[OpenBSD] Process num_fds() and open_files() may raise NSP for PI…

…D 0 (#2460)

This is weird, because of all the sudden the tests below started failing. This is despite PID 0 exists. The syscall failing with `ESRCH` is `kinfo_getfile`:
https://github.com/giampaolo/psutil/blob/f8b929b0754a4abbdadfdcb8aae382ddee8a13f9/psutil/arch/openbsd/proc.c#L57
We therefore return "null" fallback values instead of raising `NoSuchProcess`. 

```
=================================== FAILURES ===================================
___________________________ TestProcess.test_as_dict ___________________________
psutil/_psbsd.py:604: in wrapper
    return fun(self, *args, **kwargs)
psutil/_psbsd.py:914: in open_files
    rawlist = cext.proc_open_files(self.pid)
E   ProcessLookupError: [Errno 3] No such process (originated from sysctl(kinfo_file) (1/2))

During handling of the above exception, another exception occurred:
psutil/tests/test_process.py:1309: in test_as_dict
    d = p.as_dict()
psutil/__init__.py:558: in as_dict
    ret = meth()
psutil/__init__.py:1199: in open_files
    return self._proc.open_files()
psutil/_psbsd.py:609: in wrapper
    raise NoSuchProcess(self.pid, self._name)
E   psutil.NoSuchProcess: process no longer exists (pid=0)
____________________________ TestProcess.test_pid_0 ____________________________
psutil/_psbsd.py:604: in wrapper
    return fun(self, *args, **kwargs)
psutil/_psbsd.py:914: in open_files
    rawlist = cext.proc_open_files(self.pid)
E   ProcessLookupError: [Errno 3] No such process (originated from sysctl(kinfo_file) (1/2))

During handling of the above exception, another exception occurred:
psutil/tests/test_process.py:1513: in test_pid_0
    ret = fun()
psutil/__init__.py:1199: in open_files
    return self._proc.open_files()
psutil/_psbsd.py:609: in wrapper
    raise NoSuchProcess(self.pid, self._name)
E   psutil.NoSuchProcess: process no longer exists (pid=0)
________________________ TestFetchAllProcesses.test_all ________________________
psutil/_psbsd.py:604: in wrapper
    return fun(self, *args, **kwargs)
psutil/_psbsd.py:914: in open_files
    rawlist = cext.proc_open_files(self.pid)
E   ProcessLookupError: [Errno 3] No such process (originated from sysctl(kinfo_file) (1/2))

During handling of the above exception, another exception occurred:
psutil/tests/test_process_all.py:93: in proc_info
    info[fun_name] = fun()
psutil/__init__.py:1199: in open_files
    return self._proc.open_files()
psutil/_psbsd.py:609: in wrapper
    raise NoSuchProcess(self.pid, self._name)
E   psutil.NoSuchProcess: process no longer exists (pid=0, name='swapper')

During handling of the above exception, another exception occurred:
psutil/tests/test_process_all.py:135: in test_all
    for info in self.iter_proc_info():
psutil/tests/test_process_all.py:130: in iter_proc_info
    ls.append(proc_info(pid))
psutil/tests/test_process_all.py:95: in proc_info
    check_exception(exc, proc, name, ppid)
psutil/tests/test_process_all.py:65: in check_exception
    tcase.assertProcessGone(proc)
psutil/tests/__init__.py:1069: in assertProcessGone
    self.assertPidGone(proc.pid)
psutil/tests/__init__.py:1057: in assertPidGone
    with pytest.raises(psutil.NoSuchProcess) as cm:
E   Failed: DID NOT RAISE <class 'psutil.NoSuchProcess'>
```

HISTORY.rst

@@ -25,6 +25,9 @@ XXXX-XX-XX
   Python 3.13.  (patch by Sam Gross)
 - 2455_, [Linux]: ``IndexError`` may occur when reading /proc/pid/stat and
   field 40 (blkio_ticks) is missing.
+- 2460_, [OpenBSD]: `Process.num_fds()`_ and `Process.open_files()`_ may fail
+  with `NoSuchProcess`_ for PID 0. Instead, we now return "null" values (0 and
+  [] respectively).
 
 6.0.0
 ======

INSTALL.rst

@@ -82,7 +82,7 @@ OpenBSD
 
 ::
 
-    export PKG_PATH=http://ftp.eu.openbsd.org/pub/OpenBSD/`uname -r`/packages/`uname -m`/
+    export PKG_PATH=https://cdn.openbsd.org/pub/OpenBSD/`uname -r`/packages/`uname -m`/
     pkg_add -v python3 gcc
     pip install psutil
 
@@ -93,7 +93,7 @@ Assuming Python 3.11 (the most recent at the time of writing):
 
 ::
 
-    export PKG_PATH="http://ftp.netbsd.org/pub/pkgsrc/packages/NetBSD/`uname -m`/`uname -r`/All"
+    export PKG_PATH="https://ftp.netbsd.org/pub/pkgsrc/packages/NetBSD/`uname -m`/`uname -r`/All"
     pkg_add -v pkgin
     pkgin install python311-* gcc12-* py311-setuptools-* py311-pip-*
     python3.11 -m pip install psutil

psutil/arch/bsd/proc.c

@@ -442,8 +442,17 @@ psutil_proc_open_files(PyObject *self, PyObject *args) {
 
     errno = 0;
     freep = kinfo_getfile(pid, &cnt);
+
     if (freep == NULL) {
-#if !defined(PSUTIL_OPENBSD)
+#if defined(PSUTIL_OPENBSD)
+        if ((pid == 0) && (errno == ESRCH)) {
+            psutil_debug(
+                "open_files() returned ESRCH for PID 0; forcing `return []`"
+            );
+            PyErr_Clear();
+            return py_retlist;
+        }
+#else
         psutil_raise_for_pid(pid, "kinfo_getfile()");
 #endif
         goto error;

psutil/arch/openbsd/proc.c

@@ -41,7 +41,7 @@ psutil_kinfo_proc(pid_t pid, struct kinfo_proc *proc) {
 
     ret = sysctl((int*)mib, 6, proc, &size, NULL, 0);
     if (ret == -1) {
-        PyErr_SetFromErrno(PyExc_OSError);
+        psutil_PyErr_SetFromOSErrnoWithSyscall("sysctl(kinfo_proc)");
         return -1;
     }
     // sysctl stores 0 in the size if we can't find the process information.
@@ -69,7 +69,7 @@ kinfo_getfile(pid_t pid, int* cnt) {
 
     /* get the size of what would be returned */
     if (sysctl(mib, 6, NULL, &len, NULL, 0) < 0) {
-        PyErr_SetFromErrno(PyExc_OSError);
+        psutil_PyErr_SetFromOSErrnoWithSyscall("sysctl(kinfo_file) (1/2)");
         return NULL;
     }
     if ((kf = malloc(len)) == NULL) {
@@ -79,7 +79,7 @@ kinfo_getfile(pid_t pid, int* cnt) {
     mib[5] = (int)(len / sizeof(struct kinfo_file));
     if (sysctl(mib, 6, kf, &len, NULL, 0) < 0) {
         free(kf);
-        PyErr_SetFromErrno(PyExc_OSError);
+        psutil_PyErr_SetFromOSErrnoWithSyscall("sysctl(kinfo_file) (2/2)");
         return NULL;
     }
 
@@ -288,8 +288,19 @@ psutil_proc_num_fds(PyObject *self, PyObject *args) {
         return NULL;
 
     freep = kinfo_getfile(pid, &cnt);
-    if (freep == NULL)
+
+    if (freep == NULL) {
+#if defined(PSUTIL_OPENBSD)
+        if ((pid == 0) && (errno == ESRCH)) {
+            psutil_debug(
+                "num_fds() returned ESRCH for PID 0; forcing `return 0`"
+            );
+            PyErr_Clear();
+            return Py_BuildValue("i", 0);
+        }
+#endif
         return NULL;
+    }
 
     free(freep);
     return Py_BuildValue("i", cnt);