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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris || zos
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package unix
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import "unsafe"
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// readInt returns the size-bytes unsigned integer in native byte order at offset off.
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func readInt(b []byte, off, size uintptr) (u uint64, ok bool) {
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	if len(b) < int(off+size) {
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		return 0, false
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	}
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	if isBigEndian {
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		return readIntBE(b[off:], size), true
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	}
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	return readIntLE(b[off:], size), true
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}
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func readIntBE(b []byte, size uintptr) uint64 {
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	switch size {
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	case 1:
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		return uint64(b[0])
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	case 2:
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		_ = b[1] // bounds check hint to compiler; see golang.org/issue/14808
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		return uint64(b[1]) | uint64(b[0])<<8
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	case 4:
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		_ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
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		return uint64(b[3]) | uint64(b[2])<<8 | uint64(b[1])<<16 | uint64(b[0])<<24
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	case 8:
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		_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
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		return uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 |
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			uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56
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	default:
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		panic("syscall: readInt with unsupported size")
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	}
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}
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func readIntLE(b []byte, size uintptr) uint64 {
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	switch size {
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	case 1:
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		return uint64(b[0])
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	case 2:
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		_ = b[1] // bounds check hint to compiler; see golang.org/issue/14808
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		return uint64(b[0]) | uint64(b[1])<<8
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	case 4:
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		_ = b[3] // bounds check hint to compiler; see golang.org/issue/14808
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		return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24
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	case 8:
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		_ = b[7] // bounds check hint to compiler; see golang.org/issue/14808
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		return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
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			uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
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	default:
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		panic("syscall: readInt with unsupported size")
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	}
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}
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// ParseDirent parses up to max directory entries in buf,
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// appending the names to names. It returns the number of
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// bytes consumed from buf, the number of entries added
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// to names, and the new names slice.
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func ParseDirent(buf []byte, max int, names []string) (consumed int, count int, newnames []string) {
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	origlen := len(buf)
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	count = 0
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	for max != 0 && len(buf) > 0 {
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		reclen, ok := direntReclen(buf)
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		if !ok || reclen > uint64(len(buf)) {
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			return origlen, count, names
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		}
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		rec := buf[:reclen]
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		buf = buf[reclen:]
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		ino, ok := direntIno(rec)
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		if !ok {
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			break
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		}
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		if ino == 0 { // File absent in directory.
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			continue
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		}
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		const namoff = uint64(unsafe.Offsetof(Dirent{}.Name))
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		namlen, ok := direntNamlen(rec)
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		if !ok || namoff+namlen > uint64(len(rec)) {
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			break
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		}
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		name := rec[namoff : namoff+namlen]
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		for i, c := range name {
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			if c == 0 {
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				name = name[:i]
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				break
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			}
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		}
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		// Check for useless names before allocating a string.
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		if string(name) == "." || string(name) == ".." {
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			continue
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		}
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		max--
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		count++
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		names = append(names, string(name))
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	}
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	return origlen - len(buf), count, names
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}
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