120 lines
2.6 KiB
Go
120 lines
2.6 KiB
Go
// License: GPLv3 Copyright: 2022, Kovid Goyal, <kovid at kovidgoyal.net>
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//go:build linux || netbsd || openbsd || dragonfly
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package shm
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import (
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"crypto/sha256"
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"errors"
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"fmt"
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"io/fs"
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"kitty/tools/utils"
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"os"
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"path/filepath"
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"runtime"
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)
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var _ = fmt.Print
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type file_based_mmap struct {
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f *os.File
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region []byte
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unlinked bool
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special_name string
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}
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func file_mmap(f *os.File, size uint64, access AccessFlags, truncate bool, special_name string) (MMap, error) {
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if truncate {
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err := truncate_or_unlink(f, size)
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if err != nil {
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return nil, err
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}
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}
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region, err := mmap(int(size), access, int(f.Fd()), 0)
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if err != nil {
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f.Close()
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os.Remove(f.Name())
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return nil, err
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}
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return &file_based_mmap{f: f, region: region, special_name: special_name}, nil
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}
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func (self *file_based_mmap) Name() string {
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if self.special_name != "" {
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return self.special_name
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}
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return filepath.Base(self.f.Name())
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}
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func (self *file_based_mmap) FileSystemName() string {
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return self.f.Name()
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}
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func (self *file_based_mmap) Slice() []byte {
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return self.region
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}
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func (self *file_based_mmap) Close() (err error) {
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if self.region != nil {
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self.f.Close()
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err = munmap(self.region)
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self.region = nil
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}
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return err
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}
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func (self *file_based_mmap) Unlink() (err error) {
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if self.unlinked {
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return nil
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}
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self.unlinked = true
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return os.Remove(self.f.Name())
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}
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func (self *file_based_mmap) IsFileSystemBacked() bool { return true }
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func file_path_from_name(name string) string {
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// See https://github.com/openbsd/src/blob/master/lib/libc/gen/shm_open.c
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if runtime.GOOS == "openbsd" {
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hash := sha256.Sum256(utils.UnsafeStringToBytes(name))
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return filepath.Join(SHM_DIR, utils.UnsafeBytesToString(hash[:])+".shm")
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}
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return filepath.Join(SHM_DIR, name)
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}
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func create_temp(pattern string, size uint64) (ans MMap, err error) {
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special_name := ""
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var prefix, suffix string
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prefix, suffix, err = prefix_and_suffix(pattern)
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if err != nil {
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return
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}
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var f *os.File
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try := 0
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for {
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name := prefix + next_random() + suffix
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path := file_path_from_name(name)
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f, err = os.OpenFile(path, os.O_EXCL|os.O_CREATE|os.O_RDWR, 0600)
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if err != nil {
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if errors.Is(err, fs.ErrExist) {
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try += 1
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if try > 10000 {
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return nil, &os.PathError{Op: "createtemp", Path: prefix + "*" + suffix, Err: fs.ErrExist}
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}
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continue
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}
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return
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}
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break
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}
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return file_mmap(f, size, WRITE, true, special_name)
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}
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func Open(name string, size uint64) (MMap, error) {
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ans, err := os.OpenFile(file_path_from_name(name), os.O_RDONLY, 0)
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if err != nil {
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return nil, err
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}
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return file_mmap(ans, size, READ, false, name)
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}
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