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package sysfs
import (
"os"
"syscall"
"github.com/tetratelabs/wazero/experimental/sys"
)
func rename(from, to string) sys.Errno {
if from == to {
return 0
}
var fromIsDir, toIsDir bool
if fromStat, errno := stat(from); errno != 0 {
return errno // failed to stat from
} else {
fromIsDir = fromStat.Mode.IsDir()
}
if toStat, errno := stat(to); errno == sys.ENOENT {
return syscallRename(from, to) // file or dir to not-exist is ok
} else if errno != 0 {
return errno // failed to stat to
} else {
toIsDir = toStat.Mode.IsDir()
}
// Now, handle known cases
switch {
case !fromIsDir && toIsDir: // file to dir
return sys.EISDIR
case !fromIsDir && !toIsDir: // file to file
// Use os.Rename instead of syscall.Rename to overwrite a file.
// This uses MoveFileEx instead of MoveFile (used by syscall.Rename).
return sys.UnwrapOSError(os.Rename(from, to))
case fromIsDir && !toIsDir: // dir to file
return sys.ENOTDIR
default: // dir to dir
// We can't tell if a directory is empty or not, via stat information.
// Reading the directory is expensive, as it can buffer large amounts
// of data on fail. Instead, speculatively try to remove the directory.
// This is only one syscall and won't buffer anything.
if errno := rmdir(to); errno == 0 || errno == sys.ENOENT {
return syscallRename(from, to)
} else {
return errno
}
}
}
func syscallRename(from string, to string) sys.Errno {
return sys.UnwrapOSError(syscall.Rename(from, to))
}
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