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att
GitHub Repository: att/ast
 Path: blob/master/src/lib/libast/comp/eaccess.c
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/***********************************************************************

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*                                                                      *

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*               This software is part of the ast package               *

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*          Copyright (c) 1985-2011 AT&T Intellectual Property          *

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*                      and is licensed under the                       *

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*                 Eclipse Public License, Version 1.0                  *

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*                    by AT&T Intellectual Property                     *

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*                                                                      *

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*                A copy of the License is available at                 *

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*          http://www.eclipse.org/org/documents/epl-v10.html           *

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*         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *

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*                                                                      *

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*              Information and Software Systems Research               *

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*                            AT&T Research                             *

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*                           Florham Park NJ                            *

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*                                                                      *

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*                 Glenn Fowler <[email protected]>                  *

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*                  David Korn <[email protected]>                   *

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*                   Phong Vo <[email protected]>                    *

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*                                                                      *

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***********************************************************************/

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#pragma prototyped

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/*

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 * access() euid/egid implementation

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 */

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#include <ast.h>

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#include <errno.h>

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#include <ls.h>

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#include "FEATURE/eaccess"

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#if _lib_eaccess

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NoN(eaccess)

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#else

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#if defined(__EXPORT__)

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#define extern	__EXPORT__

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#endif

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extern int

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eaccess(const char* path, register int flags)

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{

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#ifdef EFF_ONLY_OK

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	return access(path, flags|EFF_ONLY_OK);

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#else

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#if _lib_euidaccess

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	return euidaccess(path, flags);

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#else

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	register int	mode;

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	struct stat	st;

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	static int	init;

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	static uid_t	ruid;

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	static uid_t	euid;

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	static gid_t	rgid;

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	static gid_t	egid;

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	if (!init)

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	{

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		ruid = getuid();

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		euid = geteuid();

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		rgid = getgid();

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		egid = getegid();

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		init = (ruid == euid && rgid == egid) ? 1 : -1;

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	}

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	if (init > 0 || flags == F_OK)

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		return access(path, flags);

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	if (stat(path, &st))

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		return -1;

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	mode = 0;

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	if (euid == 0)

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	{

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		if (!S_ISREG(st.st_mode) || !(flags & X_OK) || (st.st_mode & (S_IXUSR|S_IXGRP|S_IXOTH)))

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			return 0;

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		goto nope;

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	}

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	else if (euid == st.st_uid)

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	{

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		if (flags & R_OK)

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			mode |= S_IRUSR;

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		if (flags & W_OK)

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			mode |= S_IWUSR;

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		if (flags & X_OK)

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			mode |= S_IXUSR;

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	}

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	else if (egid == st.st_gid)

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	{

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#if _lib_getgroups

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	setgroup:

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#endif

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		if (flags & R_OK)

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			mode |= S_IRGRP;

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		if (flags & W_OK)

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			mode |= S_IWGRP;

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		if (flags & X_OK)

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			mode |= S_IXGRP;

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	}

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	else

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	{

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#if _lib_getgroups

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		register int	n;

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		static int	ngroups = -2;

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		static gid_t*	groups; 

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		if (ngroups == -2)

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		{

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			if ((ngroups = getgroups(0, (gid_t*)0)) <= 0)

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				ngroups = NGROUPS_MAX;

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			if (!(groups = newof(0, gid_t, ngroups + 1, 0)))

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				ngroups = -1;

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			else

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				ngroups = getgroups(ngroups, groups);

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		}

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		n = ngroups;

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		while (--n >= 0)

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			if (groups[n] == st.st_gid)

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				goto setgroup;

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#endif

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		if (flags & R_OK)

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			mode |= S_IROTH;

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		if (flags & W_OK)

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			mode |= S_IWOTH;

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		if (flags & X_OK)

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			mode |= S_IXOTH;

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	}

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	if ((st.st_mode & mode) == mode)

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		return 0;

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 nope:

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	errno = EACCES;

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	return -1;

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#endif

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#endif

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}

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#endif

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