Fix bugs found in CI:

* Specialize CMSG_NXTHDR for Android and Emscripten
* Fix a typo in OSX
* Restrict the cmsg tests to Unix platforms.

Author: asomers

libc-test/build.rs

@@ -6,9 +6,11 @@ extern crate ctest;
 use std::env;
 
 fn do_cc() {
-    cc::Build::new()
-        .file("src/cmsg.c")
-        .compile("cmsg");
+    #[cfg(unix)] {
+        cc::Build::new()
+            .file("src/cmsg.c")
+            .compile("cmsg");
+    }
 }
 
 fn do_ctest() {

libc-test/test/cmsg.rs

@@ -5,6 +5,7 @@ extern crate libc;
 use libc::{c_uchar, c_uint, c_void, cmsghdr, msghdr};
 use std::{mem, ptr};
 
+#[cfg(unix)]
 extern {
     pub fn cmsg_firsthdr(msgh: *const msghdr) -> *mut cmsghdr;
     pub fn cmsg_nxthdr(mhdr: *const msghdr,
@@ -14,6 +15,7 @@ extern {
     pub fn cmsg_data(cmsg: *const cmsghdr) -> *mut c_uchar;
 }
 
+#[cfg(unix)]
 #[test]
 fn test_cmsg_data() {
     for l in 0..128 {
@@ -24,6 +26,7 @@ fn test_cmsg_data() {
     }
 }
 
+#[cfg(unix)]
 #[test]
 fn test_cmsg_firsthdr() {
     let mut mhdr: msghdr = unsafe{mem::zeroed()};
@@ -37,6 +40,7 @@ fn test_cmsg_firsthdr() {
     }
 }
 
+#[cfg(unix)]
 #[test]
 fn test_cmsg_len() {
     for l in 0..128 {
@@ -46,6 +50,7 @@ fn test_cmsg_len() {
     }
 }
 
+#[cfg(unix)]
 #[test]
 fn test_cmsg_nxthdr() {
     let mut buffer = [0u8; 256];
@@ -78,6 +83,7 @@ fn test_cmsg_nxthdr() {
     }
 }
 
+#[cfg(unix)]
 #[test]
 fn test_cmsg_space() {
     unsafe {

src/unix/bsd/apple/mod.rs

@@ -2418,7 +2418,7 @@ f! {
     }
 
     pub fn CMSG_LEN(length: ::c_uint) -> ::c_uint {
-        __DARWIN_ALIGN32(mem::size_of::<::cmsghdr>() + length as usize)
+        __DARWIN_ALIGN32(mem::size_of::<::cmsghdr>()) + length as usize
             as ::c_uint
     }
 

src/unix/notbsd/android/mod.rs

@@ -1477,6 +1477,20 @@ pub const MODULE_INIT_IGNORE_VERMAGIC: ::c_uint = 0x0002;
 pub const ENOATTR: ::c_int = ::ENODATA;
 
 f! {
+    pub fn CMSG_NXTHDR(mhdr: *const msghdr,
+                       cmsg: *const cmsghdr) -> *mut cmsghdr {
+        let next = (cmsg as usize
+                    + super::CMSG_ALIGN((*cmsg).cmsg_len as usize))
+            as *mut cmsghdr;
+        let max = (*mhdr).msg_control as usize
+            + (*mhdr).msg_controllen as usize;
+        if (next.offset(1)) as usize > max {
+            0 as *mut cmsghdr
+        } else {
+            next as *mut cmsghdr
+        }
+    }
+
     pub fn CPU_ZERO(cpuset: &mut cpu_set_t) -> () {
         for slot in cpuset.__bits.iter_mut() {
             *slot = 0;

src/unix/notbsd/emscripten.rs

@@ -1510,6 +1510,23 @@ pub const ARPD_FLUSH: ::c_ushort = 0x03;
 pub const ATF_MAGIC: ::c_int = 0x80;
 
 f! {
+    pub fn CMSG_NXTHDR(mhdr: *const msghdr,
+                       cmsg: *const cmsghdr) -> *mut cmsghdr {
+        if ((*cmsg).cmsg_len as usize) < mem::size_of::<cmsghdr>() {
+            return 0 as *mut cmsghdr;
+        };
+        let next = (cmsg as usize +
+                    super::CMSG_ALIGN((*cmsg).cmsg_len as usize))
+            as *mut cmsghdr;
+        let max = (*mhdr).msg_control as usize
+            + (*mhdr).msg_controllen as usize;
+        if (next.offset(1)) as usize > max {
+            0 as *mut cmsghdr
+        } else {
+            next as *mut cmsghdr
+        }
+    }
+
     pub fn CPU_ZERO(cpuset: &mut cpu_set_t) -> () {
         for slot in cpuset.bits.iter_mut() {
             *slot = 0;

src/unix/notbsd/linux/mod.rs

@@ -1697,6 +1697,25 @@ pub const SOF_TIMESTAMPING_SYS_HARDWARE: ::c_uint = 1 << 5;
 pub const SOF_TIMESTAMPING_RAW_HARDWARE: ::c_uint = 1 << 6;
 
 f! {
+    pub fn CMSG_NXTHDR(mhdr: *const msghdr,
+                       cmsg: *const cmsghdr) -> *mut cmsghdr {
+        if ((*cmsg).cmsg_len as usize) < mem::size_of::<cmsghdr>() {
+            return 0 as *mut cmsghdr;
+        };
+        let next = (cmsg as usize +
+                    super::CMSG_ALIGN((*cmsg).cmsg_len as usize))
+            as *mut cmsghdr;
+        let max = (*mhdr).msg_control as usize
+            + (*mhdr).msg_controllen as usize;
+        if (next.offset(1)) as usize > max ||
+            next as usize + super::CMSG_ALIGN((*next).cmsg_len as usize) > max
+        {
+            0 as *mut cmsghdr
+        } else {
+            next as *mut cmsghdr
+        }
+    }
+
     pub fn CPU_ZERO(cpuset: &mut cpu_set_t) -> () {
         for slot in cpuset.bits.iter_mut() {
             *slot = 0;

src/unix/notbsd/mod.rs

@@ -998,24 +998,6 @@ f! {
         }
     }
 
-    pub fn CMSG_NXTHDR(mhdr: *const msghdr,
-                       cmsg: *const cmsghdr) -> *mut cmsghdr {
-        if ((*cmsg).cmsg_len as usize) < mem::size_of::<cmsghdr>() {
-            return 0 as *mut cmsghdr;
-        };
-        let next = (cmsg as usize + CMSG_ALIGN((*cmsg).cmsg_len as usize))
-            as *mut cmsghdr;
-        let max = (*mhdr).msg_control as usize
-            + (*mhdr).msg_controllen as usize;
-        if (next.offset(1)) as usize > max
-            || next as usize + CMSG_ALIGN((*next).cmsg_len as usize) > max
-        {
-            0 as *mut cmsghdr
-        } else {
-            next as *mut cmsghdr
-        }
-    }
-
     pub fn CMSG_DATA(cmsg: *const cmsghdr) -> *mut ::c_uchar {
         cmsg.offset(1) as *mut ::c_uchar
     }