Source file src/pkg/os/dir_unix.go

     1	// Copyright 2009 The Go Authors. All rights reserved.
     2	// Use of this source code is governed by a BSD-style
     3	// license that can be found in the LICENSE file.
     4	
     5	// +build aix dragonfly freebsd js,wasm linux nacl netbsd openbsd solaris
     6	
     7	package os
     8	
     9	import (
    10		"io"
    11		"runtime"
    12		"syscall"
    13	)
    14	
    15	// Auxiliary information if the File describes a directory
    16	type dirInfo struct {
    17		buf  []byte // buffer for directory I/O
    18		nbuf int    // length of buf; return value from Getdirentries
    19		bufp int    // location of next record in buf.
    20	}
    21	
    22	const (
    23		// More than 5760 to work around https://golang.org/issue/24015.
    24		blockSize = 8192
    25	)
    26	
    27	func (d *dirInfo) close() {}
    28	
    29	func (f *File) readdirnames(n int) (names []string, err error) {
    30		// If this file has no dirinfo, create one.
    31		if f.dirinfo == nil {
    32			f.dirinfo = new(dirInfo)
    33			// The buffer must be at least a block long.
    34			f.dirinfo.buf = make([]byte, blockSize)
    35		}
    36		d := f.dirinfo
    37	
    38		size := n
    39		if size <= 0 {
    40			size = 100
    41			n = -1
    42		}
    43	
    44		names = make([]string, 0, size) // Empty with room to grow.
    45		for n != 0 {
    46			// Refill the buffer if necessary
    47			if d.bufp >= d.nbuf {
    48				d.bufp = 0
    49				var errno error
    50				d.nbuf, errno = f.pfd.ReadDirent(d.buf)
    51				runtime.KeepAlive(f)
    52				if errno != nil {
    53					return names, wrapSyscallError("readdirent", errno)
    54				}
    55				if d.nbuf <= 0 {
    56					break // EOF
    57				}
    58			}
    59	
    60			// Drain the buffer
    61			var nb, nc int
    62			nb, nc, names = syscall.ParseDirent(d.buf[d.bufp:d.nbuf], n, names)
    63			d.bufp += nb
    64			n -= nc
    65		}
    66		if n >= 0 && len(names) == 0 {
    67			return names, io.EOF
    68		}
    69		return names, nil
    70	}
    71	

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