From 46010c4618d4602cd6999c613fce7081fad438c2 Mon Sep 17 00:00:00 2001
From: Dan Gohman <dev@sunfishcode.online>
Date: Sat, 17 Jul 2021 05:47:39 -0700
Subject: [PATCH 1/3] Remove args cleanup code.

As of 91c3eee1735ad72b579f99cbb6919c3471747d94, the global ARGC and ARGV
no longer reference dynamically-allocated memory, so they don't need to
be cleaned up.
---
 library/std/src/sys/unix/args.rs | 13 -------------
 library/std/src/sys/unix/mod.rs  |  1 -
 2 files changed, 14 deletions(-)

diff --git a/library/std/src/sys/unix/args.rs b/library/std/src/sys/unix/args.rs
index fc423e393d4a4..d9e3c29f36b1e 100644
--- a/library/std/src/sys/unix/args.rs
+++ b/library/std/src/sys/unix/args.rs
@@ -14,11 +14,6 @@ pub unsafe fn init(argc: isize, argv: *const *const u8) {
     imp::init(argc, argv)
 }
 
-/// One-time global cleanup.
-pub unsafe fn cleanup() {
-    imp::cleanup()
-}
-
 /// Returns the command line arguments
 pub fn args() -> Args {
     imp::args()
@@ -127,12 +122,6 @@ mod imp {
         init_wrapper
     };
 
-    pub unsafe fn cleanup() {
-        let _guard = LOCK.lock();
-        ARGC.store(0, Ordering::Relaxed);
-        ARGV.store(ptr::null_mut(), Ordering::Relaxed);
-    }
-
     pub fn args() -> Args {
         Args { iter: clone().into_iter() }
     }
@@ -159,8 +148,6 @@ mod imp {
 
     pub unsafe fn init(_argc: isize, _argv: *const *const u8) {}
 
-    pub fn cleanup() {}
-
     #[cfg(target_os = "macos")]
     pub fn args() -> Args {
         use crate::os::unix::prelude::*;
diff --git a/library/std/src/sys/unix/mod.rs b/library/std/src/sys/unix/mod.rs
index 2da71b2a448ac..9e553ec7682b1 100644
--- a/library/std/src/sys/unix/mod.rs
+++ b/library/std/src/sys/unix/mod.rs
@@ -123,7 +123,6 @@ pub unsafe fn init(argc: isize, argv: *const *const u8) {
 // SAFETY: must be called only once during runtime cleanup.
 // NOTE: this is not guaranteed to run, for example when the program aborts.
 pub unsafe fn cleanup() {
-    args::cleanup();
     stack_overflow::cleanup();
 }
 

From 9bb11ba51135b0398b5a8b9feca24149d96fa5e8 Mon Sep 17 00:00:00 2001
From: Dan Gohman <dev@sunfishcode.online>
Date: Sat, 17 Jul 2021 12:33:31 -0700
Subject: [PATCH 2/3] Remove an unnecessary `Mutex` around argument
 initialization.

In the command-line argument initialization code, remove the Mutex
around the `ARGV` and `ARGC` variables, and simply check whether
ARGV is non-null before dereferencing it. This way, if either of
ARGV or ARGC is not initialized, we'll get an empty argument list.

This allows simple cdylibs to avoid having
`pthread_mutex_lock`/`pthread_mutex_unlock` appear in their symbol
tables if they don't otherwise use threads.
---
 library/std/src/sys/unix/args.rs | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/library/std/src/sys/unix/args.rs b/library/std/src/sys/unix/args.rs
index d9e3c29f36b1e..a6480199e7048 100644
--- a/library/std/src/sys/unix/args.rs
+++ b/library/std/src/sys/unix/args.rs
@@ -77,16 +77,10 @@ mod imp {
     use crate::ptr;
     use crate::sync::atomic::{AtomicIsize, AtomicPtr, Ordering};
 
-    use crate::sys_common::mutex::StaticMutex;
-
     static ARGC: AtomicIsize = AtomicIsize::new(0);
     static ARGV: AtomicPtr<*const u8> = AtomicPtr::new(ptr::null_mut());
-    // We never call `ENV_LOCK.init()`, so it is UB to attempt to
-    // acquire this mutex reentrantly!
-    static LOCK: StaticMutex = StaticMutex::new();
 
     unsafe fn really_init(argc: isize, argv: *const *const u8) {
-        let _guard = LOCK.lock();
         ARGC.store(argc, Ordering::Relaxed);
         ARGV.store(argv as *mut _, Ordering::Relaxed);
     }
@@ -128,9 +122,14 @@ mod imp {
 
     fn clone() -> Vec<OsString> {
         unsafe {
-            let _guard = LOCK.lock();
-            let argc = ARGC.load(Ordering::Relaxed);
+            // Load ARGC and ARGV without a lock. If the store to either ARGV or
+            // ARGC isn't visible yet, we'll return an empty argument list.
             let argv = ARGV.load(Ordering::Relaxed);
+            let argc = if argv.is_null() {
+                0
+            } else {
+                ARGC.load(Ordering::Relaxed)
+            };
             (0..argc)
                 .map(|i| {
                     let cstr = CStr::from_ptr(*argv.offset(i) as *const libc::c_char);

From c3df0ae97f9c03ce5937b9677c27da891a4a0fe0 Mon Sep 17 00:00:00 2001
From: Dan Gohman <dev@sunfishcode.online>
Date: Sat, 17 Jul 2021 18:31:51 -0700
Subject: [PATCH 3/3] x.py fmt

---
 library/std/src/sys/unix/args.rs | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/library/std/src/sys/unix/args.rs b/library/std/src/sys/unix/args.rs
index a6480199e7048..ad93fa610c481 100644
--- a/library/std/src/sys/unix/args.rs
+++ b/library/std/src/sys/unix/args.rs
@@ -125,11 +125,7 @@ mod imp {
             // Load ARGC and ARGV without a lock. If the store to either ARGV or
             // ARGC isn't visible yet, we'll return an empty argument list.
             let argv = ARGV.load(Ordering::Relaxed);
-            let argc = if argv.is_null() {
-                0
-            } else {
-                ARGC.load(Ordering::Relaxed)
-            };
+            let argc = if argv.is_null() { 0 } else { ARGC.load(Ordering::Relaxed) };
             (0..argc)
                 .map(|i| {
                     let cstr = CStr::from_ptr(*argv.offset(i) as *const libc::c_char);