Declare field 'tv_nsec' of structure 'timespec' as 'i32' in both 32-bit and 64-bit modes for AIX.

(backport <#4750>)
(cherry picked from commit 96eb752)

Author: xingxue-ibm

libc-test/build.rs

@@ -5765,6 +5765,12 @@ fn test_aix(target: &str) {
             // The field 'data' is actually a unnamed union in the AIX header.
             "pollfd_ext" if field.ident() == "data" => true,
 
+            // On AIX, <stat.h> declares 'tv_nsec' as 'long', but the
+            // underlying system calls return a 32-bit value in both 32-bit
+            // and 64-bit modes. In the 'libc' crate it is declared as 'i32'
+            // to match the system call. Skip this field.
+            "timespec" if field.ident() == "tv_nsec" => true,
+
             _ => false,
         }
     });

src/unix/aix/mod.rs

@@ -263,6 +263,15 @@ s! {
         pub tv_nsec: c_int,
     }
 
+    // On AIX, <stat.h> declares 'tv_nsec' as 'long', but the underlying
+    // system calls return a 4-byte value in both 32-bit and 64-bit modes.
+    // It is declared as 'c_int' here to avoid using the other undefined 4
+    // bytes in the 64-bit mode.
+    pub struct timespec {
+        pub tv_sec: time_t,
+        pub tv_nsec: c_int,
+    }
+
     pub struct statfs64 {
         pub f_version: c_int,
         pub f_type: c_int,

src/unix/mod.rs

@@ -68,7 +68,7 @@ s! {
 
     // linux x32 compatibility
     // See https://sourceware.org/bugzilla/show_bug.cgi?id=16437
-    #[cfg(not(target_env = "gnu"))]
+    #[cfg(all(not(target_env = "gnu"), not(target_os = "aix")))]
     pub struct timespec {
         pub tv_sec: time_t,
         #[cfg(all(target_arch = "x86_64", target_pointer_width = "32"))]