strperm.c revision da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968
/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1985-2007 AT&T Knowledge Ventures *
* and is licensed under the *
* Common Public License, Version 1.0 *
* by AT&T Knowledge Ventures *
* *
* A copy of the License is available at *
* http://www.opensource.org/licenses/cpl1.0.txt *
* (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) *
* *
* Information and Software Systems Research *
* AT&T Research *
* Florham Park NJ *
* *
* Glenn Fowler <gsf@research.att.com> *
* David Korn <dgk@research.att.com> *
* Phong Vo <kpv@research.att.com> *
* *
***********************************************************************/
#pragma prototyped
/*
* Glenn Fowler
* AT&T Research
*
* apply file permission expression expr to perm
*
* each expression term must match
*
* [ugoa]*[-&+|^=]?[rwxst0-7]*
*
* terms may be combined using ,
*
* if non-null, e points to the first unrecognized char in expr
*/
#include <ast.h>
#include <ls.h>
#include <modex.h>
int
strperm(const char* aexpr, char** e, register int perm)
{
register char* expr = (char*)aexpr;
register int c;
register int typ;
register int who;
int num;
int op;
int mask;
int masked;
if (perm == -1)
{
perm = 0;
masked = 1;
mask = ~0;
}
else
masked = 0;
for (;;)
{
op = num = who = typ = 0;
for (;;)
{
switch (c = *expr++)
{
case 'u':
who |= S_ISVTX|S_ISUID|S_IRWXU;
continue;
case 'g':
who |= S_ISVTX|S_ISGID|S_IRWXG;
continue;
case 'o':
who |= S_ISVTX|S_IRWXO;
continue;
case 'a':
who = S_ISVTX|S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO;
continue;
default:
if (c >= '0' && c <= '7')
{
if (!who)
who = S_ISVTX|S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO;
c = '=';
}
expr--;
/*FALLTHROUGH*/
case '=':
if (who)
perm &= ~who;
else
perm = 0;
/*FALLTHROUGH*/
case '+':
case '|':
case '-':
case '&':
case '^':
op = c;
for (;;)
{
switch (c = *expr++)
{
case 'r':
typ |= S_IRUSR|S_IRGRP|S_IROTH;
continue;
case 'w':
typ |= S_IWUSR|S_IWGRP|S_IWOTH;
continue;
case 'X':
if (!S_ISDIR(perm) && !(perm & (S_IXUSR|S_IXGRP|S_IXOTH)))
continue;
/*FALLTHROUGH*/
case 'x':
typ |= S_IXUSR|S_IXGRP|S_IXOTH;
continue;
case 's':
typ |= S_ISUID|S_ISGID;
continue;
case 't':
typ |= S_ISVTX;
continue;
case 'l':
if (perm & S_IXGRP)
{
if (e)
*e = expr - 1;
return perm & S_IPERM;
}
typ |= S_ISGID;
continue;
case '=':
case '+':
case '|':
case '-':
case '&':
case '^':
case ',':
case 0:
if (who)
typ &= who;
else
switch (op)
{
case '=':
case '+':
case '|':
case '-':
case '&':
if (!masked)
{
masked = 1;
umask(mask = umask(0));
mask = ~mask;
}
typ &= mask;
break;
}
switch (op)
{
default:
if (who)
perm &= ~who;
else
perm = 0;
/*FALLTHROUGH*/
case '+':
case '|':
perm |= typ;
typ = 0;
break;
case '-':
perm &= ~typ;
typ = 0;
break;
case '&':
perm &= typ;
typ = 0;
break;
case '^':
if (typ &= perm)
{
/*
* propagate least restrictive to most restrictive
*/
if (typ & S_IXOTH)
perm |= who & (S_IXUSR|S_IXGRP);
if (typ & S_IWOTH)
perm |= who & (S_IWUSR|S_IWGRP);
if (typ & S_IROTH)
perm |= who & (S_IRUSR|S_IRGRP);
if (typ & S_IXGRP)
perm |= who & S_IXUSR;
if (typ & S_IWGRP)
perm |= who & S_IWUSR;
if (typ & S_IRGRP)
perm |= who & S_IRUSR;
/*
* if any execute then read => execute
*/
if ((typ |= perm) & (S_IXUSR|S_IXGRP|S_IXOTH))
{
if (typ & S_IRUSR)
perm |= who & S_IXUSR;
if (typ & S_IRGRP)
perm |= who & S_IXGRP;
if (typ & S_IROTH)
perm |= who & S_IXOTH;
}
typ = 0;
}
break;
}
switch (c)
{
case '=':
case '+':
case '|':
case '-':
case '&':
case '^':
op = c;
typ = 0;
continue;
}
if (c)
break;
/*FALLTHROUGH*/
default:
if (c < '0' || c > '7')
{
if (e)
*e = expr - 1;
if (typ)
{
if (who)
{
typ &= who;
perm &= ~who;
}
perm |= typ;
}
return perm & S_IPERM;
}
num = (num << 3) | (c - '0');
if (!who && (op == '+' || op == '-'))
who = S_ISVTX|S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO;
if (*expr < '0' || *expr > '7')
{
typ |= modei(num);
num = 0;
}
continue;
}
break;
}
break;
}
break;
}
}
}