From c97c85586da142df46fd2f8eef0dafc55def8568 Mon Sep 17 00:00:00 2001
From: Catherine <whitequark@whitequark.org>
Date: Sat, 26 Jul 2025 16:12:15 +0000
Subject: [PATCH] Refactor stub pthread library and enable unconditionally.

This commit changes the layout of the stub pthread library to match
that of libc-top-half: splits it into (mostly) one file per function,
and ensures the same API is exposed from both libraries, adding stub
functions as necessary.

This commit also removes `-lwasi-emulated-pthread` as well as
`-D_WASI_EMULATED_PTHREAD` and enables this functionality
unconditionally, seeing as this is necessary for building libc++ with
threading enabled.

It adds a flag `-D_WASI_STRICT_PTHREAD` that causes thread creation
functions (`pthread_create`, `pthread_detach`, `pthread_join`,
`pthread_tryjoin_np`, `pthread_timedjoin_np`) to be defined as a macro
causing a compile error, which can be used to locate the parts of
a codebase requiring changes for the single thread model.

Specifically, after this commit, the two targets `wasm32-wasip1` and
`wasm32-wasip1-threads` differ as follows (cleaned up for clarity):

    --- expected/wasm32-wasip1/defined-symbols.txt
    +++ expected/wasm32-wasip1-threads/defined-symbols.txt
    +flockfile
    +ftrylockfile
    +funlockfile
    +sem_destroy
    +sem_getvalue
    +sem_init
    +sem_post
    +sem_timedwait
    +sem_trywait
    +sem_wait
    +wasi_thread_start

    --- expected/wasm32-wasip1/predefined-macros.txt
    +++ expected/wasm32-wasip1-threads/predefined-macros.txt
    +#define _REENTRANT 1
    +#define SEM_NSEMS_MAX 256
    +#define SEM_VALUE_MAX 0x7fffffff
    +#define __wasm_atomics__ 1
    +#define __wasm_bulk_memory__ 1
---
 Makefile                                     | 60 ++++++++++--------
 expected/wasm32-wasip1/defined-symbols.txt   |  7 +-
 expected/wasm32-wasip1/predefined-macros.txt |  9 ++-
 expected/wasm32-wasip2/defined-symbols.txt   |  7 +-
 expected/wasm32-wasip2/predefined-macros.txt |  9 ++-
 libc-top-half/musl/include/pthread.h         | 25 ++------
 libc-top-half/musl/include/unistd.h          |  4 +-
 stub-pthreads/README.md                      | 16 -----
 stub-pthreads/barrier.c                      | 23 -------
 stub-pthreads/condvar.c                      | 36 -----------
 stub-pthreads/mutex.c                        | 67 --------------------
 stub-pthreads/rwlock.c                       | 60 ------------------
 stub-pthreads/spinlock.c                     | 21 ------
 stub-pthreads/stub-pthreads-emulated.c       | 40 ------------
 stub-pthreads/stub-pthreads-good.c           | 43 -------------
 thread-stub/README.md                        |  7 ++
 thread-stub/pthread_barrier_destroy.c        |  6 ++
 thread-stub/pthread_barrier_init.c           |  8 +++
 thread-stub/pthread_barrier_wait.c           |  7 ++
 thread-stub/pthread_cond_broadcast.c         |  6 ++
 thread-stub/pthread_cond_destroy.c           |  6 ++
 thread-stub/pthread_cond_init.c              |  6 ++
 thread-stub/pthread_cond_signal.c            |  6 ++
 thread-stub/pthread_cond_timedwait.c         | 13 ++++
 thread-stub/pthread_cond_wait.c              |  9 +++
 thread-stub/pthread_create.c                 | 19 ++++++
 thread-stub/pthread_detach.c                 | 13 ++++
 thread-stub/pthread_getattr_np.c             | 11 ++++
 thread-stub/pthread_join.c                   | 32 ++++++++++
 thread-stub/pthread_mutex_consistent.c       |  8 +++
 thread-stub/pthread_mutex_getprioceiling.c   |  6 ++
 thread-stub/pthread_mutex_lock.c             | 21 ++++++
 thread-stub/pthread_mutex_timedlock.c        | 10 +++
 thread-stub/pthread_mutex_trylock.c          | 21 ++++++
 thread-stub/pthread_mutex_unlock.c           | 10 +++
 thread-stub/pthread_once.c                   | 12 ++++
 thread-stub/pthread_rwlock_rdlock.c          | 11 ++++
 thread-stub/pthread_rwlock_timedrdlock.c     |  8 +++
 thread-stub/pthread_rwlock_timedwrlock.c     |  8 +++
 thread-stub/pthread_rwlock_tryrdlock.c       | 11 ++++
 thread-stub/pthread_rwlock_trywrlock.c       | 10 +++
 thread-stub/pthread_rwlock_unlock.c          | 12 ++++
 thread-stub/pthread_rwlock_wrlock.c          | 10 +++
 thread-stub/pthread_spin_lock.c              |  8 +++
 thread-stub/pthread_spin_trylock.c           |  8 +++
 thread-stub/pthread_spin_unlock.c            |  7 ++
 46 files changed, 388 insertions(+), 369 deletions(-)
 delete mode 100644 stub-pthreads/README.md
 delete mode 100644 stub-pthreads/barrier.c
 delete mode 100644 stub-pthreads/condvar.c
 delete mode 100644 stub-pthreads/mutex.c
 delete mode 100644 stub-pthreads/rwlock.c
 delete mode 100644 stub-pthreads/spinlock.c
 delete mode 100644 stub-pthreads/stub-pthreads-emulated.c
 delete mode 100644 stub-pthreads/stub-pthreads-good.c
 create mode 100644 thread-stub/README.md
 create mode 100644 thread-stub/pthread_barrier_destroy.c
 create mode 100644 thread-stub/pthread_barrier_init.c
 create mode 100644 thread-stub/pthread_barrier_wait.c
 create mode 100644 thread-stub/pthread_cond_broadcast.c
 create mode 100644 thread-stub/pthread_cond_destroy.c
 create mode 100644 thread-stub/pthread_cond_init.c
 create mode 100644 thread-stub/pthread_cond_signal.c
 create mode 100644 thread-stub/pthread_cond_timedwait.c
 create mode 100644 thread-stub/pthread_cond_wait.c
 create mode 100644 thread-stub/pthread_create.c
 create mode 100644 thread-stub/pthread_detach.c
 create mode 100644 thread-stub/pthread_getattr_np.c
 create mode 100644 thread-stub/pthread_join.c
 create mode 100644 thread-stub/pthread_mutex_consistent.c
 create mode 100644 thread-stub/pthread_mutex_getprioceiling.c
 create mode 100644 thread-stub/pthread_mutex_lock.c
 create mode 100644 thread-stub/pthread_mutex_timedlock.c
 create mode 100644 thread-stub/pthread_mutex_trylock.c
 create mode 100644 thread-stub/pthread_mutex_unlock.c
 create mode 100644 thread-stub/pthread_once.c
 create mode 100644 thread-stub/pthread_rwlock_rdlock.c
 create mode 100644 thread-stub/pthread_rwlock_timedrdlock.c
 create mode 100644 thread-stub/pthread_rwlock_timedwrlock.c
 create mode 100644 thread-stub/pthread_rwlock_tryrdlock.c
 create mode 100644 thread-stub/pthread_rwlock_trywrlock.c
 create mode 100644 thread-stub/pthread_rwlock_unlock.c
 create mode 100644 thread-stub/pthread_rwlock_wrlock.c
 create mode 100644 thread-stub/pthread_spin_lock.c
 create mode 100644 thread-stub/pthread_spin_trylock.c
 create mode 100644 thread-stub/pthread_spin_unlock.c

diff --git a/Makefile b/Makefile
index 1d44df029..26bdcfa9b 100644
--- a/Makefile
+++ b/Makefile
@@ -71,7 +71,7 @@ DLMALLOC_SOURCES = $(DLMALLOC_SRC_DIR)/dlmalloc.c
 DLMALLOC_INC = $(DLMALLOC_DIR)/include
 EMMALLOC_DIR = emmalloc
 EMMALLOC_SOURCES = $(EMMALLOC_DIR)/emmalloc.c
-STUB_PTHREADS_DIR = stub-pthreads
+THREAD_STUB_DIR = thread-stub
 LIBC_BOTTOM_HALF_DIR = libc-bottom-half
 LIBC_BOTTOM_HALF_CLOUDLIBC_SRC = $(LIBC_BOTTOM_HALF_DIR)/cloudlibc/src
 LIBC_BOTTOM_HALF_CLOUDLIBC_SRC_INC = $(LIBC_BOTTOM_HALF_CLOUDLIBC_SRC)/include
@@ -138,8 +138,6 @@ LIBWASI_EMULATED_SIGNAL_SOURCES = \
 LIBWASI_EMULATED_SIGNAL_MUSL_SOURCES = \
     $(LIBC_TOP_HALF_MUSL_SRC_DIR)/signal/psignal.c \
     $(LIBC_TOP_HALF_MUSL_SRC_DIR)/string/strsignal.c
-LIBWASI_EMULATED_PTHREAD_SOURCES = \
-    $(STUB_PTHREADS_DIR)/stub-pthreads-emulated.c
 LIBDL_SOURCES = $(LIBC_TOP_HALF_MUSL_SRC_DIR)/misc/dl.c
 LIBSETJMP_SOURCES = $(LIBC_TOP_HALF_MUSL_SRC_DIR)/setjmp/wasm32/rt.c
 LIBC_BOTTOM_HALF_CRT_SOURCES = $(wildcard $(LIBC_BOTTOM_HALF_DIR)/crt/*.c)
@@ -373,12 +371,38 @@ endif
 ifeq ($(THREAD_MODEL), single)
 # pthreads stubs for single-threaded environment
 LIBC_TOP_HALF_MUSL_SOURCES += \
-    $(STUB_PTHREADS_DIR)/barrier.c \
-    $(STUB_PTHREADS_DIR)/condvar.c \
-    $(STUB_PTHREADS_DIR)/mutex.c \
-    $(STUB_PTHREADS_DIR)/rwlock.c \
-    $(STUB_PTHREADS_DIR)/spinlock.c \
-    $(STUB_PTHREADS_DIR)/stub-pthreads-good.c
+    $(addprefix $(THREAD_STUB_DIR)/, \
+        pthread_barrier_destroy.c \
+        pthread_barrier_init.c \
+        pthread_barrier_wait.c \
+        pthread_cond_broadcast.c \
+        pthread_cond_destroy.c \
+        pthread_cond_init.c \
+        pthread_cond_signal.c \
+        pthread_cond_timedwait.c \
+        pthread_cond_wait.c \
+        pthread_create.c \
+        pthread_detach.c \
+        pthread_getattr_np.c \
+        pthread_join.c \
+        pthread_mutex_consistent.c \
+        pthread_mutex_getprioceiling.c \
+        pthread_mutex_lock.c \
+        pthread_mutex_timedlock.c \
+        pthread_mutex_trylock.c \
+        pthread_mutex_unlock.c \
+        pthread_once.c \
+        pthread_rwlock_rdlock.c \
+        pthread_rwlock_timedrdlock.c \
+        pthread_rwlock_timedwrlock.c \
+        pthread_rwlock_tryrdlock.c \
+        pthread_rwlock_trywrlock.c \
+        pthread_rwlock_unlock.c \
+        pthread_rwlock_wrlock.c \
+        pthread_spin_lock.c \
+        pthread_spin_trylock.c \
+        pthread_spin_unlock.c \
+    )
 endif
 
 MUSL_PRINTSCAN_SOURCES = \
@@ -505,7 +529,6 @@ LIBWASI_EMULATED_PROCESS_CLOCKS_OBJS = $(call objs,$(LIBWASI_EMULATED_PROCESS_CL
 LIBWASI_EMULATED_GETPID_OBJS = $(call objs,$(LIBWASI_EMULATED_GETPID_SOURCES))
 LIBWASI_EMULATED_SIGNAL_OBJS = $(call objs,$(LIBWASI_EMULATED_SIGNAL_SOURCES))
 LIBWASI_EMULATED_SIGNAL_MUSL_OBJS = $(call objs,$(LIBWASI_EMULATED_SIGNAL_MUSL_SOURCES))
-LIBWASI_EMULATED_PTHREAD_OBJS = $(call objs,$(LIBWASI_EMULATED_PTHREAD_SOURCES))
 LIBDL_OBJS = $(call objs,$(LIBDL_SOURCES))
 LIBSETJMP_OBJS = $(call objs,$(LIBSETJMP_SOURCES))
 LIBC_BOTTOM_HALF_CRT_OBJS = $(call objs,$(LIBC_BOTTOM_HALF_CRT_SOURCES))
@@ -529,7 +552,6 @@ LIBWASI_EMULATED_PROCESS_CLOCKS_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBWASI_EMULA
 LIBWASI_EMULATED_GETPID_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBWASI_EMULATED_GETPID_OBJS))
 LIBWASI_EMULATED_SIGNAL_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBWASI_EMULATED_SIGNAL_OBJS))
 LIBWASI_EMULATED_SIGNAL_MUSL_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBWASI_EMULATED_SIGNAL_MUSL_OBJS))
-LIBWASI_EMULATED_PTHREAD_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBWASI_EMULATED_PTHREAD_OBJS))
 LIBDL_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBDL_OBJS))
 LIBSETJMP_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBSETJMP_OBJS))
 BULK_MEMORY_SO_OBJS = $(patsubst %.o,%.pic.o,$(BULK_MEMORY_OBJS))
@@ -546,7 +568,6 @@ PIC_OBJS = \
 	$(LIBWASI_EMULATED_GETPID_SO_OBJS) \
 	$(LIBWASI_EMULATED_SIGNAL_SO_OBJS) \
 	$(LIBWASI_EMULATED_SIGNAL_MUSL_SO_OBJS) \
-	$(LIBWASI_EMULATED_PTHREAD_SO_OBJS) \
 	$(LIBDL_SO_OBJS) \
 	$(LIBSETJMP_SO_OBJS) \
 	$(BULK_MEMORY_SO_OBJS) \
@@ -646,8 +667,6 @@ $(OBJDIR)/libwasi-emulated-getpid.so.a: $(LIBWASI_EMULATED_GETPID_SO_OBJS)
 
 $(OBJDIR)/libwasi-emulated-signal.so.a: $(LIBWASI_EMULATED_SIGNAL_SO_OBJS) $(LIBWASI_EMULATED_SIGNAL_MUSL_SO_OBJS)
 
-$(OBJDIR)/libwasi-emulated-pthread.so.a: $(LIBWASI_EMULATED_PTHREAD_SO_OBJS)
-
 $(OBJDIR)/libdl.so.a: $(LIBDL_SO_OBJS)
 
 $(OBJDIR)/libsetjmp.so.a: $(LIBSETJMP_SO_OBJS)
@@ -666,8 +685,6 @@ $(SYSROOT_LIB)/libwasi-emulated-getpid.a: $(LIBWASI_EMULATED_GETPID_OBJS)
 
 $(SYSROOT_LIB)/libwasi-emulated-signal.a: $(LIBWASI_EMULATED_SIGNAL_OBJS) $(LIBWASI_EMULATED_SIGNAL_MUSL_OBJS)
 
-$(SYSROOT_LIB)/libwasi-emulated-pthread.a: $(LIBWASI_EMULATED_PTHREAD_OBJS)
-
 $(SYSROOT_LIB)/libdl.a: $(LIBDL_OBJS)
 
 $(SYSROOT_LIB)/libsetjmp.a: $(LIBSETJMP_OBJS)
@@ -770,12 +787,6 @@ $(FTS_OBJS) $(FTS_SO_OBJS): CFLAGS += \
 $(LIBWASI_EMULATED_PROCESS_CLOCKS_OBJS) $(LIBWASI_EMULATED_PROCESS_CLOCKS_SO_OBJS): CFLAGS += \
     -I$(LIBC_BOTTOM_HALF_CLOUDLIBC_SRC)
 
-$(LIBWASI_EMULATED_PTHREAD_OBJS) $(LIBWASI_EMULATED_PTHREAD_SO_OBJS): CFLAGS += \
-    -I$(LIBC_TOP_HALF_MUSL_SRC_DIR)/include \
-    -I$(LIBC_TOP_HALF_MUSL_SRC_DIR)/internal \
-    -I$(LIBC_TOP_HALF_MUSL_DIR)/arch/wasm32 \
-    -D_WASI_EMULATED_PTHREAD
-
 # emmalloc uses a lot of pointer type-punning, which is UB under strict aliasing,
 # and this was found to have real miscompilations in wasi-libc#421.
 $(EMMALLOC_OBJS): CFLAGS += \
@@ -816,7 +827,6 @@ LIBC_SO = \
 	$(SYSROOT_LIB)/libwasi-emulated-process-clocks.so \
 	$(SYSROOT_LIB)/libwasi-emulated-getpid.so \
 	$(SYSROOT_LIB)/libwasi-emulated-signal.so \
-	$(SYSROOT_LIB)/libwasi-emulated-pthread.so \
 	$(SYSROOT_LIB)/libdl.so
 ifeq ($(BUILD_LIBSETJMP),yes)
 LIBC_SO += \
@@ -835,10 +845,6 @@ STATIC_LIBS = \
     $(SYSROOT_LIB)/libwasi-emulated-getpid.a \
     $(SYSROOT_LIB)/libwasi-emulated-signal.a \
     $(SYSROOT_LIB)/libdl.a
-ifneq ($(THREAD_MODEL), posix)
-    STATIC_LIBS += \
-        $(SYSROOT_LIB)/libwasi-emulated-pthread.a
-endif
 ifeq ($(BUILD_LIBSETJMP),yes)
 STATIC_LIBS += \
 	$(SYSROOT_LIB)/libsetjmp.a
diff --git a/expected/wasm32-wasip1/defined-symbols.txt b/expected/wasm32-wasip1/defined-symbols.txt
index 6e06d64ff..5ec699a95 100644
--- a/expected/wasm32-wasip1/defined-symbols.txt
+++ b/expected/wasm32-wasip1/defined-symbols.txt
@@ -182,15 +182,14 @@ __progname
 __progname_full
 __pthread_cond_timedwait
 __pthread_create
-__pthread_detach
 __pthread_join
 __pthread_key_create
 __pthread_key_delete
-__pthread_mutex_consistent
 __pthread_mutex_lock
 __pthread_mutex_timedlock
 __pthread_mutex_trylock
 __pthread_mutex_unlock
+__pthread_once
 __pthread_rwlock_rdlock
 __pthread_rwlock_timedrdlock
 __pthread_rwlock_timedwrlock
@@ -991,13 +990,14 @@ pthread_condattr_setpshared
 pthread_create
 pthread_detach
 pthread_equal
-pthread_exit
+pthread_getattr_np
 pthread_getspecific
 pthread_join
 pthread_key_create
 pthread_key_delete
 pthread_mutex_consistent
 pthread_mutex_destroy
+pthread_mutex_getprioceiling
 pthread_mutex_init
 pthread_mutex_lock
 pthread_mutex_timedlock
@@ -1221,6 +1221,7 @@ tgamma
 tgammaf
 tgammal
 thrd_current
+thrd_detach
 thrd_equal
 thrd_sleep
 time
diff --git a/expected/wasm32-wasip1/predefined-macros.txt b/expected/wasm32-wasip1/predefined-macros.txt
index d1aca887a..66f4c4c88 100644
--- a/expected/wasm32-wasip1/predefined-macros.txt
+++ b/expected/wasm32-wasip1/predefined-macros.txt
@@ -2252,8 +2252,12 @@
 #define _POSIX_STREAM_MAX 8
 #define _POSIX_SYMLINK_MAX 255
 #define _POSIX_SYMLOOP_MAX 8
+#define _POSIX_THREADS _POSIX_VERSION
+#define _POSIX_THREAD_ATTR_STACKSIZE _POSIX_VERSION
 #define _POSIX_THREAD_DESTRUCTOR_ITERATIONS 4
 #define _POSIX_THREAD_KEYS_MAX 128
+#define _POSIX_THREAD_PROCESS_SHARED _POSIX_VERSION
+#define _POSIX_THREAD_SAFE_FUNCTIONS _POSIX_VERSION
 #define _POSIX_THREAD_THREADS_MAX 64
 #define _POSIX_TIMEOUTS _POSIX_VERSION
 #define _POSIX_TIMERS _POSIX_VERSION
@@ -3430,12 +3434,7 @@
 #define preadv64 preadv
 #define pthread_cleanup_pop(r) _pthread_cleanup_pop(&__cb, (r)); } while(0)
 #define pthread_cleanup_push(f,x) do { struct __ptcb __cb; _pthread_cleanup_push(&__cb, f, x);
-#define pthread_create(...) ({ _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread"); 0;})
-#define pthread_detach(...) ({ _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread"); 0;})
 #define pthread_equal(x,y) ((x)==(y))
-#define pthread_join(...) ({ _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread"); 0;})
-#define pthread_timedjoin_np(...) ({ _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread"); 0;})
-#define pthread_tryjoin_np(...) ({ _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread"); 0;})
 #define pwrite64 pwrite
 #define pwritev64 pwritev
 #define readdir64 readdir
diff --git a/expected/wasm32-wasip2/defined-symbols.txt b/expected/wasm32-wasip2/defined-symbols.txt
index 9d2e803fd..d5fc8f116 100644
--- a/expected/wasm32-wasip2/defined-symbols.txt
+++ b/expected/wasm32-wasip2/defined-symbols.txt
@@ -185,15 +185,14 @@ __progname
 __progname_full
 __pthread_cond_timedwait
 __pthread_create
-__pthread_detach
 __pthread_join
 __pthread_key_create
 __pthread_key_delete
-__pthread_mutex_consistent
 __pthread_mutex_lock
 __pthread_mutex_timedlock
 __pthread_mutex_trylock
 __pthread_mutex_unlock
+__pthread_once
 __pthread_rwlock_rdlock
 __pthread_rwlock_timedrdlock
 __pthread_rwlock_timedwrlock
@@ -1127,13 +1126,14 @@ pthread_condattr_setpshared
 pthread_create
 pthread_detach
 pthread_equal
-pthread_exit
+pthread_getattr_np
 pthread_getspecific
 pthread_join
 pthread_key_create
 pthread_key_delete
 pthread_mutex_consistent
 pthread_mutex_destroy
+pthread_mutex_getprioceiling
 pthread_mutex_init
 pthread_mutex_lock
 pthread_mutex_timedlock
@@ -1457,6 +1457,7 @@ tgamma
 tgammaf
 tgammal
 thrd_current
+thrd_detach
 thrd_equal
 thrd_sleep
 time
diff --git a/expected/wasm32-wasip2/predefined-macros.txt b/expected/wasm32-wasip2/predefined-macros.txt
index 959dd6ec8..1ae2e1fd2 100644
--- a/expected/wasm32-wasip2/predefined-macros.txt
+++ b/expected/wasm32-wasip2/predefined-macros.txt
@@ -2403,8 +2403,12 @@
 #define _POSIX_STREAM_MAX 8
 #define _POSIX_SYMLINK_MAX 255
 #define _POSIX_SYMLOOP_MAX 8
+#define _POSIX_THREADS _POSIX_VERSION
+#define _POSIX_THREAD_ATTR_STACKSIZE _POSIX_VERSION
 #define _POSIX_THREAD_DESTRUCTOR_ITERATIONS 4
 #define _POSIX_THREAD_KEYS_MAX 128
+#define _POSIX_THREAD_PROCESS_SHARED _POSIX_VERSION
+#define _POSIX_THREAD_SAFE_FUNCTIONS _POSIX_VERSION
 #define _POSIX_THREAD_THREADS_MAX 64
 #define _POSIX_TIMEOUTS _POSIX_VERSION
 #define _POSIX_TIMERS _POSIX_VERSION
@@ -3585,12 +3589,7 @@
 #define preadv64 preadv
 #define pthread_cleanup_pop(r) _pthread_cleanup_pop(&__cb, (r)); } while(0)
 #define pthread_cleanup_push(f,x) do { struct __ptcb __cb; _pthread_cleanup_push(&__cb, f, x);
-#define pthread_create(...) ({ _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread"); 0;})
-#define pthread_detach(...) ({ _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread"); 0;})
 #define pthread_equal(x,y) ((x)==(y))
-#define pthread_join(...) ({ _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread"); 0;})
-#define pthread_timedjoin_np(...) ({ _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread"); 0;})
-#define pthread_tryjoin_np(...) ({ _Static_assert(0, "This mode of WASI does not have threads enabled; to enable stub functions which always fail, compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread"); 0;})
 #define pwrite64 pwrite
 #define pwritev64 pwritev
 #define readdir64 readdir
diff --git a/libc-top-half/musl/include/pthread.h b/libc-top-half/musl/include/pthread.h
index fa9f66ae8..111c1fbf8 100644
--- a/libc-top-half/musl/include/pthread.h
+++ b/libc-top-half/musl/include/pthread.h
@@ -83,21 +83,14 @@ int pthread_detach(pthread_t);
 _Noreturn void pthread_exit(void *);
 int pthread_join(pthread_t, void **);
 #else
-#if defined(_WASI_EMULATED_PTHREAD) || defined(_REENTRANT)
+#if defined(_REENTRANT) || !defined(_WASI_STRICT_PTHREAD)
 int pthread_create(pthread_t *__restrict, const pthread_attr_t *__restrict, void *(*)(void *), void *__restrict);
 int pthread_detach(pthread_t);
 int pthread_join(pthread_t, void **);
 #else
-#include <assert.h>
-#define pthread_create(...) ({ _Static_assert(0, "This mode of WASI does not have threads enabled; \
-to enable stub functions which always fail, \
-compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread"); 0;})
-#define pthread_detach(...) ({ _Static_assert(0, "This mode of WASI does not have threads enabled; \
-to enable stub functions which always fail, \
-compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread"); 0;})
-#define pthread_join(...) ({ _Static_assert(0, "This mode of WASI does not have threads enabled; \
-to enable stub functions which always fail, \
-compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread"); 0;})
+#define pthread_create(...) ({ _Static_assert(0, "This function is not available on a single-threaded target; switch to a multi-threaded target with -pthread or enable a stub implementation by undefining _WASI_STRICT_PTHREAD"); 0;})
+#define pthread_detach(...) ({ _Static_assert(0, "This function is not available on a single-threaded target; switch to a multi-threaded target with -pthread or enable a stub implementation by undefining _WASI_STRICT_PTHREAD"); 0;})
+#define pthread_join(...) ({ _Static_assert(0, "This function is not available on a single-threaded target; switch to a multi-threaded target with -pthread or enable a stub implementation by undefining _WASI_STRICT_PTHREAD"); 0;})
 #endif
 #endif
 
@@ -249,16 +242,12 @@ int pthread_setname_np(pthread_t, const char *);
 int pthread_getname_np(pthread_t, char *, size_t);
 int pthread_getattr_default_np(pthread_attr_t *);
 int pthread_setattr_default_np(const pthread_attr_t *);
-#if defined(__wasilibc_unmodified_upstream) || defined(_WASI_EMULATED_PTHREAD) || defined(_REENTRANT)
+#if defined(__wasilibc_unmodified_upstream) || defined(_REENTRANT) || !defined(_WASI_STRICT_PTHREAD)
 int pthread_tryjoin_np(pthread_t, void **);
 int pthread_timedjoin_np(pthread_t, void **, const struct timespec *);
 #else
-#define pthread_tryjoin_np(...) ({ _Static_assert(0, "This mode of WASI does not have threads enabled; \
-to enable stub functions which always fail, \
-compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread"); 0;})
-#define pthread_timedjoin_np(...) ({ _Static_assert(0, "This mode of WASI does not have threads enabled; \
-to enable stub functions which always fail, \
-compile with -D_WASI_EMULATED_PTHREAD and link with -lwasi-emulated-pthread"); 0;})
+#define pthread_tryjoin_np(...) ({ _Static_assert(0, "This function is not available on a single-threaded target; switch to a multi-threaded target with -pthread or enable a stub implementation by undefining _WASI_STRICT_PTHREAD"); 0;})
+#define pthread_timedjoin_np(...) ({ _Static_assert(0, "This function is not available on a single-threaded target; switch to a multi-threaded target with -pthread or enable a stub implementation by undefining _WASI_STRICT_PTHREAD"); 0;})
 #endif
 #endif
 
diff --git a/libc-top-half/musl/include/unistd.h b/libc-top-half/musl/include/unistd.h
index 1c1d62d22..c3158e6e6 100644
--- a/libc-top-half/musl/include/unistd.h
+++ b/libc-top-half/musl/include/unistd.h
@@ -336,7 +336,7 @@ pid_t gettid(void);
 #endif
 #define _POSIX_VDISABLE         0
 
-#if defined(__wasilibc_unmodified_upstream) || defined(_REENTRANT)
+#if defined(__wasilibc_unmodified_upstream) || defined(_REENTRANT) || !defined(_WASI_STRICT_PTHREAD)
 #define _POSIX_THREADS          _POSIX_VERSION
 #define _POSIX_THREAD_PROCESS_SHARED _POSIX_VERSION
 #define _POSIX_THREAD_SAFE_FUNCTIONS _POSIX_VERSION
@@ -344,7 +344,7 @@ pid_t gettid(void);
 #if defined(__wasilibc_unmodified_upstream) /* wasi-libc doesn't provide pthread_attr_{get,set}stackaddr */
 #define _POSIX_THREAD_ATTR_STACKADDR _POSIX_VERSION
 #endif
-#if defined(__wasilibc_unmodified_upstream) || defined(_REENTRANT)
+#if defined(__wasilibc_unmodified_upstream) || defined(_REENTRANT) || !defined(_WASI_STRICT_PTHREAD)
 #define _POSIX_THREAD_ATTR_STACKSIZE _POSIX_VERSION
 #endif
 #if defined(__wasilibc_unmodified_upstream) /* WASI has no scheduling control, and wasi-libc doesn't provide pthread_getcpuclockid */
diff --git a/stub-pthreads/README.md b/stub-pthreads/README.md
deleted file mode 100644
index fe2161000..000000000
--- a/stub-pthreads/README.md
+++ /dev/null
@@ -1,16 +0,0 @@
-# Single-threaded pthreads stubs
-
-The goal of these files is to provide stub implementations of pthreads
-functions for `THREAD_MODEL=single`. This implementation should _always_
-follow the strict letter of the POSIX specifications. This means that
-"doing nothing", "always succeeding", etc. are not proper implementations
--- these stubs aim for higher conformance than that.
-
-The code that is "more" aligned with the spirit of the POSIX specifications
- ends up compiled into libc itself. This primarily consists of synchronization
-  primitives (which are implemented to actually track state).
-
-The code that is "less" aligned with the spirit of the specifications
-(e.g. by "rules-lawyering" and always failing) are built into a library
-`wasi-emulated-pthread.a`. The distinction is ultimately made by vibes and a
-judgement call, not formal criteria.
diff --git a/stub-pthreads/barrier.c b/stub-pthreads/barrier.c
deleted file mode 100644
index e0ceed06a..000000000
--- a/stub-pthreads/barrier.c
+++ /dev/null
@@ -1,23 +0,0 @@
-#include "pthread_impl.h"
-/*
-	Note on PTHREAD_PROCESS_SHARED:
-	Because WASM doesn't have virtual memory nor subprocesses,
-	there isn't any way for the same synchronization object to have multiple mappings.
-	Thus we can completely ignore it here.
-*/
-
-int pthread_barrier_init(pthread_barrier_t *restrict b, const pthread_barrierattr_t *restrict a, unsigned count)
-{
-	if (count-1 > INT_MAX-1) return EINVAL;
-	*b = (pthread_barrier_t){ ._b_limit = count-1 };
-	return 0;
-}
-int pthread_barrier_destroy(pthread_barrier_t *b)
-{
-	return 0;
-}
-int pthread_barrier_wait(pthread_barrier_t *b)
-{
-	if (!b->_b_limit) return PTHREAD_BARRIER_SERIAL_THREAD;
-	__builtin_trap();
-}
diff --git a/stub-pthreads/condvar.c b/stub-pthreads/condvar.c
deleted file mode 100644
index de65bac23..000000000
--- a/stub-pthreads/condvar.c
+++ /dev/null
@@ -1,36 +0,0 @@
-#include "pthread_impl.h"
-#include <time.h>
-
-int pthread_cond_init(pthread_cond_t *restrict c, const pthread_condattr_t *restrict a)
-{
-	return 0;
-}
-int pthread_cond_destroy(pthread_cond_t *c)
-{
-	return 0;
-}
-int pthread_cond_broadcast(pthread_cond_t *c)
-{
-	return 0;
-}
-int pthread_cond_signal(pthread_cond_t *c)
-{
-	return 0;
-}
-int pthread_cond_wait(pthread_cond_t *restrict c, pthread_mutex_t *restrict m)
-{
-	/* Because there is no other thread that can signal us, this is a deadlock immediately.
-	The other possible choice is to return immediately (spurious wakeup), but that is likely to
-	just result in the program spinning forever on a condition that cannot become true. */
-	__builtin_trap();
-}
-int __pthread_cond_timedwait(pthread_cond_t *restrict c, pthread_mutex_t *restrict m, const struct timespec *restrict ts)
-{
-	/* Error check mutexes must detect if they're not locked (UB for others) */
-	if (!m->_m_count) return EPERM;
-	int ret = clock_nanosleep(CLOCK_REALTIME, TIMER_ABSTIME, ts, 0);
-	if (ret == 0) return ETIMEDOUT;
-	if (ret != EINTR) return ret;
-	return 0;
-}
-weak_alias(__pthread_cond_timedwait, pthread_cond_timedwait);
diff --git a/stub-pthreads/mutex.c b/stub-pthreads/mutex.c
deleted file mode 100644
index 475bdcf8c..000000000
--- a/stub-pthreads/mutex.c
+++ /dev/null
@@ -1,67 +0,0 @@
-#include "pthread_impl.h"
-/*
-	Musl mutex (FYI)
-
-	_m_type:
-	b[7]	- process shared
-	b[3]	- priority inherit
-	b[2] 	- robust
-	b[1:0] 	- type
-		0 - normal
-		1 - recursive
-		2 - errorcheck
-
-	_m_lock:
-	b[30]	- owner dead, if robust
-	b[29:0]	- tid, if not normal
-	b[4]	- locked?, if normal
-*/
-
-int __pthread_mutex_consistent(pthread_mutex_t *m)
-{
-	/* cannot be a robust mutex, as they're entirely unsupported in WASI */
-	return EINVAL;
-}
-weak_alias(__pthread_mutex_consistent, pthread_mutex_consistent);
-
-int __pthread_mutex_lock(pthread_mutex_t *m)
-{
-	if (m->_m_type&3 != PTHREAD_MUTEX_RECURSIVE) {
-		if (m->_m_count) return EDEADLK;
-		m->_m_count = 1;
-	} else {
-		if ((unsigned)m->_m_count >= INT_MAX) return EAGAIN;
-		m->_m_count++;
-	}
-	return 0;
-}
-weak_alias(__pthread_mutex_lock, pthread_mutex_lock);
-
-int __pthread_mutex_trylock(pthread_mutex_t *m)
-{
-	if (m->_m_type&3 != PTHREAD_MUTEX_RECURSIVE) {
-		if (m->_m_count) return EBUSY;
-		m->_m_count = 1;
-	} else {
-		if ((unsigned)m->_m_count >= INT_MAX) return EAGAIN;
-		m->_m_count++;
-	}
-	return 0;
-}
-weak_alias(__pthread_mutex_trylock, pthread_mutex_trylock);
-
-int __pthread_mutex_unlock(pthread_mutex_t *m)
-{
-	if (!m->_m_count) return EPERM;
-	m->_m_count--;
-	return 0;
-}
-weak_alias(__pthread_mutex_unlock, pthread_mutex_unlock);
-
-int __pthread_mutex_timedlock(pthread_mutex_t *restrict m, const struct timespec *restrict at)
-{
-	/* "The pthread_mutex_timedlock() function may fail if: A deadlock condition was detected." */
-	/* This means that we don't have to wait and then return timeout, we can just detect deadlock. */
-	return pthread_mutex_lock(m);
-}
-weak_alias(__pthread_mutex_timedlock, pthread_mutex_timedlock);
diff --git a/stub-pthreads/rwlock.c b/stub-pthreads/rwlock.c
deleted file mode 100644
index ce0fc7a29..000000000
--- a/stub-pthreads/rwlock.c
+++ /dev/null
@@ -1,60 +0,0 @@
-#include "pthread_impl.h"
-/* Musl uses bit31 to mark "has waiters", bit[30:0] all 1s to indicate writer */
-
-/* These functions have the __ prefix to help stub out thread-specific data */
-
-int __pthread_rwlock_rdlock(pthread_rwlock_t *rw)
-{
-	if (rw->_rw_lock == 0x7fffffff) return EDEADLK;
-	if (rw->_rw_lock == 0x7ffffffe) return EAGAIN;
-	rw->_rw_lock++;
-	return 0;
-}
-weak_alias(__pthread_rwlock_rdlock, pthread_rwlock_rdlock);
-
-int __pthread_rwlock_timedrdlock(pthread_rwlock_t *restrict rw, const struct timespec *restrict at)
-{
-	return pthread_rwlock_rdlock(rw);
-}
-weak_alias(__pthread_rwlock_timedrdlock, pthread_rwlock_timedrdlock);
-
-int __pthread_rwlock_tryrdlock(pthread_rwlock_t *rw)
-{
-	if (rw->_rw_lock == 0x7fffffff) return EBUSY;
-	if (rw->_rw_lock == 0x7ffffffe) return EAGAIN;
-	rw->_rw_lock++;
-	return 0;
-}
-weak_alias(__pthread_rwlock_tryrdlock, pthread_rwlock_tryrdlock);
-
-int __pthread_rwlock_wrlock(pthread_rwlock_t *rw)
-{
-	if (rw->_rw_lock) return EDEADLK;
-	rw->_rw_lock = 0x7fffffff;
-	return 0;
-}
-weak_alias(__pthread_rwlock_wrlock, pthread_rwlock_wrlock);
-
-int __pthread_rwlock_timedwrlock(pthread_rwlock_t *restrict rw, const struct timespec *restrict at)
-{
-	return pthread_rwlock_wrlock(rw);
-}
-weak_alias(__pthread_rwlock_timedwrlock, pthread_rwlock_timedwrlock);
-
-int __pthread_rwlock_trywrlock(pthread_rwlock_t *rw)
-{
-	if (rw->_rw_lock) return EBUSY;
-	rw->_rw_lock = 0x7fffffff;
-	return 0;
-}
-weak_alias(__pthread_rwlock_trywrlock, pthread_rwlock_trywrlock);
-
-int __pthread_rwlock_unlock(pthread_rwlock_t *rw)
-{
-	if (rw->_rw_lock == 0x7fffffff)
-		rw->_rw_lock = 0;
-	else
-		rw->_rw_lock--;
-	return 0;
-}
-weak_alias(__pthread_rwlock_unlock, pthread_rwlock_unlock);
diff --git a/stub-pthreads/spinlock.c b/stub-pthreads/spinlock.c
deleted file mode 100644
index 1099f7e07..000000000
--- a/stub-pthreads/spinlock.c
+++ /dev/null
@@ -1,21 +0,0 @@
-
-#include "pthread_impl.h"
-/* The only reason why we have to do anything is trylock */
-
-int pthread_spin_lock(pthread_spinlock_t *s)
-{
-	if (*s) return EDEADLK;
-	*s = 1;
-	return 0;
-}
-int pthread_spin_trylock(pthread_spinlock_t *s)
-{
-	if (*s) return EBUSY;
-	*s = 1;
-	return 0;
-}
-int pthread_spin_unlock(pthread_spinlock_t *s)
-{
-	*s = 0;
-	return 0;
-}
diff --git a/stub-pthreads/stub-pthreads-emulated.c b/stub-pthreads/stub-pthreads-emulated.c
deleted file mode 100644
index d7e04774f..000000000
--- a/stub-pthreads/stub-pthreads-emulated.c
+++ /dev/null
@@ -1,40 +0,0 @@
-// This file is linked into wasi-emulated-pthread
-
-#include "pthread_impl.h"
-
-int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp, void *(*entry)(void *), void *restrict arg)
-{
-	/*
-		"The system lacked the necessary resources to create another thread,
-		or the system-imposed limit on the total number of threads in a process
-		{PTHREAD_THREADS_MAX} would be exceeded."
-	*/
-	return EAGAIN;
-}
-weak_alias(__pthread_create, pthread_create);
-int __pthread_detach(pthread_t t)
-{
-	/*
-		If we are the only thread, when we exit the whole process exits.
-		So the storage will be reclaimed no matter what.
-	*/
-	return 0;
-}
-weak_alias(__pthread_detach, pthread_detach);
-int __pthread_join(pthread_t t, void **res)
-{
-	/*
-		"The behavior is undefined if the value specified by the thread argument
-		to pthread_join() refers to the calling thread."
-	*/
-	return 0;
-}
-weak_alias(__pthread_join, pthread_join);
-int pthread_tryjoin_np(pthread_t t, void **res)
-{
-	return 0;
-}
-int pthread_timedjoin_np(pthread_t t, void **res, const struct timespec *at)
-{
-	return 0;
-}
diff --git a/stub-pthreads/stub-pthreads-good.c b/stub-pthreads/stub-pthreads-good.c
deleted file mode 100644
index 0f6328404..000000000
--- a/stub-pthreads/stub-pthreads-good.c
+++ /dev/null
@@ -1,43 +0,0 @@
-// This file is linked into libc
-
-#include "pthread_impl.h"
-
-static void dummy_0()
-{
-}
-weak_alias(dummy_0, __acquire_ptc);
-weak_alias(dummy_0, __release_ptc);
-weak_alias(dummy_0, __pthread_tsd_run_dtors);
-
-int pthread_once(pthread_once_t *control, void (*init)(void))
-{
-	if (!*control) {
-		init();
-		*control = 1;
-	}
-	return 0;
-}
-
-_Noreturn void pthread_exit(void *result)
-{
-	/*
-		We are the only thread, so when we exit the whole process exits.
-		But we still have to run cancellation handlers...
-	*/
-	pthread_t self = __pthread_self();
-
-	self->canceldisable = 1;
-	self->cancelasync = 0;
-	self->result = result;
-
-	while (self->cancelbuf) {
-		void (*f)(void *) = self->cancelbuf->__f;
-		void *x = self->cancelbuf->__x;
-		self->cancelbuf = self->cancelbuf->__next;
-		f(x);
-	}
-
-	__pthread_tsd_run_dtors();
-
-	exit(0);
-}
diff --git a/thread-stub/README.md b/thread-stub/README.md
new file mode 100644
index 000000000..0a78fc2fa
--- /dev/null
+++ b/thread-stub/README.md
@@ -0,0 +1,7 @@
+# Stub pthreads implementation
+
+This library provides the foundation for a POSIX conformant implementation of
+pthreads API for `THREAD_MODEL=single`. When combined with the appropriate
+parts of musl's libc-top-half, it forms a complete pthreads implementation
+that is never able to spawn new threads, but otherwise follows the letter of
+the specification in every way.
diff --git a/thread-stub/pthread_barrier_destroy.c b/thread-stub/pthread_barrier_destroy.c
new file mode 100644
index 000000000..2898c41a0
--- /dev/null
+++ b/thread-stub/pthread_barrier_destroy.c
@@ -0,0 +1,6 @@
+#include "pthread_impl.h"
+
+int pthread_barrier_destroy(pthread_barrier_t *b)
+{
+	return 0;
+}
diff --git a/thread-stub/pthread_barrier_init.c b/thread-stub/pthread_barrier_init.c
new file mode 100644
index 000000000..42eb6451b
--- /dev/null
+++ b/thread-stub/pthread_barrier_init.c
@@ -0,0 +1,8 @@
+#include "pthread_impl.h"
+
+int pthread_barrier_init(pthread_barrier_t *restrict b, const pthread_barrierattr_t *restrict a, unsigned count)
+{
+	if (count-1 > INT_MAX-1) return EINVAL;
+	*b = (pthread_barrier_t){ ._b_limit = count-1 };
+	return 0;
+}
diff --git a/thread-stub/pthread_barrier_wait.c b/thread-stub/pthread_barrier_wait.c
new file mode 100644
index 000000000..c5a4afb73
--- /dev/null
+++ b/thread-stub/pthread_barrier_wait.c
@@ -0,0 +1,7 @@
+#include "pthread_impl.h"
+
+int pthread_barrier_wait(pthread_barrier_t *b)
+{
+	if (!b->_b_limit) return PTHREAD_BARRIER_SERIAL_THREAD;
+	__builtin_trap();
+}
diff --git a/thread-stub/pthread_cond_broadcast.c b/thread-stub/pthread_cond_broadcast.c
new file mode 100644
index 000000000..ce3180996
--- /dev/null
+++ b/thread-stub/pthread_cond_broadcast.c
@@ -0,0 +1,6 @@
+#include "pthread_impl.h"
+
+int pthread_cond_broadcast(pthread_cond_t *c)
+{
+	return 0;
+}
diff --git a/thread-stub/pthread_cond_destroy.c b/thread-stub/pthread_cond_destroy.c
new file mode 100644
index 000000000..1d21a5a8b
--- /dev/null
+++ b/thread-stub/pthread_cond_destroy.c
@@ -0,0 +1,6 @@
+#include "pthread_impl.h"
+
+int pthread_cond_destroy(pthread_cond_t *c)
+{
+	return 0;
+}
diff --git a/thread-stub/pthread_cond_init.c b/thread-stub/pthread_cond_init.c
new file mode 100644
index 000000000..c32903b6c
--- /dev/null
+++ b/thread-stub/pthread_cond_init.c
@@ -0,0 +1,6 @@
+#include "pthread_impl.h"
+
+int pthread_cond_init(pthread_cond_t *restrict c, const pthread_condattr_t *restrict a)
+{
+	return 0;
+}
diff --git a/thread-stub/pthread_cond_signal.c b/thread-stub/pthread_cond_signal.c
new file mode 100644
index 000000000..4eb2774ae
--- /dev/null
+++ b/thread-stub/pthread_cond_signal.c
@@ -0,0 +1,6 @@
+#include "pthread_impl.h"
+
+int pthread_cond_signal(pthread_cond_t *c)
+{
+	return 0;
+}
diff --git a/thread-stub/pthread_cond_timedwait.c b/thread-stub/pthread_cond_timedwait.c
new file mode 100644
index 000000000..0e7f9f835
--- /dev/null
+++ b/thread-stub/pthread_cond_timedwait.c
@@ -0,0 +1,13 @@
+#include "pthread_impl.h"
+
+int __pthread_cond_timedwait(pthread_cond_t *restrict c, pthread_mutex_t *restrict m, const struct timespec *restrict ts)
+{
+	/* Error check mutexes must detect if they're not locked (UB for others) */
+	if (!m->_m_count) return EPERM;
+	int ret = clock_nanosleep(CLOCK_REALTIME, TIMER_ABSTIME, ts, 0);
+	if (ret == 0) return ETIMEDOUT;
+	if (ret != EINTR) return ret;
+	return 0;
+}
+
+weak_alias(__pthread_cond_timedwait, pthread_cond_timedwait);
diff --git a/thread-stub/pthread_cond_wait.c b/thread-stub/pthread_cond_wait.c
new file mode 100644
index 000000000..84a44b7bc
--- /dev/null
+++ b/thread-stub/pthread_cond_wait.c
@@ -0,0 +1,9 @@
+#include "pthread_impl.h"
+
+int pthread_cond_wait(pthread_cond_t *restrict c, pthread_mutex_t *restrict m)
+{
+	/* Because there is no other thread that can signal us, this is a deadlock immediately.
+	The other possible choice is to return immediately (spurious wakeup), but that is likely to
+	just result in the program spinning forever on a condition that cannot become true. */
+	__builtin_trap();
+}
diff --git a/thread-stub/pthread_create.c b/thread-stub/pthread_create.c
new file mode 100644
index 000000000..717564cd1
--- /dev/null
+++ b/thread-stub/pthread_create.c
@@ -0,0 +1,19 @@
+#include "pthread_impl.h"
+
+static void dummy_0()
+{
+}
+weak_alias(dummy_0, __acquire_ptc);
+weak_alias(dummy_0, __release_ptc);
+
+int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp, void *(*entry)(void *), void *restrict arg)
+{
+	/*
+		"The system lacked the necessary resources to create another thread,
+		or the system-imposed limit on the total number of threads in a process
+		{PTHREAD_THREADS_MAX} would be exceeded."
+	*/
+	return EAGAIN;
+}
+
+weak_alias(__pthread_create, pthread_create);
diff --git a/thread-stub/pthread_detach.c b/thread-stub/pthread_detach.c
new file mode 100644
index 000000000..55953e159
--- /dev/null
+++ b/thread-stub/pthread_detach.c
@@ -0,0 +1,13 @@
+#include "pthread_impl.h"
+
+static int __pthread_detach(pthread_t t)
+{
+	/*
+		If we are the only thread, when we exit the whole process exits.
+		So the storage will be reclaimed no matter what.
+	*/
+	return 0;
+}
+
+weak_alias(__pthread_detach, pthread_detach);
+weak_alias(__pthread_detach, thrd_detach);
diff --git a/thread-stub/pthread_getattr_np.c b/thread-stub/pthread_getattr_np.c
new file mode 100644
index 000000000..d463de143
--- /dev/null
+++ b/thread-stub/pthread_getattr_np.c
@@ -0,0 +1,11 @@
+#include "pthread_impl.h"
+
+int pthread_getattr_np(pthread_t t, pthread_attr_t *a)
+{
+	*a = (pthread_attr_t){0};
+	/* Can't join main thread. */
+	a->_a_detach = PTHREAD_CREATE_DETACHED;
+	/* WASI doesn't have memory protection required for stack guards. */
+	a->_a_guardsize = 0;
+	return 0;
+}
diff --git a/thread-stub/pthread_join.c b/thread-stub/pthread_join.c
new file mode 100644
index 000000000..cbdcedd73
--- /dev/null
+++ b/thread-stub/pthread_join.c
@@ -0,0 +1,32 @@
+#include "pthread_impl.h"
+
+static int __pthread_tryjoin_np(pthread_t t, void **res)
+{
+	/*
+		"The behavior is undefined if the value specified by the thread argument
+		to pthread_join() refers to the calling thread."
+	*/
+	return 0;
+}
+
+static int __pthread_timedjoin_np(pthread_t t, void **res, const struct timespec *at)
+{
+	/*
+		"The behavior is undefined if the value specified by the thread argument
+		to pthread_join() refers to the calling thread."
+	*/
+	return 0;
+}
+
+int __pthread_join(pthread_t t, void **res)
+{
+	/*
+		"The behavior is undefined if the value specified by the thread argument
+		to pthread_join() refers to the calling thread."
+	*/
+	return 0;
+}
+
+weak_alias(__pthread_tryjoin_np, pthread_tryjoin_np);
+weak_alias(__pthread_timedjoin_np, pthread_timedjoin_np);
+weak_alias(__pthread_join, pthread_join);
diff --git a/thread-stub/pthread_mutex_consistent.c b/thread-stub/pthread_mutex_consistent.c
new file mode 100644
index 000000000..639635361
--- /dev/null
+++ b/thread-stub/pthread_mutex_consistent.c
@@ -0,0 +1,8 @@
+#include "pthread_impl.h"
+
+int pthread_mutex_consistent(pthread_mutex_t *m)
+{
+	/* cannot be a robust mutex, as they're entirely unsupported in WASI */
+	return EINVAL;
+
+}
diff --git a/thread-stub/pthread_mutex_getprioceiling.c b/thread-stub/pthread_mutex_getprioceiling.c
new file mode 100644
index 000000000..8c75a6612
--- /dev/null
+++ b/thread-stub/pthread_mutex_getprioceiling.c
@@ -0,0 +1,6 @@
+#include "pthread_impl.h"
+
+int pthread_mutex_getprioceiling(const pthread_mutex_t *restrict m, int *restrict ceiling)
+{
+	return EINVAL;
+}
diff --git a/thread-stub/pthread_mutex_lock.c b/thread-stub/pthread_mutex_lock.c
new file mode 100644
index 000000000..9b380c50e
--- /dev/null
+++ b/thread-stub/pthread_mutex_lock.c
@@ -0,0 +1,21 @@
+#include "pthread_impl.h"
+
+int __pthread_mutex_lock(pthread_mutex_t *m)
+{
+	/*
+		_m_type[1:0] 	- type
+		0 - normal
+		1 - recursive
+		2 - errorcheck
+	*/
+	if (m->_m_type&3 != PTHREAD_MUTEX_RECURSIVE) {
+		if (m->_m_count) return EDEADLK;
+		m->_m_count = 1;
+	} else {
+		if ((unsigned)m->_m_count >= INT_MAX) return EAGAIN;
+		m->_m_count++;
+	}
+	return 0;
+}
+
+weak_alias(__pthread_mutex_lock, pthread_mutex_lock);
diff --git a/thread-stub/pthread_mutex_timedlock.c b/thread-stub/pthread_mutex_timedlock.c
new file mode 100644
index 000000000..51f260640
--- /dev/null
+++ b/thread-stub/pthread_mutex_timedlock.c
@@ -0,0 +1,10 @@
+#include "pthread_impl.h"
+
+int __pthread_mutex_timedlock(pthread_mutex_t *restrict m, const struct timespec *restrict at)
+{
+	/* "The pthread_mutex_timedlock() function may fail if: A deadlock condition was detected." */
+	/* This means that we don't have to wait and then return timeout, we can just detect deadlock. */
+	return pthread_mutex_lock(m);
+}
+
+weak_alias(__pthread_mutex_timedlock, pthread_mutex_timedlock);
diff --git a/thread-stub/pthread_mutex_trylock.c b/thread-stub/pthread_mutex_trylock.c
new file mode 100644
index 000000000..9f00f893f
--- /dev/null
+++ b/thread-stub/pthread_mutex_trylock.c
@@ -0,0 +1,21 @@
+#include "pthread_impl.h"
+
+int __pthread_mutex_trylock(pthread_mutex_t *m)
+{
+	/*
+		_m_type[1:0] 	- type
+		0 - normal
+		1 - recursive
+		2 - errorcheck
+	*/
+	if (m->_m_type&3 != PTHREAD_MUTEX_RECURSIVE) {
+		if (m->_m_count) return EBUSY;
+		m->_m_count = 1;
+	} else {
+		if ((unsigned)m->_m_count >= INT_MAX) return EAGAIN;
+		m->_m_count++;
+	}
+	return 0;
+}
+
+weak_alias(__pthread_mutex_trylock, pthread_mutex_trylock);
diff --git a/thread-stub/pthread_mutex_unlock.c b/thread-stub/pthread_mutex_unlock.c
new file mode 100644
index 000000000..33757864a
--- /dev/null
+++ b/thread-stub/pthread_mutex_unlock.c
@@ -0,0 +1,10 @@
+#include "pthread_impl.h"
+
+int __pthread_mutex_unlock(pthread_mutex_t *m)
+{
+	if (!m->_m_count) return EPERM;
+	m->_m_count--;
+	return 0;
+}
+
+weak_alias(__pthread_mutex_unlock, pthread_mutex_unlock);
diff --git a/thread-stub/pthread_once.c b/thread-stub/pthread_once.c
new file mode 100644
index 000000000..350342a1e
--- /dev/null
+++ b/thread-stub/pthread_once.c
@@ -0,0 +1,12 @@
+#include "pthread_impl.h"
+
+int __pthread_once(pthread_once_t *control, void (*init)(void))
+{
+       if (!*control) {
+               init();
+               *control = 1;
+       }
+       return 0;
+}
+
+weak_alias(__pthread_once, pthread_once);
diff --git a/thread-stub/pthread_rwlock_rdlock.c b/thread-stub/pthread_rwlock_rdlock.c
new file mode 100644
index 000000000..1b935da4e
--- /dev/null
+++ b/thread-stub/pthread_rwlock_rdlock.c
@@ -0,0 +1,11 @@
+#include "pthread_impl.h"
+
+int __pthread_rwlock_rdlock(pthread_rwlock_t *rw)
+{
+	if (rw->_rw_lock == 0x7fffffff) return EDEADLK;
+	if (rw->_rw_lock == 0x7ffffffe) return EAGAIN;
+	rw->_rw_lock++;
+	return 0;
+}
+
+weak_alias(__pthread_rwlock_rdlock, pthread_rwlock_rdlock);
diff --git a/thread-stub/pthread_rwlock_timedrdlock.c b/thread-stub/pthread_rwlock_timedrdlock.c
new file mode 100644
index 000000000..448256434
--- /dev/null
+++ b/thread-stub/pthread_rwlock_timedrdlock.c
@@ -0,0 +1,8 @@
+#include "pthread_impl.h"
+
+int __pthread_rwlock_timedrdlock(pthread_rwlock_t *restrict rw, const struct timespec *restrict at)
+{
+	return pthread_rwlock_rdlock(rw);
+}
+
+weak_alias(__pthread_rwlock_timedrdlock, pthread_rwlock_timedrdlock);
diff --git a/thread-stub/pthread_rwlock_timedwrlock.c b/thread-stub/pthread_rwlock_timedwrlock.c
new file mode 100644
index 000000000..1ee24500b
--- /dev/null
+++ b/thread-stub/pthread_rwlock_timedwrlock.c
@@ -0,0 +1,8 @@
+#include "pthread_impl.h"
+
+int __pthread_rwlock_timedwrlock(pthread_rwlock_t *restrict rw, const struct timespec *restrict at)
+{
+	return pthread_rwlock_wrlock(rw);
+}
+
+weak_alias(__pthread_rwlock_timedwrlock, pthread_rwlock_timedwrlock);
diff --git a/thread-stub/pthread_rwlock_tryrdlock.c b/thread-stub/pthread_rwlock_tryrdlock.c
new file mode 100644
index 000000000..4753a60e0
--- /dev/null
+++ b/thread-stub/pthread_rwlock_tryrdlock.c
@@ -0,0 +1,11 @@
+#include "pthread_impl.h"
+
+int __pthread_rwlock_tryrdlock(pthread_rwlock_t *rw)
+{
+	if (rw->_rw_lock == 0x7fffffff) return EBUSY;
+	if (rw->_rw_lock == 0x7ffffffe) return EAGAIN;
+	rw->_rw_lock++;
+	return 0;
+}
+
+weak_alias(__pthread_rwlock_tryrdlock, pthread_rwlock_tryrdlock);
diff --git a/thread-stub/pthread_rwlock_trywrlock.c b/thread-stub/pthread_rwlock_trywrlock.c
new file mode 100644
index 000000000..3077fdc31
--- /dev/null
+++ b/thread-stub/pthread_rwlock_trywrlock.c
@@ -0,0 +1,10 @@
+#include "pthread_impl.h"
+
+int __pthread_rwlock_trywrlock(pthread_rwlock_t *rw)
+{
+	if (rw->_rw_lock) return EBUSY;
+	rw->_rw_lock = 0x7fffffff;
+	return 0;
+}
+
+weak_alias(__pthread_rwlock_trywrlock, pthread_rwlock_trywrlock);
diff --git a/thread-stub/pthread_rwlock_unlock.c b/thread-stub/pthread_rwlock_unlock.c
new file mode 100644
index 000000000..40f047ea9
--- /dev/null
+++ b/thread-stub/pthread_rwlock_unlock.c
@@ -0,0 +1,12 @@
+#include "pthread_impl.h"
+
+int __pthread_rwlock_unlock(pthread_rwlock_t *rw)
+{
+	if (rw->_rw_lock == 0x7fffffff)
+		rw->_rw_lock = 0;
+	else
+		rw->_rw_lock--;
+	return 0;
+}
+
+weak_alias(__pthread_rwlock_unlock, pthread_rwlock_unlock);
diff --git a/thread-stub/pthread_rwlock_wrlock.c b/thread-stub/pthread_rwlock_wrlock.c
new file mode 100644
index 000000000..ce9d2099b
--- /dev/null
+++ b/thread-stub/pthread_rwlock_wrlock.c
@@ -0,0 +1,10 @@
+#include "pthread_impl.h"
+
+int __pthread_rwlock_wrlock(pthread_rwlock_t *rw)
+{
+	if (rw->_rw_lock) return EDEADLK;
+	rw->_rw_lock = 0x7fffffff;
+	return 0;
+}
+
+weak_alias(__pthread_rwlock_wrlock, pthread_rwlock_wrlock);
diff --git a/thread-stub/pthread_spin_lock.c b/thread-stub/pthread_spin_lock.c
new file mode 100644
index 000000000..4a682a6b6
--- /dev/null
+++ b/thread-stub/pthread_spin_lock.c
@@ -0,0 +1,8 @@
+#include "pthread_impl.h"
+
+int pthread_spin_lock(pthread_spinlock_t *s)
+{
+	if (*s) return EDEADLK;
+	*s = 1;
+	return 0;
+}
diff --git a/thread-stub/pthread_spin_trylock.c b/thread-stub/pthread_spin_trylock.c
new file mode 100644
index 000000000..5ef1b2a02
--- /dev/null
+++ b/thread-stub/pthread_spin_trylock.c
@@ -0,0 +1,8 @@
+#include "pthread_impl.h"
+
+int pthread_spin_trylock(pthread_spinlock_t *s)
+{
+	if (*s) return EBUSY;
+	*s = 1;
+	return 0;
+}
diff --git a/thread-stub/pthread_spin_unlock.c b/thread-stub/pthread_spin_unlock.c
new file mode 100644
index 000000000..f9d8a23dc
--- /dev/null
+++ b/thread-stub/pthread_spin_unlock.c
@@ -0,0 +1,7 @@
+#include "pthread_impl.h"
+
+int pthread_spin_unlock(pthread_spinlock_t *s)
+{
+	*s = 0;
+	return 0;
+}