path: root/lib/libarchive/archive_read_support_format_cpio.c

/*-
 * Copyright (c) 2003-2004 Tim Kientzle
 * 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
 *    in this position and unchanged.
 * 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(S) ``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(S) 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.
 */

#include "archive_platform.h"
__FBSDID("$FreeBSD$");

#include <sys/stat.h>

#include <err.h>
#include <errno.h>
/* #include <stdint.h> */ /* See archive_platform.h */
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "archive.h"
#include "archive_entry.h"
#include "archive_private.h"

struct cpio_header {
	char	c_magic[6];
	char	c_dev[6];
	char	c_ino[6];
	char	c_mode[6];
	char	c_uid[6];
	char	c_gid[6];
	char	c_nlink[6];
	char	c_rdev[6];
	char	c_mtime[11];
	char	c_namesize[6];
	char	c_filesize[11];
};

struct links_entry {
        struct links_entry      *next;
        struct links_entry      *previous;
        int                      links;
        dev_t                    dev;
        ino_t                    ino;
        char                    *name;
};

#define CPIO_MAGIC   0x13141516
struct cpio {
	int magic;
	struct links_entry	*links_head;
	struct archive_string	 entry_name;
	struct archive_string	 entry_linkname;
};

static int64_t	atol8(const char *, unsigned);
static int	archive_read_format_cpio_bid(struct archive *);
static int	archive_read_format_cpio_cleanup(struct archive *);
static int	archive_read_format_cpio_read_header(struct archive *,
		    struct archive_entry *);
static void	record_hardlink(struct cpio *cpio, struct archive_entry *entry,
		    const struct stat *st);

int
archive_read_support_format_cpio(struct archive *a)
{
	struct cpio *cpio;
	int r;

	cpio = malloc(sizeof(*cpio));
	memset(cpio, 0, sizeof(*cpio));
	cpio->magic = CPIO_MAGIC;

	r = __archive_read_register_format(a,
	    cpio,
	    archive_read_format_cpio_bid,
	    archive_read_format_cpio_read_header,
	    archive_read_format_cpio_cleanup);

	if (r != ARCHIVE_OK)
		free(cpio);
	return (ARCHIVE_OK);
}


static int
archive_read_format_cpio_bid(struct archive *a)
{
	int bid, bytes_read;
	const void *h;
	const struct cpio_header *header;

	bid = 0;
	bytes_read =
	    (a->compression_read_ahead)(a, &h, sizeof(struct cpio_header));
	if (bytes_read < (int)sizeof(struct cpio_header))
	    return (-1);

	header = h;

	if (memcmp(header->c_magic, "070707", 6)) return 0;
	bid += 48;

	/* TODO: Verify more of header: Can at least check that only octal
	   digits appear in appropriate header locations */

	return (bid);
}

static int
archive_read_format_cpio_read_header(struct archive *a,
    struct archive_entry *entry)
{
	struct stat st;
	struct cpio *cpio;
	size_t bytes;
	const struct cpio_header *header;
	const void *h;
	size_t namelength;

	a->archive_format = ARCHIVE_FORMAT_CPIO;
	a->archive_format_name = "POSIX octet-oriented cpio";
	cpio = *(a->pformat_data);
	if (cpio->magic != CPIO_MAGIC)
		errx(1, "CPIO data lost? This can't happen.\n");

	/* Read fixed-size portion of header. */
	bytes = (a->compression_read_ahead)(a, &h, sizeof(struct cpio_header));
	if (bytes < sizeof(struct cpio_header))
	    return (ARCHIVE_FATAL);
	(a->compression_read_consume)(a, sizeof(struct cpio_header));

	/* Parse out octal fields into struct stat. */
	memset(&st, 0, sizeof(st));
	header = h;

	st.st_dev = atol8(header->c_dev, sizeof(header->c_dev));
	st.st_ino = atol8(header->c_ino, sizeof(header->c_ino));
	st.st_mode = atol8(header->c_mode, sizeof(header->c_mode));
	st.st_uid = atol8(header->c_uid, sizeof(header->c_uid));
	st.st_gid = atol8(header->c_gid, sizeof(header->c_gid));
	st.st_nlink = atol8(header->c_nlink, sizeof(header->c_nlink));
	st.st_rdev = atol8(header->c_rdev, sizeof(header->c_rdev));
	st.st_mtime = atol8(header->c_mtime, sizeof(header->c_mtime));
	namelength = atol8(header->c_namesize, sizeof(header->c_namesize));

	/*
	 * Note: entry_bytes_remaining is at least 64 bits and
	 * therefore gauranteed to be big enough for a 33-bit file
	 * size.  struct stat.st_size may only be 32 bits, so
	 * assigning there first could lose information.
	 */
	a->entry_bytes_remaining =
	    atol8(header->c_filesize, sizeof(header->c_filesize));
	st.st_size = a->entry_bytes_remaining;
	a->entry_padding = 0;

	/* Assign all of the 'stat' fields at once. */
	archive_entry_copy_stat(entry, &st);

	/* Read name from buffer. */
	bytes = (a->compression_read_ahead)(a, &h, namelength);
	if (bytes < namelength)
	    return (ARCHIVE_FATAL);
	(a->compression_read_consume)(a, namelength);
	archive_strncpy(&cpio->entry_name, h, namelength);
	archive_entry_set_pathname(entry, cpio->entry_name.s);

	/* If this is a symlink, read the link contents. */
	if (S_ISLNK(st.st_mode)) {
		bytes = (a->compression_read_ahead)(a, &h,
		    a->entry_bytes_remaining);
		if ((off_t)bytes < a->entry_bytes_remaining)
			return (ARCHIVE_FATAL);
		(a->compression_read_consume)(a, a->entry_bytes_remaining);
		archive_strncpy(&cpio->entry_linkname, h,
		    a->entry_bytes_remaining);
		archive_entry_set_symlink(entry, cpio->entry_linkname.s);
		a->entry_bytes_remaining = 0;
	}

	/* Compare name to "TRAILER!!!" to test for end-of-archive. */
	if (namelength == 11 && strcmp(h,"TRAILER!!!")==0) {
	    /* TODO: Store file location of start of block. */
	    archive_set_error(a, 0, NULL);
	    return (ARCHIVE_EOF);
	}

	/* Detect and record hardlinks to previously-extracted entries. */
	record_hardlink(cpio, entry, &st);

	return (ARCHIVE_OK);
}

static int
archive_read_format_cpio_cleanup(struct archive *a)
{
	struct cpio *cpio;

	cpio = *(a->pformat_data);
        /* Free inode->name map */
        while (cpio->links_head != NULL) {
                struct links_entry *lp = cpio->links_head->next;

                if (cpio->links_head->name)
                        free(cpio->links_head->name);
                free(cpio->links_head);
                cpio->links_head = lp;
        }

	free(cpio);
	*(a->pformat_data) = NULL;
	return (ARCHIVE_OK);
}


/*
 * Note that this implementation does not (and should not!) obey
 * locale settings; you cannot simply substitute strtol here, since
 * it does obey locale.
 */
static int64_t
atol8(const char *p, unsigned char_cnt)
{
	int64_t l;
	int digit;

	static const int64_t limit = INT64_MAX / 8;
	static const int base = 8;
	static const char last_digit_limit = INT64_MAX % 8;

	l = 0;
	digit = *p - '0';
	while (digit >= 0 && digit < base  && char_cnt-- > 0) {
		if (l > limit || (l == limit && digit > last_digit_limit)) {
			l = UINT64_MAX; /* Truncate on overflow */
			break;
		}
		l = (l * base) + digit;
		digit = *++p - '0';
	}
	return (l);
}

static void
record_hardlink(struct cpio *cpio, struct archive_entry *entry,
    const struct stat *st)
{
        struct links_entry      *le;

        /*
         * First look in the list of multiply-linked files.  If we've
         * already dumped it, convert this entry to a hard link entry.
         */
        for (le = cpio->links_head; le; le = le->next) {
                if (le->dev == st->st_dev && le->ino == st->st_ino) {
                        archive_entry_set_hardlink(entry, le->name);

                        if (--le->links <= 0) {
                                if (le->previous != NULL)
                                        le->previous->next = le->next;
                                if (le->next != NULL)
                                        le->next->previous = le->previous;
                                if (cpio->links_head == le)
                                        cpio->links_head = le->next;
                                free(le);
                        }

                        return;
                }
        }

        le = malloc(sizeof(struct links_entry));
        if (cpio->links_head != NULL)
                cpio->links_head->previous = le;
        le->next = cpio->links_head;
        le->previous = NULL;
        cpio->links_head = le;
        le->dev = st->st_dev;
        le->ino = st->st_ino;
        le->links = st->st_nlink - 1;
        le->name = strdup(archive_entry_pathname(entry));
}