util_hash.c

/*-
 * Copyright (c) 2008-2012 Juan Romero Pardines.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#define _BSD_SOURCE /* for madvise(2) */
#include <sys/mman.h>
#undef _BSD_SOURCE

#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>

#include <openssl/sha.h>

#include "xbps_api_impl.h"

/**
 * @file lib/util.c
 * @brief Utility routines
 * @defgroup util Utility functions
 */
static void
digest2string(const uint8_t *digest, char *string, size_t len)
{
        while (len--) {
                if (*digest / 16 < 10)
                        *string++ = '0' + *digest / 16;
                else
                        *string++ = 'a' + *digest / 16 - 10;
                if (*digest % 16 < 10)
                        *string++ = '0' + *digest % 16;
                else
                        *string++ = 'a' + *digest % 16 - 10;
                ++digest;
        }
        *string = '\0';
}

char *
xbps_file_hash(const char *file)
{
        struct stat st;
        size_t pgsize = (size_t)sysconf(_SC_PAGESIZE);
        size_t pgmask = pgsize - 1, mapsize;
        char hash[SHA256_DIGEST_LENGTH * 2 + 1];
        unsigned char *buf = NULL, digest[SHA256_DIGEST_LENGTH];
        int fd;
        bool need_guard = false;

        assert(file != NULL);

        if ((fd = open(file, O_RDONLY|O_CLOEXEC)) == -1) {
                free(buf);
                return NULL;
        }
        memset(&st, 0, sizeof(st));
        if (fstat(fd, &st) == -1) {
                (void)close(fd);
                return NULL;
        }
        if (st.st_size > SSIZE_MAX - 1) {
                (void)close(fd);
                return NULL;
        }

        mapsize = ((size_t)st.st_size + pgmask) & ~pgmask;
        if (mapsize < (size_t)st.st_size) {
                (void)close(fd);
                return NULL;
        }
        /*
         * If the file length is an integral number of pages, then we
         * need to map a guard page at the end in order to provide the
         * necessary NUL-termination of the buffer.
         */
        if ((st.st_size & pgmask) == 0)
                need_guard = true;

        buf = mmap(NULL, need_guard ? mapsize + pgsize : mapsize,
                PROT_READ, MAP_PRIVATE, fd, 0);
        (void)close(fd);
        if (buf == MAP_FAILED)
                return NULL;

        (void)madvise(buf, mapsize, MADV_SEQUENTIAL);
        if (SHA256(buf, st.st_size, digest) == NULL) {
                munmap(buf, mapsize);
                return NULL;
        }
        (void)madvise(buf, mapsize, MADV_DONTNEED);
        munmap(buf, mapsize);

        digest2string(digest, hash, SHA256_DIGEST_LENGTH);

        return strdup(hash);
}

int
xbps_file_hash_check(const char *file, const char *sha256)
{
        char *res;

        assert(file != NULL);
        assert(sha256 != NULL);

        res = xbps_file_hash(file);
        if (res == NULL)
                return errno;

        if (strcmp(sha256, res)) {
                free(res);
                return ERANGE;
        }
        free(res);

        return 0;
}

static const char *
file_hash_dictionary(prop_dictionary_t d, const char *key, const char *file)
{
        prop_object_t obj;
        prop_object_iterator_t iter;
        const char *curfile = NULL, *sha256 = NULL;

        assert(prop_object_type(d) == PROP_TYPE_DICTIONARY);
        assert(key != NULL);
        assert(file != NULL);

        iter = xbps_array_iter_from_dict(d, key);
        if (iter == NULL) {
                errno = ENOENT;
                return NULL;
        }
        while ((obj = prop_object_iterator_next(iter)) != NULL) {
                prop_dictionary_get_cstring_nocopy(obj,
                    "file", &curfile);
                if (strcmp(file, curfile) == 0) {
                        /* file matched */
                        prop_dictionary_get_cstring_nocopy(obj,
                            "sha256", &sha256);
                        break;
                }
        }
        prop_object_iterator_release(iter);
        if (sha256 == NULL)
                errno = ENOENT;

        return sha256;
}

int HIDDEN
xbps_file_hash_check_dictionary(struct xbps_handle *xhp,
                                prop_dictionary_t d,
                                const char *key,
                                const char *file)
{
        const char *sha256d = NULL;
        char *buf;
        int rv;

        assert(prop_object_type(d) == PROP_TYPE_DICTIONARY);
        assert(key != NULL);
        assert(file != NULL);

        if ((sha256d = file_hash_dictionary(d, key, file)) == NULL) {
                if (errno == ENOENT)
                        return 1; /* no match, file not found */

                return -1; /* error */
        }

        if (strcmp(xhp->rootdir, "/") == 0) {
                rv = xbps_file_hash_check(file, sha256d);
        } else {
                buf = xbps_xasprintf("%s/%s", xhp->rootdir, file);
                rv = xbps_file_hash_check(buf, sha256d);
                free(buf);
        }
        if (rv == 0)
                return 0; /* matched */
        else if (rv == ERANGE || rv == ENOENT)
                return 1; /* no match */
        else
                return -1; /* error */
}