Used write_c_str

src/shims/unix/android/thread.rs

@@ -1,5 +1,3 @@
-use std::iter;
-
 use rustc_span::Symbol;
 use rustc_target::spec::abi::Abi;
 
@@ -49,17 +47,16 @@ pub fn prctl<'tcx>(
             let thread = ThreadId::try_from(thread).unwrap();
 
             // FIXME: we should use the program name if the thread name is not set
-            let name = this.get_thread_name(thread).unwrap_or(DEFAULT_THREAD_NAME).to_owned();
-            let name_len = name.len().max(TASK_COMM_LEN - 1);
+            let mut name = this.get_thread_name(thread).unwrap_or(DEFAULT_THREAD_NAME).to_owned();
+            let name_len = TASK_COMM_LEN - 1;
 
-            this.eval_context_mut().write_bytes_ptr(
-                name_out,
-                name.iter()
-                    .take(name_len)
-                    .copied()
-                    .chain(iter::repeat_n(0u8, TASK_COMM_LEN.strict_sub(name_len))),
-            )?;
+            if name.len() >= name_len {
+                name.drain(name_len..);
+            } else {
+                name.resize(name_len, 0);
+            }
 
+            this.write_c_str(&name, name_out, TASK_COMM_LEN as u64)?;
             Scalar::from_u32(0)
         }
         op => {

tests/pass-dep/libc/threadname.rs

@@ -59,15 +59,16 @@ fn main() {
         let result = thread::Builder::new().name(name.clone()).spawn(move || {
             assert_eq!(thread::current().name(), Some(name.as_str()));
 
-            let mut buf = vec![0u8; name.len() + 1];
+            // POSIX seems to promise at least 15 chars excluding a null terminator.
+            let mut buf = vec![0u8; 16];
             assert_eq!(get_thread_name(&mut buf), 0);
             let cstr = CStr::from_bytes_until_nul(&buf).unwrap();
             if name.len() >= 15 {
                 assert!(
                     cstr.to_bytes().len() >= 15,
                     "name is too short: len={}",
                     cstr.to_bytes().len()
-                ); // POSIX seems to promise at least 15 chars
+                );
                 assert!(name.as_bytes().starts_with(cstr.to_bytes()));
             } else {
                 assert_eq!(name.as_bytes(), cstr.to_bytes());
@@ -80,7 +81,7 @@ fn main() {
                 // But with a too long name it should fail except:
                 // * on FreeBSD where the function has no return, hence cannot indicate failure,
                 // * on Android where prctl silently truncates the string.
-                #[cfg(not(all(target_os = "freebsd", target_os = "android")))]
+                #[cfg(not(any(target_os = "freebsd", target_os = "android")))]
                 assert_ne!(set_thread_name(&std::ffi::CString::new(name).unwrap()), 0);
             }
         });