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// License: GPLv3 Copyright: 2022, Kovid Goyal, <kovid at kovidgoyal.net>
//go:build linux || netbsd || openbsd || dragonfly
package shm
import (
"crypto/sha256"
"errors"
"fmt"
"io"
"io/fs"
"os"
"path/filepath"
"runtime"
"strings"
"github.com/kovidgoyal/kitty/tools/utils"
"golang.org/x/sys/unix"
)
var _ = fmt.Print
type file_based_mmap struct {
f *os.File
pos int64
region []byte
unlinked bool
special_name string
}
func ShmUnlink(name string) error {
if runtime.GOOS == "openbsd" {
return os.Remove(openbsd_shm_path(name))
}
if strings.HasPrefix(name, "/") {
name = name[1:]
}
return os.Remove(filepath.Join(SHM_DIR, name))
}
func file_mmap(f *os.File, size uint64, access AccessFlags, truncate bool, special_name string) (MMap, error) {
if truncate {
err := truncate_or_unlink(f, size, os.Remove)
if err != nil {
return nil, err
}
}
region, err := mmap(int(size), access, int(f.Fd()), 0)
if err != nil {
f.Close()
os.Remove(f.Name())
return nil, err
}
return &file_based_mmap{f: f, region: region, special_name: special_name}, nil
}
func (self *file_based_mmap) Seek(offset int64, whence int) (ret int64, err error) {
switch whence {
case io.SeekStart:
self.pos = offset
case io.SeekEnd:
self.pos = int64(len(self.region)) + offset
case io.SeekCurrent:
self.pos += offset
}
return self.pos, nil
}
func (self *file_based_mmap) Read(b []byte) (n int, err error) {
return Read(self, b)
}
func (self *file_based_mmap) Write(b []byte) (n int, err error) {
return Write(self, b)
}
func (self *file_based_mmap) Stat() (fs.FileInfo, error) {
return self.f.Stat()
}
func (self *file_based_mmap) Name() string {
if self.special_name != "" {
return self.special_name
}
return filepath.Base(self.f.Name())
}
func (self *file_based_mmap) Flush() error {
return unix.Msync(self.region, unix.MS_SYNC)
}
func (self *file_based_mmap) FileSystemName() string {
return self.f.Name()
}
func (self *file_based_mmap) Slice() []byte {
return self.region
}
func (self *file_based_mmap) Close() (err error) {
if self.region != nil {
self.f.Close()
err = munmap(self.region)
self.region = nil
}
return err
}
func (self *file_based_mmap) Unlink() (err error) {
if self.unlinked {
return nil
}
self.unlinked = true
return os.Remove(self.f.Name())
}
func (self *file_based_mmap) IsFileSystemBacked() bool { return true }
func openbsd_shm_path(name string) string {
hash := sha256.Sum256(utils.UnsafeStringToBytes(name))
return filepath.Join(SHM_DIR, utils.UnsafeBytesToString(hash[:])+".shm")
}
func file_path_from_name(name string) string {
// See https://github.com/openbsd/src/blob/master/lib/libc/gen/shm_open.c
if runtime.GOOS == "openbsd" {
return openbsd_shm_path(name)
}
return filepath.Join(SHM_DIR, name)
}
func create_temp(pattern string, size uint64) (ans MMap, err error) {
special_name := ""
var prefix, suffix string
prefix, suffix, err = prefix_and_suffix(pattern)
if err != nil {
return
}
var f *os.File
try := 0
for {
name := prefix + utils.RandomFilename() + suffix
path := file_path_from_name(name)
f, err = os.OpenFile(path, os.O_EXCL|os.O_CREATE|os.O_RDWR, 0600)
if err != nil {
if errors.Is(err, fs.ErrExist) {
try += 1
if try > 10000 {
return nil, &os.PathError{Op: "createtemp", Path: prefix + "*" + suffix, Err: fs.ErrExist}
}
continue
}
if errors.Is(err, fs.ErrNotExist) {
return nil, &ErrNotSupported{err: err}
}
return
}
break
}
return file_mmap(f, size, WRITE, true, special_name)
}
func open(name string) (*os.File, error) {
ans, err := os.OpenFile(file_path_from_name(name), os.O_RDONLY, 0)
if err != nil {
if errors.Is(err, fs.ErrNotExist) {
if _, serr := os.Stat(SHM_DIR); serr != nil && errors.Is(serr, fs.ErrNotExist) {
return nil, &ErrNotSupported{err: serr}
}
}
return nil, err
}
return ans, nil
}
func Open(name string, size uint64) (MMap, error) {
ans, err := open(name)
if err != nil {
return nil, err
}
if size == 0 {
s, err := ans.Stat()
if err != nil {
ans.Close()
return nil, fmt.Errorf("Failed to stat SHM file with error: %w", err)
}
size = uint64(s.Size())
}
return file_mmap(ans, size, READ, false, name)
}
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