Auto merge of #2006 - djarek:linux-can.h, r=JohnTitor

Define basic Linux SocketCAN constants and types

Add definitions from `linux/can.h`, which is a "base" header for remainder of SocketCAN functionality.

CAN bus (ISO-11898) is a communication standard used in automotive, automation and industrial solutions. Linux provides a socket-like interface to access raw CAN and protocols based on CAN, such as ISO-TP(ISO-15765) or SAE-J1939.

libc-test/build.rs

@@ -2442,6 +2442,7 @@ fn test_linux(target: &str) {
     headers! {
         cfg:
         "asm/mman.h",
+        "linux/can.h",
         "linux/dccp.h",
         "linux/errqueue.h",
         "linux/falloc.h",
@@ -2556,6 +2557,9 @@ fn test_linux(target: &str) {
     });
 
     cfg.skip_struct(move |ty| {
+        if ty.starts_with("__c_anonymous_") {
+            return true;
+        }
         match ty {
             // These cannot be tested when "resolv.h" is included and are tested
             // in the `linux_elf.rs` file.
@@ -2591,6 +2595,9 @@ fn test_linux(target: &str) {
             // which is absent in musl, has to be defined.
             "__exit_status" if musl => true,
 
+            // FIXME: CI's kernel header version is old.
+            "sockaddr_can" => true,
+
             _ => false,
         }
     });
@@ -2697,6 +2704,11 @@ fn test_linux(target: &str) {
             | "IFLA_PERM_ADDRESS"
             | "IFLA_PROTO_DOWN_REASON" => true,
 
+            // FIXME: They require recent kernel header:
+            | "CAN_J1939"
+            | "CAN_RAW_FILTER_MAX"
+            | "CAN_NPROTO" => true,
+
             _ => false,
         }
     });
@@ -2757,7 +2769,9 @@ fn test_linux(target: &str) {
         // this one is an anonymous union
         (struct_ == "ff_effect" && field == "u") ||
         // `__exit_status` type is a patch which is absent in musl
-        (struct_ == "utmpx" && field == "ut_exit" && musl)
+        (struct_ == "utmpx" && field == "ut_exit" && musl) ||
+        // `can_addr` is an anonymous union
+        (struct_ == "sockaddr_can" && field == "can_addr")
     });
 
     cfg.volatile_item(|i| {

src/unix/linux_like/linux/align.rs

@@ -52,6 +52,27 @@ macro_rules! expand_align {
                 pub fd: ::c_int,
                 pub pid: ::c_int,
             }
+
+            // linux/can.h
+            #[repr(align(8))]
+            pub struct can_frame {
+                pub can_id: canid_t,
+                pub can_dlc: u8,
+                __pad: u8,
+                __res0: u8,
+                __res1: u8,
+                pub data: [u8; CAN_MAX_DLEN],
+            }
+
+            #[repr(align(8))]
+            pub struct canfd_frame {
+                pub can_id: canid_t,
+                pub len: u8,
+                pub flags: u8,
+                __res0: u8,
+                __res1: u8,
+                pub data: [u8; CANFD_MAX_DLEN],
+            }
         }
 
         s_no_extra_traits! {

src/unix/linux_like/linux/mod.rs

@@ -36,6 +36,10 @@ pub type Elf64_Sxword = i64;
 pub type Elf32_Section = u16;
 pub type Elf64_Section = u16;
 
+// linux/can.h
+pub type canid_t = u32;
+pub type can_err_mask_t = u32;
+
 #[cfg_attr(feature = "extra_traits", derive(Debug))]
 pub enum fpos64_t {} // FIXME: fill this out with a struct
 impl ::Copy for fpos64_t {}
@@ -504,6 +508,23 @@ s! {
         pub ee_info: u32,
         pub ee_data: u32,
     }
+
+    // linux/can.h
+    pub struct __c_anonymous_sockaddr_can_tp {
+        pub rx_id: canid_t,
+        pub tx_id: canid_t,
+    }
+
+    pub struct __c_anonymous_sockaddr_can_j1939 {
+        pub name: u64,
+        pub pgn: u32,
+        pub addr: u8,
+    }
+
+    pub struct can_filter {
+        pub can_id: canid_t,
+        pub can_mask: canid_t,
+    }
 }
 
 s_no_extra_traits! {
@@ -577,6 +598,26 @@ s_no_extra_traits! {
     }
 }
 
+cfg_if! {
+    if #[cfg(libc_union)] {
+        s_no_extra_traits! {
+            // linux/can.h
+            #[allow(missing_debug_implementations)]
+            pub union __c_anonymous_sockaddr_can_can_addr {
+                pub tp: __c_anonymous_sockaddr_can_tp,
+                pub j1939: __c_anonymous_sockaddr_can_j1939,
+            }
+
+            #[allow(missing_debug_implementations)]
+            pub struct sockaddr_can {
+                pub can_family: ::sa_family_t,
+                pub can_ifindex: ::c_int,
+                pub can_addr: __c_anonymous_sockaddr_can_can_addr,
+            }
+        }
+    }
+}
+
 cfg_if! {
     if #[cfg(feature = "extra_traits")] {
         impl PartialEq for sockaddr_nl {
@@ -2584,6 +2625,46 @@ pub const EDOM: ::c_int = 33;
 pub const ERANGE: ::c_int = 34;
 pub const EWOULDBLOCK: ::c_int = EAGAIN;
 
+// linux/can.h
+pub const CAN_EFF_FLAG: canid_t = 0x80000000;
+pub const CAN_RTR_FLAG: canid_t = 0x40000000;
+pub const CAN_ERR_FLAG: canid_t = 0x20000000;
+pub const CAN_SFF_MASK: canid_t = 0x000007FF;
+pub const CAN_EFF_MASK: canid_t = 0x1FFFFFFF;
+pub const CAN_ERR_MASK: canid_t = 0x1FFFFFFF;
+
+pub const CAN_SFF_ID_BITS: ::c_int = 11;
+pub const CAN_EFF_ID_BITS: ::c_int = 29;
+
+pub const CAN_MAX_DLC: ::c_int = 8;
+pub const CAN_MAX_DLEN: usize = 8;
+pub const CANFD_MAX_DLC: ::c_int = 15;
+pub const CANFD_MAX_DLEN: usize = 64;
+
+pub const CANFD_BRS: ::c_int = 0x01;
+pub const CANFD_ESI: ::c_int = 0x02;
+
+cfg_if! {
+    if #[cfg(libc_align)] {
+        pub const CAN_MTU: usize = ::mem::size_of::<can_frame>();
+        pub const CANFD_MTU: usize = ::mem::size_of::<canfd_frame>();
+    }
+}
+
+pub const CAN_RAW: ::c_int = 1;
+pub const CAN_BCM: ::c_int = 2;
+pub const CAN_TP16: ::c_int = 3;
+pub const CAN_TP20: ::c_int = 4;
+pub const CAN_MCNET: ::c_int = 5;
+pub const CAN_ISOTP: ::c_int = 6;
+pub const CAN_J1939: ::c_int = 7;
+pub const CAN_NPROTO: ::c_int = 8;
+
+pub const SOL_CAN_BASE: ::c_int = 100;
+
+pub const CAN_INV_FILTER: canid_t = 0x20000000;
+pub const CAN_RAW_FILTER_MAX: ::c_int = 512;
+
 f! {
     pub fn NLA_ALIGN(len: ::c_int) -> ::c_int {
         return ((len) + NLA_ALIGNTO - 1) & !(NLA_ALIGNTO - 1)