shadow/lib/gshadow.c
Alejandro Colomar 62172f6fb5 Call NULL by its name
In variadic functions we still do the cast.  In POSIX, it's not
necessary, since NULL is required to be of type 'void *', and 'void *'
is guaranteed to have the same alignment and representation as 'char *'.
However, since ISO C still doesn't mandate that, and moreover they're
doing dubious stuff by adding nullptr, let's be on the cautious side.
Also, C++ requires that NULL is _not_ 'void *', but either plain 0 or
some magic stuff.

Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-02-02 13:08:30 -06:00

507 lines
9.0 KiB
C

/*
* SPDX-FileCopyrightText: 1990 - 1994, Julianne Frances Haugh
* SPDX-FileCopyrightText: 1996 - 1998, Marek Michałkiewicz
* SPDX-FileCopyrightText: 2005 , Tomasz Kłoczko
* SPDX-FileCopyrightText: 2008 - 2009, Nicolas François
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <config.h>
/* Newer versions of Linux libc already have shadow support. */
#if defined(SHADOWGRP) && !defined(HAVE_SHADOWGRP) /*{ */
#ident "$Id$"
#include <stdio.h>
#include <string.h>
#include "prototypes.h"
#include "defines.h"
static /*@null@*/FILE *shadow;
static /*@null@*//*@only@*/char **members = NULL;
static size_t nmembers = 0;
static /*@null@*//*@only@*/char **admins = NULL;
static size_t nadmins = 0;
static struct sgrp sgroup;
#define FIELDS 4
#ifdef USE_NIS
static bool nis_used;
static bool nis_ignore;
static enum { native, start, middle, native2 } nis_state;
static bool nis_bound;
static char *nis_domain;
static char *nis_key;
static int nis_keylen;
static char *nis_val;
static int nis_vallen;
#define IS_NISCHAR(c) ((c)=='+')
#endif
#ifdef USE_NIS
/*
* bind_nis - bind to NIS server
*/
static int bind_nis (void)
{
if (yp_get_default_domain (&nis_domain))
return -1;
nis_bound = true;
return 0;
}
#endif
static /*@null@*/char **build_list (char *s, char **list[], size_t * nlist)
{
char **ptr = *list;
size_t nelem = *nlist, size;
while (s != NULL && *s != '\0') {
size = (nelem + 1) * sizeof (ptr);
ptr = realloc (*list, size);
if (NULL != ptr) {
ptr[nelem] = s;
nelem++;
*list = ptr;
*nlist = nelem;
s = strchr (s, ',');
if (NULL != s) {
*s = '\0';
s++;
}
}
}
size = (nelem + 1) * sizeof (ptr);
ptr = realloc (*list, size);
if (NULL != ptr) {
ptr[nelem] = NULL;
*list = ptr;
}
return ptr;
}
void setsgent (void)
{
#ifdef USE_NIS
nis_state = native;
#endif
if (NULL != shadow) {
rewind (shadow);
} else {
shadow = fopen (SGROUP_FILE, "r");
}
}
void endsgent (void)
{
if (NULL != shadow) {
(void) fclose (shadow);
}
shadow = NULL;
}
/*@observer@*//*@null@*/struct sgrp *sgetsgent (const char *string)
{
static char *sgrbuf = NULL;
static size_t sgrbuflen = 0;
char *fields[FIELDS];
char *cp;
int i;
size_t len = strlen (string) + 1;
if (len > sgrbuflen) {
char *buf = (char *) realloc (sgrbuf, sizeof (char) * len);
if (NULL == buf) {
return NULL;
}
sgrbuf = buf;
sgrbuflen = len;
}
strlcpy (sgrbuf, string, len);
cp = strrchr (sgrbuf, '\n');
if (NULL != cp) {
*cp = '\0';
}
/*
* There should be exactly 4 colon separated fields. Find
* all 4 of them and save the starting addresses in fields[].
*/
for (cp = sgrbuf, i = 0; (i < FIELDS) && (NULL != cp); i++) {
fields[i] = cp;
cp = strchr (cp, ':');
if (NULL != cp) {
*cp++ = '\0';
}
}
/*
* If there was an extra field somehow, or perhaps not enough,
* the line is invalid.
*/
if ((NULL != cp) || (i != FIELDS)) {
#ifdef USE_NIS
if (!IS_NISCHAR (fields[0][0])) {
return 0;
} else {
nis_used = true;
}
#else
return 0;
#endif
}
sgroup.sg_name = fields[0];
sgroup.sg_passwd = fields[1];
if (0 != nadmins) {
nadmins = 0;
free (admins);
admins = NULL;
}
if (0 != nmembers) {
nmembers = 0;
free (members);
members = NULL;
}
sgroup.sg_adm = build_list (fields[2], &admins, &nadmins);
sgroup.sg_mem = build_list (fields[3], &members, &nmembers);
return &sgroup;
}
/*
* fgetsgent - convert next line in stream to (struct sgrp)
*
* fgetsgent() reads the next line from the provided stream and
* converts it to a (struct sgrp). NULL is returned on EOF.
*/
/*@observer@*//*@null@*/struct sgrp *fgetsgent (/*@null@*/FILE * fp)
{
static size_t buflen = 0;
static char *buf = NULL;
char *cp;
if (0 == buflen) {
buf = (char *) malloc (BUFSIZ);
if (NULL == buf) {
return NULL;
}
buflen = BUFSIZ;
}
if (NULL == fp) {
return NULL;
}
#ifdef USE_NIS
while (fgetsx (buf, (int) buflen, fp) == buf)
#else
if (fgetsx (buf, (int) buflen, fp) == buf)
#endif
{
while ( ((cp = strrchr (buf, '\n')) == NULL)
&& (feof (fp) == 0)) {
size_t len;
cp = (char *) realloc (buf, buflen*2);
if (NULL == cp) {
return NULL;
}
buf = cp;
buflen *= 2;
len = strlen (buf);
if (fgetsx (&buf[len],
(int) (buflen - len),
fp) != &buf[len]) {
return NULL;
}
}
cp = strrchr (buf, '\n');
if (NULL != cp) {
*cp = '\0';
}
#ifdef USE_NIS
if (nis_ignore && IS_NISCHAR (buf[0])) {
continue;
}
#endif
return (sgetsgent (buf));
}
return NULL;
}
/*
* getsgent - get a single shadow group entry
*/
/*@observer@*//*@null@*/struct sgrp *getsgent (void)
{
#ifdef USE_NIS
bool nis_1_group = false;
struct sgrp *val;
#endif
if (NULL == shadow) {
setsgent ();
}
#ifdef USE_NIS
again:
/*
* See if we are reading from the local file.
*/
if (nis_state == native || nis_state == native2) {
/*
* Get the next entry from the shadow group file. Return
* NULL right away if there is none.
*/
val = fgetsgent (shadow);
if (NULL == val) {
return 0;
}
/*
* If this entry began with a NIS escape character, we have
* to see if this is just a single group, or if the entire
* map is being asked for.
*/
if (IS_NISCHAR (val->sg_name[0])) {
if ('\0' != val->sg_name[1]) {
nis_1_group = true;
} else {
nis_state = start;
}
}
/*
* If this isn't a NIS group and this isn't an escape to go
* use a NIS map, it must be a regular local group.
*/
if (!nis_1_group && (nis_state != start)) {
return val;
}
/*
* If this is an escape to use an NIS map, switch over to
* that bunch of code.
*/
if (nis_state == start) {
goto again;
}
/*
* NEEDSWORK. Here we substitute pieces-parts of this entry.
*/
return 0;
} else {
if (!nis_bound) {
if (bind_nis ()) {
nis_state = native2;
goto again;
}
}
if (nis_state == start) {
if (yp_first (nis_domain, "gshadow.byname", &nis_key,
&nis_keylen, &nis_val, &nis_vallen)) {
nis_state = native2;
goto again;
}
nis_state = middle;
} else if (nis_state == middle) {
if (yp_next (nis_domain, "gshadow.byname", nis_key,
nis_keylen, &nis_key, &nis_keylen,
&nis_val, &nis_vallen)) {
nis_state = native2;
goto again;
}
}
return sgetsgent (nis_val);
}
#else
return (fgetsgent (shadow));
#endif
}
/*
* getsgnam - get a shadow group entry by name
*/
/*@observer@*//*@null@*/struct sgrp *getsgnam (const char *name)
{
struct sgrp *sgrp;
#ifdef USE_NIS
static char save_name[16];
int nis_disabled = 0;
#endif
setsgent ();
#ifdef USE_NIS
if (nis_used) {
again:
/*
* Search the gshadow.byname map for this group.
*/
if (!nis_bound) {
bind_nis ();
}
if (nis_bound) {
char *cp;
if (yp_match (nis_domain, "gshadow.byname", name,
strlen (name), &nis_val,
&nis_vallen) == 0) {
cp = strchr (nis_val, '\n');
if (NULL != cp) {
*cp = '\0';
}
nis_state = middle;
sgrp = sgetsgent (nis_val);
if (NULL != sgrp) {
strcpy (save_name, sgrp->sg_name);
nis_key = save_name;
nis_keylen = strlen (save_name);
}
return sgrp;
}
}
nis_state = native2;
}
#endif
#ifdef USE_NIS
if (nis_used) {
nis_ignore = true;
nis_disabled = true;
}
#endif
while ((sgrp = getsgent ()) != NULL) {
if (strcmp (name, sgrp->sg_name) == 0) {
break;
}
}
#ifdef USE_NIS
nis_ignore = false;
#endif
return sgrp;
}
/*
* putsgent - output shadow group entry in text form
*
* putsgent() converts the contents of a (struct sgrp) to text and
* writes the result to the given stream. This is the logical
* opposite of fgetsgent.
*/
int putsgent (const struct sgrp *sgrp, FILE * fp)
{
char *buf, *cp;
int i;
size_t size;
if ((NULL == fp) || (NULL == sgrp)) {
return -1;
}
/* calculate the required buffer size */
size = strlen (sgrp->sg_name) + strlen (sgrp->sg_passwd) + 10;
for (i = 0; (NULL != sgrp->sg_adm) && (NULL != sgrp->sg_adm[i]); i++) {
size += strlen (sgrp->sg_adm[i]) + 1;
}
for (i = 0; (NULL != sgrp->sg_mem) && (NULL != sgrp->sg_mem[i]); i++) {
size += strlen (sgrp->sg_mem[i]) + 1;
}
buf = malloc (size);
if (NULL == buf) {
return -1;
}
cp = buf;
/*
* Copy the group name and passwd.
*/
strcpy (cp, sgrp->sg_name);
cp += strlen (cp);
*cp++ = ':';
strcpy (cp, sgrp->sg_passwd);
cp += strlen (cp);
*cp++ = ':';
/*
* Copy the administrators, separating each from the other
* with a ",".
*/
for (i = 0; NULL != sgrp->sg_adm[i]; i++) {
if (i > 0) {
*cp++ = ',';
}
strcpy (cp, sgrp->sg_adm[i]);
cp += strlen (cp);
}
*cp = ':';
cp++;
/*
* Now do likewise with the group members.
*/
for (i = 0; NULL != sgrp->sg_mem[i]; i++) {
if (i > 0) {
*cp = ',';
cp++;
}
strcpy (cp, sgrp->sg_mem[i]);
cp += strlen (cp);
}
*cp = '\n';
cp++;
*cp = '\0';
/*
* Output using the function which understands the line
* continuation conventions.
*/
if (fputsx (buf, fp) == EOF) {
free (buf);
return -1;
}
free (buf);
return 0;
}
#else
extern int ISO_C_forbids_an_empty_translation_unit;
#endif /*} SHADOWGRP */