Build error with GCC 10 in NetworkInterface.c and k_standard.c

[Koichi Sakata]

Hi Andrew,

I just formatted the patch to be same as the other code.

Moreover, I saw the following code in k_standard.c.

if (_LIB_VERSION == _SVID_)
   exc.retval = zero;
else
   exc.retval = zero/zero;

Do we need to do like that in this patch? It seems to be related to the 
old matherr(), but I'm not sure about that.

Thanks,
Koichi

===== PATCH =====
diff --git a/src/java.base/share/native/libfdlibm/k_standard.c 
b/src/java.base/share/native/libfdlibm/k_standard.c
--- a/src/java.base/share/native/libfdlibm/k_standard.c
+++ b/src/java.base/share/native/libfdlibm/k_standard.c
@@ -739,6 +739,10 @@
                          errno = EDOM;
                  }
                  break;
+            default:
+                exc.retval = zero/zero;
+                errno = EINVAL;
+                break;
          }
          return exc.retval;
  }
diff --git a/src/java.base/unix/native/libnet/NetworkInterface.c 
b/src/java.base/unix/native/libnet/NetworkInterface.c
--- a/src/java.base/unix/native/libnet/NetworkInterface.c
+++ b/src/java.base/unix/native/libnet/NetworkInterface.c
@@ -1296,7 +1296,8 @@
  static int getIndex(int sock, const char *name) {
      struct ifreq if2;
      memset((char *)&if2, 0, sizeof(if2));
-    strncpy(if2.ifr_name, name, sizeof(if2.ifr_name) - 1);
+    strncpy(if2.ifr_name, name, sizeof(if2.ifr_name));
+    if2.ifr_name[sizeof(if2.ifr_name) - 1] = 0;

      if (ioctl(sock, SIOCGIFINDEX, (char *)&if2) < 0) {
          return -1;
@@ -1359,7 +1360,8 @@
  static int getFlags(int sock, const char *ifname, int *flags) {
      struct ifreq if2;
      memset((char *)&if2, 0, sizeof(if2));
-    strncpy(if2.ifr_name, ifname, sizeof(if2.ifr_name) - 1);
+    strncpy(if2.ifr_name, ifname, sizeof(if2.ifr_name));
+    if2.ifr_name[sizeof(if2.ifr_name) - 1] = 0;

      if (ioctl(sock, SIOCGIFFLAGS, (char *)&if2) < 0) {
          return -1;


On 2020/07/22 23:48, Koichi Sakata wrote:
> Hi Andrew,
> 
> Thank you for teaching me.
> I made the patch that returns NaN. Could you please sponsor it?
> 
> In this case I think it is better to fix k_standard.c itself rather than 
> ignoring the warning. However, I was able to learn there are some good 
> ways to suppress warnings. So I'd like to thank Ioi and Yasumasa.
> 
> Thanks,
> Koichi
> 
> ===== PATCH =====
> diff --git a/src/java.base/share/native/libfdlibm/k_standard.c 
> b/src/java.base/share/native/libfdlibm/k_standard.c
> --- a/src/java.base/share/native/libfdlibm/k_standard.c
> +++ b/src/java.base/share/native/libfdlibm/k_standard.c
> @@ -739,6 +739,10 @@
>                           errno = EDOM;
>                   }
>                   break;
> +            default:
> +                exc.retval = zero / zero;
> +                errno = EINVAL;
> +                break;
>           }
>           return exc.retval;
>   }
> diff --git a/src/java.base/unix/native/libnet/NetworkInterface.c 
> b/src/java.base/unix/native/libnet/NetworkInterface.c
> --- a/src/java.base/unix/native/libnet/NetworkInterface.c
> +++ b/src/java.base/unix/native/libnet/NetworkInterface.c
> @@ -1296,7 +1296,8 @@
>   static int getIndex(int sock, const char *name) {
>       struct ifreq if2;
>       memset((char *)&if2, 0, sizeof(if2));
> -    strncpy(if2.ifr_name, name, sizeof(if2.ifr_name) - 1);
> +    strncpy(if2.ifr_name, name, sizeof(if2.ifr_name));
> +    if2.ifr_name[sizeof(if2.ifr_name) - 1] = 0;
> 
>       if (ioctl(sock, SIOCGIFINDEX, (char *)&if2) < 0) {
>           return -1;
> @@ -1359,7 +1360,8 @@
>   static int getFlags(int sock, const char *ifname, int *flags) {
>       struct ifreq if2;
>       memset((char *)&if2, 0, sizeof(if2));
> -    strncpy(if2.ifr_name, ifname, sizeof(if2.ifr_name) - 1);
> +    strncpy(if2.ifr_name, ifname, sizeof(if2.ifr_name));
> +    if2.ifr_name[sizeof(if2.ifr_name) - 1] = 0;
> 
>       if (ioctl(sock, SIOCGIFFLAGS, (char *)&if2) < 0) {
>           return -1;
> 
> 
> On 2020/07/22 17:24, Andrew Haley wrote:
>> On 17/07/2020 12:26, Koichi Sakata wrote:
>>>
>>>   > You'll need to find a reviewer that understands what that
>>>   > method is supposed to do in that case, that's not me ;-)
>>>
>>> I understand. This ML is suitable for finding a reviewer, isn't it?
>>> Or, there is another way. We can avoid the error by the accepting
>>> maybe-uninitialized warning in libfdlibm instead of fixing k_standard.c.
>>
>> I think it'd be better to fix it. Although the logic is such that all of
>> the cases are covered by the switch statement in k_standard.c, the 
>> default
>> case should return NaN in retval: use zero/zero.
>>
>> I'll approve that.
>>