libarchive/test/test_write_format_zip_file.c - third_party/libarchive - Git at Google

 /*-
  * Copyright (c) 2003-2008 Tim Kientzle
  * Copyright (c) 2008 Anselm Strauss
  * 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.
  */

 #include "test.h"
 __FBSDID("$FreeBSD: head/lib/libarchive/test/test_write_format_zip.c 201247 2009-12-30 05:59:21Z kientzle $");

 /*
  * Detailed byte-for-byte verification of the format of a zip archive
  * with a single file written to it.
  */

 static unsigned long
 bitcrc32(unsigned long c, void *_p, size_t s)
 {
 	/* This is a drop-in replacement for crc32() from zlib.
 	 * Libarchive should be able to correctly generate
 	 * uncompressed zip archives (including correct CRCs) even
 	 * when zlib is unavailable, and this function helps us verify
 	 * that.  Yes, this is very, very slow and unsuitable for
 	 * production use, but it's correct, compact, and works well
 	 * enough for this particular usage.  Libarchive internally
 	 * uses a much more efficient implementation.  */
 	const unsigned char *p = _p;
 	int bitctr;

 	if (p == NULL)
 		return (0);

 	for (; s > 0; --s) {
 		c ^= *p++;
 		for (bitctr = 8; bitctr > 0; --bitctr) {
 			if (c & 1) c = (c >> 1);
 			else	   c = (c >> 1) ^ 0xedb88320;
 			c ^= 0x80000000;
 		}
 	}
 	return (c);
 }

 /* Quick and dirty: Read 2-byte and 4-byte integers from Zip file. */
 static unsigned i2(const unsigned char *p) { return ((p[0] & 0xff) | ((p[1] & 0xff) << 8)); }
 static unsigned i4(const unsigned char *p) { return (i2(p) | (i2(p + 2) << 16)); }

 DEFINE_TEST(test_write_format_zip_file)
 {
 	struct archive *a;
 	struct archive_entry *ae;
 	time_t t = 1234567890;
 	struct tm *tm = localtime(&t);
 	size_t used, buffsize = 1000000;
 	unsigned long crc;
 	int file_perm = 00644;
 	int zip_version = 20;
 	int zip_compression = 8;
 	short file_uid = 10, file_gid = 20;
 	unsigned char *buff, *buffend, *p;
 	unsigned char *central_header, *local_header, *eocd, *eocd_record;
 	unsigned char *extension_start, *extension_end;
 	char file_data[] = {'1', '2', '3', '4', '5', '6', '7', '8'};
 	char *file_name = "file";

 #ifndef HAVE_ZLIB_H
 	zip_version = 10;
 	zip_compression = 0;
 #endif

 	buff = malloc(buffsize);

 	/* Create a new archive in memory. */
 	assert((a = archive_write_new()) != NULL);
 	assertEqualIntA(a, ARCHIVE_OK, archive_write_set_format_zip(a));
 	assertEqualIntA(a, ARCHIVE_OK,
 	    archive_write_set_options(a, "zip:experimental"));
 	assertEqualIntA(a, ARCHIVE_OK,
 	    archive_write_open_memory(a, buff, buffsize, &used));

 	assert((ae = archive_entry_new()) != NULL);
 	archive_entry_copy_pathname(ae, file_name);
 	archive_entry_set_mode(ae, AE_IFREG | file_perm);
 	archive_entry_set_size(ae, sizeof(file_data));
 	archive_entry_set_uid(ae, file_uid);
 	archive_entry_set_gid(ae, file_gid);
 	archive_entry_set_mtime(ae, t, 0);
 	assertEqualInt(0, archive_write_header(a, ae));
 	archive_entry_free(ae);
 	assertEqualInt(8, archive_write_data(a, file_data, sizeof(file_data)));
 	assertEqualIntA(a, ARCHIVE_OK, archive_write_close(a));
 	assertEqualInt(ARCHIVE_OK, archive_write_free(a));
 	buffend = buff + used;
 	dumpfile("constructed.zip", buff, used);

 	/* Verify "End of Central Directory" record. */
 	/* Get address of end-of-central-directory record. */
 	eocd_record = p = buffend - 22; /* Assumes there is no zip comment field. */
 	failure("End-of-central-directory begins with PK\\005\\006 signature");
 	assertEqualMem(p, "PK\005\006", 4);
 	failure("This must be disk 0");
 	assertEqualInt(i2(p + 4), 0);
 	failure("Central dir must start on disk 0");
 	assertEqualInt(i2(p + 6), 0);
 	failure("All central dir entries are on this disk");
 	assertEqualInt(i2(p + 8), i2(p + 10));
 	eocd = buff + i4(p + 12) + i4(p + 16);
 	failure("no zip comment");
 	assertEqualInt(i2(p + 20), 0);

 	/* Get address of first entry in central directory. */
 	central_header = p = buff + i4(buffend - 6);
 	failure("Central file record at offset %d should begin with"
 	    " PK\\001\\002 signature",
 	    i4(buffend - 10));

 	/* Verify file entry in central directory. */
 	assertEqualMem(p, "PK\001\002", 4); /* Signature */
 	assertEqualInt(i2(p + 4), 3 * 256 + zip_version); /* Version made by */
 	assertEqualInt(i2(p + 6), zip_version); /* Version needed to extract */
 	assertEqualInt(i2(p + 8), 8); /* Flags */
 	assertEqualInt(i2(p + 10), zip_compression); /* Compression method */
 	assertEqualInt(i2(p + 12), (tm->tm_hour * 2048) + (tm->tm_min * 32) + (tm->tm_sec / 2)); /* File time */
 	assertEqualInt(i2(p + 14), ((tm->tm_year - 80) * 512) + ((tm->tm_mon + 1) * 32) + tm->tm_mday); /* File date */
 	crc = bitcrc32(0, file_data, sizeof(file_data));
 	assertEqualInt(i4(p + 16), crc); /* CRC-32 */
 	/* assertEqualInt(i4(p + 20), sizeof(file_data)); */ /* Compressed size */
 	assertEqualInt(i4(p + 24), sizeof(file_data)); /* Uncompressed size */
 	assertEqualInt(i2(p + 28), strlen(file_name)); /* Pathname length */
 	/* assertEqualInt(i2(p + 30), 28); */ /* Extra field length: See below */
 	assertEqualInt(i2(p + 32), 0); /* File comment length */
 	assertEqualInt(i2(p + 34), 0); /* Disk number start */
 	assertEqualInt(i2(p + 36), 0); /* Internal file attrs */
 	assertEqualInt(i4(p + 38) >> 16 & 01777, file_perm); /* External file attrs */
 	assertEqualInt(i4(p + 42), 0); /* Offset of local header */
 	assertEqualMem(p + 46, file_name, strlen(file_name)); /* Pathname */
 	p = extension_start = central_header + 46 + strlen(file_name);
 	extension_end = extension_start + i2(central_header + 30);

 	assertEqualInt(i2(p), 0x5455);  /* 'UT' extension header */
 	assertEqualInt(i2(p + 2), 5); /* 'UT' size */
 	assertEqualInt(p[4], 1); /* 'UT' flags */
 	assertEqualInt(i4(p + 5), t); /* 'UT' mtime */
 	p += 4 + i2(p + 2);

 	assertEqualInt(i2(p), 0x7875);  /* 'ux' extension header */
 	assertEqualInt(i2(p + 2), 11); /* 'ux' size */
 	/* TODO: verify 'ux' contents */
 	p += 4 + i2(p + 2);

 	/* Just in case: Report any extra extensions. */
 	while (p < extension_end) {
 		failure("Unexpected extension 0x%04X", i2(p));
 		assert(0);
 		p += 4 + i2(p + 2);
 	}

 	/* Should have run exactly to end of extra data. */
 	assert(p == extension_end);

 	assert(p == eocd);

 	/* Regular EOCD immediately follows central directory. */
 	assert(p == eocd_record);

 	/* Verify local header of file entry. */
 	p = local_header = buff;
 	assertEqualMem(p, "PK\003\004", 4); /* Signature */
 	assertEqualInt(i2(p + 4), zip_version); /* Version needed to extract */
 	assertEqualInt(i2(p + 6), 8); /* Flags */
 	assertEqualInt(i2(p + 8), zip_compression); /* Compression method */
 	assertEqualInt(i2(p + 10), (tm->tm_hour * 2048) + (tm->tm_min * 32) + (tm->tm_sec / 2)); /* File time */
 	assertEqualInt(i2(p + 12), ((tm->tm_year - 80) * 512) + ((tm->tm_mon + 1) * 32) + tm->tm_mday); /* File date */
 	assertEqualInt(i4(p + 14), 0); /* CRC-32 */
 	/* assertEqualInt(i4(p + 18), sizeof(file_data)); */ /* Compressed size */
 	/* assertEqualInt(i4(p + 22), sizeof(file_data)); */ /* Uncompressed size not stored because we're using length-at-end. */
 	assertEqualInt(i2(p + 26), strlen(file_name)); /* Pathname length */
 	assertEqualInt(i2(p + 28), 37); /* Extra field length */
 	assertEqualMem(p + 30, file_name, strlen(file_name)); /* Pathname */
 	p = extension_start = local_header + 30 + strlen(file_name);
 	extension_end = extension_start + i2(local_header + 28);

 	assertEqualInt(i2(p), 0x5455);  /* 'UT' extension header */
 	assertEqualInt(i2(p + 2), 5); /* size */
 	assertEqualInt(p[4], 1); /* 'UT' flags */
 	assertEqualInt(i4(p + 5), t); /* 'UT' mtime */
 	p += 4 + i2(p + 2);

 	assertEqualInt(i2(p), 0x7875);  /* 'ux' extension header */
 	assertEqualInt(i2(p + 2), 11); /* size */
 	assertEqualInt(p[4], 1); /* 'ux' version */
 	assertEqualInt(p[5], 4); /* 'ux' uid size */
 	assertEqualInt(i4(p + 6), file_uid); /* 'Ux' UID */
 	assertEqualInt(p[10], 4); /* 'ux' gid size */
 	assertEqualInt(i4(p + 11), file_gid); /* 'Ux' GID */
 	p += 4 + i2(p + 2);

 	assertEqualInt(i2(p), 0x6c78); /* 'xl' experimental extension block */
 	assertEqualInt(i2(p + 2), 9); /* size */
 	assertEqualInt(p[4], 7); /* bitmap of fields in this block */
 	assertEqualInt(i2(p + 5) >> 8, 3); /* System & version made by */
 	assertEqualInt(i2(p + 7), 0); /* internal file attributes */
 	assertEqualInt(i4(p + 9) >> 16 & 01777, file_perm); /* external file attributes */
 	p += 4 + i2(p + 2);

 	/* Just in case: Report any extra extensions. */
 	while (p < extension_end) {
 		failure("Unexpected extension 0x%04X", i2(p));
 		assert(0);
 		p += 4 + i2(p + 2);
 	}

 	/* Should have run exactly to end of extra data. */
 	assert(p == extension_end);

 	/* Data descriptor should follow compressed data. */
 	while (p < central_header && memcmp(p, "PK\007\010", 4) != 0)
 		++p;
 	assertEqualMem(p, "PK\007\010", 4);
 	assertEqualInt(i4(p + 4), crc); /* CRC-32 */
 	/* assertEqualInt(i4(p + 8), ???); */ /* compressed size */
 	assertEqualInt(i4(p + 12), sizeof(file_data)); /* uncompressed size */

 	/* Central directory should immediately follow the only entry. */
 	assert(p + 16 == central_header);

 	free(buff);
 }
	/*-
	* Copyright (c) 2003-2008 Tim Kientzle
	* Copyright (c) 2008 Anselm Strauss
	* 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.
	*/

	#include "test.h"
	__FBSDID("$FreeBSD: head/lib/libarchive/test/test_write_format_zip.c 201247 2009-12-30 05:59:21Z kientzle $");

	/*
	* Detailed byte-for-byte verification of the format of a zip archive
	* with a single file written to it.
	*/

	static unsigned long
	bitcrc32(unsigned long c, void *_p, size_t s)
	{
	/* This is a drop-in replacement for crc32() from zlib.
	* Libarchive should be able to correctly generate
	* uncompressed zip archives (including correct CRCs) even
	* when zlib is unavailable, and this function helps us verify
	* that. Yes, this is very, very slow and unsuitable for
	* production use, but it's correct, compact, and works well
	* enough for this particular usage. Libarchive internally
	* uses a much more efficient implementation. */
	const unsigned char *p = _p;
	int bitctr;

	if (p == NULL)
	return (0);

	for (; s > 0; --s) {
	c ^= *p++;
	for (bitctr = 8; bitctr > 0; --bitctr) {
	if (c & 1) c = (c >> 1);
	else c = (c >> 1) ^ 0xedb88320;
	c ^= 0x80000000;
	}
	}
	return (c);
	}

	/* Quick and dirty: Read 2-byte and 4-byte integers from Zip file. */
	static unsigned i2(const unsigned char *p) { return ((p[0] & 0xff) \| ((p[1] & 0xff) << 8)); }
	static unsigned i4(const unsigned char *p) { return (i2(p) \| (i2(p + 2) << 16)); }

	DEFINE_TEST(test_write_format_zip_file)
	{
	struct archive *a;
	struct archive_entry *ae;
	time_t t = 1234567890;
	struct tm *tm = localtime(&t);
	size_t used, buffsize = 1000000;
	unsigned long crc;
	int file_perm = 00644;
	int zip_version = 20;
	int zip_compression = 8;
	short file_uid = 10, file_gid = 20;
	unsigned char buff, buffend, *p;
	unsigned char central_header, local_header, eocd, eocd_record;
	unsigned char extension_start, extension_end;
	char file_data[] = {'1', '2', '3', '4', '5', '6', '7', '8'};
	char *file_name = "file";

	#ifndef HAVE_ZLIB_H
	zip_version = 10;
	zip_compression = 0;
	#endif

	buff = malloc(buffsize);

	/* Create a new archive in memory. */
	assert((a = archive_write_new()) != NULL);
	assertEqualIntA(a, ARCHIVE_OK, archive_write_set_format_zip(a));
	assertEqualIntA(a, ARCHIVE_OK,
	archive_write_set_options(a, "zip:experimental"));
	assertEqualIntA(a, ARCHIVE_OK,
	archive_write_open_memory(a, buff, buffsize, &used));

	assert((ae = archive_entry_new()) != NULL);
	archive_entry_copy_pathname(ae, file_name);
	archive_entry_set_mode(ae, AE_IFREG \| file_perm);
	archive_entry_set_size(ae, sizeof(file_data));
	archive_entry_set_uid(ae, file_uid);
	archive_entry_set_gid(ae, file_gid);
	archive_entry_set_mtime(ae, t, 0);
	assertEqualInt(0, archive_write_header(a, ae));
	archive_entry_free(ae);
	assertEqualInt(8, archive_write_data(a, file_data, sizeof(file_data)));
	assertEqualIntA(a, ARCHIVE_OK, archive_write_close(a));
	assertEqualInt(ARCHIVE_OK, archive_write_free(a));
	buffend = buff + used;
	dumpfile("constructed.zip", buff, used);

	/* Verify "End of Central Directory" record. */
	/* Get address of end-of-central-directory record. */
	eocd_record = p = buffend - 22; /* Assumes there is no zip comment field. */
	failure("End-of-central-directory begins with PK\\005\\006 signature");
	assertEqualMem(p, "PK\005\006", 4);
	failure("This must be disk 0");
	assertEqualInt(i2(p + 4), 0);
	failure("Central dir must start on disk 0");
	assertEqualInt(i2(p + 6), 0);
	failure("All central dir entries are on this disk");
	assertEqualInt(i2(p + 8), i2(p + 10));
	eocd = buff + i4(p + 12) + i4(p + 16);
	failure("no zip comment");
	assertEqualInt(i2(p + 20), 0);

	/* Get address of first entry in central directory. */
	central_header = p = buff + i4(buffend - 6);
	failure("Central file record at offset %d should begin with"
	" PK\\001\\002 signature",
	i4(buffend - 10));

	/* Verify file entry in central directory. */
	assertEqualMem(p, "PK\001\002", 4); /* Signature */
	assertEqualInt(i2(p + 4), 3 * 256 + zip_version); /* Version made by */
	assertEqualInt(i2(p + 6), zip_version); /* Version needed to extract */
	assertEqualInt(i2(p + 8), 8); /* Flags */
	assertEqualInt(i2(p + 10), zip_compression); /* Compression method */
	assertEqualInt(i2(p + 12), (tm->tm_hour * 2048) + (tm->tm_min * 32) + (tm->tm_sec / 2)); /* File time */
	assertEqualInt(i2(p + 14), ((tm->tm_year - 80) * 512) + ((tm->tm_mon + 1) * 32) + tm->tm_mday); /* File date */
	crc = bitcrc32(0, file_data, sizeof(file_data));
	assertEqualInt(i4(p + 16), crc); /* CRC-32 */
	/* assertEqualInt(i4(p + 20), sizeof(file_data)); / / Compressed size */
	assertEqualInt(i4(p + 24), sizeof(file_data)); /* Uncompressed size */
	assertEqualInt(i2(p + 28), strlen(file_name)); /* Pathname length */
	/* assertEqualInt(i2(p + 30), 28); / / Extra field length: See below */
	assertEqualInt(i2(p + 32), 0); /* File comment length */
	assertEqualInt(i2(p + 34), 0); /* Disk number start */
	assertEqualInt(i2(p + 36), 0); /* Internal file attrs */
	assertEqualInt(i4(p + 38) >> 16 & 01777, file_perm); /* External file attrs */
	assertEqualInt(i4(p + 42), 0); /* Offset of local header */
	assertEqualMem(p + 46, file_name, strlen(file_name)); /* Pathname */
	p = extension_start = central_header + 46 + strlen(file_name);
	extension_end = extension_start + i2(central_header + 30);

	assertEqualInt(i2(p), 0x5455); /* 'UT' extension header */
	assertEqualInt(i2(p + 2), 5); /* 'UT' size */
	assertEqualInt(p[4], 1); /* 'UT' flags */
	assertEqualInt(i4(p + 5), t); /* 'UT' mtime */
	p += 4 + i2(p + 2);

	assertEqualInt(i2(p), 0x7875); /* 'ux' extension header */
	assertEqualInt(i2(p + 2), 11); /* 'ux' size */
	/* TODO: verify 'ux' contents */
	p += 4 + i2(p + 2);

	/* Just in case: Report any extra extensions. */
	while (p < extension_end) {
	failure("Unexpected extension 0x%04X", i2(p));
	assert(0);
	p += 4 + i2(p + 2);
	}

	/* Should have run exactly to end of extra data. */
	assert(p == extension_end);

	assert(p == eocd);

	/* Regular EOCD immediately follows central directory. */
	assert(p == eocd_record);

	/* Verify local header of file entry. */
	p = local_header = buff;
	assertEqualMem(p, "PK\003\004", 4); /* Signature */
	assertEqualInt(i2(p + 4), zip_version); /* Version needed to extract */
	assertEqualInt(i2(p + 6), 8); /* Flags */
	assertEqualInt(i2(p + 8), zip_compression); /* Compression method */
	assertEqualInt(i2(p + 10), (tm->tm_hour * 2048) + (tm->tm_min * 32) + (tm->tm_sec / 2)); /* File time */
	assertEqualInt(i2(p + 12), ((tm->tm_year - 80) * 512) + ((tm->tm_mon + 1) * 32) + tm->tm_mday); /* File date */
	assertEqualInt(i4(p + 14), 0); /* CRC-32 */
	/* assertEqualInt(i4(p + 18), sizeof(file_data)); / / Compressed size */
	/* assertEqualInt(i4(p + 22), sizeof(file_data)); / / Uncompressed size not stored because we're using length-at-end. */
	assertEqualInt(i2(p + 26), strlen(file_name)); /* Pathname length */
	assertEqualInt(i2(p + 28), 37); /* Extra field length */
	assertEqualMem(p + 30, file_name, strlen(file_name)); /* Pathname */
	p = extension_start = local_header + 30 + strlen(file_name);
	extension_end = extension_start + i2(local_header + 28);

	assertEqualInt(i2(p), 0x5455); /* 'UT' extension header */
	assertEqualInt(i2(p + 2), 5); /* size */
	assertEqualInt(p[4], 1); /* 'UT' flags */
	assertEqualInt(i4(p + 5), t); /* 'UT' mtime */
	p += 4 + i2(p + 2);

	assertEqualInt(i2(p), 0x7875); /* 'ux' extension header */
	assertEqualInt(i2(p + 2), 11); /* size */
	assertEqualInt(p[4], 1); /* 'ux' version */
	assertEqualInt(p[5], 4); /* 'ux' uid size */
	assertEqualInt(i4(p + 6), file_uid); /* 'Ux' UID */
	assertEqualInt(p[10], 4); /* 'ux' gid size */
	assertEqualInt(i4(p + 11), file_gid); /* 'Ux' GID */
	p += 4 + i2(p + 2);

	assertEqualInt(i2(p), 0x6c78); /* 'xl' experimental extension block */
	assertEqualInt(i2(p + 2), 9); /* size */
	assertEqualInt(p[4], 7); /* bitmap of fields in this block */
	assertEqualInt(i2(p + 5) >> 8, 3); /* System & version made by */
	assertEqualInt(i2(p + 7), 0); /* internal file attributes */
	assertEqualInt(i4(p + 9) >> 16 & 01777, file_perm); /* external file attributes */
	p += 4 + i2(p + 2);

	/* Just in case: Report any extra extensions. */
	while (p < extension_end) {
	failure("Unexpected extension 0x%04X", i2(p));
	assert(0);
	p += 4 + i2(p + 2);
	}

	/* Should have run exactly to end of extra data. */
	assert(p == extension_end);

	/* Data descriptor should follow compressed data. */
	while (p < central_header && memcmp(p, "PK\007\010", 4) != 0)
	++p;
	assertEqualMem(p, "PK\007\010", 4);
	assertEqualInt(i4(p + 4), crc); /* CRC-32 */
	/* assertEqualInt(i4(p + 8), ???); / / compressed size */
	assertEqualInt(i4(p + 12), sizeof(file_data)); /* uncompressed size */

	/* Central directory should immediately follow the only entry. */
	assert(p + 16 == central_header);

	free(buff);
	}