Implement psutil_proc_exe for NetBSD

Keep fallback for versions <8.0 without KERN_PROC_PATHNAME.

psutil/_psbsd.py

@@ -632,14 +632,8 @@ def name(self):
 
     @wrap_exceptions
     def exe(self):
-        if FREEBSD:
+        if FREEBSD or NETBSD:
             return cext.proc_exe(self.pid)
-        elif NETBSD:
-            if self.pid == 0:
-                # /proc/0 dir exists but /proc/0/exe doesn't
-                return ""
-            with wrap_exceptions_procfs(self):
-                return os.readlink("/proc/%s/exe" % self.pid)
         else:
             # OpenBSD: exe cannot be determined; references:
             # https://chromium.googlesource.com/chromium/src/base/+/

psutil/_psutil_bsd.c

@@ -934,9 +934,11 @@ PsutilMethods[] = {
     {"proc_num_threads", psutil_proc_num_threads, METH_VARARGS,
      "Return number of threads used by process"},
 #endif
-#if defined(PSUTIL_FREEBSD)
+#if defined(PSUTIL_FREEBSD) || defined(PSUTIL_NETBSD)
     {"proc_exe", psutil_proc_exe, METH_VARARGS,
      "Return process pathname executable"},
+#endif
+#if defined(PSUTIL_FREEBSD)
     {"proc_memory_maps", psutil_proc_memory_maps, METH_VARARGS,
      "Return a list of tuples for every process's memory map"},
     {"proc_cpu_affinity_get", psutil_proc_cpu_affinity_get, METH_VARARGS,

psutil/arch/netbsd/specific.c

@@ -679,3 +679,38 @@ psutil_cpu_stats(PyObject *self, PyObject *args) {
         uv.forks  // forks
     );
 }
+
+PyObject *
+psutil_proc_exe(PyObject *self, PyObject *args) {
+    long pid;
+
+    char path[MAXPATHLEN];
+    size_t pathlen = sizeof path;
+
+    if (! PyArg_ParseTuple(args, "l", &pid))
+        return NULL;
+
+#ifdef KERN_PROC_PATHNAME
+    int name[] = { CTL_KERN, KERN_PROC_ARGS, pid, KERN_PROC_PATHNAME};
+    if (sysctl(name, 4, path, &pathlen, NULL, 0) != 0) {
+        PyErr_SetFromErrno(PyExc_OSError);
+        return NULL;
+    }
+#else
+    char *buf;
+    if (asprintf(&buf, "/proc/%d/exe", (int)pid) < 0) {
+        PyErr_NoMemory();
+        return NULL;
+    }
+
+    ssize_t len = readlink(buf, path, pathlen - 1);
+    free(buf);
+    if (len == -1) {
+        PyErr_SetFromErrno(PyExc_OSError);
+        return NULL;
+    }
+    path[len] = '\0';
+#endif
+
+    return PyUnicode_DecodeFSDefault(path);
+}

psutil/arch/netbsd/specific.h

@@ -27,3 +27,4 @@ PyObject* psutil_proc_exe(PyObject* self, PyObject* args);
 PyObject* psutil_proc_num_threads(PyObject* self, PyObject* args);
 PyObject* psutil_cpu_stats(PyObject* self, PyObject* args);
 PyObject *psutil_proc_cwd(PyObject *self, PyObject *args);
+PyObject *psutil_proc_exe(PyObject *self, PyObject *args);