src/lookup_table.c - master - githubmirror/libcap-ng

src/lookup_table.c
137 строк4 KB
Steve Grubb
Tighten static analysis linkage hygiene
03 июн 2026, 02:24
03 июн 2026, 02:24e8cd41f
/* lookup_table.c --
 * Copyright 2009, 2013, 2025 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 <sgrubb@redhat.com>
 */

#include "config.h"
#include <stddef.h>
#include <linux/capability.h>
#include <strings.h>
#include <stdio.h>
#include "cap-ng.h"


#pragma GCC optimize("O3")
#define hidden __attribute__ ((visibility ("hidden")))
extern unsigned int last_cap hidden;

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


struct transtab {
    unsigned int value;
    unsigned 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 inline int capng_lookup_name(const char *name)
{
	// brute force search
	for (size_t i = 0; i < CAP_NG_CAPABILITY_NAMES; i++) {
		if (!strcasecmp(captab_msgstr.str + captab[i].offset, name))
			return captab[i].value;
	}
	return -1;
}

static inline const char *capng_lookup_number(unsigned int number)
{
	if (number >= CAP_NG_CAPABILITY_NAMES)
		return NULL;

	if (captab[number].value == number)
		return captab_msgstr.str + captab[number].offset;

	// Fallback to old search in case a capability is retired
	for (size_t i = 0; i < CAP_NG_CAPABILITY_NAMES; i++) {
		if (captab[i].value == number)
			return captab_msgstr.str + captab[i].offset;
	}
	return NULL;
}

/*
 * capng_name_to_capability - given a string with the name of the capabilty
 * return its number.
 * @name  - the name of the capability to lookup
 *
 * returns the number associated with the string.
 */
int capng_name_to_capability(const char *name)
{
	return capng_lookup_name(name);
}

/*
 * capng_capability_to_name - given a number, return a string with the name of
 * the capabilty.
 * @capability  - the number of the capability to lookup
 *
 * returns the string associated with the number.
 */
static __thread char ptr2[32];
const char *capng_capability_to_name(unsigned int capability)
{
	const char *ptr;

	if (!cap_valid(capability))
		return NULL;

	ptr = capng_lookup_number(capability);
	if (ptr == NULL) {
		snprintf(ptr2, sizeof(ptr2), "cap_%u", capability);
		ptr = ptr2;
	}
	return ptr;
}