gh-48511: Make pwd and grp expose inner errors

Distinguish
between the case when the user/group does not exist and error
conditions.
If the user does not exit, raise KeyError as  now, for errors raise OSError.

Author: simaoafonso-pwt

Misc/NEWS.d/next/Library/2023-02-24-18-17-01.gh-issue-48511.a7Tra5.rst

@@ -0,0 +1,6 @@
+The Unix user (:func:`pwd.getpwuid`, :func:`pwd.getpwnam`) and group (
+:func:`grp.getgrgid`, :func:`grp.getgrnam`) database functions now 
+differentiate between a lack of record (:exc:`KeyError` is risen, the current behaviour)
+and a database access error (:exc:`OSError` is risen).
+
+Based on a patch by Oleg Iarygin.

Modules/grpmodule.c

@@ -158,21 +158,25 @@ grp_getgrgid_impl(PyObject *module, PyObject *id)
     p = getgrgid(gid);
 #endif
     if (p == NULL) {
-        PyMem_RawFree(buf);
         if (nomem == 1) {
-            return PyErr_NoMemory();
+            retval = PyErr_NoMemory();
+        }
+        else if (errno == 0) {
+            PyObject *gid_obj = _PyLong_FromGid(gid);
+            if (gid_obj == NULL)
+                return NULL;
+            retval = PyErr_Format(PyExc_KeyError,
+                                  "getgrgid(): gid not found: %S", gid_obj);
+            Py_DECREF(gid_obj);
+        }
+        else {
+            retval = PyErr_SetFromErrno(PyExc_OSError);
         }
-        PyObject *gid_obj = _PyLong_FromGid(gid);
-        if (gid_obj == NULL)
-            return NULL;
-        PyErr_Format(PyExc_KeyError, "getgrgid(): gid not found: %S", gid_obj);
-        Py_DECREF(gid_obj);
-        return NULL;
     }
-    retval = mkgrent(module, p);
-#ifdef HAVE_GETGRGID_R
+    else {
+        retval = mkgrent(module, p);
+    }
     PyMem_RawFree(buf);
-#endif
     return retval;
 }
 
@@ -240,14 +244,19 @@ grp_getgrnam_impl(PyObject *module, PyObject *name)
 #endif
     if (p == NULL) {
         if (nomem == 1) {
-            PyErr_NoMemory();
+            retval = PyErr_NoMemory();
+        }
+        else if (errno == 0) {
+            retval = PyErr_Format(PyExc_KeyError,
+                                  "getgrnam(): name not found: %R", name);
         }
         else {
-            PyErr_Format(PyExc_KeyError, "getgrnam(): name not found: %R", name);
+            retval = PyErr_SetFromErrno(PyExc_OSError);
         }
-        goto out;
     }
-    retval = mkgrent(module, p);
+    else {
+        retval = mkgrent(module, p);
+    }
 out:
     PyMem_RawFree(buf);
     Py_DECREF(bytes);

Modules/pwdmodule.c

@@ -178,22 +178,25 @@ pwd_getpwuid(PyObject *module, PyObject *uidobj)
     p = getpwuid(uid);
 #endif
     if (p == NULL) {
-        PyMem_RawFree(buf);
         if (nomem == 1) {
-            return PyErr_NoMemory();
+            retval = PyErr_NoMemory();
+        }
+        else if (errno == 0) {
+            PyObject *uid_obj = _PyLong_FromUid(uid);
+            if (uid_obj == NULL)
+                return NULL;
+            retval = PyErr_Format(PyExc_KeyError,
+                                  "getpwuid(): uid not found: %S", uid_obj);
+            Py_DECREF(uid_obj);
+        }
+        else {
+            retval = PyErr_SetFromErrno(PyExc_OSError);
         }
-        PyObject *uid_obj = _PyLong_FromUid(uid);
-        if (uid_obj == NULL)
-            return NULL;
-        PyErr_Format(PyExc_KeyError,
-                     "getpwuid(): uid not found: %S", uid_obj);
-        Py_DECREF(uid_obj);
-        return NULL;
     }
-    retval = mkpwent(module, p);
-#ifdef HAVE_GETPWUID_R
+    else {
+        retval = mkpwent(module, p);
+    }
     PyMem_RawFree(buf);
-#endif
     return retval;
 }
 
@@ -262,15 +265,19 @@ pwd_getpwnam_impl(PyObject *module, PyObject *name)
 #endif
     if (p == NULL) {
         if (nomem == 1) {
-            PyErr_NoMemory();
+            retval = PyErr_NoMemory();
+        }
+        else if (errno == 0) {
+            retval = PyErr_Format(PyExc_KeyError,
+                                  "getpwnam(): name not found: %R", name);
         }
         else {
-            PyErr_Format(PyExc_KeyError,
-                         "getpwnam(): name not found: %R", name);
+            retval = PyErr_SetFromErrno(PyExc_OSError);
         }
-        goto out;
     }
-    retval = mkpwent(module, p);
+    else {
+        retval = mkpwent(module, p);
+    }
 out:
     PyMem_RawFree(buf);
     Py_DECREF(bytes);