solaris add suport for threadname.

from std::unix::thread::set_name, pthread_setname_np is a weak symbol
(not always had been available). Other than that, similar to
linux only having twice of its buffer limit.

src/tools/miri/ci/ci.sh

@@ -148,8 +148,8 @@ case $HOST_TARGET in
     UNIX="panic/panic panic/unwind concurrency/simple atomic libc-mem libc-misc libc-random env num_cpus" # the things that are very similar across all Unixes, and hence easily supported there
     TEST_TARGET=x86_64-unknown-freebsd run_tests_minimal $BASIC $UNIX threadname libc-time fs
     TEST_TARGET=i686-unknown-freebsd   run_tests_minimal $BASIC $UNIX threadname libc-time fs
-    TEST_TARGET=x86_64-unknown-illumos run_tests_minimal $BASIC $UNIX pthread-sync libc-time
-    TEST_TARGET=x86_64-pc-solaris      run_tests_minimal $BASIC $UNIX pthread-sync libc-time
+    TEST_TARGET=x86_64-unknown-illumos run_tests_minimal $BASIC $UNIX threadname pthread-sync libc-time
+    TEST_TARGET=x86_64-pc-solaris      run_tests_minimal $BASIC $UNIX threadname pthread-sync libc-time
     TEST_TARGET=aarch64-linux-android  run_tests_minimal $BASIC $UNIX
     TEST_TARGET=wasm32-wasip2          run_tests_minimal empty_main wasm heap_alloc libc-mem
     TEST_TARGET=wasm32-unknown-unknown run_tests_minimal empty_main wasm

src/tools/miri/src/shims/extern_static.rs

@@ -82,6 +82,9 @@ impl<'mir, 'tcx> MiriMachine<'mir, 'tcx> {
                 let val = ImmTy::from_int(0, this.machine.layouts.u8);
                 Self::alloc_extern_static(this, "_tls_used", val)?;
             }
+            "illumos" | "solaris" => {
+                Self::weak_symbol_extern_statics(this, &["pthread_setname_np"])?;
+            }
             _ => {} // No "extern statics" supported on this target
         }
         Ok(())

src/tools/miri/src/shims/unix/solarish/foreign_items.rs

@@ -1,10 +1,11 @@
 use rustc_span::Symbol;
 use rustc_target::spec::abi::Abi;
 
+use crate::shims::unix::*;
 use crate::*;
 
-pub fn is_dyn_sym(_name: &str) -> bool {
-    false
+pub fn is_dyn_sym(name: &str) -> bool {
+    matches!(name, "pthread_setname_np")
 }
 
 impl<'mir, 'tcx: 'mir> EvalContextExt<'mir, 'tcx> for crate::MiriInterpCx<'mir, 'tcx> {}
@@ -18,6 +19,31 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
     ) -> InterpResult<'tcx, EmulateItemResult> {
         let this = self.eval_context_mut();
         match link_name.as_str() {
+            // Threading
+            "pthread_setname_np" => {
+                let [thread, name] =
+                    this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
+                // THREAD_NAME_MAX allows a thread name of 31+1 length
+                // https://github.com/illumos/illumos-gate/blob/7671517e13b8123748eda4ef1ee165c6d9dba7fe/usr/src/uts/common/sys/thread.h#L613
+                let max_len = 32;
+                let res = this.pthread_setname_np(
+                    this.read_scalar(thread)?,
+                    this.read_scalar(name)?,
+                    max_len,
+                )?;
+                this.write_scalar(res, dest)?;
+            }
+            "pthread_getname_np" => {
+                let [thread, name, len] =
+                    this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
+                let res = this.pthread_getname_np(
+                    this.read_scalar(thread)?,
+                    this.read_scalar(name)?,
+                    this.read_scalar(len)?,
+                )?;
+                this.write_scalar(res, dest)?;
+            }
+
             // Miscellaneous
             "___errno" => {
                 let [] = this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;

src/tools/miri/tests/pass-dep/libc/pthread-threadname.rs

@@ -10,7 +10,7 @@ fn main() {
         .collect::<String>();
 
     fn set_thread_name(name: &CStr) -> i32 {
-        #[cfg(target_os = "linux")]
+        #[cfg(any(target_os = "linux", target_os = "illumos", target_os = "solaris"))]
         return unsafe { libc::pthread_setname_np(libc::pthread_self(), name.as_ptr().cast()) };
         #[cfg(target_os = "freebsd")]
         unsafe {