Merge #1603

1603: uclibc support r=rtzoeller a=skrap

uclibc is a libc alternative (peer to glibc and musl) which is used in low-resource embedded linux applications.

It's supported in rust as the `target_env` of several tier 3 targets, but `nix` currently doesn't build.  This patch provides a few customizations to get uclibc building.

To test:
* Get nightly rust
* Follow directions for getting a cross toolchain and env setup here: https://github.com/rust-lang/rust/blob/master/src/doc/rustc/src/platform-support/armv7-unknown-linux-uclibceabihf.md

Thanks for your consideration!



Co-authored-by: Jonah Petri <jonah@petri.us>

.cirrus.yml

@@ -281,6 +281,9 @@ task:
     - name: OpenBSD x86_64
       env:
         TARGET: x86_64-unknown-openbsd
+    - name: Linux armv7 uclibceabihf
+      env:
+        TARGET: armv7-unknown-linux-uclibceabihf
   setup_script:
     - rustup component add rust-src
   << : *BUILD

README.md

@@ -78,6 +78,7 @@ Tier 2:
   * x86_64-unknown-netbsd
 
 Tier 3:
+  * armv7-unknown-linux-uclibceabihf
   * x86_64-fuchsia
   * x86_64-unknown-dragonfly
   * x86_64-unknown-linux-gnux32

bors.toml

@@ -14,6 +14,7 @@ status = [
   "Linux arm gnueabi",
   "Linux arm-musleabi",
   "Linux armv7 gnueabihf",
+  "Linux armv7 uclibceabihf",
   "Linux i686 musl",
   "Linux i686",
   "Linux mipsel",

src/sys/mod.rs

@@ -2,7 +2,7 @@
 #[cfg(any(target_os = "dragonfly",
           target_os = "freebsd",
           target_os = "ios",
-          target_os = "linux",
+          all(target_os = "linux", not(target_env = "uclibc")),
           target_os = "macos",
           target_os = "netbsd"))]
 feature! {

src/sys/personality.rs

@@ -11,13 +11,13 @@ libc_bitflags! {
         ADDR_NO_RANDOMIZE;
         ADDR_LIMIT_32BIT;
         ADDR_LIMIT_3GB;
-        #[cfg(not(target_env = "musl"))]
+        #[cfg(not(any(target_env = "musl", target_env = "uclibc")))]
         FDPIC_FUNCPTRS;
         MMAP_PAGE_ZERO;
         READ_IMPLIES_EXEC;
         SHORT_INODE;
         STICKY_TIMEOUTS;
-        #[cfg(not(target_env = "musl"))]
+        #[cfg(not(any(target_env = "musl", target_env = "uclibc")))]
         UNAME26;
         WHOLE_SECONDS;
     }

src/sys/ptrace/linux.rs

@@ -20,7 +20,8 @@ use libc::user_regs_struct;
 
 cfg_if! {
     if #[cfg(any(all(target_os = "linux", target_arch = "s390x"),
-                 all(target_os = "linux", target_env = "gnu")))] {
+                 all(target_os = "linux", target_env = "gnu"),
+                 target_env = "uclibc"))] {
         #[doc(hidden)]
         pub type RequestType = ::libc::c_uint;
     } else {
@@ -30,8 +31,8 @@ cfg_if! {
 }
 
 libc_enum!{
-    #[cfg_attr(not(any(target_env = "musl", target_os = "android")), repr(u32))]
-    #[cfg_attr(any(target_env = "musl", target_os = "android"), repr(i32))]
+    #[cfg_attr(not(any(target_env = "musl", target_env = "uclibc", target_os = "android")), repr(u32))]
+    #[cfg_attr(any(target_env = "musl", target_env = "uclibc", target_os = "android"), repr(i32))]
     /// Ptrace Request enum defining the action to be taken.
     #[non_exhaustive]
     pub enum Request {

src/sys/resource.rs

@@ -7,9 +7,9 @@ pub use libc::rlim_t;
 use std::mem;
 
 cfg_if! {
-    if #[cfg(all(target_os = "linux", target_env = "gnu"))]{
+    if #[cfg(all(target_os = "linux", any(target_env = "gnu", target_env = "uclibc")))]{
         use libc::{__rlimit_resource_t, rlimit, RLIM_INFINITY};
-    }else if #[cfg(any(
+    } else if #[cfg(any(
         target_os = "freebsd",
         target_os = "openbsd",
         target_os = "netbsd",
@@ -199,9 +199,9 @@ pub fn getrlimit(resource: Resource) -> Result<(Option<rlim_t>, Option<rlim_t>)>
     let mut old_rlim = mem::MaybeUninit::<rlimit>::uninit();
 
     cfg_if! {
-        if #[cfg(all(target_os = "linux", target_env = "gnu"))]{
+        if #[cfg(all(target_os = "linux", any(target_env = "gnu", target_env = "uclibc")))]{
             let res = unsafe { libc::getrlimit(resource as __rlimit_resource_t, old_rlim.as_mut_ptr()) };
-        }else{
+        } else {
             let res = unsafe { libc::getrlimit(resource as c_int, old_rlim.as_mut_ptr()) };
         }
     }
@@ -253,7 +253,7 @@ pub fn setrlimit(
         rlim_max: hard_limit.unwrap_or(RLIM_INFINITY),
     };
     cfg_if! {
-        if #[cfg(all(target_os = "linux", target_env = "gnu"))]{
+        if #[cfg(all(target_os = "linux", any(target_env = "gnu", target_env = "uclibc")))]{
             let res = unsafe { libc::setrlimit(resource as __rlimit_resource_t, &new_rlim as *const rlimit) };
         }else{
             let res = unsafe { libc::setrlimit(resource as c_int, &new_rlim as *const rlimit) };

src/sys/signal.rs

@@ -11,6 +11,7 @@ use std::str::FromStr;
 #[cfg(any(target_os = "dragonfly", target_os = "freebsd"))]
 use std::os::unix::io::RawFd;
 use std::ptr;
+use cfg_if::cfg_if;
 
 #[cfg(not(any(target_os = "openbsd", target_os = "redox")))]
 #[cfg(any(feature = "aio", feature = "signal"))]
@@ -420,10 +421,15 @@ pub const SIGPOLL : Signal = SIGIO;
 /// Alias for [`SIGSYS`]
 pub const SIGUNUSED : Signal = SIGSYS;
 
-#[cfg(not(target_os = "redox"))]
-type SaFlags_t = libc::c_int;
-#[cfg(target_os = "redox")]
-type SaFlags_t = libc::c_ulong;
+cfg_if! {
+    if #[cfg(target_os = "redox")] {
+        type SaFlags_t = libc::c_ulong;
+    } else if #[cfg(target_env = "uclibc")] {
+        type SaFlags_t = libc::c_ulong;
+    } else {
+        type SaFlags_t = libc::c_int;
+    }
+}
 }
 
 #[cfg(feature = "signal")]
@@ -1046,6 +1052,8 @@ mod sigevent {
                 SigevNotify::SigevThreadId{..} => libc::SIGEV_THREAD_ID,
                 #[cfg(all(target_os = "linux", target_env = "gnu", not(target_arch = "mips")))]
                 SigevNotify::SigevThreadId{..} => libc::SIGEV_THREAD_ID,
+                #[cfg(all(target_os = "linux", target_env = "uclibc"))]
+                SigevNotify::SigevThreadId{..} => libc::SIGEV_THREAD_ID,
                 #[cfg(any(all(target_os = "linux", target_env = "musl"), target_arch = "mips"))]
                 SigevNotify::SigevThreadId{..} => 4  // No SIGEV_THREAD_ID defined
             };

src/sys/socket/addr.rs

@@ -120,10 +120,10 @@ pub enum AddressFamily {
     #[cfg(any(target_os = "android", target_os = "linux"))]
     #[cfg_attr(docsrs, doc(cfg(all())))]
     Llc = libc::AF_LLC,
-    #[cfg(target_os = "linux")]
+    #[cfg(all(target_os = "linux", not(target_env = "uclibc")))]
     #[cfg_attr(docsrs, doc(cfg(all())))]
     Ib = libc::AF_IB,
-    #[cfg(target_os = "linux")]
+    #[cfg(all(target_os = "linux", not(target_env = "uclibc")))]
     #[cfg_attr(docsrs, doc(cfg(all())))]
     Mpls = libc::AF_MPLS,
     #[cfg(any(target_os = "android", target_os = "linux"))]

src/sys/statfs.rs

@@ -31,7 +31,9 @@ type fs_type_t = libc::c_ulong;
 type fs_type_t = libc::c_uint;
 #[cfg(all(target_os = "linux", target_env = "musl"))]
 type fs_type_t = libc::c_ulong;
-#[cfg(all(target_os = "linux", not(any(target_arch = "s390x", target_env = "musl"))))]
+#[cfg(all(target_os = "linux", target_env = "uclibc"))]
+type fs_type_t = libc::c_int;
+#[cfg(all(target_os = "linux", not(any(target_arch = "s390x", target_env = "musl", target_env = "uclibc"))))]
 type fs_type_t = libc::__fsword_t;
 
 /// Describes the file system type as known by the operating system.
@@ -71,7 +73,7 @@ pub const EXT3_SUPER_MAGIC: FsType = FsType(libc::EXT3_SUPER_MAGIC as fs_type_t)
 #[cfg(all(target_os = "linux", not(target_env = "musl")))]
 #[allow(missing_docs)]
 pub const EXT4_SUPER_MAGIC: FsType = FsType(libc::EXT4_SUPER_MAGIC as fs_type_t);
-#[cfg(all(target_os = "linux", not(target_env = "musl")))]
+#[cfg(all(target_os = "linux", not(any(target_env = "musl", target_env = "uclibc"))))]
 #[allow(missing_docs)]
 pub const FUSE_SUPER_MAGIC: FsType = FsType(libc::FUSE_SUPER_MAGIC as fs_type_t);
 #[cfg(all(target_os = "linux", not(target_env = "musl")))]
@@ -192,12 +194,19 @@ impl Statfs {
     }
 
     /// Optimal transfer block size
-    #[cfg(all(target_os = "linux", not(any(target_arch = "s390x", target_env = "musl"))))]
+    #[cfg(all(target_os = "linux", not(any(target_arch = "s390x", target_env = "musl", target_env = "uclibc"))))]
     #[cfg_attr(docsrs, doc(cfg(all())))]
     pub fn optimal_transfer_size(&self) -> libc::__fsword_t {
         self.0.f_bsize
     }
 
+    /// Optimal transfer block size
+    #[cfg(all(target_os = "linux", target_env = "uclibc"))]
+    #[cfg_attr(docsrs, doc(cfg(all())))]
+    pub fn optimal_transfer_size(&self) -> libc::c_int {
+        self.0.f_bsize
+    }
+
     /// Optimal transfer block size
     #[cfg(target_os = "dragonfly")]
     #[cfg_attr(docsrs, doc(cfg(all())))]
@@ -237,7 +246,15 @@ impl Statfs {
 
     /// Size of a block
     // f_bsize on linux: https://github.com/torvalds/linux/blob/master/fs/nfs/super.c#L471
-    #[cfg(all(target_os = "linux", not(any(target_arch = "s390x", target_env = "musl"))))]
+    #[cfg(all(target_os = "linux", target_env = "uclibc"))]
+    #[cfg_attr(docsrs, doc(cfg(all())))]
+    pub fn block_size(&self) -> libc::c_int {
+        self.0.f_bsize
+    }
+
+    /// Size of a block
+    // f_bsize on linux: https://github.com/torvalds/linux/blob/master/fs/nfs/super.c#L471
+    #[cfg(all(target_os = "linux", not(any(target_arch = "s390x", target_env = "musl", target_env = "uclibc"))))]
     #[cfg_attr(docsrs, doc(cfg(all())))]
     pub fn block_size(&self) -> libc::__fsword_t {
         self.0.f_bsize
@@ -286,7 +303,14 @@ impl Statfs {
     }
 
     /// Maximum length of filenames
-    #[cfg(all(target_os = "linux", not(any(target_arch = "s390x", target_env = "musl"))))]
+    #[cfg(all(target_os = "linux", target_env = "uclibc"))]
+    #[cfg_attr(docsrs, doc(cfg(all())))]
+    pub fn maximum_name_length(&self) -> libc::c_int {
+        self.0.f_namelen
+    }
+
+    /// Maximum length of filenames
+    #[cfg(all(target_os = "linux", not(any(target_arch = "s390x", target_env = "musl", target_env = "uclibc"))))]
     #[cfg_attr(docsrs, doc(cfg(all())))]
     pub fn maximum_name_length(&self) -> libc::__fsword_t {
         self.0.f_namelen

src/sys/uio.rs

@@ -34,6 +34,8 @@ pub fn readv(fd: RawFd, iov: &mut [IoVec<&mut [u8]>]) -> Result<usize> {
 #[cfg_attr(docsrs, doc(cfg(all())))]
 pub fn pwritev(fd: RawFd, iov: &[IoVec<&[u8]>],
                offset: off_t) -> Result<usize> {
+    #[cfg(target_env = "uclibc")]
+    let offset = offset as libc::off64_t; // uclibc doesn't use off_t
     let res = unsafe {
         libc::pwritev(fd, iov.as_ptr() as *const libc::iovec, iov.len() as c_int, offset)
     };
@@ -52,6 +54,8 @@ pub fn pwritev(fd: RawFd, iov: &[IoVec<&[u8]>],
 #[cfg_attr(docsrs, doc(cfg(all())))]
 pub fn preadv(fd: RawFd, iov: &[IoVec<&mut [u8]>],
               offset: off_t) -> Result<usize> {
+    #[cfg(target_env = "uclibc")]
+    let offset = offset as libc::off64_t; // uclibc doesn't use off_t
     let res = unsafe {
         libc::preadv(fd, iov.as_ptr() as *const libc::iovec, iov.len() as c_int, offset)
     };
@@ -127,7 +131,7 @@ feature! {
 /// [ptrace]: ../ptrace/index.html
 /// [`IoVec`]: struct.IoVec.html
 /// [`RemoteIoVec`]: struct.RemoteIoVec.html
-#[cfg(target_os = "linux")]
+#[cfg(all(target_os = "linux", not(target_env = "uclibc")))]
 pub fn process_vm_writev(
     pid: crate::unistd::Pid,
     local_iov: &[IoVec<&[u8]>],
@@ -162,7 +166,7 @@ pub fn process_vm_writev(
 /// [`ptrace`]: ../ptrace/index.html
 /// [`IoVec`]: struct.IoVec.html
 /// [`RemoteIoVec`]: struct.RemoteIoVec.html
-#[cfg(any(target_os = "linux"))]
+#[cfg(all(target_os = "linux", not(target_env = "uclibc")))]
 pub fn process_vm_readv(
     pid: crate::unistd::Pid,
     local_iov: &[IoVec<&mut [u8]>],

src/time.rs

@@ -237,7 +237,6 @@ pub fn clock_gettime(clock_id: ClockId) -> Result<TimeSpec> {
 #[cfg(not(any(
     target_os = "macos",
     target_os = "ios",
-    target_env = "uclibc",
     target_os = "redox",
     target_os = "hermit",
 )))]

test/sys/mod.rs

@@ -7,7 +7,7 @@ mod test_signal;
 // cases on DragonFly.
 #[cfg(any(target_os = "freebsd",
           target_os = "ios",
-          target_os = "linux",
+          all(target_os = "linux", not(target_env = "uclibc")),
           target_os = "macos",
           target_os = "netbsd"))]
 mod test_aio;

test/sys/test_aio_drop.rs

@@ -4,6 +4,7 @@
 #[test]
 #[should_panic(expected = "Dropped an in-progress AioCb")]
 #[cfg(all(not(target_env = "musl"),
+          not(target_env = "uclibc"),
           any(target_os = "linux",
               target_os = "ios",
               target_os = "macos",

test/sys/test_uio.rs

@@ -204,7 +204,7 @@ fn test_preadv() {
 }
 
 #[test]
-#[cfg(target_os = "linux")]
+#[cfg(all(target_os = "linux", not(target_env = "uclibc")))] // uclibc doesn't implement process_vm_readv
 // qemu-user doesn't implement process_vm_readv/writev on most arches
 #[cfg_attr(qemu, ignore)]
 fn test_process_vm_readv() {

test/test_fcntl.rs

@@ -30,6 +30,9 @@ use std::os::unix::fs;
 
 #[test]
 #[cfg(not(target_os = "redox"))]
+// QEMU does not handle openat well enough to satisfy this test
+// https://gitlab.com/qemu-project/qemu/-/issues/829
+#[cfg_attr(qemu, ignore)]
 fn test_openat() {
     const CONTENTS: &[u8] = b"abcd";
     let mut tmp = NamedTempFile::new().unwrap();
@@ -357,6 +360,7 @@ mod linux_android {
 
     #[test]
     #[cfg(all(target_os = "linux", not(target_env = "musl")))]
+    #[cfg_attr(target_env = "uclibc", ignore)]  // uclibc doesn't support OFD locks, but the test should still compile
     fn test_ofd_write_lock() {
         use nix::sys::stat::fstat;
         use std::mem;
@@ -394,6 +398,7 @@ mod linux_android {
 
     #[test]
     #[cfg(all(target_os = "linux", not(target_env = "musl")))]
+    #[cfg_attr(target_env = "uclibc", ignore)]  // uclibc doesn't support OFD locks, but the test should still compile
     fn test_ofd_read_lock() {
         use nix::sys::stat::fstat;
         use std::mem;