Add makedev for the BSDs

Also, make Linux's makedev function safe and const.
Add an integration test for makedev, too, since it's a macro that we
must reimplement.

libc-test/Cargo.toml

@@ -66,6 +66,11 @@ name = "cmsg"
 path = "test/cmsg.rs"
 harness = true
 
+[[test]]
+name = "makedev"
+path = "test/makedev.rs"
+harness = true
+
 [[test]]
 name = "errqueue"
 path = "test/errqueue.rs"

libc-test/build.rs

@@ -22,6 +22,15 @@ fn do_cc() {
             }
             cmsg.compile("cmsg");
         }
+
+        if target.contains("linux")
+            || target.contains("android")
+            || target.contains("emscripten")
+            || target.contains("fuchsia")
+            || target.contains("bsd")
+        {
+            cc::Build::new().file("src/makedev.c").compile("makedev");
+        }
     }
     if target.contains("android") || target.contains("linux") {
         cc::Build::new().file("src/errqueue.c").compile("errqueue");

libc-test/src/makedev.c

@@ -0,0 +1,13 @@
+#include <sys/types.h>
+#ifdef __linux__
+#include <sys/sysmacros.h>
+#endif
+
+// Since makedev is a macro instead of a function, it isn't available to FFI.
+// libc must reimplement it, which is error-prone.  This file provides FFI
+// access to the actual macro so it can be tested against the Rust
+// reimplementation.
+
+dev_t makedev_ffi(unsigned major, unsigned minor) {
+	return makedev(major, minor);
+}

libc-test/test/makedev.rs

@@ -0,0 +1,103 @@
+//! Compare libc's makdev function against the actual C macros, for various
+//! inputs.
+
+extern crate libc;
+
+#[cfg(any(
+    target_os = "android",
+    target_os = "dragonfly",
+    target_os = "emscripten",
+    target_os = "freebsd",
+    target_os = "fuchsia",
+    target_os = "linux",
+    target_os = "netbsd",
+    target_os = "openbsd",
+))]
+mod t {
+    use libc::{self, c_uint, dev_t};
+
+    extern "C" {
+        pub fn makedev_ffi(major: c_uint, minor: c_uint) -> dev_t;
+    }
+
+    fn compare(major: c_uint, minor: c_uint) {
+        let expected = unsafe { makedev_ffi(major, minor) };
+        assert_eq!(libc::makedev(major, minor), expected);
+    }
+
+    // Every OS should be able to handle 8 bit major and minor numbers
+    #[test]
+    fn test_8bits() {
+        for major in 0..256 {
+            for minor in 0..256 {
+                compare(major, minor);
+            }
+        }
+    }
+
+    // Android allows 12 bits for major and 20 for minor
+    #[test]
+    #[cfg(target_os = "android")]
+    fn test_android_like() {
+        for major in [0, 1, 255, 256, 4095] {
+            for minor_exp in [1, 8, 16] {
+                for minor in [(1 << minor_exp) - 1, (1 << minor_exp)] {
+                    compare(major, minor);
+                }
+            }
+            compare(major, (1 << 20) - 1);
+        }
+    }
+
+    // These OSes allow 32 bits for minor, but only 8 for major
+    #[test]
+    #[cfg(any(target_os = "dragonfly", target_os = "freebsd", target_os = "netbsd",))]
+    fn test_fbsd11_like() {
+        for major in [0, 1, 255] {
+            for minor_exp in [1, 8, 16, 24, 31] {
+                for minor in [(1 << minor_exp) - 1, (1 << minor_exp)] {
+                    compare(major, minor);
+                }
+            }
+            compare(major, c_uint::MAX);
+        }
+    }
+
+    // OpenBSD allows 8 bits for major and 24 for minor
+    #[test]
+    #[cfg(target_os = "openbsd")]
+    fn test_openbsd_like() {
+        for major in [0, 1, 255] {
+            for minor_exp in [1, 8, 16] {
+                for minor in [(1 << minor_exp) - 1, (1 << minor_exp)] {
+                    compare(major, minor);
+                }
+            }
+            compare(major, (1 << 24) - 1);
+        }
+    }
+
+    // These OSes allow 32 bits for both minor and major
+    #[cfg(any(
+        target_os = "empscripten",
+        target_os = "fuchsia",
+        target_os = "linux",
+        freebsd12,
+        freebsd13,
+        freebsd14
+    ))]
+    #[test]
+    fn test_fbsd12_like() {
+        for major_exp in [16, 24, 31] {
+            for major in [(1 << major_exp) - 1, (1 << major_exp)] {
+                for minor_exp in [1, 8, 16, 24, 31] {
+                    for minor in [(1 << minor_exp) - 1, (1 << minor_exp)] {
+                        compare(major, minor);
+                    }
+                }
+                compare(major, c_uint::MAX);
+            }
+            compare(c_uint::MAX, c_uint::MAX);
+        }
+    }
+}

src/unix/bsd/freebsdlike/dragonfly/mod.rs

@@ -1571,6 +1571,15 @@ safe_f! {
     pub {const} fn WIFSIGNALED(status: ::c_int) -> bool {
         (status & 0o177) != 0o177 && (status & 0o177) != 0
     }
+
+    pub {const} fn makedev(major: ::c_uint, minor: ::c_uint) -> ::dev_t {
+        let major = major as ::dev_t;
+        let minor = minor as ::dev_t;
+        let mut dev = 0;
+        dev |= major << 8;
+        dev |= minor;
+        dev
+    }
 }
 
 extern "C" {

src/unix/bsd/freebsdlike/freebsd/mod.rs

@@ -3840,6 +3840,20 @@ safe_f! {
     pub {const} fn WIFSIGNALED(status: ::c_int) -> bool {
         (status & 0o177) != 0o177 && (status & 0o177) != 0 && status != 0x13
     }
+
+    // This is the version of makedev used in FreeBSD 12.0 and later.  It is
+    // backwards compatible with FreeBSD 11's makedev, within that version's
+    // more restricted domain of major and minor numbers.
+    pub {const} fn makedev(major: ::c_uint, minor: ::c_uint) -> ::dev_t {
+        let major = major as ::dev_t;
+        let minor = minor as ::dev_t;
+        let mut dev = 0;
+        dev |= ((major & 0xffffff00) as dev_t) << 32;
+        dev |= ((major & 0x000000ff) as dev_t) << 8;
+        dev |= ((minor & 0x0000ff00) as dev_t) << 24;
+        dev |= ((minor & 0xffff00ff) as dev_t) << 0;
+        dev
+    }
 }
 
 cfg_if! {

src/unix/bsd/netbsdlike/netbsd/mod.rs

@@ -2351,6 +2351,16 @@ safe_f! {
     pub {const} fn WIFCONTINUED(status: ::c_int) -> bool {
         status == 0xffff
     }
+
+    pub {const} fn makedev(major: ::c_uint, minor: ::c_uint) -> ::dev_t {
+        let major = major as ::dev_t;
+        let minor = minor as ::dev_t;
+        let mut dev = 0;
+        dev |= (major << 8) & 0x000ff00;
+        dev |= (minor << 12) & 0xfff00000;
+        dev |= minor & 0xff;
+        dev
+    }
 }
 
 extern "C" {

src/unix/bsd/netbsdlike/openbsd/mod.rs

@@ -1695,6 +1695,16 @@ safe_f! {
     pub {const} fn WIFCONTINUED(status: ::c_int) -> bool {
         (status & 0o177777) == 0o177777
     }
+
+    pub {const} fn makedev(major: ::c_uint, minor: ::c_uint) -> ::dev_t {
+        let major = major as ::dev_t;
+        let minor = minor as ::dev_t;
+        let mut dev = 0;
+        dev |= (major & 0xff) << 8;
+        dev |= (minor & 0xff);
+        dev |= (minor & 0xffff00) << 8;
+        dev
+    }
 }
 
 extern "C" {

src/unix/linux_like/linux/mod.rs

@@ -3351,17 +3351,6 @@ f! {
         minor as ::c_uint
     }
 
-    pub fn makedev(major: ::c_uint, minor: ::c_uint) -> ::dev_t {
-        let major = major as ::dev_t;
-        let minor = minor as ::dev_t;
-        let mut dev = 0;
-        dev |= (major & 0x00000fff) << 8;
-        dev |= (major & 0xfffff000) << 32;
-        dev |= (minor & 0x000000ff) << 0;
-        dev |= (minor & 0xffffff00) << 12;
-        dev
-    }
-
     pub fn IPTOS_TOS(tos: u8) -> u8 {
         tos & IPTOS_TOS_MASK
     }
@@ -3403,6 +3392,19 @@ f! {
     }
 }
 
+safe_f! {
+    pub {const} fn makedev(major: ::c_uint, minor: ::c_uint) -> ::dev_t {
+        let major = major as ::dev_t;
+        let minor = minor as ::dev_t;
+        let mut dev = 0;
+        dev |= (major & 0x00000fff) << 8;
+        dev |= (major & 0xfffff000) << 32;
+        dev |= (minor & 0x000000ff) << 0;
+        dev |= (minor & 0xffffff00) << 12;
+        dev
+    }
+}
+
 cfg_if! {
     if #[cfg(not(target_env = "uclibc"))] {
         extern "C" {