diff options
Diffstat (limited to 'libgo/go/io/io.go')
| -rw-r--r-- | libgo/go/io/io.go | 42 |
1 files changed, 27 insertions, 15 deletions
diff --git a/libgo/go/io/io.go b/libgo/go/io/io.go index 2724321..1ea01d5 100644 --- a/libgo/go/io/io.go +++ b/libgo/go/io/io.go @@ -47,7 +47,7 @@ var EOF = errors.New("EOF") // middle of reading a fixed-size block or data structure. var ErrUnexpectedEOF = errors.New("unexpected EOF") -// ErrNoProgress is returned by some clients of an Reader when +// ErrNoProgress is returned by some clients of a Reader when // many calls to Read have failed to return any data or error, // usually the sign of a broken Reader implementation. var ErrNoProgress = errors.New("multiple Read calls return no data or error") @@ -113,11 +113,12 @@ type Closer interface { // SeekCurrent means relative to the current offset, and // SeekEnd means relative to the end. // Seek returns the new offset relative to the start of the -// file and an error, if any. +// file or an error, if any. // // Seeking to an offset before the start of the file is an error. -// Seeking to any positive offset is legal, but the behavior of subsequent -// I/O operations on the underlying object is implementation-dependent. +// Seeking to any positive offset may be allowed, but if the new offset exceeds +// the size of the underlying object the behavior of subsequent I/O operations +// is implementation-dependent. type Seeker interface { Seek(offset int64, whence int) (int64, error) } @@ -261,10 +262,11 @@ type ByteReader interface { // ByteScanner is the interface that adds the UnreadByte method to the // basic ReadByte method. // -// UnreadByte causes the next call to ReadByte to return the same byte -// as the previous call to ReadByte. -// It may be an error to call UnreadByte twice without an intervening -// call to ReadByte. +// UnreadByte causes the next call to ReadByte to return the last byte read. +// If the last operation was not a successful call to ReadByte, UnreadByte may +// return an error, unread the last byte read (or the byte prior to the +// last-unread byte), or (in implementations that support the Seeker interface) +// seek to one byte before the current offset. type ByteScanner interface { ByteReader UnreadByte() error @@ -277,7 +279,7 @@ type ByteWriter interface { // RuneReader is the interface that wraps the ReadRune method. // -// ReadRune reads a single UTF-8 encoded Unicode character +// ReadRune reads a single encoded Unicode character // and returns the rune and its size in bytes. If no character is // available, err will be set. type RuneReader interface { @@ -287,10 +289,11 @@ type RuneReader interface { // RuneScanner is the interface that adds the UnreadRune method to the // basic ReadRune method. // -// UnreadRune causes the next call to ReadRune to return the same rune -// as the previous call to ReadRune. -// It may be an error to call UnreadRune twice without an intervening -// call to ReadRune. +// UnreadRune causes the next call to ReadRune to return the last rune read. +// If the last operation was not a successful call to ReadRune, UnreadRune may +// return an error, unread the last rune read (or the rune prior to the +// last-unread rune), or (in implementations that support the Seeker interface) +// seek to the start of the rune before the current offset. type RuneScanner interface { RuneReader UnreadRune() error @@ -478,7 +481,16 @@ func (l *LimitedReader) Read(p []byte) (n int, err error) { // NewSectionReader returns a SectionReader that reads from r // starting at offset off and stops with EOF after n bytes. func NewSectionReader(r ReaderAt, off int64, n int64) *SectionReader { - return &SectionReader{r, off, off, off + n} + var remaining int64 + const maxint64 = 1<<63 - 1 + if off <= maxint64-n { + remaining = n + off + } else { + // Overflow, with no way to return error. + // Assume we can read up to an offset of 1<<63 - 1. + remaining = maxint64 + } + return &SectionReader{r, off, off, remaining} } // SectionReader implements Read, Seek, and ReadAt on a section @@ -585,7 +597,7 @@ func (discard) WriteString(s string) (int, error) { } var blackHolePool = sync.Pool{ - New: func() interface{} { + New: func() any { b := make([]byte, 8192) return &b }, |