Auto merge of #2960 - folkertdev:linux-ifreq, r=JohnTitor

implement ifreq for linux

defines the `ifreq` struct, for use with `ioctl`. I used the definition from the [manpages](https://man7.org/linux/man-pages/man7/netdevice.7.html)

libc-test/build.rs

@@ -2887,6 +2887,7 @@ fn test_linux(target: &str) {
         "linux/if_ether.h",
         "linux/if_tun.h",
         "linux/input.h",
+        "linux/ipv6.h",
         "linux/keyctl.h",
         "linux/magic.h",
         "linux/memfd.h",
@@ -3479,7 +3480,9 @@ fn test_linux(target: &str) {
         (struct_ == "user_fpsimd_struct" && field == "vregs") ||
         // Linux >= 5.11 tweaked the `svm_zero` field of the `sockaddr_vm` struct.
         // https://github.com/torvalds/linux/commit/dc8eeef73b63ed8988224ba6b5ed19a615163a7f
-        (struct_ == "sockaddr_vm" && field == "svm_zero")
+        (struct_ == "sockaddr_vm" && field == "svm_zero") ||
+        // the `ifr_ifru` field is an anonymous union
+        (struct_ == "ifreq" && field == "ifr_ifru")
     });
 
     cfg.skip_roundtrip(move |s| match s {

libc-test/semver/linux.txt

@@ -2971,6 +2971,8 @@ idtype_t
 if_freenameindex
 if_nameindex
 ifaddrs
+ifreq
+in6_ifreq
 in6_pktinfo
 in6_rtmsg
 in_pktinfo

src/unix/linux_like/linux/mod.rs

@@ -603,6 +603,21 @@ s! {
         pub src_length: ::__u64,
         pub dest_offset: ::__u64,
     }
+
+    pub struct __c_anonymous_ifru_map {
+        pub mem_start: ::c_ulong,
+        pub mem_end: ::c_ulong,
+        pub base_addr: ::c_ushort,
+        pub irq: ::c_uchar,
+        pub dma: ::c_uchar,
+        pub port: ::c_uchar,
+    }
+
+   pub struct in6_ifreq {
+       pub ifr6_addr: ::in6_addr,
+       pub ifr6_prefixlen: u32,
+       pub ifr6_ifindex: ::c_int,
+   }
 }
 
 s_no_extra_traits! {
@@ -690,6 +705,32 @@ s_no_extra_traits! {
         #[cfg(not(all(target_arch = "x86_64", target_pointer_width = "32")))]
         pad: [::c_long; 4],
     }
+
+    #[cfg(libc_union)]
+    pub union __c_anonymous_ifr_ifru {
+        pub ifru_addr: ::sockaddr,
+        pub ifru_dstaddr: ::sockaddr,
+        pub ifru_broadaddr: ::sockaddr,
+        pub ifru_netmask: ::sockaddr,
+        pub ifru_hwaddr: ::sockaddr,
+        pub ifru_flags: ::c_short,
+        pub ifru_ifindex: ::c_int,
+        pub ifru_metric: ::c_int,
+        pub ifru_mtu: ::c_int,
+        pub ifru_map: __c_anonymous_ifru_map,
+        pub ifru_slave: [::c_char; ::IFNAMSIZ],
+        pub ifru_newname: [::c_char; ::IFNAMSIZ],
+        pub ifru_data: *mut ::c_char,
+    }
+
+    pub struct ifreq {
+        /// interface name, e.g. "en0"
+        pub ifr_name: [::c_char; ::IFNAMSIZ],
+        #[cfg(libc_union)]
+        pub ifr_ifru: __c_anonymous_ifr_ifru,
+        #[cfg(not(libc_union))]
+        pub ifr_ifru: ::sockaddr,
+    }
 }
 
 s_no_extra_traits! {
@@ -1063,6 +1104,34 @@ cfg_if! {
                 self.mq_curmsgs.hash(state);
             }
         }
+        #[cfg(libc_union)]
+        impl ::fmt::Debug for __c_anonymous_ifr_ifru {
+            fn fmt(&self, f: &mut ::fmt::Formatter) -> ::fmt::Result {
+                f.debug_struct("ifr_ifru")
+                    .field("ifru_addr", unsafe { &self.ifru_addr })
+                    .field("ifru_dstaddr", unsafe { &self.ifru_dstaddr })
+                    .field("ifru_broadaddr", unsafe { &self.ifru_broadaddr })
+                    .field("ifru_netmask", unsafe { &self.ifru_netmask })
+                    .field("ifru_hwaddr", unsafe { &self.ifru_hwaddr })
+                    .field("ifru_flags", unsafe { &self.ifru_flags })
+                    .field("ifru_ifindex", unsafe { &self.ifru_ifindex })
+                    .field("ifru_metric", unsafe { &self.ifru_metric })
+                    .field("ifru_mtu", unsafe { &self.ifru_mtu })
+                    .field("ifru_map", unsafe { &self.ifru_map })
+                    .field("ifru_slave", unsafe { &self.ifru_slave })
+                    .field("ifru_newname", unsafe { &self.ifru_newname })
+                    .field("ifru_data", unsafe { &self.ifru_data })
+                    .finish()
+            }
+        }
+        impl ::fmt::Debug for ifreq {
+            fn fmt(&self, f: &mut ::fmt::Formatter) -> ::fmt::Result {
+                f.debug_struct("ifreq")
+                    .field("ifr_name", &self.ifr_name)
+                    .field("ifr_ifru", &self.ifr_ifru)
+                    .finish()
+            }
+        }
     }
 }