Zip write support for libarchive.

The initial implementation was developed by Anselm Strauss as part of
Google Summer of Code 2008, then completed by Joerg Sonnenberger.

lib/libarchive/Makefile

@@ -87,6 +87,7 @@ SRCS=	archive_check_magic.c				\
 	archive_write_set_format_pax.c			\
 	archive_write_set_format_shar.c			\
 	archive_write_set_format_ustar.c		\
+	archive_write_set_format_zip.c			\
 	filter_fork.c
 
 # Man pages to be installed.

lib/libarchive/archive.h

@@ -538,6 +538,7 @@ __LA_DECL int		 archive_write_set_format_pax_restricted(struct archive *);
 __LA_DECL int		 archive_write_set_format_shar(struct archive *);
 __LA_DECL int		 archive_write_set_format_shar_dump(struct archive *);
 __LA_DECL int		 archive_write_set_format_ustar(struct archive *);
+__LA_DECL int		 archive_write_set_format_zip(struct archive *);
 __LA_DECL int		 archive_write_open(struct archive *, void *,
 		     archive_open_callback *, archive_write_callback *,
 		     archive_close_callback *);

lib/libarchive/archive_write_set_format.c

@@ -53,6 +53,7 @@ struct { int code; int (*setter)(struct archive *); } codes[] =
 	{ ARCHIVE_FORMAT_TAR_PAX_RESTRICTED,
 				archive_write_set_format_pax_restricted },
 	{ ARCHIVE_FORMAT_TAR_USTAR,	archive_write_set_format_ustar },
+	{ ARCHIVE_FORMAT_ZIP,	archive_write_set_format_zip },
 	{ 0,		NULL }
 };
 

lib/libarchive/archive_write_set_format_by_name.c

@@ -57,6 +57,7 @@ struct { const char *name; int (*setter)(struct archive *); } names[] =
 	{ "shar",	archive_write_set_format_shar },
 	{ "shardump",	archive_write_set_format_shar_dump },
 	{ "ustar",	archive_write_set_format_ustar },
+	{ "zip",	archive_write_set_format_zip },
 	{ NULL,		NULL }
 };
 

lib/libarchive/archive_write_set_format_zip.c

@@ -0,0 +1,667 @@
+/*-
+ * Copyright (c) 2008 Anselm Strauss
+ * Copyright (c) 2009 Joerg Sonnenberger
+ * 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(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.
+ */
+
+/*
+ * Development supported by Google Summer of Code 2008.
+ */
+
+/*
+ * The current implementation is very limited:
+ *
+ *   - No encryption support.
+ *   - No ZIP64 support.
+ *   - No support for splitting and spanning.
+ *   - Only supports regular file and folder entries.
+ *
+ * Note that generally data in ZIP files is little-endian encoded,
+ * with some exceptions.
+ *
+ * TODO: Since Libarchive is generally 64bit oriented, but this implementation
+ * does not yet support sizes exceeding 32bit, it is highly fragile for
+ * big archives. This should change when ZIP64 is finally implemented, otherwise
+ * some serious checking has to be done.
+ *
+ */
+
+#include "archive_platform.h"
+__FBSDID("$FreeBSD$");
+
+#ifdef HAVE_ERRNO_H
+#include <errno.h>
+#endif
+#include <stdio.h>
+#ifdef HAVE_STDLIB_H
+#include <stdlib.h>
+#endif
+#ifdef HAVE_STRING_H
+#include <string.h>
+#endif
+#ifdef HAVE_ZLIB_H
+#include <zlib.h>
+#endif
+
+#include "archive.h"
+#include "archive_endian.h"
+#include "archive_entry.h"
+#include "archive_private.h"
+#include "archive_write_private.h"
+
+#ifndef HAVE_ZLIB_H
+#include "archive_crc32.h"
+#endif
+
+#define ZIP_SIGNATURE_LOCAL_FILE_HEADER 0x04034b50
+#define ZIP_SIGNATURE_DATA_DESCRIPTOR 0x08074b50
+#define ZIP_SIGNATURE_FILE_HEADER 0x02014b50
+#define ZIP_SIGNATURE_CENTRAL_DIRECTORY_END 0x06054b50
+#define ZIP_SIGNATURE_EXTRA_TIMESTAMP 0x5455
+#define ZIP_SIGNATURE_EXTRA_UNIX 0x7855
+#define ZIP_VERSION_EXTRACT 0x0014 /* ZIP version 2.0 is needed. */
+#define ZIP_VERSION_BY 0x0314 /* Made by UNIX, using ZIP version 2.0. */
+#define ZIP_FLAGS 0x08 /* Flagging bit 3 (count from 0) for using data descriptor. */
+
+enum compression {
+	COMPRESSION_STORE = 0
+#ifdef HAVE_ZLIB_H
+	,
+	COMPRESSION_DEFLATE = 8
+#endif
+};
+
+static ssize_t archive_write_zip_data(struct archive_write *, const void *buff, size_t s);
+static int archive_write_zip_finish(struct archive_write *);
+static int archive_write_zip_destroy(struct archive_write *);
+static int archive_write_zip_finish_entry(struct archive_write *);
+static int archive_write_zip_header(struct archive_write *, struct archive_entry *);
+static unsigned int dos_time(const time_t);
+static size_t path_length(struct archive_entry *);
+static int write_path(struct archive_entry *, struct archive_write *);
+
+struct zip_local_file_header {
+	char signature[4];
+	char version[2];
+	char flags[2];
+	char compression[2];
+	char timedate[4];
+	char crc32[4];
+	char compressed_size[4];
+	char uncompressed_size[4];
+	char filename_length[2];
+	char extra_length[2];
+};
+
+struct zip_file_header {
+	char signature[4];
+	char version_by[2];
+	char version_extract[2];
+	char flags[2];
+	char compression[2];
+	char timedate[4];
+	char crc32[4];
+	char compressed_size[4];
+	char uncompressed_size[4];
+	char filename_length[2];
+	char extra_length[2];
+	char comment_length[2];
+	char disk_number[2];
+	char attributes_internal[2];
+	char attributes_external[4];
+	char offset[4];
+};
+
+struct zip_data_descriptor {
+	char signature[4]; /* Not mandatory, but recommended by specification. */
+	char crc32[4];
+	char compressed_size[4];
+	char uncompressed_size[4];
+};
+
+struct zip_extra_data_local {
+	char time_id[2];
+	char time_size[2];
+	char time_flag[1];
+	char mtime[4];
+	char atime[4];
+	char ctime[4];
+	char unix_id[2];
+	char unix_size[2];
+	char unix_uid[2];
+	char unix_gid[2];
+};
+
+struct zip_extra_data_central {
+	char time_id[2];
+	char time_size[2];
+	char time_flag[1];
+	char mtime[4];
+	char unix_id[2];
+	char unix_size[2];
+};
+
+struct zip_file_header_link {
+	struct zip_file_header_link *next;
+	struct archive_entry *entry;
+	off_t offset;
+	unsigned long crc32;
+	off_t compressed_size;
+	enum compression compression;
+};
+
+struct zip {
+	struct zip_data_descriptor data_descriptor;
+	struct zip_file_header_link *central_directory;
+	struct zip_file_header_link *central_directory_end;
+	int64_t offset;
+	int64_t written_bytes;
+	int64_t remaining_data_bytes;
+	enum compression compression;
+
+#ifdef HAVE_ZLIB_H
+	z_stream stream;
+	size_t len_buf;
+	unsigned char *buf;
+#endif
+};
+
+struct zip_central_directory_end {
+	char signature[4];
+	char disk[2];
+	char start_disk[2];
+	char entries_disk[2];
+	char entries[2];
+	char size[4];
+	char offset[4];
+	char comment_length[2];
+};
+
+static int
+archive_write_zip_options(struct archive_write *a, const char *key,
+    const char *value)
+{
+	struct zip *zip = a->format_data;
+
+	if (strcmp(key, "compression") == 0) {
+		if (strcmp(value, "deflate") == 0) {
+#ifdef HAVE_ZLIB_H
+			zip->compression = COMPRESSION_DEFLATE;
+#else
+			archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
+			    "deflate compression not supported");
+			return ARCHIVE_WARN;
+#endif
+		} else if (strcmp(value, "store") == 0)
+			zip->compression = COMPRESSION_STORE;
+		else
+			return (ARCHIVE_WARN);
+		return (ARCHIVE_OK);
+	}
+	return (ARCHIVE_WARN);
+}
+
+int
+archive_write_set_format_zip(struct archive *_a)
+{
+	struct archive_write *a = (struct archive_write *)_a;
+	struct zip *zip;
+
+	/* If another format was already registered, unregister it. */
+	if (a->format_destroy != NULL)
+		(a->format_destroy)(a);
+
+	zip = (struct zip *) malloc(sizeof(*zip));
+	if (zip == NULL) {
+		archive_set_error(&a->archive, ENOMEM, "Can't allocate zip data");
+		return (ARCHIVE_FATAL);
+	}
+	zip->central_directory = NULL;
+	zip->central_directory_end = NULL;
+	zip->offset = 0;
+	zip->written_bytes = 0;
+	zip->remaining_data_bytes = 0;
+
+#ifdef HAVE_ZLIB_H
+	zip->compression = COMPRESSION_DEFLATE;
+	zip->len_buf = 65536;
+	zip->buf = malloc(zip->len_buf);
+	if (zip->buf == NULL) {
+		archive_set_error(&a->archive, ENOMEM, "Can't allocate compression buffer");
+		return (ARCHIVE_FATAL);
+	}
+#else
+	zip->compression = COMPRESSION_STORE;
+#endif
+
+	a->format_data = zip;
+
+	a->pad_uncompressed = 0; /* Actually not needed for now, since no compression support yet. */
+	a->format_name = "zip";
+	a->format_options = archive_write_zip_options;
+	a->format_write_header = archive_write_zip_header;
+	a->format_write_data = archive_write_zip_data;
+	a->format_finish_entry = archive_write_zip_finish_entry;
+	a->format_finish = archive_write_zip_finish;
+	a->format_destroy = archive_write_zip_destroy;
+	a->archive.archive_format = ARCHIVE_FORMAT_ZIP;
+	a->archive.archive_format_name = "ZIP";
+
+	archive_le32enc(&zip->data_descriptor.signature,
+	    ZIP_SIGNATURE_DATA_DESCRIPTOR);
+
+	return (ARCHIVE_OK);
+}
+
+static int
+archive_write_zip_header(struct archive_write *a, struct archive_entry *entry)
+{
+	struct zip *zip;
+	struct zip_local_file_header h;
+	struct zip_extra_data_local e;
+	struct zip_data_descriptor *d;
+	struct zip_file_header_link *l;
+	int ret;
+	int64_t size;
+	mode_t type;
+
+	/* Entries other than a regular file or a folder are skipped. */
+	type = archive_entry_filetype(entry);
+	if ((type != AE_IFREG) & (type != AE_IFDIR)) {
+		archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC, "Filetype not supported");
+		return ARCHIVE_FAILED;
+	};
+
+	/* Directory entries should have a size of 0. */
+	if (type == AE_IFDIR)
+		archive_entry_set_size(entry, 0);
+
+	zip = a->format_data;
+	d = &zip->data_descriptor;
+	size = archive_entry_size(entry);
+	zip->remaining_data_bytes = size;
+
+	/* Append archive entry to the central directory data. */
+	l = (struct zip_file_header_link *) malloc(sizeof(*l));
+	if (l == NULL) {
+		archive_set_error(&a->archive, ENOMEM, "Can't allocate zip header data");
+		return (ARCHIVE_FATAL);
+	}
+	l->entry = archive_entry_clone(entry);
+	/* Initialize the CRC variable and potentially the local crc32(). */
+	l->crc32 = crc32(0, NULL, 0);
+	l->compression = zip->compression;
+	l->compressed_size = 0;
+	l->next = NULL;
+	if (zip->central_directory == NULL) {
+		zip->central_directory = l;
+	} else {
+		zip->central_directory_end->next = l;
+	}
+	zip->central_directory_end = l;
+
+	/* Store the offset of this header for later use in central directory. */
+	l->offset = zip->written_bytes;
+
+	memset(&h, 0, sizeof(h));
+	archive_le32enc(&h.signature, ZIP_SIGNATURE_LOCAL_FILE_HEADER);
+	archive_le16enc(&h.version, ZIP_VERSION_EXTRACT);
+	archive_le16enc(&h.flags, ZIP_FLAGS);
+	archive_le16enc(&h.compression, zip->compression);
+	archive_le32enc(&h.timedate, dos_time(archive_entry_mtime(entry)));
+	archive_le16enc(&h.filename_length, (uint16_t)path_length(entry));
+
+	switch (zip->compression) {
+	case COMPRESSION_STORE:
+		/* Setting compressed and uncompressed sizes even when specification says
+		 * to set to zero when using data descriptors. Otherwise the end of the
+		 * data for an entry is rather difficult to find. */
+		archive_le32enc(&h.compressed_size, size);
+		archive_le32enc(&h.uncompressed_size, size);
+		break;
+#ifdef HAVE_ZLIB_H
+	case COMPRESSION_DEFLATE:
+		archive_le32enc(&h.uncompressed_size, size);
+
+		zip->stream.zalloc = Z_NULL;
+		zip->stream.zfree = Z_NULL;
+		zip->stream.opaque = Z_NULL;
+		zip->stream.next_out = zip->buf;
+		zip->stream.avail_out = zip->len_buf;
+		if (deflateInit2(&zip->stream, Z_DEFAULT_COMPRESSION, Z_DEFLATED,
+		    -15, 8, Z_DEFAULT_STRATEGY) != Z_OK) {
+			archive_set_error(&a->archive, ENOMEM, "Can't init deflate compressor");
+			return (ARCHIVE_FATAL);
+		}
+		break;
+#endif
+	}
+
+	/* Formatting extra data. */
+	archive_le16enc(&h.extra_length, sizeof(e));
+	archive_le16enc(&e.time_id, ZIP_SIGNATURE_EXTRA_TIMESTAMP);
+	archive_le16enc(&e.time_size, sizeof(e.time_flag) +
+	    sizeof(e.mtime) + sizeof(e.atime) + sizeof(e.ctime));
+	e.time_flag[0] = 0x07;
+	archive_le32enc(&e.mtime, archive_entry_mtime(entry));
+	archive_le32enc(&e.atime, archive_entry_atime(entry));
+	archive_le32enc(&e.ctime, archive_entry_ctime(entry));
+	    
+	archive_le16enc(&e.unix_id, ZIP_SIGNATURE_EXTRA_UNIX);
+	archive_le16enc(&e.unix_size, sizeof(e.unix_uid) + sizeof(e.unix_gid));
+	archive_le16enc(&e.unix_uid, archive_entry_uid(entry));
+	archive_le16enc(&e.unix_gid, archive_entry_gid(entry));
+
+	archive_le32enc(&d->uncompressed_size, size);
+
+	ret = (a->compressor.write)(a, &h, sizeof(h));
+	if (ret != ARCHIVE_OK)
+		return (ARCHIVE_FATAL);
+	zip->written_bytes += sizeof(h);
+
+	ret = write_path(entry, a);
+	if (ret <= ARCHIVE_OK)
+		return (ARCHIVE_FATAL);
+	zip->written_bytes += ret;
+
+	ret = (a->compressor.write)(a, &e, sizeof(e));
+	if (ret != ARCHIVE_OK)
+		return (ARCHIVE_FATAL);
+	zip->written_bytes += sizeof(e);
+
+	return (ARCHIVE_OK);
+}
+
+static ssize_t
+archive_write_zip_data(struct archive_write *a, const void *buff, size_t s)
+{
+	int ret;
+	struct zip *zip = a->format_data;
+	struct zip_file_header_link *l = zip->central_directory_end;
+
+	if ((int64_t)s > zip->remaining_data_bytes)
+		s = (size_t)zip->remaining_data_bytes;
+
+	if (s == 0) return 0;
+
+	switch (zip->compression) {
+	case COMPRESSION_STORE:
+		ret = (a->compressor.write)(a, buff, s);
+		if (ret != ARCHIVE_OK) return (ret);
+		zip->written_bytes += s;
+		zip->remaining_data_bytes -= s;
+		l->compressed_size += s;
+		l->crc32 = crc32(l->crc32, buff, s);
+		return (s);
+#if HAVE_ZLIB_H
+	case COMPRESSION_DEFLATE:
+		zip->stream.next_in = (unsigned char*)(uintptr_t)buff;
+		zip->stream.avail_in = s;
+		do {
+			ret = deflate(&zip->stream, Z_NO_FLUSH);
+			if (ret == Z_STREAM_ERROR)
+				return (ARCHIVE_FATAL);
+			if (zip->stream.avail_out == 0) {
+				ret = (a->compressor.write)(a, zip->buf, zip->len_buf);
+				if (ret != ARCHIVE_OK)
+					return (ret);
+				l->compressed_size += zip->len_buf;
+				zip->written_bytes += zip->len_buf;
+				zip->stream.next_out = zip->buf;
+				zip->stream.avail_out = zip->len_buf;
+			}
+		} while (zip->stream.avail_in != 0);
+		zip->remaining_data_bytes -= s;
+		/* If we have it, use zlib's fast crc32() */
+		l->crc32 = crc32(l->crc32, buff, s);
+		return (s);
+#endif
+
+	default:
+		archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
+		    "Invalid ZIP compression type");
+		return ARCHIVE_FATAL;
+	}
+}
+
+static int
+archive_write_zip_finish_entry(struct archive_write *a)
+{
+	/* Write the data descripter after file data has been written. */
+	int ret;
+	struct zip *zip = a->format_data;
+	struct zip_data_descriptor *d = &zip->data_descriptor;
+	struct zip_file_header_link *l = zip->central_directory_end;
+#if HAVE_ZLIB_H
+	size_t reminder;
+#endif
+
+	switch(zip->compression) {
+	case COMPRESSION_STORE:
+		break;
+#if HAVE_ZLIB_H
+	case COMPRESSION_DEFLATE:
+		for (;;) {
+			ret = deflate(&zip->stream, Z_FINISH);
+			if (ret == Z_STREAM_ERROR)
+				return (ARCHIVE_FATAL);
+			reminder = zip->len_buf - zip->stream.avail_out;
+			ret = (a->compressor.write)(a, zip->buf, reminder);
+			if (ret != ARCHIVE_OK)
+				return (ret);
+			l->compressed_size += reminder;
+			zip->written_bytes += reminder;
+			zip->stream.next_out = zip->buf;
+			if (zip->stream.avail_out != 0)
+				break;
+			zip->stream.avail_out = zip->len_buf;
+		}
+		deflateEnd(&zip->stream);
+		break;
+#endif
+	}
+
+	archive_le32enc(&d->crc32, l->crc32);
+	archive_le32enc(&d->compressed_size, l->compressed_size);
+	ret = (a->compressor.write)(a, d, sizeof(*d));
+	if (ret != ARCHIVE_OK)
+		return (ARCHIVE_FATAL);
+	zip->written_bytes += sizeof(*d);
+	return (ARCHIVE_OK);
+}
+
+static int
+archive_write_zip_finish(struct archive_write *a)
+{
+	struct zip *zip;
+	struct zip_file_header_link *l;
+	struct zip_file_header h;
+	struct zip_central_directory_end end;
+	struct zip_extra_data_central e;
+	off_t offset_start, offset_end;
+	int entries;
+	int ret;
+
+	zip = a->format_data;
+	l = zip->central_directory;
+
+	/*
+	 * Formatting central directory file header fields that are fixed for all entries.
+	 * Fields not used (and therefor 0) are:
+	 *
+	 *   - comment_length
+	 *   - disk_number
+	 *   - attributes_internal
+	 */
+	memset(&h, 0, sizeof(h));
+	archive_le32enc(&h.signature, ZIP_SIGNATURE_FILE_HEADER);
+	archive_le16enc(&h.version_by, ZIP_VERSION_BY);
+	archive_le16enc(&h.version_extract, ZIP_VERSION_EXTRACT);
+	archive_le16enc(&h.flags, ZIP_FLAGS);
+
+	entries = 0;
+	offset_start = zip->written_bytes;
+
+	/* Formatting individual header fields per entry and
+	 * writing each entry. */
+	while (l != NULL) {
+		archive_le16enc(&h.compression, l->compression);
+		archive_le32enc(&h.timedate, dos_time(archive_entry_mtime(l->entry)));
+		archive_le32enc(&h.crc32, l->crc32);
+		archive_le32enc(&h.compressed_size, l->compressed_size);
+		archive_le32enc(&h.uncompressed_size, archive_entry_size(l->entry));
+		archive_le16enc(&h.filename_length, (uint16_t)path_length(l->entry));
+		archive_le16enc(&h.extra_length, sizeof(e));
+		archive_le16enc(&h.attributes_external[2], archive_entry_mode(l->entry));
+		archive_le32enc(&h.offset, l->offset);
+
+		/* Formatting extra data. */
+		archive_le16enc(&e.time_id, ZIP_SIGNATURE_EXTRA_TIMESTAMP);
+		archive_le16enc(&e.time_size, sizeof(e.mtime) + sizeof(e.time_flag));
+		e.time_flag[0] = 0x07;
+		archive_le32enc(&e.mtime, archive_entry_mtime(l->entry));
+		archive_le16enc(&e.unix_id, ZIP_SIGNATURE_EXTRA_UNIX);
+		archive_le16enc(&e.unix_size, 0x0000);
+
+		ret = (a->compressor.write)(a, &h, sizeof(h));
+		if (ret != ARCHIVE_OK)
+			return (ARCHIVE_FATAL);
+		zip->written_bytes += sizeof(h);
+
+		ret = write_path(l->entry, a);
+		if (ret <= ARCHIVE_OK)
+			return (ARCHIVE_FATAL);
+		zip->written_bytes += ret;
+
+		ret = (a->compressor.write)(a, &e, sizeof(e));
+		if (ret != ARCHIVE_OK)
+			return (ARCHIVE_FATAL);
+		zip->written_bytes += sizeof(e);
+
+		l = l->next;
+		entries++;
+	}
+	offset_end = zip->written_bytes;
+
+	/* Formatting end of central directory. */
+	memset(&end, 0, sizeof(end));
+	archive_le32enc(&end.signature, ZIP_SIGNATURE_CENTRAL_DIRECTORY_END);
+	archive_le16enc(&end.entries_disk, entries);
+	archive_le16enc(&end.entries, entries);
+	archive_le32enc(&end.size, offset_end - offset_start);
+	archive_le32enc(&end.offset, offset_start);
+
+	/* Writing end of central directory. */
+	ret = (a->compressor.write)(a, &end, sizeof(end));
+	if (ret != ARCHIVE_OK)
+		return (ARCHIVE_FATAL);
+	zip->written_bytes += sizeof(end);
+	return (ARCHIVE_OK);
+}
+
+static int
+archive_write_zip_destroy(struct archive_write *a)
+{
+	struct zip *zip;
+	struct zip_file_header_link *l;
+
+	zip = a->format_data;
+	while (zip->central_directory != NULL) {
+	   l = zip->central_directory;
+	   zip->central_directory = l->next;
+	   archive_entry_free(l->entry);
+	   free(l);
+	}
+#ifdef HAVE_ZLIB_H
+	free(zip->buf);
+#endif
+	free(zip);
+	a->format_data = NULL;
+	return (ARCHIVE_OK);
+}
+
+/* Convert into MSDOS-style date/time. */
+static unsigned int
+dos_time(const time_t unix_time)
+{
+	struct tm *t;
+	unsigned int dt;
+
+	/* This will not preserve time when creating/extracting the archive
+	 * on two systems with different time zones. */
+	t = localtime(&unix_time);
+
+	dt = 0;
+	dt += ((t->tm_year - 80) & 0x7f) << 9;
+	dt += ((t->tm_mon + 1) & 0x0f) << 5;
+	dt += (t->tm_mday & 0x1f);
+	dt <<= 16;
+	dt += (t->tm_hour & 0x1f) << 11;
+	dt += (t->tm_min & 0x3f) << 5;
+	dt += (t->tm_sec & 0x3e) >> 1; /* Only counting every 2 seconds. */
+	return dt;
+}
+
+static size_t
+path_length(struct archive_entry *entry)
+{
+	mode_t type;
+	const char *path;
+
+	type = archive_entry_filetype(entry);
+	path = archive_entry_pathname(entry);
+
+	if ((type == AE_IFDIR) & (path[strlen(path) - 1] != '/')) {
+		return strlen(path) + 1;
+	} else {
+		return strlen(path);
+	}
+}
+
+static int
+write_path(struct archive_entry *entry, struct archive_write *archive)
+{
+	int ret;
+	const char *path;
+	mode_t type;
+	size_t written_bytes;
+
+	path = archive_entry_pathname(entry);
+	type = archive_entry_filetype(entry);
+	written_bytes = 0;
+
+	ret = (archive->compressor.write)(archive, path, strlen(path));
+	if (ret != ARCHIVE_OK)
+		return (ARCHIVE_FATAL);
+	written_bytes += strlen(path);
+
+	/* Folders are recognized by a traling slash. */
+	if ((type == AE_IFDIR) & (path[strlen(path) - 1] != '/')) {
+		ret = (archive->compressor.write)(archive, "/", 1);
+		if (ret != ARCHIVE_OK)
+			return (ARCHIVE_FATAL);
+		written_bytes += 1;
+	}
+
+	return ((int)written_bytes);
+}