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      1 /* lookup_table.c --
      2  * Copyright 2009 Red Hat Inc., Durham, North Carolina.
      3  * All Rights Reserved.
      4  *
      5  * This library is free software; you can redistribute it and/or
      6  * modify it under the terms of the GNU Lesser General Public
      7  * License as published by the Free Software Foundation; either
      8  * version 2.1 of the License, or (at your option) any later version.
      9  *
     10  * This library is distributed in the hope that it will be useful,
     11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
     12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     13  * Lesser General Public License for more details.
     14  *
     15  * You should have received a copy of the GNU Lesser General Public
     16  * License along with this library; if not, write to the Free Software
     17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
     18  *
     19  * Authors:
     20  *      Steve Grubb <sgrubb (at) redhat.com>
     21  */
     22 
     23 #include "config.h"
     24 #include <stddef.h>
     25 #include <linux/capability.h>
     26 #include <strings.h>
     27 
     28 
     29 #ifndef CAP_LAST_CAP
     30 #define CAP_LAST_CAP CAP_AUDIT_CONTROL
     31 #endif
     32 #undef cap_valid
     33 #define cap_valid(x) ((x) <= CAP_LAST_CAP)
     34 
     35 
     36 struct transtab {
     37     int   value;
     38     int   offset;
     39 };
     40 
     41 #define MSGSTRFIELD(line) MSGSTRFIELD1(line)
     42 #define MSGSTRFIELD1(line) str##line
     43 
     44 
     45 /* To create the following tables in a DSO-friendly way we split them in
     46    two separate variables: a long string which is created by concatenating
     47    all strings referenced in the table and the table itself, which uses
     48    offsets instead of string pointers.  To do this without increasing
     49    the maintenance burden we use a lot of preprocessor magic.  All the
     50    maintainer has to do is to add a new entry to the included file and
     51    recompile.  */
     52 
     53 static const union captab_msgstr_t {
     54     struct {
     55 #define _S(n, s) char MSGSTRFIELD(__LINE__)[sizeof (s)];
     56 #include "captab.h"
     57 #undef _S
     58     };
     59     char str[0];
     60 } captab_msgstr = { {
     61 #define _S(n, s) s,
     62 #include "captab.h"
     63 #undef _S
     64 } };
     65 static const struct transtab captab[] = {
     66 #define _S(n, s) { n, offsetof(union captab_msgstr_t,  \
     67                                MSGSTRFIELD(__LINE__)) },
     68 #include "captab.h"
     69 #undef _S
     70 };
     71 #define CAP_NG_CAPABILITY_NAMES (sizeof(captab)/sizeof(captab[0]))
     72 
     73 
     74 
     75 
     76 static int capng_lookup_name(const struct transtab *table,
     77 		const char *tabstr, size_t length, const char *name)
     78 {
     79 	size_t i;
     80 
     81 	for (i = 0; i < length; i++) {
     82 		if (!strcasecmp(tabstr + table[i].offset, name))
     83 			return table[i].value;
     84 	}
     85 	return -1;
     86 }
     87 
     88 static const char *capng_lookup_number(const struct transtab *table,
     89                                        const char *tabstr, size_t length,
     90                                        int number)
     91 {
     92 	size_t i;
     93 
     94 	for (i = 0; i < length; i++) {
     95 		if (table[i].value == number)
     96 			return tabstr + table[i].offset;
     97 	}
     98 	return NULL;
     99 }
    100 
    101 int capng_name_to_capability(const char *name)
    102 {
    103 	return capng_lookup_name(captab, captab_msgstr.str,
    104                                  CAP_NG_CAPABILITY_NAMES, name);
    105 }
    106 
    107 const char *capng_capability_to_name(unsigned int capability)
    108 {
    109 	if (!cap_valid(capability))
    110 		return NULL;
    111 
    112 	return capng_lookup_number(captab, captab_msgstr.str,
    113                                    CAP_NG_CAPABILITY_NAMES, capability);
    114 }
    115 
    116