Rollup merge of #32476 - diwic:63-null-thread-name, r=alexcrichton

Fix unsound behaviour with null characters in thread names (issue #32475)

Previously, the thread name (&str) was converted to a CString in the
new thread, but outside unwind::try, causing a panic to continue into FFI.

This patch changes that behaviour, so that the panic instead happens
in the parent thread (where panic infrastructure is properly set up),
not the new thread.

This could potentially be a breaking change for architectures who don't
support thread names.

2 files changed, 12 insertions, 17 deletions

diff --git a/src/libstd/sys/unix/thread.rs b/src/libstd/sys/unix/thread.rs
index 793a2ecae89..6d966a0f694 100644
--- a/src/libstd/sys/unix/thread.rs
+++ b/src/libstd/sys/unix/thread.rs
@@ -13,7 +13,7 @@ use prelude::v1::*;
 use alloc::boxed::FnBox;
 use cmp;
 #[cfg(not(any(target_env = "newlib", target_os = "solaris")))]
-use ffi::CString;
+use ffi::CStr;
 use io;
 use libc;
 use mem;
@@ -84,15 +84,12 @@ impl Thread {
     #[cfg(any(target_os = "linux",
               target_os = "android",
               target_os = "emscripten"))]
-    pub fn set_name(name: &str) {
+    pub fn set_name(name: &CStr) {
         const PR_SET_NAME: libc::c_int = 15;
-        let cname = CString::new(name).unwrap_or_else(|_| {
-            panic!("thread name may not contain interior null bytes")
-        });
         // pthread wrapper only appeared in glibc 2.12, so we use syscall
         // directly.
         unsafe {
-            libc::prctl(PR_SET_NAME, cname.as_ptr() as libc::c_ulong, 0, 0, 0);
+            libc::prctl(PR_SET_NAME, name.as_ptr() as libc::c_ulong, 0, 0, 0);
         }
     }
 
@@ -100,32 +97,30 @@ impl Thread {
               target_os = "dragonfly",
               target_os = "bitrig",
               target_os = "openbsd"))]
-    pub fn set_name(name: &str) {
-        let cname = CString::new(name).unwrap();
+    pub fn set_name(name: &CStr) {
         unsafe {
-            libc::pthread_set_name_np(libc::pthread_self(), cname.as_ptr());
+            libc::pthread_set_name_np(libc::pthread_self(), name.as_ptr());
         }
     }
 
     #[cfg(any(target_os = "macos", target_os = "ios"))]
-    pub fn set_name(name: &str) {
-        let cname = CString::new(name).unwrap();
+    pub fn set_name(name: &CStr) {
         unsafe {
-            libc::pthread_setname_np(cname.as_ptr());
+            libc::pthread_setname_np(name.as_ptr());
         }
     }
 
     #[cfg(target_os = "netbsd")]
-    pub fn set_name(name: &str) {
+    pub fn set_name(name: &CStr) {
+        use ffi::CString;
         let cname = CString::new(&b"%s"[..]).unwrap();
-        let carg = CString::new(name).unwrap();
         unsafe {
             libc::pthread_setname_np(libc::pthread_self(), cname.as_ptr(),
-                                     carg.as_ptr() as *mut libc::c_void);
+                                     name.as_ptr() as *mut libc::c_void);
         }
     }
     #[cfg(any(target_env = "newlib", target_os = "solaris"))]
-    pub fn set_name(_name: &str) {
+    pub fn set_name(_name: &CStr) {
         // Newlib and Illumos has no way to set a thread name.
     }
 
diff --git a/src/libstd/sys/windows/thread.rs b/src/libstd/sys/windows/thread.rs
index b18772c0c24..6908775e86f 100644
--- a/src/libstd/sys/windows/thread.rs
+++ b/src/libstd/sys/windows/thread.rs
@@ -54,7 +54,7 @@ impl Thread {
         }
     }
 
-    pub fn set_name(_name: &str) {
+    pub fn set_name(_name: &CStr) {
         // Windows threads are nameless
         // The names in MSVC debugger are obtained using a "magic" exception,
         // which requires a use of MS C++ extensions.