Use NULL instead of 0 as null pointer constant

GCC 15 enabled "-Wzero-as-null-pointer-constant" for C, which checks for
places where '0' has been used as a null pointer constant.

This showed a few places in Unit where we were using '0' instead of the
more correct NULL macro. E.g.

  $ make -j4 EXTRA_CFLAGS=-Wzero-as-null-pointer-constant
  ...
  src/nxt_buf.c: In function ‘nxt_buf_mmap_alloc’:
  src/nxt_buf.h:192:21: error: zero as null pointer constant [-Werror=zero-as-null-pointer-constant]
    192 |         (bm)->start = 0;                                                      \
        |                     ^
  src/nxt_buf.c:135:9: note: in expansion of macro ‘nxt_buf_mem_set_size’
    135 |         nxt_buf_mem_set_size(&b->mem, size);
        |         ^~~~~~~~~~~~~~~~~~~~

Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

4 files changed, 16 insertions, 16 deletions

diff --git a/src/python/nxt_python_asgi_http.c b/src/python/nxt_python_asgi_http.c
index fc489bc1..27b3e0e0 100644
--- a/src/python/nxt_python_asgi_http.c
+++ b/src/python/nxt_python_asgi_http.c
@@ -45,10 +45,10 @@ static PyObject *nxt_py_asgi_http_done(PyObject *self, PyObject *future);
 
 
 static PyMethodDef nxt_py_asgi_http_methods[] = {
-    { "receive",   nxt_py_asgi_http_receive, METH_NOARGS, 0 },
-    { "send",      nxt_py_asgi_http_send,    METH_O,      0 },
-    { "_done",     nxt_py_asgi_http_done,    METH_O,      0 },
-    { NULL, NULL, 0, 0 }
+    { "receive",   nxt_py_asgi_http_receive, METH_NOARGS, NULL },
+    { "send",      nxt_py_asgi_http_send,    METH_O,      NULL },
+    { "_done",     nxt_py_asgi_http_done,    METH_O,      NULL },
+    {}
 };
 
 static PyAsyncMethods nxt_py_asgi_async_methods = {
diff --git a/src/python/nxt_python_asgi_lifespan.c b/src/python/nxt_python_asgi_lifespan.c
index 041cca21..8ef78377 100644
--- a/src/python/nxt_python_asgi_lifespan.c
+++ b/src/python/nxt_python_asgi_lifespan.c
@@ -48,10 +48,10 @@ static void nxt_py_asgi_lifespan_dealloc(PyObject *self);
 
 
 static PyMethodDef nxt_py_asgi_lifespan_methods[] = {
-    { "receive",   nxt_py_asgi_lifespan_receive, METH_NOARGS, 0 },
-    { "send",      nxt_py_asgi_lifespan_send,    METH_O,      0 },
-    { "_done",     nxt_py_asgi_lifespan_done,    METH_O,      0 },
-    { NULL, NULL, 0, 0 }
+    { "receive",   nxt_py_asgi_lifespan_receive, METH_NOARGS, NULL },
+    { "send",      nxt_py_asgi_lifespan_send,    METH_O,      NULL },
+    { "_done",     nxt_py_asgi_lifespan_done,    METH_O,      NULL },
+    {}
 };
 
 static PyMemberDef nxt_py_asgi_lifespan_members[] = {
diff --git a/src/python/nxt_python_asgi_websocket.c b/src/python/nxt_python_asgi_websocket.c
index ab1d0324..e3c37e74 100644
--- a/src/python/nxt_python_asgi_websocket.c
+++ b/src/python/nxt_python_asgi_websocket.c
@@ -70,10 +70,10 @@ static PyObject *nxt_py_asgi_websocket_done(PyObject *self, PyObject *future);
 
 
 static PyMethodDef nxt_py_asgi_websocket_methods[] = {
-    { "receive",   nxt_py_asgi_websocket_receive, METH_NOARGS, 0 },
-    { "send",      nxt_py_asgi_websocket_send,    METH_O,      0 },
-    { "_done",     nxt_py_asgi_websocket_done,    METH_O,      0 },
-    { NULL, NULL, 0, 0 }
+    { "receive",   nxt_py_asgi_websocket_receive, METH_NOARGS, NULL },
+    { "send",      nxt_py_asgi_websocket_send,    METH_O,      NULL },
+    { "_done",     nxt_py_asgi_websocket_done,    METH_O,      NULL },
+    {}
 };
 
 static PyAsyncMethods nxt_py_asgi_async_methods = {
diff --git a/src/python/nxt_python_wsgi.c b/src/python/nxt_python_wsgi.c
index c621097e..ec9fefca 100644
--- a/src/python/nxt_python_wsgi.c
+++ b/src/python/nxt_python_wsgi.c
@@ -108,10 +108,10 @@ static PyMethodDef nxt_py_write_method[] = {
 
 
 static PyMethodDef nxt_py_input_methods[] = {
-    { "read",      (PyCFunction) nxt_py_input_read,      METH_VARARGS, 0 },
-    { "readline",  (PyCFunction) nxt_py_input_readline,  METH_VARARGS, 0 },
-    { "readlines", (PyCFunction) nxt_py_input_readlines, METH_VARARGS, 0 },
-    { NULL, NULL, 0, 0 }
+    { "read",      (PyCFunction) nxt_py_input_read,      METH_VARARGS, NULL },
+    { "readline",  (PyCFunction) nxt_py_input_readline,  METH_VARARGS, NULL },
+    { "readlines", (PyCFunction) nxt_py_input_readlines, METH_VARARGS, NULL },
+    {}
 };