Add minimal support for Hermit OS

.github/workflows/main.yml

@@ -54,6 +54,7 @@ jobs:
         cargo update --package=half --precise=2.2.1
         cargo update --package=flate2 --precise=1.0.35
         cargo update --package=serde --precise=1.0.228
+        cargo update --package=web-sys --precise=0.3.104
         cargo update --package=syn --precise=2.0.106
         cargo update --package=textwrap --precise=0.16.1
         cargo update --package=parking_lot --precise=0.12.4
@@ -596,6 +597,7 @@ jobs:
         cargo update --package=half --precise=2.2.1
         cargo update --package=flate2 --precise=1.0.35
         cargo update --package=serde --precise=1.0.228
+        cargo update --package=web-sys --precise=0.3.104
         cargo update --package=syn --precise=2.0.106
         cargo update --package=textwrap --precise=0.16.1
         cargo update --package=parking_lot --precise=0.12.4

Cargo.toml

@@ -274,3 +274,6 @@ check-cfg = [
     'cfg(target_arch, values("xtensa"))',
     'cfg(target_os, values("cygwin"))',
 ]
+
+[patch.crates-io]
+libc = { git = "https://github.com/rust-lang/libc", branch = "libc-0.2" }

src/backend/libc/c.rs

@@ -474,30 +474,27 @@ mod readwrite_pv64v2 {
 ))]
 pub(super) use readwrite_pv64v2::{preadv64v2 as preadv2, pwritev64v2 as pwritev2};
 
-// Rust's libc crate lacks statx for Non-glibc targets.
+// Rust's libc crate > v0.2.189 may also define these constants,
+// so we use an explicit import.
 #[cfg(feature = "fs")]
 #[cfg(all(
     linux_like,
     linux_raw_dep,
     not(any(
+        target_os = "android",
         target_os = "emscripten",
         target_env = "gnu",
         all(target_arch = "loongarch64", target_env = "musl")
     ))
 ))]
-mod statx_flags {
-    pub(crate) use linux_raw_sys::general::{
-        STATX_ALL, STATX_ATIME, STATX_BASIC_STATS, STATX_BLOCKS, STATX_BTIME, STATX_CTIME,
-        STATX_DIOALIGN, STATX_GID, STATX_INO, STATX_MNT_ID, STATX_MODE, STATX_MTIME, STATX_NLINK,
-        STATX_SIZE, STATX_TYPE, STATX_UID,
-    };
-
-    pub(crate) use linux_raw_sys::general::{
-        STATX_ATTR_APPEND, STATX_ATTR_AUTOMOUNT, STATX_ATTR_COMPRESSED, STATX_ATTR_DAX,
-        STATX_ATTR_ENCRYPTED, STATX_ATTR_IMMUTABLE, STATX_ATTR_MOUNT_ROOT, STATX_ATTR_NODUMP,
-        STATX_ATTR_VERITY,
-    };
-}
+pub(crate) use linux_raw_sys::general::{
+    STATX_ALL, STATX_ATIME, STATX_BASIC_STATS, STATX_BLOCKS, STATX_BTIME, STATX_CTIME,
+    STATX_DIOALIGN, STATX_GID, STATX_INO, STATX_MNT_ID, STATX_MODE, STATX_MTIME, STATX_NLINK,
+    STATX_SIZE, STATX_TYPE, STATX_UID,
+};
+
+// Rust's libc crate > v0.2.189 may also define these constants,
+// so we use an explicit import.
 #[cfg(feature = "fs")]
 #[cfg(all(
     linux_like,
@@ -509,7 +506,11 @@ mod statx_flags {
         all(target_arch = "loongarch64", target_env = "musl")
     ))
 ))]
-pub(crate) use statx_flags::*;
+pub(crate) use linux_raw_sys::general::{
+    STATX_ATTR_APPEND, STATX_ATTR_AUTOMOUNT, STATX_ATTR_COMPRESSED, STATX_ATTR_DAX,
+    STATX_ATTR_ENCRYPTED, STATX_ATTR_IMMUTABLE, STATX_ATTR_MOUNT_ROOT, STATX_ATTR_NODUMP,
+    STATX_ATTR_VERITY,
+};
 
 #[cfg(feature = "fs")]
 #[cfg(target_os = "android")]

src/backend/libc/event/syscalls.rs

@@ -580,7 +580,7 @@ pub(crate) unsafe fn epoll_wait(
         if let Some(epoll_pwait2_func) = epoll_pwait2.get() {
             return ret_u32(epoll_pwait2_func(
                 borrowed_fd(epoll),
-                events.0.cast::<c::epoll_event>(),
+                events.0.cast(),
                 events.1.try_into().unwrap_or(i32::MAX),
                 crate::utils::option_as_ptr(timeout).cast(),
                 null(),
@@ -604,7 +604,7 @@ pub(crate) unsafe fn epoll_wait(
 
         ret_u32(epoll_pwait2(
             borrowed_fd(epoll),
-            events.0.cast::<c::epoll_event>(),
+            events.0.cast(),
             events.1.try_into().unwrap_or(i32::MAX),
             crate::utils::option_as_ptr(timeout).cast(),
             null(),
@@ -622,7 +622,7 @@ pub(crate) unsafe fn epoll_wait(
 
         ret_u32(c::epoll_wait(
             borrowed_fd(epoll),
-            events.0.cast::<c::epoll_event>(),
+            events.0.cast(),
             events.1.try_into().unwrap_or(i32::MAX),
             timeout,
         ))

src/backend/libc/fs/syscalls.rs

@@ -327,7 +327,7 @@ pub(crate) fn getdents_uninit(
     unsafe {
         ret_usize(getdents64(
             borrowed_fd(fd),
-            buf.as_mut_ptr().cast::<c::c_void>(),
+            buf.as_mut_ptr().cast(),
             buf.len(),
         ))
     }
@@ -941,6 +941,7 @@ pub(crate) fn utimensat(
                 c::c_int
             ) -> c::c_int
         }
+        #[cfg(not(any(target_os = "tvos", target_os = "watchos")))]
         extern "C" {
             fn setattrlist(
                 path: *const ffi::c_char,
@@ -950,6 +951,7 @@ pub(crate) fn utimensat(
                 options: c::c_ulong,
             ) -> c::c_int;
         }
+        #[cfg(not(any(target_os = "tvos", target_os = "watchos")))]
         const FSOPT_NOFOLLOW: c::c_ulong = 0x0000_0001;
 
         // If we have `utimensat`, use it.
@@ -962,15 +964,22 @@ pub(crate) fn utimensat(
             ));
         }
 
+        // Return `NOSYS` on platforms where `utimensat` cannot be emulated
+        // because `fork` is unavailable.
+        #[cfg(any(target_os = "tvos", target_os = "watchos"))]
+        return Err(io::Errno::NOSYS);
+
         // Convert `times`. We only need this in the child, but do it before
         // calling `fork` because it might fail.
+        #[cfg(not(any(target_os = "tvos", target_os = "watchos")))]
         let (attrbuf_size, times, attrs) = times_to_attrlist(times)?;
 
         // `setattrlistat` was introduced in 10.13 along with `utimensat`, so
         // if we don't have `utimensat`, we don't have `setattrlistat` either.
         // Emulate it using `fork`, and `fchdir` and [`setattrlist`].
         //
         // [`setattrlist`]: https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/setattrlist.2.html
+        #[cfg(not(any(target_os = "tvos", target_os = "watchos")))]
         match c::fork() {
             -1 => Err(io::Errno::IO),
             0 => {
@@ -2377,7 +2386,7 @@ pub(crate) unsafe fn getxattr(
         ret_usize(c::getxattr(
             path.as_ptr(),
             name.as_ptr(),
-            value.0.cast::<c::c_void>(),
+            value.0.cast(),
             value.1,
         ))
     }
@@ -2389,7 +2398,7 @@ pub(crate) unsafe fn getxattr(
         let ptr = if value.1 == 0 {
             core::ptr::null_mut()
         } else {
-            value.0.cast::<c::c_void>()
+            value.0.cast()
         };
         ret_usize(c::getxattr(
             path.as_ptr(),
@@ -2413,7 +2422,7 @@ pub(crate) unsafe fn lgetxattr(
         ret_usize(c::lgetxattr(
             path.as_ptr(),
             name.as_ptr(),
-            value.0.cast::<c::c_void>(),
+            value.0.cast(),
             value.1,
         ))
     }
@@ -2425,7 +2434,7 @@ pub(crate) unsafe fn lgetxattr(
         let ptr = if value.1 == 0 {
             core::ptr::null_mut()
         } else {
-            value.0.cast::<c::c_void>()
+            value.0.cast()
         };
 
         ret_usize(c::getxattr(
@@ -2450,7 +2459,7 @@ pub(crate) unsafe fn fgetxattr(
         ret_usize(c::fgetxattr(
             borrowed_fd(fd),
             name.as_ptr(),
-            value.0.cast::<c::c_void>(),
+            value.0.cast(),
             value.1,
         ))
     }
@@ -2462,7 +2471,7 @@ pub(crate) unsafe fn fgetxattr(
         let ptr = if value.1 == 0 {
             core::ptr::null_mut()
         } else {
-            value.0.cast::<c::c_void>()
+            value.0.cast()
         };
         ret_usize(c::fgetxattr(
             borrowed_fd(fd),
@@ -2487,7 +2496,7 @@ pub(crate) fn setxattr(
         ret(c::setxattr(
             path.as_ptr(),
             name.as_ptr(),
-            value.as_ptr().cast::<c::c_void>(),
+            value.as_ptr().cast(),
             value.len(),
             flags.bits() as i32,
         ))
@@ -2498,7 +2507,7 @@ pub(crate) fn setxattr(
         ret(c::setxattr(
             path.as_ptr(),
             name.as_ptr(),
-            value.as_ptr().cast::<c::c_void>(),
+            value.as_ptr().cast(),
             value.len(),
             0,
             flags.bits() as i32,
@@ -2518,7 +2527,7 @@ pub(crate) fn lsetxattr(
         ret(c::lsetxattr(
             path.as_ptr(),
             name.as_ptr(),
-            value.as_ptr().cast::<c::c_void>(),
+            value.as_ptr().cast(),
             value.len(),
             flags.bits() as i32,
         ))
@@ -2529,7 +2538,7 @@ pub(crate) fn lsetxattr(
         ret(c::setxattr(
             path.as_ptr(),
             name.as_ptr(),
-            value.as_ptr().cast::<c::c_void>(),
+            value.as_ptr().cast(),
             value.len(),
             0,
             flags.bits() as i32 | c::XATTR_NOFOLLOW,
@@ -2549,7 +2558,7 @@ pub(crate) fn fsetxattr(
         ret(c::fsetxattr(
             borrowed_fd(fd),
             name.as_ptr(),
-            value.as_ptr().cast::<c::c_void>(),
+            value.as_ptr().cast(),
             value.len(),
             flags.bits() as i32,
         ))
@@ -2560,7 +2569,7 @@ pub(crate) fn fsetxattr(
         ret(c::fsetxattr(
             borrowed_fd(fd),
             name.as_ptr(),
-            value.as_ptr().cast::<c::c_void>(),
+            value.as_ptr().cast(),
             value.len(),
             0,
             flags.bits() as i32,
@@ -2572,40 +2581,27 @@ pub(crate) fn fsetxattr(
 pub(crate) unsafe fn listxattr(path: &CStr, list: (*mut u8, usize)) -> io::Result<usize> {
     #[cfg(not(apple))]
     {
-        ret_usize(c::listxattr(
-            path.as_ptr(),
-            list.0.cast::<ffi::c_char>(),
-            list.1,
-        ))
+        ret_usize(c::listxattr(path.as_ptr(), list.0.cast(), list.1))
     }
 
     #[cfg(apple)]
     {
-        ret_usize(c::listxattr(
-            path.as_ptr(),
-            list.0.cast::<ffi::c_char>(),
-            list.1,
-            0,
-        ))
+        ret_usize(c::listxattr(path.as_ptr(), list.0.cast(), list.1, 0))
     }
 }
 
 #[cfg(any(apple, linux_kernel, target_os = "hurd"))]
 pub(crate) unsafe fn llistxattr(path: &CStr, list: (*mut u8, usize)) -> io::Result<usize> {
     #[cfg(not(apple))]
     {
-        ret_usize(c::llistxattr(
-            path.as_ptr(),
-            list.0.cast::<ffi::c_char>(),
-            list.1,
-        ))
+        ret_usize(c::llistxattr(path.as_ptr(), list.0.cast(), list.1))
     }
 
     #[cfg(apple)]
     {
         ret_usize(c::listxattr(
             path.as_ptr(),
-            list.0.cast::<ffi::c_char>(),
+            list.0.cast(),
             list.1,
             c::XATTR_NOFOLLOW,
         ))
@@ -2618,12 +2614,12 @@ pub(crate) unsafe fn flistxattr(fd: BorrowedFd<'_>, list: (*mut u8, usize)) -> i
 
     #[cfg(not(apple))]
     {
-        ret_usize(c::flistxattr(fd, list.0.cast::<ffi::c_char>(), list.1))
+        ret_usize(c::flistxattr(fd, list.0.cast(), list.1))
     }
 
     #[cfg(apple)]
     {
-        ret_usize(c::flistxattr(fd, list.0.cast::<ffi::c_char>(), list.1, 0))
+        ret_usize(c::flistxattr(fd, list.0.cast(), list.1, 0))
     }
 }
 

src/backend/libc/io/errno.rs

@@ -791,7 +791,7 @@ impl Errno {
     #[cfg(not(target_os = "l4re"))]
     pub const NOTSOCK: Self = Self(c::ENOTSOCK);
     /// `ENOTSUP`
-    #[cfg(not(any(windows, target_os = "redox")))]
+    #[cfg(not(any(windows, target_os = "hermit", target_os = "redox")))]
     pub const NOTSUP: Self = Self(c::ENOTSUP);
     /// `ENOTTY`
     #[cfg(not(windows))]