Add support for SIGSYS in signalfd

Linux 4.18 added support for SIGSYS info in signalfd. Add the new
fields to signalfd_siginfo.

While the kernel has support for these new fields now, no libc has
shipped a release with the new signalfd fields.

libc-test/build.rs

@@ -841,7 +841,13 @@ fn main() {
         // musl seems to define this as an *anonymous* bitfield
         (musl && struct_ == "statvfs" && field == "__f_unused") ||
         // sigev_notify_thread_id is actually part of a sigev_un union
-        (struct_ == "sigevent" && field == "sigev_notify_thread_id")
+        (struct_ == "sigevent" && field == "sigev_notify_thread_id") ||
+        // signalfd had SIGSYS fields added in Linux 4.18, but no libc release has them yet.
+        (struct_ == "signalfd_siginfo" && (field == "ssi_addr_lsb" ||
+                                           field == "_pad2" ||
+                                           field == "ssi_syscall" ||
+                                           field == "ssi_call_addr" ||
+                                           field == "ssi_arch"))
     });
 
     cfg.fn_cname(move |name, cname| {

src/fuchsia/mod.rs

@@ -685,7 +685,12 @@ s! {
         pub ssi_utime: ::uint64_t,
         pub ssi_stime: ::uint64_t,
         pub ssi_addr: ::uint64_t,
-        _pad: [::uint8_t; 48],
+        pub ssi_addr_lsb: ::uint16_t,
+        _pad2: ::uint16_t,
+        pub ssi_syscall: ::int32_t,
+        pub ssi_call_addr: ::uint64_t,
+        pub ssi_arch: ::uint32_t,
+        _pad: [::uint8_t; 28],
     }
 
     pub struct itimerspec {

src/unix/notbsd/android/mod.rs

@@ -172,12 +172,16 @@ s! {
         pub ssi_trapno: ::uint32_t,
         pub ssi_status: ::int32_t,
         pub ssi_int: ::int32_t,
-        pub ssi_ptr: ::c_ulonglong,
+        pub ssi_ptr: ::uint64_t,
-        pub ssi_utime: ::c_ulonglong,
+        pub ssi_utime: ::uint64_t,
-        pub ssi_stime: ::c_ulonglong,
+        pub ssi_stime: ::uint64_t,
-        pub ssi_addr: ::c_ulonglong,
+        pub ssi_addr: ::uint64_t,
         pub ssi_addr_lsb: ::uint16_t,
-        _pad: [::uint8_t; 46],
+        _pad2: ::uint16_t,
+        pub ssi_syscall: ::int32_t,
+        pub ssi_call_addr: ::uint64_t,
+        pub ssi_arch: ::uint32_t,
+        _pad: [::uint8_t; 28],
     }
 
     pub struct ucred {

src/unix/notbsd/emscripten.rs

@@ -184,7 +184,12 @@ s! {
         pub ssi_utime: ::uint64_t,
         pub ssi_stime: ::uint64_t,
         pub ssi_addr: ::uint64_t,
-        _pad: [::uint8_t; 48],
+        pub ssi_addr_lsb: ::uint16_t,
+        _pad2: ::uint16_t,
+        pub ssi_syscall: ::int32_t,
+        pub ssi_call_addr: ::uint64_t,
+        pub ssi_arch: ::uint32_t,
+        _pad: [::uint8_t; 28],
     }
 
     pub struct fsid_t {

src/unix/notbsd/linux/mod.rs

@@ -270,7 +270,12 @@ s! {
         pub ssi_utime: ::uint64_t,
         pub ssi_stime: ::uint64_t,
         pub ssi_addr: ::uint64_t,
-        _pad: [::uint8_t; 48],
+        pub ssi_addr_lsb: ::uint16_t,
+        _pad2: ::uint16_t,
+        pub ssi_syscall: ::int32_t,
+        pub ssi_call_addr: ::uint64_t,
+        pub ssi_arch: ::uint32_t,
+        _pad: [::uint8_t; 28],
     }
 
     pub struct itimerspec {

src/unix/uclibc/mod.rs

@@ -391,7 +391,12 @@ s! {
         pub ssi_utime: ::uint64_t,
         pub ssi_stime: ::uint64_t,
         pub ssi_addr: ::uint64_t,
-        _pad: [::uint8_t; 48],
+        pub ssi_addr_lsb: ::uint16_t,
+        _pad2: ::uint16_t,
+        pub ssi_syscall: ::int32_t,
+        pub ssi_call_addr: ::uint64_t,
+        pub ssi_arch: ::uint32_t,
+        _pad: [::uint8_t; 28],
     }
 
     pub struct fsid_t {