/* UNIX password file access module */

#include "Python.h"

#include "posixmodule.h"

#include <errno.h>                // ERANGE

#include <pwd.h>                  // getpwuid()

#include <unistd.h>               // sysconf()

#include "clinic/pwdmodule.c.h"

/*[clinic input]

module pwd

[clinic start generated code]*/

/*[clinic end generated code: output=da39a3ee5e6b4b0d input=60f628ef356b97b6]*/

static PyStructSequence_Field struct_pwd_type_fields[] = {

    {"pw_name", "user name"},

    {"pw_passwd", "password"},

    {"pw_uid", "user id"},

    {"pw_gid", "group id"},

    {"pw_gecos", "real name"},

    {"pw_dir", "home directory"},

    {"pw_shell", "shell program"},

    {0}

};

PyDoc_STRVAR(struct_passwd__doc__,

"pwd.struct_passwd: Results from getpw*() routines.\n\n\

This object may be accessed either as a tuple of\n\

  (pw_name,pw_passwd,pw_uid,pw_gid,pw_gecos,pw_dir,pw_shell)\n\

or via the object attributes as named in the above tuple.");

static PyStructSequence_Desc struct_pwd_type_desc = {

    "pwd.struct_passwd",

    struct_passwd__doc__,

    struct_pwd_type_fields,

    7,

};

PyDoc_STRVAR(pwd__doc__,

"This module provides access to the Unix password database.\n\

It is available on all Unix versions.\n\

\n\

Password database entries are reported as 7-tuples containing the following\n\

items from the password database (see `<pwd.h>'), in order:\n\

pw_name, pw_passwd, pw_uid, pw_gid, pw_gecos, pw_dir, pw_shell.\n\

The uid and gid items are integers, all others are strings. An\n\

exception is raised if the entry asked for cannot be found.");

typedef struct {

    PyTypeObject *StructPwdType;

} pwdmodulestate;

static inline pwdmodulestate*

get_pwd_state(PyObject *module)

{

    void *state = PyModule_GetState(module);

    assert(state != NULL);

    return (pwdmodulestate *)state;

}

static struct PyModuleDef pwdmodule;

/* Mutex to protect calls to getpwuid(), getpwnam(), and getpwent().

 * These functions return pointer to static data structure, which

 * may be overwritten by any subsequent calls. */

static PyMutex pwd_db_mutex = {0};

#define DEFAULT_BUFFER_SIZE 1024

static PyObject *

mkpwent(PyObject *module, struct passwd *p)

{

    PyObject *v = PyStructSequence_New(get_pwd_state(module)->StructPwdType);

    if (v == NULL) {

        return NULL;

    }

    int setIndex = 0;

#define SET_STRING(VAL) \

    SET_RESULT((VAL) ? PyUnicode_DecodeFSDefault((VAL)) : Py_NewRef(Py_None))

#define SET_RESULT(CALL)                                     \

    do {                                                     \

        PyObject *item = (CALL);                             \

        if (item == NULL) {                                  \

            goto error;                                      \

        }                                                    \

        PyStructSequence_SetItem(v, setIndex++, item);       \

    } while(0)

    SET_STRING(p->pw_name);

#if defined(HAVE_STRUCT_PASSWD_PW_PASSWD) && !defined(__ANDROID__)

    SET_STRING(p->pw_passwd);

#else

    SET_STRING("");

#endif

    SET_RESULT(_PyLong_FromUid(p->pw_uid));

    SET_RESULT(_PyLong_FromGid(p->pw_gid));

#if defined(HAVE_STRUCT_PASSWD_PW_GECOS)

    SET_STRING(p->pw_gecos);

#else

    SET_STRING("");

#endif

    SET_STRING(p->pw_dir);

    SET_STRING(p->pw_shell);

#undef SET_STRING

#undef SET_RESULT

    return v;

error:

    Py_DECREF(v);

    return NULL;

}

/*[clinic input]

pwd.getpwuid

    uidobj as uid: uid_t

    /

Return the password database entry for the given numeric user ID.

See `help(pwd)` for more on password database entries.

[clinic start generated code]*/

static PyObject *

pwd_getpwuid_impl(PyObject *module, uid_t uid)

/*[clinic end generated code: output=631bad376fa670c3 input=506d3a592ef19799]*/

{

    PyObject *retval = NULL;

    int nomem = 0;

    struct passwd *p;

    char *buf = NULL, *buf2 = NULL;

#ifdef HAVE_GETPWUID_R

    int status;

    Py_ssize_t bufsize;

    /* Note: 'pwd' will be used via pointer 'p' on getpwuid_r success. */

    struct passwd pwd;

    Py_BEGIN_ALLOW_THREADS

    bufsize = sysconf(_SC_GETPW_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 = getpwuid_r(uid, &pwd, 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

    PyMutex_Lock(&pwd_db_mutex);

    // The getpwuid() function is not required to be thread-safe.

    // https://pubs.opengroup.org/onlinepubs/009604499/functions/getpwuid.html

    p = getpwuid(uid);

#endif

    if (p == NULL) {

#ifndef HAVE_GETPWUID_R

        PyMutex_Unlock(&pwd_db_mutex);

#endif

        PyMem_RawFree(buf);

        if (nomem == 1) {

            return PyErr_NoMemory();

        }

        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

    PyMem_RawFree(buf);

#else

    PyMutex_Unlock(&pwd_db_mutex);

#endif

    return retval;

}

/*[clinic input]

pwd.getpwnam

    name: unicode

    /

Return the password database entry for the given user name.

See `help(pwd)` for more on password database entries.

[clinic start generated code]*/

static PyObject *

pwd_getpwnam_impl(PyObject *module, PyObject *name)

/*[clinic end generated code: output=359ce1ddeb7a824f input=a6aeb5e3447fb9e0]*/

{

    char *buf = NULL, *buf2 = NULL, *name_chars;

    int nomem = 0;

    struct passwd *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_GETPWNAM_R

    int status;

    Py_ssize_t bufsize;

    /* Note: 'pwd' will be used via pointer 'p' on getpwnam_r success. */

    struct passwd pwd;

    Py_BEGIN_ALLOW_THREADS

    bufsize = sysconf(_SC_GETPW_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 = getpwnam_r(name_chars, &pwd, 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

    PyMutex_Lock(&pwd_db_mutex);

    // The getpwnam() function is not required to be thread-safe.

    // https://pubs.opengroup.org/onlinepubs/009604599/functions/getpwnam.html

    p = getpwnam(name_chars);

#endif

    if (p == NULL) {

#ifndef HAVE_GETPWNAM_R

        PyMutex_Unlock(&pwd_db_mutex);

#endif

        if (nomem == 1) {

            PyErr_NoMemory();

        }

        else {

            PyErr_Format(PyExc_KeyError,

                         "getpwnam(): name not found: %R", name);

        }

        goto out;

    }

    retval = mkpwent(module, p);

#ifndef HAVE_GETPWNAM_R

    PyMutex_Unlock(&pwd_db_mutex);

#endif

out:

    PyMem_RawFree(buf);

    Py_DECREF(bytes);

    return retval;

}

#ifdef HAVE_GETPWENT

/*[clinic input]

@permit_long_summary

pwd.getpwall

Return a list of all available password database entries, in arbitrary order.

See help(pwd) for more on password database entries.

[clinic start generated code]*/

static PyObject *

pwd_getpwall_impl(PyObject *module)

/*[clinic end generated code: output=4853d2f5a0afac8a input=f8145e0d9a79e32c]*/

{

    PyObject *d;

    struct passwd *p;

    if ((d = PyList_New(0)) == NULL)

        return NULL;

    PyMutex_Lock(&pwd_db_mutex);

    int failure = 0;

    PyObject *v = NULL;

    // The setpwent(), getpwent() and endpwent() functions are not required to

    // be thread-safe.

    // https://pubs.opengroup.org/onlinepubs/009696799/functions/setpwent.html

    setpwent();

    while ((p = getpwent()) != NULL) {

        v = mkpwent(module, p);

        if (v == NULL || PyList_Append(d, v) != 0) {

            /* NOTE: cannot dec-ref here, while holding the mutex. */

            failure = 1;

            goto done;

        }

        Py_DECREF(v);

    }

done:

    endpwent();

    PyMutex_Unlock(&pwd_db_mutex);

    if (failure) {

        Py_XDECREF(v);

        Py_CLEAR(d);

    }

    return d;

}

#endif

static PyMethodDef pwd_methods[] = {

    PWD_GETPWUID_METHODDEF

    PWD_GETPWNAM_METHODDEF

#ifdef HAVE_GETPWENT

    PWD_GETPWALL_METHODDEF

#endif

    {NULL,              NULL}           /* sentinel */

};

static int

pwdmodule_exec(PyObject *module)

{

    pwdmodulestate *state = get_pwd_state(module);

    state->StructPwdType = PyStructSequence_NewType(&struct_pwd_type_desc);

    if (state->StructPwdType == NULL) {

        return -1;

    }

    if (PyModule_AddType(module, state->StructPwdType) < 0) {

        return -1;

    }

    return 0;

}

static PyModuleDef_Slot pwdmodule_slots[] = {

    _Py_ABI_SLOT,

    {Py_mod_exec, pwdmodule_exec},

    {Py_mod_multiple_interpreters, Py_MOD_PER_INTERPRETER_GIL_SUPPORTED},

    {Py_mod_gil, Py_MOD_GIL_NOT_USED},

    {0, NULL}

};

static int pwdmodule_traverse(PyObject *m, visitproc visit, void *arg) {

    Py_VISIT(get_pwd_state(m)->StructPwdType);

    return 0;

}

static int pwdmodule_clear(PyObject *m) {

    Py_CLEAR(get_pwd_state(m)->StructPwdType);

    return 0;

}

static void pwdmodule_free(void *m) {

    pwdmodule_clear((PyObject *)m);

}

static struct PyModuleDef pwdmodule = {

    PyModuleDef_HEAD_INIT,

    .m_name = "pwd",

    .m_doc = pwd__doc__,

    .m_size = sizeof(pwdmodulestate),

    .m_methods = pwd_methods,

    .m_slots = pwdmodule_slots,

    .m_traverse = pwdmodule_traverse,

    .m_clear = pwdmodule_clear,

    .m_free = pwdmodule_free,

};

PyMODINIT_FUNC

PyInit_pwd(void)

{

    return PyModuleDef_Init(&pwdmodule);

}