Added the vfork functionality

expected/wasm32-wasi/defined-symbols.txt

@@ -559,6 +559,7 @@ __year_to_secs
 _environ
 _exit
 _flushlbf
+_fork_internal
 _initialize
 _pthread_cleanup_pop
 _pthread_cleanup_push

expected/wasm64-wasi/defined-symbols.txt

@@ -559,6 +559,7 @@ __year_to_secs
 _environ
 _exit
 _flushlbf
+_fork_internal
 _initialize
 _pthread_cleanup_pop
 _pthread_cleanup_push

libc-bottom-half/headers/public/wasi/api.h

@@ -4552,6 +4552,12 @@ __wasi_errno_t __wasi_proc_raise(
  * number then its the current process and the $pid represents the child.
  */
 __wasi_errno_t __wasi_proc_fork(
+    /**
+     * Indicates if the memory will be copied into the new process
+     * (if it is not copied this then becomes similar to `vfork` in
+     *  that the current process pauses until `proc_exec` is called)
+     */
+    __wasi_bool_t copy_memory,
     __wasi_pid_t *retptr0
 ) __attribute__((__warn_unused_result__));
 /**

libc-bottom-half/sources/__wasilibc_real.c

@@ -967,15 +967,16 @@ __wasi_errno_t __wasi_proc_raise(
     return (uint16_t) ret;
 }
 
-int32_t __imported_wasix_64v1_proc_fork(int64_t arg0) __attribute__((
+int32_t __imported_wasix_64v1_proc_fork(int32_t arg0, int64_t arg1) __attribute__((
     __import_module__("wasix_64v1"),
     __import_name__("proc_fork")
 ));
 
 __wasi_errno_t __wasi_proc_fork(
+    __wasi_bool_t copy_memory,
     __wasi_pid_t *retptr0
 ){
-    int32_t ret = __imported_wasix_64v1_proc_fork((intptr_t) retptr0);
+    int32_t ret = __imported_wasix_64v1_proc_fork((int32_t) copy_memory, (intptr_t) retptr0);
     return (uint16_t) ret;
 }
 

libc-top-half/musl/include/unistd.h

@@ -131,7 +131,8 @@ int pause(void);
 #endif
 
 pid_t fork(void);
-pid_t _Fork(void);
+pid_t _fork_internal(int copy_mem);
+pid_t _Fork(int copy_mem);
 int execve(const char *, char *const [], char *const []);
 int execv(const char *, char *const []);
 int execle(const char *, const char *, ...);

libc-top-half/musl/src/process/_Fork.c

@@ -13,7 +13,7 @@
 static void dummy(int x) { }
 weak_alias(dummy, __aio_atfork);
 
-pid_t _Fork(void)
+pid_t _Fork(int copy_mem)
 {
 	pid_t ret;
 	sigset_t set;
@@ -28,7 +28,7 @@ pid_t _Fork(void)
 #endif
 #else
 	__wasi_pid_t pid = -1;
-    int err = __wasi_proc_fork(&pid);
+    int err = __wasi_proc_fork(copy_mem, &pid);
 	if (err != 0) {
 		ret = -err;
 	} else {

libc-top-half/musl/src/process/fork.c

@@ -52,6 +52,11 @@ weak_alias(dummy_0, __tl_unlock);
 #endif
 
 pid_t fork(void)
+{
+	return _fork_internal(1);
+}
+
+pid_t _fork_internal(int copy_mem)
 {
 	sigset_t set;
 	__fork_handler(-1);
@@ -68,7 +73,7 @@ pid_t fork(void)
 		__tl_lock();
 	}
 	pthread_t self=__pthread_self(), next=self->next;
-	pid_t ret = _Fork();
+	pid_t ret = _Fork(copy_mem);
 	int errno_save = errno;
 	if (need_locks) {
 		if (!ret) {

libc-top-half/musl/src/process/vfork.c

@@ -15,6 +15,6 @@ pid_t vfork(void)
 	return syscall(SYS_clone, SIGCHLD, 0);
 #endif
 #else
-	return fork();
+	return _fork_internal(0);
 #endif
 }