podman

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// Copyright (c) 2019 FOSS contributors of https://github.com/nxadm/tail
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// +build windows
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package winfile
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import (
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	"os"
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	"syscall"
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	"unsafe"
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)
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// issue also described here
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//https://codereview.appspot.com/8203043/
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// https://github.com/jnwhiteh/golang/blob/master/src/pkg/syscall/syscall_windows.go#L218
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func Open(path string, mode int, perm uint32) (fd syscall.Handle, err error) {
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	if len(path) == 0 {
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		return syscall.InvalidHandle, syscall.ERROR_FILE_NOT_FOUND
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	}
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	pathp, err := syscall.UTF16PtrFromString(path)
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	if err != nil {
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		return syscall.InvalidHandle, err
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	}
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	var access uint32
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	switch mode & (syscall.O_RDONLY | syscall.O_WRONLY | syscall.O_RDWR) {
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	case syscall.O_RDONLY:
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		access = syscall.GENERIC_READ
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	case syscall.O_WRONLY:
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		access = syscall.GENERIC_WRITE
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	case syscall.O_RDWR:
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		access = syscall.GENERIC_READ | syscall.GENERIC_WRITE
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	}
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	if mode&syscall.O_CREAT != 0 {
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		access |= syscall.GENERIC_WRITE
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	}
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	if mode&syscall.O_APPEND != 0 {
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		access &^= syscall.GENERIC_WRITE
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		access |= syscall.FILE_APPEND_DATA
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	}
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	sharemode := uint32(syscall.FILE_SHARE_READ | syscall.FILE_SHARE_WRITE | syscall.FILE_SHARE_DELETE)
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	var sa *syscall.SecurityAttributes
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	if mode&syscall.O_CLOEXEC == 0 {
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		sa = makeInheritSa()
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	}
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	var createmode uint32
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	switch {
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	case mode&(syscall.O_CREAT|syscall.O_EXCL) == (syscall.O_CREAT | syscall.O_EXCL):
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		createmode = syscall.CREATE_NEW
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	case mode&(syscall.O_CREAT|syscall.O_TRUNC) == (syscall.O_CREAT | syscall.O_TRUNC):
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		createmode = syscall.CREATE_ALWAYS
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	case mode&syscall.O_CREAT == syscall.O_CREAT:
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		createmode = syscall.OPEN_ALWAYS
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	case mode&syscall.O_TRUNC == syscall.O_TRUNC:
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		createmode = syscall.TRUNCATE_EXISTING
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	default:
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		createmode = syscall.OPEN_EXISTING
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	}
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	h, e := syscall.CreateFile(pathp, access, sharemode, sa, createmode, syscall.FILE_ATTRIBUTE_NORMAL, 0)
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	return h, e
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}
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// https://github.com/jnwhiteh/golang/blob/master/src/pkg/syscall/syscall_windows.go#L211
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func makeInheritSa() *syscall.SecurityAttributes {
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	var sa syscall.SecurityAttributes
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	sa.Length = uint32(unsafe.Sizeof(sa))
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	sa.InheritHandle = 1
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	return &sa
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}
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// https://github.com/jnwhiteh/golang/blob/master/src/pkg/os/file_windows.go#L133
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func OpenFile(name string, flag int, perm os.FileMode) (file *os.File, err error) {
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	r, e := Open(name, flag|syscall.O_CLOEXEC, syscallMode(perm))
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	if e != nil {
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		return nil, e
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	}
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	return os.NewFile(uintptr(r), name), nil
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}
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// https://github.com/jnwhiteh/golang/blob/master/src/pkg/os/file_posix.go#L61
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func syscallMode(i os.FileMode) (o uint32) {
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	o |= uint32(i.Perm())
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	if i&os.ModeSetuid != 0 {
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		o |= syscall.S_ISUID
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	}
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	if i&os.ModeSetgid != 0 {
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		o |= syscall.S_ISGID
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	}
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	if i&os.ModeSticky != 0 {
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		o |= syscall.S_ISVTX
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	}
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	// No mapping for Go's ModeTemporary (plan9 only).
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	return
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}
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