1
0
mirror of https://github.com/go-gitea/gitea.git synced 2024-12-04 14:46:57 -05:00
gitea/vendor/github.com/ulikunitz/xz/lzma/buffer.go
6543 12a1f914f4
Vendor Update Go Libs (#13166)
* update github.com/alecthomas/chroma v0.8.0 -> v0.8.1

* github.com/blevesearch/bleve v1.0.10 -> v1.0.12

* editorconfig-core-go v2.1.1 -> v2.3.7

* github.com/gliderlabs/ssh v0.2.2 -> v0.3.1

* migrate editorconfig.ParseBytes to Parse

* github.com/shurcooL/vfsgen to 0d455de96546

* github.com/go-git/go-git/v5 v5.1.0 -> v5.2.0

* github.com/google/uuid v1.1.1 -> v1.1.2

* github.com/huandu/xstrings v1.3.0 -> v1.3.2

* github.com/klauspost/compress v1.10.11 -> v1.11.1

* github.com/markbates/goth v1.61.2 -> v1.65.0

* github.com/mattn/go-sqlite3 v1.14.0 -> v1.14.4

* github.com/mholt/archiver v3.3.0 -> v3.3.2

* github.com/microcosm-cc/bluemonday 4f7140c49acb -> v1.0.4

* github.com/minio/minio-go v7.0.4 -> v7.0.5

* github.com/olivere/elastic v7.0.9 -> v7.0.20

* github.com/urfave/cli v1.20.0 -> v1.22.4

* github.com/prometheus/client_golang v1.1.0 -> v1.8.0

* github.com/xanzy/go-gitlab v0.37.0 -> v0.38.1

* mvdan.cc/xurls v2.1.0 -> v2.2.0

Co-authored-by: Lauris BH <lauris@nix.lv>
2020-10-16 01:06:27 -04:00

172 lines
4.0 KiB
Go
Vendored

// Copyright 2014-2019 Ulrich Kunitz. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package lzma
import (
"errors"
)
// buffer provides a circular buffer of bytes. If the front index equals
// the rear index the buffer is empty. As a consequence front cannot be
// equal rear for a full buffer. So a full buffer has a length that is
// one byte less the the length of the data slice.
type buffer struct {
data []byte
front int
rear int
}
// newBuffer creates a buffer with the given size.
func newBuffer(size int) *buffer {
return &buffer{data: make([]byte, size+1)}
}
// Cap returns the capacity of the buffer.
func (b *buffer) Cap() int {
return len(b.data) - 1
}
// Resets the buffer. The front and rear index are set to zero.
func (b *buffer) Reset() {
b.front = 0
b.rear = 0
}
// Buffered returns the number of bytes buffered.
func (b *buffer) Buffered() int {
delta := b.front - b.rear
if delta < 0 {
delta += len(b.data)
}
return delta
}
// Available returns the number of bytes available for writing.
func (b *buffer) Available() int {
delta := b.rear - 1 - b.front
if delta < 0 {
delta += len(b.data)
}
return delta
}
// addIndex adds a non-negative integer to the index i and returns the
// resulting index. The function takes care of wrapping the index as
// well as potential overflow situations.
func (b *buffer) addIndex(i int, n int) int {
// subtraction of len(b.data) prevents overflow
i += n - len(b.data)
if i < 0 {
i += len(b.data)
}
return i
}
// Read reads bytes from the buffer into p and returns the number of
// bytes read. The function never returns an error but might return less
// data than requested.
func (b *buffer) Read(p []byte) (n int, err error) {
n, err = b.Peek(p)
b.rear = b.addIndex(b.rear, n)
return n, err
}
// Peek reads bytes from the buffer into p without changing the buffer.
// Peek will never return an error but might return less data than
// requested.
func (b *buffer) Peek(p []byte) (n int, err error) {
m := b.Buffered()
n = len(p)
if m < n {
n = m
p = p[:n]
}
k := copy(p, b.data[b.rear:])
if k < n {
copy(p[k:], b.data)
}
return n, nil
}
// Discard skips the n next bytes to read from the buffer, returning the
// bytes discarded.
//
// If Discards skips fewer than n bytes, it returns an error.
func (b *buffer) Discard(n int) (discarded int, err error) {
if n < 0 {
return 0, errors.New("buffer.Discard: negative argument")
}
m := b.Buffered()
if m < n {
n = m
err = errors.New(
"buffer.Discard: discarded less bytes then requested")
}
b.rear = b.addIndex(b.rear, n)
return n, err
}
// ErrNoSpace indicates that there is insufficient space for the Write
// operation.
var ErrNoSpace = errors.New("insufficient space")
// Write puts data into the buffer. If less bytes are written than
// requested ErrNoSpace is returned.
func (b *buffer) Write(p []byte) (n int, err error) {
m := b.Available()
n = len(p)
if m < n {
n = m
p = p[:m]
err = ErrNoSpace
}
k := copy(b.data[b.front:], p)
if k < n {
copy(b.data, p[k:])
}
b.front = b.addIndex(b.front, n)
return n, err
}
// WriteByte writes a single byte into the buffer. The error ErrNoSpace
// is returned if no single byte is available in the buffer for writing.
func (b *buffer) WriteByte(c byte) error {
if b.Available() < 1 {
return ErrNoSpace
}
b.data[b.front] = c
b.front = b.addIndex(b.front, 1)
return nil
}
// prefixLen returns the length of the common prefix of a and b.
func prefixLen(a, b []byte) int {
if len(a) > len(b) {
a, b = b, a
}
for i, c := range a {
if b[i] != c {
return i
}
}
return len(a)
}
// matchLen returns the length of the common prefix for the given
// distance from the rear and the byte slice p.
func (b *buffer) matchLen(distance int, p []byte) int {
var n int
i := b.rear - distance
if i < 0 {
if n = prefixLen(p, b.data[len(b.data)+i:]); n < -i {
return n
}
p = p[n:]
i = 0
}
n += prefixLen(p, b.data[i:])
return n
}