Add F_SEAL_FUTURE_WRITE on Linux/Android

This was added in Linux 5.1 and will only show up in the next glibc
release, thus skip in tests.

Author: tklauser

libc-test/build.rs

@@ -1378,6 +1378,8 @@ fn test_android(target: &str) {
             "SIG_DFL" | "SIG_ERR" | "SIG_IGN" => true, // sighandler_t weirdness
             // FIXME: still necessary?
             "SIGUNUSED" => true, // removed in glibc 2.26
+            // FIXME: remove once Android uses kernel headers >= 5.1 which expose this constant
+            "F_SEAL_FUTURE_WRITE" => true,
 
             _ => false,
         }
@@ -1872,7 +1874,7 @@ fn test_emscripten(target: &str) {
             "F_CANCELLK" | "F_ADD_SEALS" | "F_GET_SEALS" => true,
             // FIXME: is this necessary?
             "F_SEAL_SEAL" | "F_SEAL_SHRINK" | "F_SEAL_GROW"
-                | "F_SEAL_WRITE" => true,
+                | "F_SEAL_WRITE" | "F_SEAL_FUTURE_WRITE" => true,
             // FIXME: is this necessary?
             "BOTHER" => true,
 
@@ -2382,7 +2384,7 @@ fn test_linux(target: &str) {
             "F_CANCELLK" | "F_ADD_SEALS" | "F_GET_SEALS" => true,
             // FIXME: is this necessary?
             "F_SEAL_SEAL" | "F_SEAL_SHRINK" | "F_SEAL_GROW"
-                | "F_SEAL_WRITE" => true,
+                | "F_SEAL_WRITE" | "F_SEAL_FUTURE_WRITE" => true,
             // FIXME: is this necessary?
             "QFMT_VFS_OLD" | "QFMT_VFS_V0" | "QFMT_VFS_V1"
                 if mips =>

src/unix/notbsd/mod.rs

@@ -465,6 +465,7 @@ pub const F_SEAL_SEAL: ::c_int = 0x0001;
 pub const F_SEAL_SHRINK: ::c_int = 0x0002;
 pub const F_SEAL_GROW: ::c_int = 0x0004;
 pub const F_SEAL_WRITE: ::c_int = 0x0008;
+pub const F_SEAL_FUTURE_WRITE: ::c_int = 0x0010;
 
 // TODO(#235): Include file sealing fcntls once we have a way to verify them.