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message should not be chunked

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This commit is contained in:
hslam 2020-11-28 16:04:08 +08:00
parent 42ac113bcc
commit e89ebdacd9
2 changed files with 18 additions and 32 deletions
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2
msg_test.go
View File

@ -8,7 +8,7 @@ import (
)
func TestMsg(t *testing.T) {
context := strings.Repeat("1", maxText+1)
context := strings.Repeat("1", 128)
done := make(chan struct{})
go func() {
key, err := ftok.Ftok("/tmp", 0x22)

48
msg_unix.go
View File

@ -4,6 +4,7 @@
package msg
import (
"errors"
"syscall"
"unsafe"
)
@ -15,12 +16,14 @@ const (
// IPC_RMID removes identifier
IPC_RMID = 0
maxText = 512
maxText = 8192
)
// ErrTooLong is returned when the Text length is bigger than maxText.
var ErrTooLong = errors.New("Text length is too long")
type message struct {
Type uint
flag uint8
Text [maxText]byte
}
@ -41,26 +44,14 @@ func Get(key int, msgflg int) (uintptr, error) {
// Snd calls the msgsnd system call.
func Snd(msgid uintptr, msg *Msg, flags uint) error {
offset := 0
if len(msg.Text) > maxText {
return ErrTooLong
}
m := message{Type: msg.Type}
for len(msg.Text)-offset > 0 {
if len(msg.Text)-offset > maxText {
m.flag = 1
copy(m.Text[:], msg.Text[offset:offset+maxText])
_, _, err := syscall.Syscall6(syscall.SYS_MSGSND, msgid, uintptr(unsafe.Pointer(&m)), 1+maxText, uintptr(flags), 0, 0)
if err != 0 {
return err
}
offset += maxText
} else {
m.flag = 0
copy(m.Text[:], msg.Text[offset:len(msg.Text)])
_, _, err := syscall.Syscall6(syscall.SYS_MSGSND, msgid, uintptr(unsafe.Pointer(&m)), 1+uintptr(len(msg.Text)-offset), uintptr(flags), 0, 0)
if err != 0 {
return err
}
offset += len(msg.Text) - offset
}
copy(m.Text[:], msg.Text)
_, _, err := syscall.Syscall6(syscall.SYS_MSGSND, msgid, uintptr(unsafe.Pointer(&m)), uintptr(len(msg.Text)), uintptr(flags), 0, 0)
if err != 0 {
return err
}
return nil
}
@ -68,17 +59,12 @@ func Snd(msgid uintptr, msg *Msg, flags uint) error {
// Rcv calls the msgrcv system call.
func Rcv(msgid uintptr, msg *Msg, flags uint) error {
m := message{Type: msg.Type}
for {
length, _, err := syscall.Syscall6(syscall.SYS_MSGRCV, msgid, uintptr(unsafe.Pointer(&m)), 1+maxText, uintptr(msg.Type), uintptr(flags), 0)
if err != 0 {
return err
}
msg.Type = m.Type
msg.Text = append(msg.Text, m.Text[:length-1]...)
if m.flag == 0 {
break
}
length, _, err := syscall.Syscall6(syscall.SYS_MSGRCV, msgid, uintptr(unsafe.Pointer(&m)), maxText, uintptr(msg.Type), uintptr(flags), 0)
if err != 0 {
return err
}
msg.Type = m.Type
msg.Text = m.Text[:length]
return nil
}