bsd-user: Add message queue implementations

Add implementations for:
- msgsnd(2): Send message to queue with size validation
- msgget(2): Get message queue identifier
- msgrcv(2): Receive message from queue with size validation

Signed-off-by: Stacey Son <sson@FreeBSD.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Warner Losh <imp@bsdimp.com>

bsd-user/bsd-misc.h

@@ -17,6 +17,8 @@
 
 #include "qemu-bsd.h"
 
+static int bsd_msgmax;
+
 /* quotactl(2) */
 static inline abi_long do_bsd_quotactl(abi_ulong path, abi_long cmd,
         __unused abi_ulong target_addr)
@@ -260,6 +262,101 @@ static inline abi_long do_bsd_msgctl(int msgid, int target_cmd, abi_long ptr)
     return ret;
 }
 
+struct kern_mymsg {
+    long mtype;
+    char mtext[1];
+};
+
+static inline abi_long bsd_validate_msgsz(abi_ulong msgsz)
+{
+    /* Fetch msgmax the first time we need it. */
+    if (bsd_msgmax == 0) {
+        size_t len = sizeof(bsd_msgmax);
+
+        if (sysctlbyname("kern.ipc.msgmax", &bsd_msgmax, &len, NULL, 0) == -1) {
+            return -TARGET_EINVAL;
+        }
+    }
+
+    if (msgsz > bsd_msgmax) {
+        return -TARGET_EINVAL;
+    }
+    return 0;
+}
+
+/* msgsnd(2) */
+static inline abi_long do_bsd_msgsnd(int msqid, abi_long msgp,
+        abi_ulong msgsz, int msgflg)
+{
+    struct target_msgbuf *target_mb;
+    struct kern_mymsg *host_mb;
+    abi_long ret;
+
+    ret = bsd_validate_msgsz(msgsz);
+    if (is_error(ret)) {
+        return ret;
+    }
+    if (!lock_user_struct(VERIFY_READ, target_mb, msgp, 0)) {
+        return -TARGET_EFAULT;
+    }
+    host_mb = g_malloc(msgsz + sizeof(long));
+    host_mb->mtype = (abi_long) tswapal(target_mb->mtype);
+    memcpy(host_mb->mtext, target_mb->mtext, msgsz);
+    ret = get_errno(msgsnd(msqid, host_mb, msgsz, msgflg));
+    g_free(host_mb);
+    unlock_user_struct(target_mb, msgp, 0);
+
+    return ret;
+}
+
+/* msgget(2) */
+static inline abi_long do_bsd_msgget(abi_long key, abi_long msgflag)
+{
+    abi_long ret;
+
+    ret = get_errno(msgget(key, msgflag));
+    return ret;
+}
+
+/* msgrcv(2) */
+static inline abi_long do_bsd_msgrcv(int msqid, abi_long msgp,
+        abi_ulong msgsz, abi_long msgtyp, int msgflg)
+{
+    struct target_msgbuf *target_mb = NULL;
+    char *target_mtext;
+    struct kern_mymsg *host_mb;
+    abi_long ret = 0;
+
+    ret = bsd_validate_msgsz(msgsz);
+    if (is_error(ret)) {
+        return ret;
+    }
+    if (!lock_user_struct(VERIFY_WRITE, target_mb, msgp, 0)) {
+        return -TARGET_EFAULT;
+    }
+    host_mb = g_malloc(msgsz + sizeof(long));
+    ret = get_errno(msgrcv(msqid, host_mb, msgsz, tswapal(msgtyp), msgflg));
+    if (ret > 0) {
+        abi_ulong target_mtext_addr = msgp + sizeof(abi_ulong);
+        target_mtext = lock_user(VERIFY_WRITE, target_mtext_addr, ret, 0);
+        if (target_mtext == NULL) {
+            ret = -TARGET_EFAULT;
+            goto end;
+        }
+        memcpy(target_mb->mtext, host_mb->mtext, ret);
+        unlock_user(target_mtext, target_mtext_addr, ret);
+    }
+    if (!is_error(ret)) {
+        target_mb->mtype = tswapal(host_mb->mtype);
+    }
+end:
+    if (target_mb != NULL) {
+        unlock_user_struct(target_mb, msgp, 1);
+    }
+    g_free(host_mb);
+    return ret;
+}
+
 /* getdtablesize(2) */
 static inline abi_long do_bsd_getdtablesize(void)
 {