Fixed get/set thread name implementations for macOS and FreeBSD So, the story of fixing `pthread_getname_np` and `pthread_setname_np` continues, but this time I fixed the macOS implementation. ### [`pthread_getname_np`](https://github.com/apple-oss-distributions/libpthread/blob/c032e0b076700a0a47db75528a282b8d3a06531a/src/pthread.c#L1160-L1175) The function never fails except for an invalid thread. Miri never verifies thread identifiers and uses them as indices when accessing a vector of threads. Therefore, the only possible result is `0` and a possibly trimmed output. ```c int pthread_getname_np(pthread_t thread, char *threadname, size_t len) { if (thread == pthread_self()) { strlcpy(threadname, thread->pthread_name, len); return 0; } if (!_pthread_validate_thread_and_list_lock(thread)) { return ESRCH; } strlcpy(threadname, thread->pthread_name, len); _pthread_lock_unlock(&_pthread_list_lock); return 0; } ``` #### [`strcpy`](https://www.man7.org/linux/man-pages/man7/strlcpy.7.html) ``` strlcpy(3bsd) strlcat(3bsd) Copy and catenate the input string into a destination string. If the destination buffer, limited by its size, isn't large enough to hold the copy, the resulting string is truncated (but it is guaranteed to be null-terminated). They return the length of the total string they tried to create. ``` ### [`pthread_setname_np`](https://github.com/apple-oss-distributions/libpthread/blob/c032e0b076700a0a47db75528a282b8d3a06531a/src/pthread.c#L1178-L1200) ```c pthread_setname_np(const char *name) { int res; pthread_t self = pthread_self(); size_t len = 0; if (name != NULL) { len = strlen(name); } _pthread_validate_signature(self); res = __proc_info(5, getpid(), 2, (uint64_t)0, (void*)name, (int)len); if (res == 0) { if (len > 0) { strlcpy(self->pthread_name, name, MAXTHREADNAMESIZE); } else { bzero(self->pthread_name, MAXTHREADNAMESIZE); } } return res; } ``` Where `5` is [`PROC_INFO_CALL_SETCONTROL`](https://github.com/apple-oss-distributions/xnu/blob/8d741a5de7ff4191bf97d57b9f54c2f6d4a15585/bsd/sys/proc_info_private.h#L274), and `2` is [`PROC_INFO_CALL_SETCONTROL`](https://github.com/apple-oss-distributions/xnu/blob/8d741a5de7ff4191bf97d57b9f54c2f6d4a15585/bsd/sys/proc_info.h#L821). And `__proc_info` is a syscall handled by the XNU kernel by [`proc_info_internal`](https://github.com/apple-oss-distributions/xnu/blob/8d741a5de7ff4191bf97d57b9f54c2f6d4a15585/bsd/kern/proc_info.c#L300-L314): ```c int proc_info_internal(int callnum, int pid, uint32_t flags, uint64_t ext_id, int flavor, uint64_t arg, user_addr_t buffer, uint32_t buffersize, int32_t * retval) { switch (callnum) { // ... case PROC_INFO_CALL_SETCONTROL: return proc_setcontrol(pid, flavor, arg, buffer, buffersize, retval); ``` And the actual logic from [`proc_setcontrol`](https://github.com/apple-oss-distributions/xnu/blob/8d741a5de7ff4191bf97d57b9f54c2f6d4a15585/bsd/kern/proc_info.c#L3218-L3227): ```c case PROC_SELFSET_THREADNAME: { /* * This is a bit ugly, as it copies the name into the kernel, and then * invokes bsd_setthreadname again to copy it into the uthread name * buffer. Hopefully this isn't such a hot codepath that an additional * MAXTHREADNAMESIZE copy is a big issue. */ if (buffersize > (MAXTHREADNAMESIZE - 1)) { return ENAMETOOLONG; } ``` Unrelated to the current pull request, but perhaps, there's a very ugly thing in the kernel/libc because the last thing happening in `PROC_SELFSET_THREADNAME` is `bsd_setthreadname` which sets the name in the user space. But we just saw that `pthread_setname_np` sets the name in the user space too. Guess, I need to open a ticket in one of Apple's repositories at least to clarify that :D

Make sure that derivable methods actually have derivable signatures #3957

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