flags.go

package disko

import (
	"os"
)

////////////////////////////////////////////////////////////////////////////////
// File attribute flags

const (
	S_IXOTH = os.FileMode(1 << iota)
	S_IWOTH = os.FileMode(1 << iota)
	S_IROTH = os.FileMode(1 << iota)
	S_IXGRP = os.FileMode(1 << iota)
	S_IWGRP = os.FileMode(1 << iota)
	S_IRGRP = os.FileMode(1 << iota)
	S_IXUSR = os.FileMode(1 << iota)
	S_IWUSR = os.FileMode(1 << iota)
	S_IRUSR = os.FileMode(1 << iota)
	S_ISVTX = os.FileMode(1 << iota)
	S_ISGID = os.FileMode(1 << iota)
	S_ISUID = os.FileMode(1 << iota)
	S_IFIFO = os.FileMode(1 << iota)
	S_IFCHR = os.FileMode(1 << iota)
	S_IFDIR = os.FileMode(1 << iota)
	S_IFREG = os.FileMode(1 << iota)
)

const S_IEXEC = S_IXUSR
const S_IWRITE = S_IWUSR
const S_IREAD = S_IRUSR

const S_IFBLK = 0x6000  // 0110 0000 0000 0000
const S_IFLNK = 0xa000  // 1010 0000 0000 0000
const S_IFSOCK = 0xc000 // 1100 0000 0000 0000
const S_IFMT = 0xf000

const S_IRWXO = S_IXOTH | S_IWOTH | S_IROTH
const S_IRWXG = S_IXGRP | S_IWGRP | S_IRGRP
const S_IRWXU = S_IXUSR | S_IWUSR | S_IRUSR

const DefaultFileModeFlags = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH
const DefaultDirModeFlags = os.ModeDir | S_IRWXU | S_IXGRP | S_IRGRP | S_IXOTH | S_IROTH

////////////////////////////////////////////////////////////////////////////////

type IOFlags int

const O_RDONLY = IOFlags(0x00000000)
const O_WRONLY = IOFlags(0x00000001)
const O_RDWR = IOFlags(0x00000002)
const O_APPEND = IOFlags(0x00000008)
const O_CREATE = IOFlags(0x00000200)
const O_TRUNC = IOFlags(0x00000400)
const O_EXCL = IOFlags(0x00000800)
const O_SYNC = IOFlags(0x00002000)
const O_NOFOLLOW = IOFlags(0x00100000)
const O_DIRECTORY = IOFlags(0x00200000)
const O_TMPFILE = IOFlags(0x00800000) // Probably don't need this
const O_NOATIME = IOFlags(0x01000000)
const O_PATH = IOFlags(0x02000000)

const O_ACCMODE = O_RDONLY | O_RDWR | O_WRONLY
const osModeFlagMask = os.O_RDONLY | os.O_RDWR | os.O_WRONLY

// OSFlagsToIOFlags converts mode flags used for [os.OpenFile] into [IOFlags]
// recognized by Disko.
func OSFlagsToIOFlags(flags int) IOFlags {
	var ioFlags IOFlags

	switch flags & osModeFlagMask {
	case os.O_WRONLY:
		ioFlags = O_WRONLY
	case os.O_RDWR:
		ioFlags = O_RDWR
	default:
		ioFlags = O_RDONLY
	}

	if flags&os.O_APPEND != 0 {
		ioFlags |= O_APPEND
	}
	if flags&os.O_CREATE != 0 {
		ioFlags |= O_CREATE
	}
	if flags&os.O_EXCL != 0 {
		ioFlags |= O_EXCL
	}
	if flags&os.O_TRUNC != 0 {
		ioFlags |= O_TRUNC
	}
	if flags&os.O_SYNC != 0 {
		ioFlags |= O_SYNC
	}
	return ioFlags
}

// Append indicates if the mode flags require appending to the end of a file
// stream.
func (flags IOFlags) Append() bool {
	return flags&O_APPEND != 0
}

func (flags IOFlags) Read() bool {
	masked := flags & O_ACCMODE
	return masked == O_RDWR || masked == O_RDONLY
}

func (flags IOFlags) Write() bool {
	masked := flags & O_ACCMODE
	return masked == O_RDWR || masked == O_WRONLY
}

func (flags IOFlags) Create() bool {
	return flags&O_CREATE != 0
}

func (flags IOFlags) Truncate() bool {
	return flags&O_TRUNC != 0
}

func (flags IOFlags) Exclusive() bool {
	return flags&O_EXCL != 0
}

func (flags IOFlags) Synchronous() bool {
	return flags&O_SYNC != 0
}

func (flags IOFlags) NoFollow() bool {
	return flags&O_NOFOLLOW != 0
}

func (flags IOFlags) RequiresWritePerm() bool {
	return flags.Write() || flags.Truncate()
}