xref: /aosp_15_r20/external/libcap-ng/src/lookup_table.c (revision 8dd5e09d5faf27a871e8654ddaa2d2af7c696578)

/* lookup_table.c --
 * Copyright 2009, 2013 Red Hat Inc.
 * All Rights Reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; see the file COPYING.LIB. If not, write to the
 * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor
 * Boston, MA 02110-1335, USA.
 *
 * Authors:
 *      Steve Grubb <[email protected]>
 */

#include "config.h"
#include <stddef.h>
#include <linux/capability.h>
#include <strings.h>
#include <stdio.h>
#include <stdlib.h>  // free


#define hidden __attribute__ ((visibility ("hidden")))
extern unsigned int last_cap hidden;

#undef cap_valid
#define cap_valid(x) ((x) <= last_cap)


struct transtab {
    int   value;
    int   offset;
};

#define MSGSTRFIELD(line) MSGSTRFIELD1(line)
#define MSGSTRFIELD1(line) str##line


/* To create the following tables in a DSO-friendly way we split them in
   two separate variables: a long string which is created by concatenating
   all strings referenced in the table and the table itself, which uses
   offsets instead of string pointers.  To do this without increasing
   the maintenance burden we use a lot of preprocessor magic.  All the
   maintainer has to do is to add a new entry to the included file and
   recompile.  */

static const union captab_msgstr_t {
    struct {
#define _S(n, s) char MSGSTRFIELD(__LINE__)[sizeof (s)];
#include "captab.h"
#undef _S
    };
    char str[0];
} captab_msgstr = { {
#define _S(n, s) s,
#include "captab.h"
#undef _S
} };
static const struct transtab captab[] = {
#define _S(n, s) { n, offsetof(union captab_msgstr_t,  \
                               MSGSTRFIELD(__LINE__)) },
#include "captab.h"
#undef _S
};
#define CAP_NG_CAPABILITY_NAMES (sizeof(captab)/sizeof(captab[0]))




static int capng_lookup_name(const struct transtab *table,
		const char *tabstr, size_t length, const char *name)
{
	size_t i;

	for (i = 0; i < length; i++) {
		if (!strcasecmp(tabstr + table[i].offset, name))
			return table[i].value;
	}
	return -1;
}

static const char *capng_lookup_number(const struct transtab *table,
                                       const char *tabstr, size_t length,
                                       int number)
{
	size_t i;

	for (i = 0; i < length; i++) {
		if (table[i].value == number)
			return tabstr + table[i].offset;
	}
	return NULL;
}

int capng_name_to_capability(const char *name)
{
	return capng_lookup_name(captab, captab_msgstr.str,
                                 CAP_NG_CAPABILITY_NAMES, name);
}

static char *ptr2 = NULL;
const char *capng_capability_to_name(unsigned int capability)
{
	const char *ptr;

	if (!cap_valid(capability))
		return NULL;

	ptr = capng_lookup_number(captab, captab_msgstr.str,
                                   CAP_NG_CAPABILITY_NAMES, capability);
	if (ptr == NULL) { // This leaks memory, but should almost never be used
		free(ptr2);
		if (asprintf(&ptr2, "cap_%u", capability) < 0)
			ptr = NULL;
		else
			ptr = ptr2;
	}
	return ptr;
}