shadow/lib/gshadow.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 *) reallocarray (sgrbuf, len, sizeof (char));
		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, buflen, fp) == buf)
#else
	if (fgetsx (buf, 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 */