path: root/lib/libarchive/archive_read.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.
 */

/*
 * This file contains the "essential" portions of the read API, that
 * is, stuff that will probably always be used by any client that
 * actually needs to read an archive.  Optional pieces have been, as
 * far as possible, separated out into separate files to avoid
 * needlessly bloating statically-linked clients.
 */

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

#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

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

static int	choose_decompressor(struct archive *, const void*, size_t);
static int	choose_format(struct archive *);

/*
 * Allocate, initialize and return a struct archive object.
 */
struct archive *
archive_read_new(void)
{
	struct archive	*a;
	char		*nulls;

	a = malloc(sizeof(*a));
	memset(a, 0, sizeof(*a));

	a->user_uid = geteuid();
	a->magic = ARCHIVE_READ_MAGIC;
	a->bytes_per_block = ARCHIVE_DEFAULT_BYTES_PER_BLOCK;

	a->null_length = 1024;
	nulls = malloc(a->null_length);
	memset(nulls, 0, a->null_length);
	a->nulls = nulls;

	a->state = ARCHIVE_STATE_NEW;
	a->entry = archive_entry_new();

	/* We always support uncompressed archives. */
	archive_read_support_compression_none((struct archive*)a);

	return (a);
}

/*
 * Set the block size.
 */
/*
int
archive_read_set_bytes_per_block(struct archive *a, int bytes_per_block)
{
	archive_check_magic(a, ARCHIVE_READ_MAGIC, ARCHIVE_STATE_NEW);
	if (bytes_per_block < 1)
		bytes_per_block = 1;
	a->bytes_per_block = bytes_per_block;
	return (0);
}
*/

/*
 * Open the archive
 */
int
archive_read_open(struct archive *a, void *client_data,
    archive_open_callback *opener, archive_read_callback *reader,
    archive_close_callback *closer)
{
	const void *buffer;
	size_t bytes_read;
	int high_bidder;
	int e;

	archive_check_magic(a, ARCHIVE_READ_MAGIC, ARCHIVE_STATE_NEW);

	if (reader == NULL)
		errx(1,
		    "Fatal: No reader function provided to archive_read_open");

	a->client_reader = reader;
	a->client_opener = opener;
	a->client_closer = closer;
	a->client_data = client_data;

	a->state = ARCHIVE_STATE_HEADER;

	/* Open data source. */
	if (a->client_opener != NULL) {
		e =(a->client_opener)(a, a->client_data);
		if (e != 0)
			return (e);
	}

	/* Read first block now for format detection. */
	bytes_read = (a->client_reader)(a, a->client_data, &buffer);

	/* Select a decompression routine. */
	high_bidder = choose_decompressor(a, buffer, bytes_read);
	if (high_bidder < 0)
		return (ARCHIVE_FATAL);

	/* Initialize decompression routine with the first block of data. */
	e = (a->decompressors[high_bidder].init)(a, buffer, bytes_read);
	return (e);
}

/*
 * Allow each registered decompression routine to bid on whether it
 * wants to handle this stream.  Return index of winning bidder.
 */
static int
choose_decompressor(struct archive *a, const void *buffer, size_t bytes_read)
{
	int decompression_slots, i, bid, best_bid, best_bid_slot;

	decompression_slots = sizeof(a->decompressors) /
	    sizeof(a->decompressors[0]);

	best_bid = -1;
	best_bid_slot = -1;

	for (i = 0; i < decompression_slots; i++) {
		if (a->decompressors[i].bid) {
			bid = (a->decompressors[i].bid)(buffer, bytes_read);
			if ((bid > best_bid) || (best_bid_slot < 0)) {
				best_bid = bid;
				best_bid_slot = i;
			}
		}
	}

	/*
	 * There were no bidders; this is a serious programmer error
	 * and demands a quick and definitive abort.
	 */
	if (best_bid_slot < 0)
		errx(1, "Fatal: No decompressors were registered; you "
		    "must call at least one "
		    "archive_read_support_compression_XXX function in order "
		    "to successfully read an archive.");

	/*
	 * There were bidders, but no non-zero bids; this means we  can't
	 * support this stream.
	 */
	if (best_bid < 1) {
		archive_set_error(a, ARCHIVE_ERRNO_FILE_FORMAT,
		    "Unrecognized archive format");
		return (ARCHIVE_FATAL);
	}

	return (best_bid_slot);
}

/*
 * Read header of next entry.
 */
int
archive_read_next_header(struct archive *a, struct archive_entry **entryp)
{
	struct archive_entry *entry;
	int slot, ret;

	archive_check_magic(a, ARCHIVE_READ_MAGIC,
	    ARCHIVE_STATE_HEADER | ARCHIVE_STATE_DATA);

	*entryp = NULL;
	entry = a->entry;
	archive_entry_clear(entry);

	/*
	 * If client didn't consume entire data, skip any remainder
	 * (This is especially important for GNU incremental directories.)
	 */
	if (a->state == ARCHIVE_STATE_DATA) {
		ret = archive_read_data_skip(a);
		if (ret == ARCHIVE_EOF) {
			archive_set_error(a, EIO, "Premature end-of-file.");
			a->state = ARCHIVE_STATE_FATAL;
			return (ARCHIVE_FATAL);
		}
	}

	/* Record start-of-header. */
	a->header_position = a->file_position;

	slot = choose_format(a);
	if (slot < 0) {
		a->state = ARCHIVE_STATE_FATAL;
		return (ARCHIVE_FATAL);
	}
	a->format = &(a->formats[slot]);
	a->pformat_data = &(a->format->format_data);
	ret = (a->format->read_header)(a, entry);

	/*
	 * EOF and FATAL are persistent at this layer.  By
	 * modifying the state, we gaurantee that future calls to
	 * read a header or read data will fail.
	 */
	switch (ret) {
	case ARCHIVE_EOF:
		a->state = ARCHIVE_STATE_EOF;
		break;
	case ARCHIVE_OK:
		a->state = ARCHIVE_STATE_DATA;
		break;
	case ARCHIVE_WARN:
		a->state = ARCHIVE_STATE_DATA;
		break;
	case ARCHIVE_RETRY:
		break;
	case ARCHIVE_FATAL:
		a->state = ARCHIVE_STATE_FATAL;
		break;
	}

	*entryp = entry;
	return (ret);
}

/*
 * Allow each registered format to bid on whether it wants to handle
 * the next entry.  Return index of winning bidder.
 */
static int
choose_format(struct archive *a)
{
	int slots;
	int i;
	int bid, best_bid;
	int best_bid_slot;

	slots = sizeof(a->formats) / sizeof(a->formats[0]);
	best_bid = -1;
	best_bid_slot = -1;

	/* Set up a->format and a->pformat_data for convenience of bidders. */
	a->format = &(a->formats[0]);
	for (i = 0; i < slots; i++, a->format++) {
		if (a->format->bid) {
			a->pformat_data = &(a->format->format_data);
			bid = (a->format->bid)(a);
			if (bid == ARCHIVE_FATAL)
				return (ARCHIVE_FATAL);
			if ((bid > best_bid) || (best_bid_slot < 0)) {
				best_bid = bid;
				best_bid_slot = i;
			}
		}
	}

	/*
	 * There were no bidders; this is a serious programmer error
	 * and demands a quick and definitive abort.
	 */
	if (best_bid_slot < 0)
		errx(1, "Fatal: No formats were registered; you must "
		    "invoke at least one archive_read_support_format_XXX "
		    "function in order to successfully read an archive.");

	/*
	 * There were bidders, but no non-zero bids; this means we
	 * can't support this stream.
	 */
	if (best_bid < 1) {
		archive_set_error(a, ARCHIVE_ERRNO_FILE_FORMAT,
		    "Unrecognized archive format");
		return (ARCHIVE_FATAL);
	}

	return (best_bid_slot);
}

/*
 * Return the file offset (within the uncompressed data stream) where
 * the last header started.
 */
int64_t
archive_read_header_position(struct archive *a)
{
	return (a->header_position);
}

/*
 * Read data from an archive entry.
 */
ssize_t
archive_read_data(struct archive *a, void *buff, size_t s)
{
	const void *data;
	ssize_t bytes_read;

	archive_check_magic(a, ARCHIVE_READ_MAGIC, ARCHIVE_STATE_DATA);
	/*
	 * off_t is generally at least as wide as size_t, so widen for
	 * comparison and narrow for the assignment.  Otherwise, on
	 * platforms with 32-bit size_t and 64-bit off_t, we won't be
	 * able to correctly read archives with entries larger than
	 * 4gig.
	 */
	if ((off_t)s > a->entry_bytes_remaining)
		s = (size_t)a->entry_bytes_remaining;
	if (s > 0) {
		bytes_read = (a->compression_read_ahead)(a, &data, 1);
		if (bytes_read < 0) {
			a->state = ARCHIVE_STATE_FATAL;
			return (bytes_read);
		}
		if ((size_t)bytes_read > s)
			bytes_read = s;
	} else
		bytes_read = 0;

	if (bytes_read > 0) {
		memcpy(buff, data, bytes_read);
		(a->compression_read_consume)(a, bytes_read);
	}

	a->entry_bytes_remaining -= bytes_read;
	return (bytes_read);
}

/*
 * Skip over all remaining data in this entry.
 */
int
archive_read_data_skip(struct archive *a)
{
	const void *buff;
	ssize_t bytes_read, to_skip;

	archive_check_magic(a, ARCHIVE_READ_MAGIC, ARCHIVE_STATE_DATA);

	to_skip = a->entry_bytes_remaining + a->entry_padding;
	a->entry_bytes_remaining = 0;

	for (; to_skip > 0; to_skip -= bytes_read) {
		/* TODO: Optimize skip in compression layer. */
		bytes_read = (a->compression_read_ahead)(a, &buff, to_skip);
		if (bytes_read < 0) {
			a->entry_padding = to_skip;
			return (ARCHIVE_FATAL);
		}
		if (bytes_read == 0) {
			archive_set_error(a, EIO,
			    "Premature end of archive entry");
			return (ARCHIVE_FATAL);
		}
		if (bytes_read > to_skip)
			bytes_read = to_skip;
		(a->compression_read_consume)(a, bytes_read);
	}
	a->entry_padding = 0;
	a->state = ARCHIVE_STATE_HEADER;
	return (ARCHIVE_OK);
}

/*
 * Cleanup and free the archive object.
 *
 * Be careful: client might just call read_new and then read_finish.
 * Don't assume we actually read anything or performed any non-trivial
 * initialization.
 */
void
archive_read_finish(struct archive *a)
{
	int i;
	int slots;

	archive_check_magic(a, ARCHIVE_READ_MAGIC, ARCHIVE_STATE_ANY);
	a->state = ARCHIVE_STATE_CLOSED;

	/* Call cleanup functions registered by optional components. */
	if (a->cleanup_archive_extract != NULL)
		(a->cleanup_archive_extract)(a);

	/* TODO: Finish the format processing. */

	/* Close the input machinery. */
	if (a->compression_finish != NULL)
		(a->compression_finish)(a);

	/* Cleanup format-specific data. */
	slots = sizeof(a->formats) / sizeof(a->formats[0]);
	for (i = 0; i < slots; i++) {
		a->pformat_data = &(a->formats[i].format_data);
		if (a->formats[i].cleanup)
			(a->formats[i].cleanup)(a);
	}

	/* Casting a pointer to int allows us to remove 'const.' */
	free((void *)(uintptr_t)(const void *)a->nulls);
	archive_string_free(&a->extract_mkdirpath);
	archive_string_free(&a->error_string);
	if (a->entry)
		archive_entry_free(a->entry);
	a->magic = 0;
	free(a);
}

/*
 * Used internally by read format handlers to register their bid and
 * initialization functions.
 */
int
__archive_read_register_format(struct archive *a,
    void *format_data,
    int (*bid)(struct archive *),
    int (*read_header)(struct archive *, struct archive_entry *),
    int (*cleanup)(struct archive *))
{
	int i, number_slots;

	archive_check_magic(a, ARCHIVE_READ_MAGIC, ARCHIVE_STATE_NEW);

	number_slots = sizeof(a->formats) / sizeof(a->formats[0]);

	for (i = 0; i < number_slots; i++) {
		if (a->formats[i].bid == bid)
			return (ARCHIVE_WARN); /* We've already installed */
		if (a->formats[i].bid == NULL) {
			a->formats[i].bid = bid;
			a->formats[i].read_header = read_header;
			a->formats[i].cleanup = cleanup;
			a->formats[i].format_data = format_data;
			return (ARCHIVE_OK);
		}
	}

	errx(1, "Fatal: Not enough slots for format registration");
}

/*
 * Used internally by decompression routines to register their bid and
 * initialization functions.
 */
int
__archive_read_register_compression(struct archive *a,
    int (*bid)(const void *, size_t),
    int (*init)(struct archive *, const void *, size_t))
{
	int i, number_slots;

	archive_check_magic(a, ARCHIVE_READ_MAGIC, ARCHIVE_STATE_NEW);

	number_slots = sizeof(a->decompressors) / sizeof(a->decompressors[0]);

	for (i = 0; i < number_slots; i++) {
		if (a->decompressors[i].bid == bid)
			return (ARCHIVE_OK); /* We've already installed */
		if (a->decompressors[i].bid == NULL) {
			a->decompressors[i].bid = bid;
			a->decompressors[i].init = init;
			return (ARCHIVE_OK);
		}
	}

	errx(1, "Fatal: Not enough slots for compression registration");
}