cpython/Modules/grpmodule.c
Brett Simmers c2627d6eea
gh-116322: Add Py_mod_gil module slot (#116882)
This PR adds the ability to enable the GIL if it was disabled at
interpreter startup, and modifies the multi-phase module initialization
path to enable the GIL when loading a module, unless that module's spec
includes a slot indicating it can run safely without the GIL.

PEP 703 called the constant for the slot `Py_mod_gil_not_used`; I went
with `Py_MOD_GIL_NOT_USED` for consistency with gh-104148.

A warning will be issued up to once per interpreter for the first
GIL-using module that is loaded. If `-v` is given, a shorter message
will be printed to stderr every time a GIL-using module is loaded
(including the first one that issues a warning).
2024-05-03 11:30:55 -04:00

380 lines
9.1 KiB
C

/* UNIX group file access module */
// Need limited C API version 3.13 for PyMem_RawRealloc()
#include "pyconfig.h" // Py_GIL_DISABLED
#ifndef Py_GIL_DISABLED
#define Py_LIMITED_API 0x030d0000
#endif
#include "Python.h"
#include "posixmodule.h"
#include <errno.h> // ERANGE
#include <grp.h> // getgrgid_r()
#include <string.h> // memcpy()
#include <unistd.h> // sysconf()
#include "clinic/grpmodule.c.h"
/*[clinic input]
module grp
[clinic start generated code]*/
/*[clinic end generated code: output=da39a3ee5e6b4b0d input=cade63f2ed1bd9f8]*/
static PyStructSequence_Field struct_group_type_fields[] = {
{"gr_name", "group name"},
{"gr_passwd", "password"},
{"gr_gid", "group id"},
{"gr_mem", "group members"},
{0}
};
PyDoc_STRVAR(struct_group__doc__,
"grp.struct_group: Results from getgr*() routines.\n\n\
This object may be accessed either as a tuple of\n\
(gr_name,gr_passwd,gr_gid,gr_mem)\n\
or via the object attributes as named in the above tuple.\n");
static PyStructSequence_Desc struct_group_type_desc = {
"grp.struct_group",
struct_group__doc__,
struct_group_type_fields,
4,
};
typedef struct {
PyTypeObject *StructGrpType;
} grpmodulestate;
static inline grpmodulestate*
get_grp_state(PyObject *module)
{
void *state = PyModule_GetState(module);
assert(state != NULL);
return (grpmodulestate *)state;
}
static struct PyModuleDef grpmodule;
#define DEFAULT_BUFFER_SIZE 1024
static PyObject *
mkgrent(PyObject *module, struct group *p)
{
int setIndex = 0;
PyObject *v, *w;
char **member;
v = PyStructSequence_New(get_grp_state(module)->StructGrpType);
if (v == NULL)
return NULL;
if ((w = PyList_New(0)) == NULL) {
Py_DECREF(v);
return NULL;
}
for (member = p->gr_mem; ; member++) {
char *group_member;
// member can be misaligned
memcpy(&group_member, member, sizeof(group_member));
if (group_member == NULL) {
break;
}
PyObject *x = PyUnicode_DecodeFSDefault(group_member);
if (x == NULL || PyList_Append(w, x) != 0) {
Py_XDECREF(x);
Py_DECREF(w);
Py_DECREF(v);
return NULL;
}
Py_DECREF(x);
}
#define SET(i,val) PyStructSequence_SetItem(v, i, val)
SET(setIndex++, PyUnicode_DecodeFSDefault(p->gr_name));
if (p->gr_passwd)
SET(setIndex++, PyUnicode_DecodeFSDefault(p->gr_passwd));
else {
SET(setIndex++, Py_None);
Py_INCREF(Py_None);
}
SET(setIndex++, _PyLong_FromGid(p->gr_gid));
SET(setIndex++, w);
#undef SET
if (PyErr_Occurred()) {
Py_DECREF(v);
return NULL;
}
return v;
}
/*[clinic input]
grp.getgrgid
id: object
Return the group database entry for the given numeric group ID.
If id is not valid, raise KeyError.
[clinic start generated code]*/
static PyObject *
grp_getgrgid_impl(PyObject *module, PyObject *id)
/*[clinic end generated code: output=30797c289504a1ba input=15fa0e2ccf5cda25]*/
{
PyObject *retval = NULL;
int nomem = 0;
char *buf = NULL, *buf2 = NULL;
gid_t gid;
struct group *p;
if (!_Py_Gid_Converter(id, &gid)) {
return NULL;
}
#ifdef HAVE_GETGRGID_R
int status;
Py_ssize_t bufsize;
/* Note: 'grp' will be used via pointer 'p' on getgrgid_r success. */
struct group grp;
Py_BEGIN_ALLOW_THREADS
bufsize = sysconf(_SC_GETGR_R_SIZE_MAX);
if (bufsize == -1) {
bufsize = DEFAULT_BUFFER_SIZE;
}
while (1) {
buf2 = PyMem_RawRealloc(buf, bufsize);
if (buf2 == NULL) {
p = NULL;
nomem = 1;
break;
}
buf = buf2;
status = getgrgid_r(gid, &grp, buf, bufsize, &p);
if (status != 0) {
p = NULL;
}
if (p != NULL || status != ERANGE) {
break;
}
if (bufsize > (PY_SSIZE_T_MAX >> 1)) {
nomem = 1;
break;
}
bufsize <<= 1;
}
Py_END_ALLOW_THREADS
#else
p = getgrgid(gid);
#endif
if (p == NULL) {
PyMem_RawFree(buf);
if (nomem == 1) {
return PyErr_NoMemory();
}
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
PyMem_RawFree(buf);
#endif
return retval;
}
/*[clinic input]
grp.getgrnam
name: unicode
Return the group database entry for the given group name.
If name is not valid, raise KeyError.
[clinic start generated code]*/
static PyObject *
grp_getgrnam_impl(PyObject *module, PyObject *name)
/*[clinic end generated code: output=67905086f403c21c input=08ded29affa3c863]*/
{
char *buf = NULL, *buf2 = NULL, *name_chars;
int nomem = 0;
struct group *p;
PyObject *bytes, *retval = NULL;
if ((bytes = PyUnicode_EncodeFSDefault(name)) == NULL)
return NULL;
/* check for embedded null bytes */
if (PyBytes_AsStringAndSize(bytes, &name_chars, NULL) == -1)
goto out;
#ifdef HAVE_GETGRNAM_R
int status;
Py_ssize_t bufsize;
/* Note: 'grp' will be used via pointer 'p' on getgrnam_r success. */
struct group grp;
Py_BEGIN_ALLOW_THREADS
bufsize = sysconf(_SC_GETGR_R_SIZE_MAX);
if (bufsize == -1) {
bufsize = DEFAULT_BUFFER_SIZE;
}
while(1) {
buf2 = PyMem_RawRealloc(buf, bufsize);
if (buf2 == NULL) {
p = NULL;
nomem = 1;
break;
}
buf = buf2;
status = getgrnam_r(name_chars, &grp, buf, bufsize, &p);
if (status != 0) {
p = NULL;
}
if (p != NULL || status != ERANGE) {
break;
}
if (bufsize > (PY_SSIZE_T_MAX >> 1)) {
nomem = 1;
break;
}
bufsize <<= 1;
}
Py_END_ALLOW_THREADS
#else
p = getgrnam(name_chars);
#endif
if (p == NULL) {
if (nomem == 1) {
PyErr_NoMemory();
}
else {
PyErr_Format(PyExc_KeyError, "getgrnam(): name not found: %R", name);
}
goto out;
}
retval = mkgrent(module, p);
out:
PyMem_RawFree(buf);
Py_DECREF(bytes);
return retval;
}
/*[clinic input]
grp.getgrall
Return a list of all available group entries, in arbitrary order.
An entry whose name starts with '+' or '-' represents an instruction
to use YP/NIS and may not be accessible via getgrnam or getgrgid.
[clinic start generated code]*/
static PyObject *
grp_getgrall_impl(PyObject *module)
/*[clinic end generated code: output=585dad35e2e763d7 input=d7df76c825c367df]*/
{
PyObject *d;
struct group *p;
if ((d = PyList_New(0)) == NULL)
return NULL;
setgrent();
while ((p = getgrent()) != NULL) {
PyObject *v = mkgrent(module, p);
if (v == NULL || PyList_Append(d, v) != 0) {
Py_XDECREF(v);
Py_DECREF(d);
endgrent();
return NULL;
}
Py_DECREF(v);
}
endgrent();
return d;
}
static PyMethodDef grp_methods[] = {
GRP_GETGRGID_METHODDEF
GRP_GETGRNAM_METHODDEF
GRP_GETGRALL_METHODDEF
{NULL, NULL}
};
PyDoc_STRVAR(grp__doc__,
"Access to the Unix group database.\n\
\n\
Group entries are reported as 4-tuples containing the following fields\n\
from the group database, in order:\n\
\n\
gr_name - name of the group\n\
gr_passwd - group password (encrypted); often empty\n\
gr_gid - numeric ID of the group\n\
gr_mem - list of members\n\
\n\
The gid is an integer, name and password are strings. (Note that most\n\
users are not explicitly listed as members of the groups they are in\n\
according to the password database. Check both databases to get\n\
complete membership information.)");
static int
grpmodule_exec(PyObject *module)
{
grpmodulestate *state = get_grp_state(module);
state->StructGrpType = PyStructSequence_NewType(&struct_group_type_desc);
if (state->StructGrpType == NULL) {
return -1;
}
if (PyModule_AddType(module, state->StructGrpType) < 0) {
return -1;
}
return 0;
}
static PyModuleDef_Slot grpmodule_slots[] = {
{Py_mod_exec, grpmodule_exec},
{Py_mod_multiple_interpreters, Py_MOD_PER_INTERPRETER_GIL_SUPPORTED},
{Py_mod_gil, Py_MOD_GIL_NOT_USED},
{0, NULL}
};
static int grpmodule_traverse(PyObject *m, visitproc visit, void *arg) {
Py_VISIT(get_grp_state(m)->StructGrpType);
return 0;
}
static int grpmodule_clear(PyObject *m) {
Py_CLEAR(get_grp_state(m)->StructGrpType);
return 0;
}
static void grpmodule_free(void *m) {
grpmodule_clear((PyObject *)m);
}
static struct PyModuleDef grpmodule = {
PyModuleDef_HEAD_INIT,
.m_name = "grp",
.m_doc = grp__doc__,
.m_size = sizeof(grpmodulestate),
.m_methods = grp_methods,
.m_slots = grpmodule_slots,
.m_traverse = grpmodule_traverse,
.m_clear = grpmodule_clear,
.m_free = grpmodule_free,
};
PyMODINIT_FUNC
PyInit_grp(void)
{
return PyModuleDef_Init(&grpmodule);
}