.fill()
-
- // Search new part of buffer
- if i := bytes.IndexByte(b.buf[n:b.w], delim); i >= 0 {
- line := b.buf[0 : n+i+1]
- b.r = n + i + 1
- return line, nil
+ // Pending error?
+ if b.err != nil {
+ line = b.buf[b.r:b.w]
+ b.r = b.w
+ err = b.readErr()
+ break
}
- // Buffer is full?
- if b.Buffered() >= len(b.buf) {
+ // Buffer full?
+ if n := b.Buffered(); n >= len(b.buf) {
b.r = b.w
- return b.buf, ErrBufferFull
+ line = b.buf
+ err = ErrBufferFull
+ break
}
+
+ b.fill() // buffer is not full
}
+
+ // Handle last byte, if any.
+ if i := len(line) - 1; i >= 0 {
+ b.lastByte = int(line[i])
+ }
+
+ return
}
// ReadLine is a low-level line-reading primitive. Most callers should use
@@ -301,6 +319,9 @@ func (b *Reader) ReadSlice(delim byte) (line []byte, err error) {
//
// The text returned from ReadLine does not include the line end ("\r\n" or "\n").
// No indication or error is given if the input ends without a final line end.
+// Calling UnreadByte after ReadLine will always unread the last byte read
+// (possibly a character belonging to the line end) even if that byte is not
+// part of the line returned by ReadLine.
func (b *Reader) ReadLine() (line []byte, isPrefix bool, err error) {
line, err = b.ReadSlice('\n')
if err == ErrBufferFull {
@@ -410,12 +431,24 @@ func (b *Reader) WriteTo(w io.Writer) (n int64, err error) {
return n, err
}
- for b.fill(); b.r < b.w; b.fill() {
+ if w, ok := w.(io.ReaderFrom); ok {
+ m, err := w.ReadFrom(b.rd)
+ n += m
+ return n, err
+ }
+
+ if b.w-b.r < len(b.buf) {
+ b.fill() // buffer not full
+ }
+
+ for b.r < b.w {
+ // b.r < b.w => buffer is not empty
m, err := b.writeBuf(w)
n += m
if err != nil {
return n, err
}
+ b.fill() // buffer is empty
}
if b.err == io.EOF {
@@ -428,6 +461,9 @@ func (b *Reader) WriteTo(w io.Writer) (n int64, err error) {
// writeBuf writes the Reader's buffer to the writer.
func (b *Reader) writeBuf(w io.Writer) (int64, error) {
n, err := w.Write(b.buf[b.r:b.w])
+ if n < b.r-b.w {
+ panic(errors.New("bufio: writer did not write all data"))
+ }
b.r += n
return int64(n), err
}
@@ -619,9 +655,16 @@ func (b *Writer) ReadFrom(r io.Reader) (n int64, err error) {
return n, err1
}
}
- m, err = r.Read(b.buf[b.n:])
- if m == 0 {
- break
+ nr := 0
+ for nr < maxConsecutiveEmptyReads {
+ m, err = r.Read(b.buf[b.n:])
+ if m != 0 || err != nil {
+ break
+ }
+ nr++
+ }
+ if nr == maxConsecutiveEmptyReads {
+ return n, io.ErrNoProgress
}
b.n += m
n += int64(m)
generated by cgit v1.2.3 (git 2.39.1) at 2024-05-21 01:27:34 +0000