gh-74667: Address review: larger netdb buffer, clearer probe comment and test diagnostics

Author: tonghuaroot

Lib/test/test_socket.py

@@ -7546,20 +7546,26 @@ def test_getservby_getprotobyname_race(self):
 
         def check_servbyname(name, proto, expected):
             for _ in range(loops):
-                if socket.getservbyname(name, proto) != expected:
-                    errors.append('getservbyname')
+                got = socket.getservbyname(name, proto)
+                if got != expected:
+                    errors.append(f'getservbyname({name!r}, {proto!r}): '
+                                  f'{got!r} != {expected!r}')
                     return
 
         def check_servbyport(port, proto, expected):
             for _ in range(loops):
-                if socket.getservbyport(port, proto) != expected:
-                    errors.append('getservbyport')
+                got = socket.getservbyport(port, proto)
+                if got != expected:
+                    errors.append(f'getservbyport({port!r}, {proto!r}): '
+                                  f'{got!r} != {expected!r}')
                     return
 
         def check_protobyname(name, expected):
             for _ in range(loops):
-                if socket.getprotobyname(name) != expected:
-                    errors.append('getprotobyname')
+                got = socket.getprotobyname(name)
+                if got != expected:
+                    errors.append(f'getprotobyname({name!r}): '
+                                  f'{got!r} != {expected!r}')
                     return
 
         threads = [

Modules/socketmodule.c

@@ -6379,7 +6379,7 @@ socket_getservbyname(PyObject *self, PyObject *args)
 #ifdef HAVE_GETSERVBYNAME_R
     struct servent serv;
     char *buf = NULL;
-    size_t buf_len = 1024;
+    size_t buf_len = 16384;
     int err = 0;
 #endif
     if (!PyArg_ParseTuple(args, "s|s:getservbyname", &name, &proto))
@@ -6450,7 +6450,7 @@ socket_getservbyport(PyObject *self, PyObject *args)
 #ifdef HAVE_GETSERVBYPORT_R
     struct servent serv;
     char *buf = NULL;
-    size_t buf_len = 1024;
+    size_t buf_len = 16384;
     int err = 0;
 #endif
     if (!PyArg_ParseTuple(args, "i|s:getservbyport", &port, &proto))
@@ -6527,7 +6527,7 @@ socket_getprotobyname(PyObject *self, PyObject *args)
 #ifdef HAVE_GETPROTOBYNAME_R
     struct protoent proto;
     char *buf = NULL;
-    size_t buf_len = 1024;
+    size_t buf_len = 16384;
     int err = 0;
 #endif
     if (!PyArg_ParseTuple(args, "s:getprotobyname", &name))

configure

@@ -6211,8 +6211,9 @@ AC_SUBST([HAVE_GETHOSTBYNAME_R])
 AC_SUBST([HAVE_GETHOSTBYNAME])
 
 # Check for the reentrant getservbyname_r(), getservbyport_r() and
-# getprotobyname_r() functions. Unlike gethostbyname_r() they have a single,
-# POSIX-style signature, so a compile test with that prototype is enough.
+# getprotobyname_r() functions. These compile tests use the glibc/POSIX-TSF
+# 6-argument form; platforms with a different arity (e.g. the 5-argument
+# Solaris/illumos form) fail the probe and fall back to the netdb lock.
 OLD_CFLAGS=$CFLAGS
 CFLAGS="$CFLAGS $MY_CPPFLAGS $MY_THREAD_CPPFLAGS $MY_CFLAGS"