With this change we emulate a case sensitive filesystem on top of insensitive filesystems. This means we correctly pick up case-only renames and throw a case conflict error when there would be multiple files differing only in case. This safety check has a small performance hit (about 20% more filesystem operations when scanning for changes). The new advanced folder option `caseSensitiveFS` can be used to disable the safety checks, retaining the previous behavior on systems known to be fully case sensitive. Co-authored-by: Jakob Borg <jakob@kastelo.net>
141 lines
4.5 KiB
Go
141 lines
4.5 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package fs
|
|
|
|
import (
|
|
"os"
|
|
"path/filepath"
|
|
"syscall"
|
|
)
|
|
|
|
// DebugSymlinkForTestsOnly is os.Symlink taken from the 1.9.2 stdlib,
|
|
// hacked with the SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE flag to
|
|
// create symlinks when not elevated.
|
|
//
|
|
// This is not and should not be used in Syncthing code, hence the
|
|
// cumbersome name to make it obvious if this ever leaks. Nonetheless it's
|
|
// useful in tests.
|
|
func DebugSymlinkForTestsOnly(oldFs, newFS Filesystem, oldname, newname string) error {
|
|
oldname = filepath.Join(oldFs.URI(), oldname)
|
|
newname = filepath.Join(newFS.URI(), newname)
|
|
|
|
// CreateSymbolicLink is not supported before Windows Vista
|
|
if syscall.LoadCreateSymbolicLink() != nil {
|
|
return &os.LinkError{"symlink", oldname, newname, syscall.EWINDOWS}
|
|
}
|
|
|
|
// '/' does not work in link's content
|
|
oldname = filepath.FromSlash(oldname)
|
|
|
|
// need the exact location of the oldname when it's relative to determine if it's a directory
|
|
destpath := oldname
|
|
if !filepath.IsAbs(oldname) {
|
|
destpath = filepath.Dir(newname) + `\` + oldname
|
|
}
|
|
|
|
fi, err := os.Lstat(destpath)
|
|
isdir := err == nil && fi.IsDir()
|
|
|
|
n, err := syscall.UTF16PtrFromString(fixLongPath(newname))
|
|
if err != nil {
|
|
return &os.LinkError{"symlink", oldname, newname, err}
|
|
}
|
|
o, err := syscall.UTF16PtrFromString(fixLongPath(oldname))
|
|
if err != nil {
|
|
return &os.LinkError{"symlink", oldname, newname, err}
|
|
}
|
|
|
|
var flags uint32
|
|
if isdir {
|
|
flags |= syscall.SYMBOLIC_LINK_FLAG_DIRECTORY
|
|
}
|
|
flags |= 0x02 // SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE
|
|
err = syscall.CreateSymbolicLink(n, o, flags)
|
|
if err != nil {
|
|
return &os.LinkError{"symlink", oldname, newname, err}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// fixLongPath returns the extended-length (\\?\-prefixed) form of
|
|
// path when needed, in order to avoid the default 260 character file
|
|
// path limit imposed by Windows. If path is not easily converted to
|
|
// the extended-length form (for example, if path is a relative path
|
|
// or contains .. elements), or is short enough, fixLongPath returns
|
|
// path unmodified.
|
|
//
|
|
// See https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx#maxpath
|
|
func fixLongPath(path string) string {
|
|
// Do nothing (and don't allocate) if the path is "short".
|
|
// Empirically (at least on the Windows Server 2013 builder),
|
|
// the kernel is arbitrarily okay with < 248 bytes. That
|
|
// matches what the docs above say:
|
|
// "When using an API to create a directory, the specified
|
|
// path cannot be so long that you cannot append an 8.3 file
|
|
// name (that is, the directory name cannot exceed MAX_PATH
|
|
// minus 12)." Since MAX_PATH is 260, 260 - 12 = 248.
|
|
//
|
|
// The MSDN docs appear to say that a normal path that is 248 bytes long
|
|
// will work; empirically the path must be less than 248 bytes long.
|
|
if len(path) < 248 {
|
|
// Don't fix. (This is how Go 1.7 and earlier worked,
|
|
// not automatically generating the \\?\ form)
|
|
return path
|
|
}
|
|
|
|
// The extended form begins with \\?\, as in
|
|
// \\?\c:\windows\foo.txt or \\?\UNC\server\share\foo.txt.
|
|
// The extended form disables evaluation of . and .. path
|
|
// elements and disables the interpretation of / as equivalent
|
|
// to \. The conversion here rewrites / to \ and elides
|
|
// . elements as well as trailing or duplicate separators. For
|
|
// simplicity it avoids the conversion entirely for relative
|
|
// paths or paths containing .. elements. For now,
|
|
// \\server\share paths are not converted to
|
|
// \\?\UNC\server\share paths because the rules for doing so
|
|
// are less well-specified.
|
|
if len(path) >= 2 && path[:2] == `\\` {
|
|
// Don't canonicalize UNC paths.
|
|
return path
|
|
}
|
|
if !filepath.IsAbs(path) {
|
|
// Relative path
|
|
return path
|
|
}
|
|
|
|
const prefix = `\\?`
|
|
|
|
pathbuf := make([]byte, len(prefix)+len(path)+len(`\`))
|
|
copy(pathbuf, prefix)
|
|
n := len(path)
|
|
r, w := 0, len(prefix)
|
|
for r < n {
|
|
switch {
|
|
case os.IsPathSeparator(path[r]):
|
|
// empty block
|
|
r++
|
|
case path[r] == '.' && (r+1 == n || os.IsPathSeparator(path[r+1])):
|
|
// /./
|
|
r++
|
|
case r+1 < n && path[r] == '.' && path[r+1] == '.' && (r+2 == n || os.IsPathSeparator(path[r+2])):
|
|
// /../ is currently unhandled
|
|
return path
|
|
default:
|
|
pathbuf[w] = '\\'
|
|
w++
|
|
for ; r < n && !os.IsPathSeparator(path[r]); r++ {
|
|
pathbuf[w] = path[r]
|
|
w++
|
|
}
|
|
}
|
|
}
|
|
// A drive's root directory needs a trailing \
|
|
if w == len(`\\?\c:`) {
|
|
pathbuf[w] = '\\'
|
|
w++
|
|
}
|
|
return string(pathbuf[:w])
|
|
}
|