Support the x86_64 x32 ABI

[hvdijk]

When trying to build for x86_64-unknown-linux-gnux32, a lot of errors are shown (the first ones not related to x32). It would be nice to see support for this. The problem is that many places use libc::c_long, which for x86_64-unknown-linux-gnux32 is i32, where the actual types to use are i64 for compatibility with x86_64-unknown-linux-gnu.

I am just reporting this as an issue for the moment: I had taken a stab at fixing this myself, but quickly found I don't really know Rust well enough yet. If someone else doesn't get it working first, I will try again when I have some more time to learn the language properly.

$ cargo build --target=x86_64-unknown-linux-gnux32
    Updating crates.io index
   Compiling libc v0.2.85
   Compiling bitflags v1.2.1
   Compiling cfg-if v1.0.0
   Compiling nix v0.19.0 (/home/harald/rust-nix)
error[E0308]: mismatched types
  --> src/mqueue.rs:47:29
   |
47 |             (*p).mq_flags = mq_flags;
   |                             ^^^^^^^^
   |                             |
   |                             expected `i64`, found `i32`
   |                             help: you can convert an `i32` to an `i64`: `mq_flags.into()`

error[E0308]: mismatched types
  --> src/mqueue.rs:48:30
   |
48 |             (*p).mq_maxmsg = mq_maxmsg;
   |                              ^^^^^^^^^
   |                              |
   |                              expected `i64`, found `i32`
   |                              help: you can convert an `i32` to an `i64`: `mq_maxmsg.into()`

error[E0308]: mismatched types
  --> src/mqueue.rs:49:31
   |
49 |             (*p).mq_msgsize = mq_msgsize;
   |                               ^^^^^^^^^^
   |                               |
   |                               expected `i64`, found `i32`
   |                               help: you can convert an `i32` to an `i64`: `mq_msgsize.into()`

error[E0308]: mismatched types
  --> src/mqueue.rs:50:31
   |
50 |             (*p).mq_curmsgs = mq_curmsgs;
   |                               ^^^^^^^^^^
   |                               |
   |                               expected `i64`, found `i32`
   |                               help: you can convert an `i32` to an `i64`: `mq_curmsgs.into()`

error[E0308]: mismatched types
  --> src/mqueue.rs:56:9
   |
55 |     pub fn flags(&self) -> c_long {
   |                            ------ expected `i32` because of return type
56 |         self.mq_attr.mq_flags
   |         ^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `i64`
   |
help: you can convert an `i64` to an `i32` and panic if the converted value doesn't fit
   |
56 |         self.mq_attr.mq_flags.try_into().unwrap()
   |

error[E0308]: mismatched types
   --> src/mqueue.rs:154:31
    |
154 | ...                   oldattr.mq_attr.mq_maxmsg,
    |                       ^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `i64`
    |
help: you can convert an `i64` to an `i32` and panic if the converted value doesn't fit
    |
154 |                               oldattr.mq_attr.mq_maxmsg.try_into().unwrap(),
    |                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0308]: mismatched types
   --> src/mqueue.rs:155:31
    |
155 | ...                   oldattr.mq_attr.mq_msgsize,
    |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `i64`
    |
help: you can convert an `i64` to an `i32` and panic if the converted value doesn't fit
    |
155 |                               oldattr.mq_attr.mq_msgsize.try_into().unwrap(),
    |                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0308]: mismatched types
   --> src/mqueue.rs:156:31
    |
156 | ...                   oldattr.mq_attr.mq_curmsgs);
    |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `i64`
    |
help: you can convert an `i64` to an `i32` and panic if the converted value doesn't fit
    |
156 |                               oldattr.mq_attr.mq_curmsgs.try_into().unwrap());
    |                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0308]: mismatched types
   --> src/mqueue.rs:166:31
    |
166 | ...                   oldattr.mq_attr.mq_maxmsg,
    |                       ^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `i64`
    |
help: you can convert an `i64` to an `i32` and panic if the converted value doesn't fit
    |
166 |                               oldattr.mq_attr.mq_maxmsg.try_into().unwrap(),
    |                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0308]: mismatched types
   --> src/mqueue.rs:167:31
    |
167 | ...                   oldattr.mq_attr.mq_msgsize,
    |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `i64`
    |
help: you can convert an `i64` to an `i32` and panic if the converted value doesn't fit
    |
167 |                               oldattr.mq_attr.mq_msgsize.try_into().unwrap(),
    |                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0308]: mismatched types
   --> src/mqueue.rs:168:31
    |
168 | ...                   oldattr.mq_attr.mq_curmsgs);
    |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found `i64`
    |
help: you can convert an `i64` to an `i32` and panic if the converted value doesn't fit
    |
168 |                               oldattr.mq_attr.mq_curmsgs.try_into().unwrap());
    |                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0308]: mismatched types
   --> src/sys/statfs.rs:102:16
    |
102 |         FsType(self.0.f_type)
    |                ^^^^^^^^^^^^^ expected `i32`, found `i64`
    |
help: you can convert an `i64` to an `i32` and panic if the converted value doesn't fit
    |
102 |         FsType(self.0.f_type.try_into().unwrap())
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0308]: mismatched types
   --> src/sys/statfs.rs:142:9
    |
141 |     pub fn optimal_transfer_size(&self) -> libc::c_long {
    |                                            ------------ expected `i32` because of return type
142 |         self.0.f_bsize
    |         ^^^^^^^^^^^^^^ expected `i32`, found `i64`
    |
help: you can convert an `i64` to an `i32` and panic if the converted value doesn't fit
    |
142 |         self.0.f_bsize.try_into().unwrap()
    |

error[E0308]: mismatched types
   --> src/sys/statfs.rs:181:9
    |
180 |     pub fn block_size(&self) -> libc::c_long {
    |                                 ------------ expected `i32` because of return type
181 |         self.0.f_bsize
    |         ^^^^^^^^^^^^^^ expected `i32`, found `i64`
    |
help: you can convert an `i64` to an `i32` and panic if the converted value doesn't fit
    |
181 |         self.0.f_bsize.try_into().unwrap()
    |

error[E0308]: mismatched types
   --> src/sys/statfs.rs:223:9
    |
222 |     pub fn maximum_name_length(&self) -> libc::c_long {
    |                                          ------------ expected `i32` because of return type
223 |         self.0.f_namelen
    |         ^^^^^^^^^^^^^^^^ expected `i32`, found `i64`
    |
help: you can convert an `i64` to an `i32` and panic if the converted value doesn't fit
    |
223 |         self.0.f_namelen.try_into().unwrap()
    |

error[E0308]: mismatched types
   --> src/sys/statfs.rs:267:9
    |
266 |     pub fn blocks(&self) -> libc::c_ulong {
    |                             ------------- expected `u32` because of return type
267 |         self.0.f_blocks
    |         ^^^^^^^^^^^^^^^ expected `u32`, found `u64`
    |
help: you can convert a `u64` to a `u32` and panic if the converted value doesn't fit
    |
267 |         self.0.f_blocks.try_into().unwrap()
    |

error[E0308]: mismatched types
   --> src/sys/statfs.rs:305:9
    |
304 |     pub fn blocks_free(&self) -> libc::c_ulong {
    |                                  ------------- expected `u32` because of return type
305 |         self.0.f_bfree
    |         ^^^^^^^^^^^^^^ expected `u32`, found `u64`
    |
help: you can convert a `u64` to a `u32` and panic if the converted value doesn't fit
    |
305 |         self.0.f_bfree.try_into().unwrap()
    |

error[E0308]: mismatched types
   --> src/sys/statfs.rs:343:9
    |
342 |     pub fn blocks_available(&self) -> libc::c_ulong {
    |                                       ------------- expected `u32` because of return type
343 |         self.0.f_bavail
    |         ^^^^^^^^^^^^^^^ expected `u32`, found `u64`
    |
help: you can convert a `u64` to a `u32` and panic if the converted value doesn't fit
    |
343 |         self.0.f_bavail.try_into().unwrap()
    |

error[E0308]: mismatched types
   --> src/sys/statfs.rs:381:9
    |
380 |     pub fn files(&self) -> libc::c_ulong {
    |                            ------------- expected `u32` because of return type
381 |         self.0.f_files
    |         ^^^^^^^^^^^^^^ expected `u32`, found `u64`
    |
help: you can convert a `u64` to a `u32` and panic if the converted value doesn't fit
    |
381 |         self.0.f_files.try_into().unwrap()
    |

error[E0308]: mismatched types
   --> src/sys/statfs.rs:419:9
    |
418 |     pub fn files_free(&self) -> libc::c_ulong {
    |                                 ------------- expected `u32` because of return type
419 |         self.0.f_ffree
    |         ^^^^^^^^^^^^^^ expected `u32`, found `u64`
    |
help: you can convert a `u64` to a `u32` and panic if the converted value doesn't fit
    |
419 |         self.0.f_ffree.try_into().unwrap()
    |

error[E0308]: mismatched types
  --> src/sys/sysinfo.rs:39:24
   |
39 |         self.scale_mem(self.0.totalswap)
   |                        ^^^^^^^^^^^^^^^^ expected `u32`, found `u64`
   |
help: you can convert a `u64` to a `u32` and panic if the converted value doesn't fit
   |
39 |         self.scale_mem(self.0.totalswap.try_into().unwrap())
   |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0308]: mismatched types
  --> src/sys/sysinfo.rs:44:24
   |
44 |         self.scale_mem(self.0.freeswap)
   |                        ^^^^^^^^^^^^^^^ expected `u32`, found `u64`
   |
help: you can convert a `u64` to a `u32` and panic if the converted value doesn't fit
   |
44 |         self.scale_mem(self.0.freeswap.try_into().unwrap())
   |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0308]: mismatched types
  --> src/sys/sysinfo.rs:49:24
   |
49 |         self.scale_mem(self.0.totalram)
   |                        ^^^^^^^^^^^^^^^ expected `u32`, found `u64`
   |
help: you can convert a `u64` to a `u32` and panic if the converted value doesn't fit
   |
49 |         self.scale_mem(self.0.totalram.try_into().unwrap())
   |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0308]: mismatched types
  --> src/sys/sysinfo.rs:58:24
   |
58 |         self.scale_mem(self.0.freeram)
   |                        ^^^^^^^^^^^^^^ expected `u32`, found `u64`
   |
help: you can convert a `u64` to a `u32` and panic if the converted value doesn't fit
   |
58 |         self.scale_mem(self.0.freeram.try_into().unwrap())
   |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0308]: mismatched types
  --> src/sys/time.rs:76:22
   |
76 |             tv_nsec: duration.subsec_nanos() as c_long
   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `i64`, found `i32`

error[E0308]: mismatched types
   --> src/sys/time.rs:151:37
    |
151 | ...                   tv_nsec: nanos as c_long })
    |                                ^^^^^^^^^^^^^^^ expected `i64`, found `i32`

error[E0308]: mismatched types
   --> src/sys/time.rs:192:9
    |
191 |     pub fn tv_nsec(&self) -> c_long {
    |                              ------ expected `i32` because of return type
192 |         self.0.tv_nsec
    |         ^^^^^^^^^^^^^^ expected `i32`, found `i64`
    |
help: you can convert an `i64` to an `i32` and panic if the converted value doesn't fit
    |
192 |         self.0.tv_nsec.try_into().unwrap()
    |

error: aborting due to 27 previous errors

For more information about this error, try `rustc --explain E0308`.
error: could not compile `nix`

To learn more, run the command again with --verbose.

[hvdijk]

Ah, I searched for issues, but not PRs. There is an open PR for this, #1366, which shows a test failure on CI but is likely to be a good starting point.

[hvdijk]

Actually, aside from needing some more updates to the test code, that PR already looks good. The test failure that was displayed for CI previously was not related to x32. As I cannot update someone else's PR (nor should I be able to), I will put in a comment here the additional patch I needed to get tests to pass, with the exception of sys::test_socket::test_vsock which fails for unrelated reasons the same way as on x86_64-unknown-linux-gnu. @nabijaczleweli, does this look like something you could add to your PR, or would you want me to submit this independently somehow?

diff --git a/test/sys/test_ptrace.rs b/test/sys/test_ptrace.rs
index 38cf408b..5be99c1b 100644
--- a/test/sys/test_ptrace.rs
+++ b/test/sys/test_ptrace.rs
@@ -150,11 +150,11 @@ fn test_ptrace_syscall() {
             // set this option to recognize syscall-stops
             ptrace::setoptions(child, ptrace::Options::PTRACE_O_TRACESYSGOOD).unwrap();
 
-            #[cfg(target_pointer_width = "64")]
-            let get_syscall_id = || ptrace::getregs(child).unwrap().orig_rax as i64;
+            #[cfg(target_arch = "x86_64")]
+            let get_syscall_id = || ptrace::getregs(child).unwrap().orig_rax as libc::c_long;
 
-            #[cfg(target_pointer_width = "32")]
-            let get_syscall_id = || ptrace::getregs(child).unwrap().orig_eax as i32;
+            #[cfg(target_arch = "x86")]
+            let get_syscall_id = || ptrace::getregs(child).unwrap().orig_eax as libc::c_long;
 
             // kill entry
             ptrace::syscall(child, None).unwrap();
diff --git a/test/test_mq.rs b/test/test_mq.rs
index ecee2009..1667a35b 100644
--- a/test/test_mq.rs
+++ b/test/test_mq.rs
@@ -1,17 +1,15 @@
-use libc::c_long;
-
 use std::ffi::CString;
 use std::str;
 
 use nix::errno::Errno::*;
 use nix::Error::Sys;
-use nix::mqueue::{mq_open, mq_close, mq_send, mq_receive};
+use nix::mqueue::{mq_open, mq_close, mq_send, mq_receive, mq_attr_member_t};
 use nix::mqueue::{MqAttr, MQ_OFlag};
 use nix::sys::stat::Mode;
 
 #[test]
 fn test_mq_send_and_receive() {
-    const MSG_SIZE: c_long =  32;
+    const MSG_SIZE: mq_attr_member_t = 32;
     let attr =  MqAttr::new(0, 10, MSG_SIZE, 0);
     let mq_name= &CString::new(b"/a_nix_test_queue".as_ref()).unwrap();
 
@@ -43,7 +41,7 @@ fn test_mq_send_and_receive() {
 #[cfg(not(any(target_os = "netbsd")))]
 fn test_mq_getattr() {
     use nix::mqueue::mq_getattr;
-    const MSG_SIZE: c_long =  32;
+    const MSG_SIZE: mq_attr_member_t = 32;
     let initial_attr =  MqAttr::new(0, 10, MSG_SIZE, 0);
     let mq_name = &CString::new(b"/attr_test_get_attr".as_ref()).unwrap();
     let oflag = MQ_OFlag::O_CREAT | MQ_OFlag::O_WRONLY;
@@ -66,7 +64,7 @@ fn test_mq_getattr() {
 #[cfg_attr(any(target_arch = "mips", target_arch = "mips64"), ignore)]
 fn test_mq_setattr() {
     use nix::mqueue::{mq_getattr, mq_setattr};
-    const MSG_SIZE: c_long =  32;
+    const MSG_SIZE: mq_attr_member_t = 32;
     let initial_attr =  MqAttr::new(0, 10, MSG_SIZE, 0);
     let mq_name = &CString::new(b"/attr_test_get_attr".as_ref()).unwrap();
     let oflag = MQ_OFlag::O_CREAT | MQ_OFlag::O_WRONLY;
@@ -87,7 +85,7 @@ fn test_mq_setattr() {
     // O_NONBLOCK can be set (see tests below)
     assert_ne!(new_attr_get, new_attr);
 
-    let new_attr_non_blocking =  MqAttr::new(MQ_OFlag::O_NONBLOCK.bits() as c_long, 10, MSG_SIZE, 0);
+    let new_attr_non_blocking =  MqAttr::new(MQ_OFlag::O_NONBLOCK.bits() as mq_attr_member_t, 10, MSG_SIZE, 0);
     mq_setattr(mqd, &new_attr_non_blocking).unwrap();
     let new_attr_get = mq_getattr(mqd).unwrap();
 
@@ -103,7 +101,7 @@ fn test_mq_setattr() {
 #[cfg_attr(any(target_arch = "mips", target_arch = "mips64"), ignore)]
 fn test_mq_set_nonblocking() {
     use nix::mqueue::{mq_getattr, mq_set_nonblock, mq_remove_nonblock};
-    const MSG_SIZE: c_long =  32;
+    const MSG_SIZE: mq_attr_member_t = 32;
     let initial_attr =  MqAttr::new(0, 10, MSG_SIZE, 0);
     let mq_name = &CString::new(b"/attr_test_get_attr".as_ref()).unwrap();
     let oflag = MQ_OFlag::O_CREAT | MQ_OFlag::O_WRONLY;
@@ -116,7 +114,7 @@ fn test_mq_set_nonblocking() {
     let mqd = r.unwrap();
     mq_set_nonblock(mqd).unwrap();
     let new_attr = mq_getattr(mqd);
-    assert_eq!(new_attr.unwrap().flags(), MQ_OFlag::O_NONBLOCK.bits() as c_long);
+    assert_eq!(new_attr.unwrap().flags(), MQ_OFlag::O_NONBLOCK.bits() as mq_attr_member_t);
     mq_remove_nonblock(mqd).unwrap();
     let new_attr = mq_getattr(mqd);
     assert_eq!(new_attr.unwrap().flags(), 0);
@@ -127,7 +125,7 @@ fn test_mq_set_nonblocking() {
 #[cfg(not(any(target_os = "netbsd")))]
 fn test_mq_unlink() {
     use nix::mqueue::mq_unlink;
-    const MSG_SIZE: c_long =  32;
+    const MSG_SIZE: mq_attr_member_t = 32;
     let initial_attr =  MqAttr::new(0, 10, MSG_SIZE, 0);
     let mq_name_opened = &CString::new(b"/mq_unlink_test".as_ref()).unwrap();
     let mq_name_not_opened = &CString::new(b"/mq_unlink_test".as_ref()).unwrap();

There was also a problem in caps that prevented getting to the point where tests run; I have submitted a PR for that.

[nabijaczleweli]

I've added (a derivative of) your patch to #1366, thanks!

[asomers]

Closing this issue, as it was fixed by #1366