Fix SHM on OpenBSD

tools/utils/shm/shm.go

@@ -7,7 +7,6 @@ import (
 	"fmt"
 	"math/rand"
 	"os"
-	"path/filepath"
 	"strconv"
 	"strings"
 
@@ -86,59 +85,6 @@ func munmap(s []byte) error {
 	return unix.Munmap(s)
 }
 
-type file_based_mmap struct {
-	f        *os.File
-	region   []byte
-	unlinked bool
-}
-
-func file_mmap(f *os.File, size uint64, access AccessFlags, truncate bool) (MMap, error) {
-	if truncate {
-		err := truncate_or_unlink(f, size)
-		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}, nil
-}
-
-func (self *file_based_mmap) Name() string {
-	return filepath.Base(self.f.Name())
-}
-
-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 CreateTemp(pattern string, size uint64) (MMap, error) {
 	return create_temp(pattern, size)
 }

tools/utils/shm/shm_fs.go

@@ -4,29 +4,116 @@
 package shm
 
 import (
+	"crypto/sha256"
+	"errors"
 	"fmt"
+	"io/fs"
+	"kitty/tools/utils"
 	"os"
 	"path/filepath"
+	"runtime"
 )
 
 var _ = fmt.Print
 
-func create_temp(pattern string, size uint64) (MMap, error) {
-	pattern = modify_pattern(pattern)
-	ans, err := os.CreateTemp(SHM_DIR, pattern)
+type file_based_mmap struct {
+	f            *os.File
+	region       []byte
+	unlinked     bool
+	special_name string
+}
+
+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)
 		if err != nil {
 			return nil, err
 		}
-	return file_mmap(ans, size, WRITE, true)
+	}
+	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) Name() string {
+	if self.special_name != "" {
+		return self.special_name
+	}
+	return filepath.Base(self.f.Name())
+}
+
+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 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" {
+		hash := sha256.Sum256(utils.UnsafeStringToBytes(name))
+		return filepath.Join(SHM_DIR, utils.UnsafeBytesToString(hash[:])+".shm")
+	}
+	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 + next_random() + 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
+			}
+			return
+		}
+		break
+	}
+	return file_mmap(f, size, WRITE, true, special_name)
 }
 
 func Open(name string, size uint64) (MMap, error) {
-	if !filepath.IsAbs(name) {
-		name = filepath.Join(SHM_DIR, name)
-	}
-	ans, err := os.OpenFile(name, os.O_RDONLY, 0)
+	ans, err := os.OpenFile(file_path_from_name(name), os.O_RDONLY, 0)
 	if err != nil {
 		return nil, err
 	}
-	return file_mmap(ans, size, READ, false)
+	return file_mmap(ans, size, READ, false, name)
 }

tools/utils/shm/specific_dragonfly.go

@@ -10,7 +10,3 @@ var _ = fmt.Print
 
 // https://www.dragonflybsd.org/cgi/web-man?command=shm_open&section=3
 const SHM_DIR = "/var/run/shm"
-
-func modify_pattern(pattern string) string {
-	return pattern
-}

tools/utils/shm/specific_linux.go

@@ -9,7 +9,3 @@ import (
 var _ = fmt.Print
 
 const SHM_DIR = "/dev/shm"
-
-func modify_pattern(pattern string) string {
-	return pattern
-}

tools/utils/shm/specific_netbsd.go

@@ -9,7 +9,3 @@ import (
 var _ = fmt.Print
 
 const SHM_DIR = "/var/shm"
-
-func modify_pattern(pattern string) string {
-	return pattern
-}

tools/utils/shm/specific_openbsd.go

@@ -9,13 +9,3 @@ import (
 var _ = fmt.Print
 
 const SHM_DIR = "/tmp"
-
-func modify_pattern(pattern string) string {
-	// https://github.com/openbsd/src/blob/master/lib/libc/gen/shm_open.c
-	if strings.Contains(pattern, "*") {
-		pattern += ".shm"
-	} else {
-		pattern += "*.shm"
-	}
-	return pattern
-}