src: add uv_thread_set/getname() methods (#4599)

`uv_thread_setname()` sets the name of the current thread. Different
platforms define different limits on the max number of characters
a thread name can be: Linux, IBMi (16), macOS (64), Windows (32767),
and NetBSD (32), etc. `uv_thread_setname()` will truncate it in case
`name` is larger than the limit of the platform.

`uv_thread_getname()` gets the name of the thread specified by `tid`.
The thread name is copied into the buffer pointed to by `name`. The
`size` parameter specifies the size of the buffer pointed to by `name`.
The buffer should be large enough to hold the name of the thread plus
the trailing NUL, or it will be truncated to fit.

5 files changed, 183 insertions, 18 deletions

diff --git a/src/unix/darwin-proctitle.c b/src/unix/darwin-proctitle.c
index 5288083e..5e564297 100644
--- a/src/unix/darwin-proctitle.c
+++ b/src/unix/darwin-proctitle.c
@@ -33,25 +33,9 @@
 #include "darwin-stub.h"
 #endif
 
-
-static int uv__pthread_setname_np(const char* name) {
-  char namebuf[64];  /* MAXTHREADNAMESIZE */
-  int err;
-
-  strncpy(namebuf, name, sizeof(namebuf) - 1);
-  namebuf[sizeof(namebuf) - 1] = '\0';
-
-  err = pthread_setname_np(namebuf);
-  if (err)
-    return UV__ERR(err);
-
-  return 0;
-}
-
-
 int uv__set_process_title(const char* title) {
 #if TARGET_OS_IPHONE
-  return uv__pthread_setname_np(title);
+  return uv__thread_setname(title);
 #else
   CFStringRef (*pCFStringCreateWithCString)(CFAllocatorRef,
                                             const char*,
@@ -177,7 +161,7 @@ int uv__set_process_title(const char* title) {
     goto out;
   }
 
-  uv__pthread_setname_np(title);  /* Don't care if it fails. */
+  uv__thread_setname(title);  /* Don't care if it fails. */
   err = 0;
 
 out:
diff --git a/src/unix/internal.h b/src/unix/internal.h
index 698caf17..b1d2b217 100644
--- a/src/unix/internal.h
+++ b/src/unix/internal.h
@@ -327,6 +327,8 @@ void uv__prepare_close(uv_prepare_t* handle);
 void uv__process_close(uv_process_t* handle);
 void uv__stream_close(uv_stream_t* handle);
 void uv__tcp_close(uv_tcp_t* handle);
+int uv__thread_setname(const char* name);
+int uv__thread_getname(uv_thread_t* tid, char* name, size_t size);
 size_t uv__thread_stack_size(void);
 void uv__udp_close(uv_udp_t* handle);
 void uv__udp_finish_close(uv_udp_t* handle);
diff --git a/src/unix/thread.c b/src/unix/thread.c
index 4d6ddc2b..e51c2904 100644
--- a/src/unix/thread.c
+++ b/src/unix/thread.c
@@ -23,6 +23,9 @@
 #include "internal.h"
 
 #include <pthread.h>
+#ifdef __OpenBSD__
+#include <pthread_np.h>
+#endif
 #include <assert.h>
 #include <errno.h>
 
@@ -297,6 +300,18 @@ int uv_thread_equal(const uv_thread_t* t1, const uv_thread_t* t2) {
   return pthread_equal(*t1, *t2);
 }
 
+int uv_thread_setname(const char* name) {
+  if (name == NULL)
+    return UV_EINVAL;
+  return uv__thread_setname(name);
+}
+
+int uv_thread_getname(uv_thread_t* tid, char* name, size_t size) {
+  if (name == NULL || size == 0)
+    return UV_EINVAL;
+
+  return uv__thread_getname(tid, name, size);
+}
 
 int uv_mutex_init(uv_mutex_t* mutex) {
 #if defined(NDEBUG) || !defined(PTHREAD_MUTEX_ERRORCHECK)
@@ -881,3 +896,80 @@ void uv_key_set(uv_key_t* key, void* value) {
   if (pthread_setspecific(*key, value))
     abort();
 }
+
+#if defined(_AIX) || defined(__MVS__) || defined(__PASE__)
+int uv__thread_setname(const char* name) {
+  return UV_ENOSYS;
+}
+#elif defined(__APPLE__)
+int uv__thread_setname(const char* name) {
+  char namebuf[UV_PTHREAD_MAX_NAMELEN_NP];
+  strncpy(namebuf, name, sizeof(namebuf) - 1);
+  namebuf[sizeof(namebuf) - 1] = '\0';
+  int err = pthread_setname_np(namebuf);
+  if (err)
+    return UV__ERR(errno);
+  return 0;
+}
+#elif defined(__NetBSD__)
+int uv__thread_setname(const char* name) {
+  char namebuf[UV_PTHREAD_MAX_NAMELEN_NP];
+  strncpy(namebuf, name, sizeof(namebuf) - 1);
+  namebuf[sizeof(namebuf) - 1] = '\0';
+  return UV__ERR(pthread_setname_np(pthread_self(), "%s", namebuf));
+}
+#elif defined(__OpenBSD__)
+int uv__thread_setname(const char* name) {
+  char namebuf[UV_PTHREAD_MAX_NAMELEN_NP];
+  strncpy(namebuf, name, sizeof(namebuf) - 1);
+  namebuf[sizeof(namebuf) - 1] = '\0';
+  pthread_set_name_np(pthread_self(), namebuf);
+  return 0;
+}
+#else
+int uv__thread_setname(const char* name) {
+  char namebuf[UV_PTHREAD_MAX_NAMELEN_NP];
+  strncpy(namebuf, name, sizeof(namebuf) - 1);
+  namebuf[sizeof(namebuf) - 1] = '\0';
+  return UV__ERR(pthread_setname_np(pthread_self(), namebuf));
+}
+#endif
+
+#if (defined(__ANDROID_API__) && __ANDROID_API__ < 26) || \
+    defined(_AIX) || \
+    defined(__MVS__) || \
+    defined(__PASE__)
+int uv__thread_getname(uv_thread_t* tid, char* name, size_t size) {
+  return UV_ENOSYS;
+}
+#elif defined(__OpenBSD__)
+int uv__thread_getname(uv_thread_t* tid, char* name, size_t size) {
+  char thread_name[UV_PTHREAD_MAX_NAMELEN_NP];
+  pthread_get_name_np(*tid, thread_name, sizeof(thread_name));
+  strncpy(name, thread_name, size - 1);
+  name[size - 1] = '\0';
+  return 0;
+}
+#elif defined(__APPLE__)
+int uv__thread_getname(uv_thread_t* tid, char* name, size_t size) {
+  char thread_name[UV_PTHREAD_MAX_NAMELEN_NP];
+  if (pthread_getname_np(*tid, thread_name, sizeof(thread_name)) != 0)
+    return UV__ERR(errno);
+
+  strncpy(name, thread_name, size - 1);
+  name[size - 1] = '\0';
+  return 0;
+}
+#else
+int uv__thread_getname(uv_thread_t* tid, char* name, size_t size) {
+  int r;
+  char thread_name[UV_PTHREAD_MAX_NAMELEN_NP];
+  r = pthread_getname_np(*tid, thread_name, sizeof(thread_name));
+  if (r != 0)
+    return UV__ERR(r);
+
+  strncpy(name, thread_name, size - 1);
+  name[size - 1] = '\0';
+  return 0;
+}
+#endif
diff --git a/src/uv-common.h b/src/uv-common.h
index 4baede2e..10df1706 100644
--- a/src/uv-common.h
+++ b/src/uv-common.h
@@ -428,4 +428,18 @@ struct uv__loop_internal_fields_s {
 #endif  /* __linux__ */
 };
 
+#if defined(_WIN32)
+# define UV_PTHREAD_MAX_NAMELEN_NP 32767
+#elif defined(__APPLE__)
+# define UV_PTHREAD_MAX_NAMELEN_NP 64
+#elif defined(__NetBSD__) || defined(__illumos__)
+# define UV_PTHREAD_MAX_NAMELEN_NP PTHREAD_MAX_NAMELEN_NP
+#elif defined (__linux__)
+# define UV_PTHREAD_MAX_NAMELEN_NP 16
+#elif defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__DragonFly__)
+# define UV_PTHREAD_MAX_NAMELEN_NP (MAXCOMLEN + 1)
+#else
+# define UV_PTHREAD_MAX_NAMELEN_NP 16
+#endif
+
 #endif /* UV_COMMON_H_ */
diff --git a/src/win/thread.c b/src/win/thread.c
index 28f5e6bf..0b4e71b9 100644
--- a/src/win/thread.c
+++ b/src/win/thread.c
@@ -278,6 +278,79 @@ int uv_thread_equal(const uv_thread_t* t1, const uv_thread_t* t2) {
 }
 
 
+int uv_thread_setname(const char* name) {
+#ifdef __MINGW32__
+  return UV_ENOSYS;
+#else
+  HRESULT hr;
+  WCHAR* namew;
+  int err;
+  char namebuf[UV_PTHREAD_MAX_NAMELEN_NP];
+
+  if (name == NULL)
+    return UV_EINVAL;
+
+  strncpy(namebuf, name, sizeof(namebuf) - 1);
+  namebuf[sizeof(namebuf) - 1] = '\0';
+
+  namew = NULL;
+  err = uv__convert_utf8_to_utf16(namebuf, &namew);
+  if (err)
+    return err;
+
+  hr = SetThreadDescription(GetCurrentThread(), namew);
+  uv__free(namew);
+  if (FAILED(hr))
+    return uv_translate_sys_error(HRESULT_CODE(hr));
+
+  return 0;
+#endif /* __MINGW32__ */
+}
+
+
+int uv_thread_getname(uv_thread_t* tid, char* name, size_t size) {
+#ifdef __MINGW32__
+  return UV_ENOSYS;
+#else
+  HRESULT hr;
+  WCHAR* namew;
+  char* thread_name;
+  size_t buf_size;
+  int r;
+  DWORD exit_code;
+
+  if (name == NULL || size == 0)
+    return UV_EINVAL;
+
+  if (tid == NULL || *tid == NULL)
+    return UV_EINVAL;
+
+  /* Check if the thread handle is valid */
+  if (!GetExitCodeThread(*tid, &exit_code) || exit_code != STILL_ACTIVE)
+    return UV_ENOENT;
+
+  namew = NULL;
+  thread_name = NULL;
+  hr = GetThreadDescription(*tid, &namew);
+  if (FAILED(hr))
+    return uv_translate_sys_error(HRESULT_CODE(hr));
+
+  buf_size = size;
+  r = uv__copy_utf16_to_utf8(namew, -1, name, &buf_size);
+  if (r == UV_ENOBUFS) {
+    r = uv__convert_utf16_to_utf8(namew, wcslen(namew), &thread_name);
+    if (r == 0) {
+      uv__strscpy(name, thread_name, size);
+      uv__free(thread_name);
+    }
+  }
+
+  LocalFree(namew);
+  return r;
+#endif /* __MINGW32__ */
+}
+
+
 int uv_mutex_init(uv_mutex_t* mutex) {
   InitializeCriticalSection(mutex);
   return 0;