fix: skiping ifconf and adding debug trait to ifconf

Author: Brijeshkrishna

libc-test/build.rs

@@ -4039,6 +4039,8 @@ fn test_linux(target: &str) {
         (struct_ == "sockaddr_vm" && field == "svm_zero") ||
         // the `ifr_ifru` field is an anonymous union
         (struct_ == "ifreq" && field == "ifr_ifru") ||
+        // the `ifc_ifcu` field is an anonymous union
+        (struct_ == "ifconf" && field == "ifc_ifcu") ||
         // glibc uses a single array `uregs` instead of individual fields.
         (struct_ == "user_regs" && arm)
     });

src/unix/linux_like/linux/mod.rs

@@ -792,17 +792,21 @@ s_no_extra_traits! {
         pub ifr_ifru: ::sockaddr,
     }
 
+    #[cfg(libc_union)]
     pub union __c_anonymous_ifc_ifcu {
-        ifcu_buf: *mut ::c_char,
-        ifcu_req: *mut ::ifreq,
+        pub ifcu_buf: *mut ::c_char,
+        pub ifcu_req: *mut ::ifreq,
     }
 
     /*  Structure used in SIOCGIFCONF request.  Used to retrieve interface
-        configuration for machine (useful for programs which must know all
-        networks accessible).  */
+    configuration for machine (useful for programs which must know all
+    networks accessible).  */
     pub struct ifconf {
         pub ifc_len: ::c_int,       /* Size of buffer.  */
+        #[cfg(libc_union)]
         pub ifc_ifcu: __c_anonymous_ifc_ifcu,
+        #[cfg(not(libc_union))]
+        pub ifc_ifcu: *mut ::ifreq,
     }
 
     pub struct hwtstamp_config {
@@ -1241,7 +1245,23 @@ cfg_if! {
                     .finish()
             }
         }
-
+        #[cfg(libc_union)]
+        impl ::fmt::Debug for __c_anonymous_ifc_ifcu {
+            fn fmt(&self, f: &mut ::fmt::Formatter) -> ::fmt::Result {
+                f.debug_struct("ifr_ifru")
+                    .field("ifcu_buf", unsafe { &self.ifcu_buf })
+                    .field("ifcu_req", unsafe { &self.ifcu_req })
+                    .finish()
+            }
+        }
+        impl ::fmt::Debug for ifconf {
+            fn fmt(&self, f: &mut ::fmt::Formatter) -> ::fmt::Result {
+                f.debug_struct("ifconf")
+                    .field("ifc_len", &self.ifc_len)
+                    .field("ifc_ifcu", &self.ifc_ifcu)
+                    .finish()
+            }
+        }
         impl ::fmt::Debug for hwtstamp_config {
             fn fmt(&self, f: &mut ::fmt::Formatter) -> ::fmt::Result {
                 f.debug_struct("hwtstamp_config")