github.com/metacubex/mihomo@v1.18.5/common/net/bufconn_unsafe.go (about)

     1  package net
     2  
     3  import (
     4  	"io"
     5  	"unsafe"
     6  )
     7  
     8  // bufioReader copy from stdlib bufio/bufio.go
     9  // This structure has remained unchanged from go1.5 to go1.21.
    10  type bufioReader struct {
    11  	buf          []byte
    12  	rd           io.Reader // reader provided by the client
    13  	r, w         int       // buf read and write positions
    14  	err          error
    15  	lastByte     int // last byte read for UnreadByte; -1 means invalid
    16  	lastRuneSize int // size of last rune read for UnreadRune; -1 means invalid
    17  }
    18  
    19  func (c *BufferedConn) AppendData(buf []byte) (ok bool) {
    20  	b := (*bufioReader)(unsafe.Pointer(c.r))
    21  	pos := len(b.buf) - b.w - len(buf)
    22  	if pos >= -b.r { // len(b.buf)-(b.w - b.r) >= len(buf)
    23  		if pos < 0 { // len(b.buf)-b.w < len(buf)
    24  			// Slide existing data to beginning.
    25  			copy(b.buf, b.buf[b.r:b.w])
    26  			b.w -= b.r
    27  			b.r = 0
    28  		}
    29  
    30  		b.w += copy(b.buf[b.w:], buf)
    31  		return true
    32  	}
    33  	return false
    34  }