/*-

 * Copyright (c) 2010 Nokia Corporation and/or its subsidiary(-ies).

 * Author: Jonas Gastal <jgastal@profusion.mobi>

 * Copyright (c) 2011-2012 Michihiro NAKAJIMA

 *

 * 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.

 */

#include "archive_platform.h"

__FBSDID("$FreeBSD: head/lib/libarchive/archive_write_set_format_gnu_tar.c 191579 2009-04-27 18:35:03Z gastal $");

#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

#include "archive.h"

#include "archive_entry.h"

#include "archive_entry_locale.h"

#include "archive_private.h"

#include "archive_write_private.h"

struct gnutar {

	uint64_t	entry_bytes_remaining;

	uint64_t	entry_padding;

	const char *	linkname;

	size_t		linkname_length;

	const char *	pathname;

	size_t		pathname_length;

	const char *	uname;

	size_t		uname_length;

	const char *	gname;

	size_t		gname_length;

	struct archive_string_conv *opt_sconv;

	struct archive_string_conv *sconv_default;

	int init_default_conversion;

};

/*

 * Define structure of GNU tar header.

 */

#define	GNUTAR_name_offset 0

#define	GNUTAR_name_size 100

#define	GNUTAR_mode_offset 100

#define	GNUTAR_mode_size 7

#define	GNUTAR_mode_max_size 8

#define	GNUTAR_uid_offset 108

#define	GNUTAR_uid_size 7

#define	GNUTAR_uid_max_size 8

#define	GNUTAR_gid_offset 116

#define	GNUTAR_gid_size 7

#define	GNUTAR_gid_max_size 8

#define	GNUTAR_size_offset 124

#define	GNUTAR_size_size 11

#define	GNUTAR_size_max_size 12

#define	GNUTAR_mtime_offset 136

#define	GNUTAR_mtime_size 11

#define	GNUTAR_mtime_max_size 11

#define	GNUTAR_checksum_offset 148

#define	GNUTAR_checksum_size 8

#define	GNUTAR_typeflag_offset 156

#define	GNUTAR_typeflag_size 1

#define	GNUTAR_linkname_offset 157

#define	GNUTAR_linkname_size 100

#define	GNUTAR_magic_offset 257

#define	GNUTAR_magic_size 6

#define	GNUTAR_version_offset 263

#define	GNUTAR_version_size 2

#define	GNUTAR_uname_offset 265

#define	GNUTAR_uname_size 32

#define	GNUTAR_gname_offset 297

#define	GNUTAR_gname_size 32

#define	GNUTAR_rdevmajor_offset 329

#define	GNUTAR_rdevmajor_size 6

#define	GNUTAR_rdevmajor_max_size 8

#define	GNUTAR_rdevminor_offset 337

#define	GNUTAR_rdevminor_size 6

#define	GNUTAR_rdevminor_max_size 8

/*

 * A filled-in copy of the header for initialization.

 */

static const char template_header[] = {

	/* name: 100 bytes */

	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,

	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,

	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,

	0,0,0,0,

	/* Mode, null termination: 8 bytes */

	'0','0','0','0','0','0', '0','\0',

	/* uid, null termination: 8 bytes */

	'0','0','0','0','0','0', '0','\0',

	/* gid, null termination: 8 bytes */

	'0','0','0','0','0','0', '0','\0',

	/* size, space termination: 12 bytes */

	'0','0','0','0','0','0','0','0','0','0','0', '\0',

	/* mtime, space termination: 12 bytes */

	'0','0','0','0','0','0','0','0','0','0','0', '\0',

	/* Initial checksum value: 8 spaces */

	' ',' ',' ',' ',' ',' ',' ',' ',

	/* Typeflag: 1 byte */

	'0',			/* '0' = regular file */

	/* Linkname: 100 bytes */

	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,

	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,

	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,

	0,0,0,0,

	/* Magic: 8 bytes */

	'u','s','t','a','r',' ', ' ','\0',

	/* Uname: 32 bytes */

	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,

	/* Gname: 32 bytes */

	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,

	/* rdevmajor + null padding: 8 bytes */

	'\0','\0','\0','\0','\0','\0', '\0','\0',

	/* rdevminor + null padding: 8 bytes */

	'\0','\0','\0','\0','\0','\0', '\0','\0',

	/* Padding: 167 bytes */

	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,

	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,

	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,

	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,

	0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,

	0,0,0,0,0,0,0

};

static int      archive_write_gnutar_options(struct archive_write *,

		    const char *, const char *);

static int	archive_format_gnutar_header(struct archive_write *, char h[512],

		    struct archive_entry *, int tartype);

static int      archive_write_gnutar_header(struct archive_write *,

		    struct archive_entry *entry);

static ssize_t	archive_write_gnutar_data(struct archive_write *a, const void *buff,

		    size_t s);

static int	archive_write_gnutar_free(struct archive_write *);

static int	archive_write_gnutar_close(struct archive_write *);

static int	archive_write_gnutar_finish_entry(struct archive_write *);

static int	format_256(int64_t, char *, int);

static int	format_number(int64_t, char *, int size, int maxsize);

static int	format_octal(int64_t, char *, int);

/*

 * Set output format to 'GNU tar' format.

 */

int

archive_write_set_format_gnutar(struct archive *_a)

{

	struct archive_write *a = (struct archive_write *)_a;

	struct gnutar *gnutar;

	gnutar = (struct gnutar *)calloc(1, sizeof(*gnutar));

	if (gnutar == NULL) {

		archive_set_error(&a->archive, ENOMEM,

		    "Can't allocate gnutar data");

		return (ARCHIVE_FATAL);

	}

	a->format_data = gnutar;

	a->format_name = "gnutar";

	a->format_options = archive_write_gnutar_options;

	a->format_write_header = archive_write_gnutar_header;

	a->format_write_data = archive_write_gnutar_data;

	a->format_close = archive_write_gnutar_close;

	a->format_free = archive_write_gnutar_free;

	a->format_finish_entry = archive_write_gnutar_finish_entry;

	a->archive.archive_format = ARCHIVE_FORMAT_TAR_GNUTAR;

	a->archive.archive_format_name = "GNU tar";

	return (ARCHIVE_OK);

}

static int

archive_write_gnutar_options(struct archive_write *a, const char *key,

    const char *val)

{

	struct gnutar *gnutar = (struct gnutar *)a->format_data;

	int ret = ARCHIVE_FAILED;

	if (strcmp(key, "hdrcharset")  == 0) {

		if (val == NULL || val[0] == 0)

			archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,

			    "%s: hdrcharset option needs a character-set name",

			    a->format_name);

		else {

			gnutar->opt_sconv = archive_string_conversion_to_charset(

			    &a->archive, val, 0);

			if (gnutar->opt_sconv != NULL)

				ret = ARCHIVE_OK;

			else

				ret = ARCHIVE_FATAL;

		}

		return (ret);

	}

	/* Note: The "warn" return is just to inform the options

	 * supervisor that we didn't handle it.  It will generate

	 * a suitable error if no one used this option. */

	return (ARCHIVE_WARN);

}

static int

archive_write_gnutar_close(struct archive_write *a)

{

	return (__archive_write_nulls(a, 512*2));

}

static int

archive_write_gnutar_free(struct archive_write *a)

{

	struct gnutar *gnutar;

	gnutar = (struct gnutar *)a->format_data;

	free(gnutar);

	a->format_data = NULL;

	return (ARCHIVE_OK);

}

static int

archive_write_gnutar_finish_entry(struct archive_write *a)

{

	struct gnutar *gnutar;

	int ret;

	gnutar = (struct gnutar *)a->format_data;

	ret = __archive_write_nulls(a, (size_t)

	    (gnutar->entry_bytes_remaining + gnutar->entry_padding));

	gnutar->entry_bytes_remaining = gnutar->entry_padding = 0;

	return (ret);

}

static ssize_t

archive_write_gnutar_data(struct archive_write *a, const void *buff, size_t s)

{

	struct gnutar *gnutar;

	int ret;

	gnutar = (struct gnutar *)a->format_data;

	if (s > gnutar->entry_bytes_remaining)

		s = (size_t)gnutar->entry_bytes_remaining;

	ret = __archive_write_output(a, buff, s);

	gnutar->entry_bytes_remaining -= s;

	if (ret != ARCHIVE_OK)

		return (ret);

	return (s);

}

static int

archive_write_gnutar_header(struct archive_write *a,

     struct archive_entry *entry)

{

	char buff[512];

	int r, ret, ret2 = ARCHIVE_OK;

	int tartype;

	struct gnutar *gnutar;

	struct archive_string_conv *sconv;

	struct archive_entry *entry_main;

	gnutar = (struct gnutar *)a->format_data;

	/* Setup default string conversion. */

	if (gnutar->opt_sconv == NULL) {

		if (!gnutar->init_default_conversion) {

			gnutar->sconv_default =

			    archive_string_default_conversion_for_write(

				&(a->archive));

			gnutar->init_default_conversion = 1;

		}

		sconv = gnutar->sconv_default;

	} else

		sconv = gnutar->opt_sconv;

	/* Only regular files (not hardlinks) have data. */

	if (archive_entry_hardlink(entry) != NULL ||

	    archive_entry_symlink(entry) != NULL ||

	    !(archive_entry_filetype(entry) == AE_IFREG))

		archive_entry_set_size(entry, 0);

	if (AE_IFDIR == archive_entry_filetype(entry)) {

		const char *p;

		size_t path_length;

		/*

		 * Ensure a trailing '/'.  Modify the entry so

		 * the client sees the change.

		 */

#if defined(_WIN32) && !defined(__CYGWIN__)

		const wchar_t *wp;

		wp = archive_entry_pathname_w(entry);

		if (wp != NULL && wp[wcslen(wp) -1] != L'/') {

			struct archive_wstring ws;

			archive_string_init(&ws);

			path_length = wcslen(wp);

			if (archive_wstring_ensure(&ws,

			    path_length + 2) == NULL) {

				archive_set_error(&a->archive, ENOMEM,

				    "Can't allocate ustar data");

				archive_wstring_free(&ws);

				return(ARCHIVE_FATAL);

			}

			/* Should we keep '\' ? */

			if (wp[path_length -1] == L'\\')

				path_length--;

			archive_wstrncpy(&ws, wp, path_length);

			archive_wstrappend_wchar(&ws, L'/');

			archive_entry_copy_pathname_w(entry, ws.s);

			archive_wstring_free(&ws);

			p = NULL;

		} else

#endif

			p = archive_entry_pathname(entry);

		/*

		 * On Windows, this is a backup operation just in

		 * case getting WCS failed. On POSIX, this is a

		 * normal operation.

		 */

		if (p != NULL && p[strlen(p) - 1] != '/') {

			struct archive_string as;

			archive_string_init(&as);

			path_length = strlen(p);

			if (archive_string_ensure(&as,

			    path_length + 2) == NULL) {

				archive_set_error(&a->archive, ENOMEM,

				    "Can't allocate ustar data");

				archive_string_free(&as);

				return(ARCHIVE_FATAL);

			}

#if defined(_WIN32) && !defined(__CYGWIN__)

			/* NOTE: This might break the pathname

			 * if the current code page is CP932 and

			 * the pathname includes a character '\'

			 * as a part of its multibyte pathname. */

			if (p[strlen(p) -1] == '\\')

				path_length--;

			else

#endif

			archive_strncpy(&as, p, path_length);

			archive_strappend_char(&as, '/');

			archive_entry_copy_pathname(entry, as.s);

			archive_string_free(&as);

		}

	}

#if defined(_WIN32) && !defined(__CYGWIN__)

	/* Make sure the path separators in pathname, hardlink and symlink

	 * are all slash '/', not the Windows path separator '\'. */

	entry_main = __la_win_entry_in_posix_pathseparator(entry);

	if (entry_main == NULL) {

		archive_set_error(&a->archive, ENOMEM,

		    "Can't allocate ustar data");

		return(ARCHIVE_FATAL);

	}

	if (entry != entry_main)

		entry = entry_main;

	else

		entry_main = NULL;

#else

	entry_main = NULL;

#endif

	r = archive_entry_pathname_l(entry, &(gnutar->pathname),

	    &(gnutar->pathname_length), sconv);

	if (r != 0) {

		if (errno == ENOMEM) {

			archive_set_error(&a->archive, ENOMEM,

			    "Can't allocate memory for Pathame");

			ret = ARCHIVE_FATAL;

			goto exit_write_header;

		}

		archive_set_error(&a->archive, ARCHIVE_ERRNO_FILE_FORMAT,

		    "Can't translate pathname '%s' to %s",

		    archive_entry_pathname(entry),

		    archive_string_conversion_charset_name(sconv));

		ret2 = ARCHIVE_WARN;

	}

	r = archive_entry_uname_l(entry, &(gnutar->uname),

	    &(gnutar->uname_length), sconv);

	if (r != 0) {

		if (errno == ENOMEM) {

			archive_set_error(&a->archive, ENOMEM,

			    "Can't allocate memory for Uname");

			ret = ARCHIVE_FATAL;

			goto exit_write_header;

		}

		archive_set_error(&a->archive,

		    ARCHIVE_ERRNO_FILE_FORMAT,

		    "Can't translate uname '%s' to %s",

		    archive_entry_uname(entry),

		    archive_string_conversion_charset_name(sconv));

		ret2 = ARCHIVE_WARN;

	}

	r = archive_entry_gname_l(entry, &(gnutar->gname),

	    &(gnutar->gname_length), sconv);

	if (r != 0) {

		if (errno == ENOMEM) {

			archive_set_error(&a->archive, ENOMEM,

			    "Can't allocate memory for Gname");

			ret = ARCHIVE_FATAL;

			goto exit_write_header;

		}

		archive_set_error(&a->archive,

		    ARCHIVE_ERRNO_FILE_FORMAT,

		    "Can't translate gname '%s' to %s",

		    archive_entry_gname(entry),

		    archive_string_conversion_charset_name(sconv));

		ret2 = ARCHIVE_WARN;

	}

	/* If linkname is longer than 100 chars we need to add a 'K' header. */

	r = archive_entry_hardlink_l(entry, &(gnutar->linkname),

	    &(gnutar->linkname_length), sconv);

	if (r != 0) {

		if (errno == ENOMEM) {

			archive_set_error(&a->archive, ENOMEM,

			    "Can't allocate memory for Linkname");

			ret = ARCHIVE_FATAL;

			goto exit_write_header;

		}

		archive_set_error(&a->archive,

		    ARCHIVE_ERRNO_FILE_FORMAT,

		    "Can't translate linkname '%s' to %s",

		    archive_entry_hardlink(entry),

		    archive_string_conversion_charset_name(sconv));

		ret2 = ARCHIVE_WARN;

	}

	if (gnutar->linkname_length == 0) {

		r = archive_entry_symlink_l(entry, &(gnutar->linkname),

		    &(gnutar->linkname_length), sconv);

		if (r != 0) {

			if (errno == ENOMEM) {

				archive_set_error(&a->archive, ENOMEM,

				    "Can't allocate memory for Linkname");

				ret = ARCHIVE_FATAL;

				goto exit_write_header;

			}

			archive_set_error(&a->archive,

			    ARCHIVE_ERRNO_FILE_FORMAT,

			    "Can't translate linkname '%s' to %s",

			    archive_entry_hardlink(entry),

			    archive_string_conversion_charset_name(sconv));

			ret2 = ARCHIVE_WARN;

		}

	}

	if (gnutar->linkname_length > GNUTAR_linkname_size) {

		size_t length = gnutar->linkname_length + 1;

		struct archive_entry *temp = archive_entry_new2(&a->archive);

		/* Uname/gname here don't really matter since no one reads them;

		 * these are the values that GNU tar happens to use on FreeBSD. */

		archive_entry_set_uname(temp, "root");

		archive_entry_set_gname(temp, "wheel");

		archive_entry_set_pathname(temp, "././@LongLink");

		archive_entry_set_size(temp, length);

		ret = archive_format_gnutar_header(a, buff, temp, 'K');

		archive_entry_free(temp);

		if (ret < ARCHIVE_WARN)

			goto exit_write_header;

		ret = __archive_write_output(a, buff, 512);

		if (ret < ARCHIVE_WARN)

			goto exit_write_header;

		/* Write name and trailing null byte. */

		ret = __archive_write_output(a, gnutar->linkname, length);

		if (ret < ARCHIVE_WARN)

			goto exit_write_header;

		/* Pad to 512 bytes */

		ret = __archive_write_nulls(a, 0x1ff & (-(ssize_t)length));

		if (ret < ARCHIVE_WARN)

			goto exit_write_header;

	}

	/* If pathname is longer than 100 chars we need to add an 'L' header. */

	if (gnutar->pathname_length > GNUTAR_name_size) {

		const char *pathname = gnutar->pathname;

		size_t length = gnutar->pathname_length + 1;

		struct archive_entry *temp = archive_entry_new2(&a->archive);

		/* Uname/gname here don't really matter since no one reads them;

		 * these are the values that GNU tar happens to use on FreeBSD. */

		archive_entry_set_uname(temp, "root");

		archive_entry_set_gname(temp, "wheel");

		archive_entry_set_pathname(temp, "././@LongLink");

		archive_entry_set_size(temp, length);

		ret = archive_format_gnutar_header(a, buff, temp, 'L');

		archive_entry_free(temp);

		if (ret < ARCHIVE_WARN)

			goto exit_write_header;

		ret = __archive_write_output(a, buff, 512);

		if(ret < ARCHIVE_WARN)

			goto exit_write_header;

		/* Write pathname + trailing null byte. */

		ret = __archive_write_output(a, pathname, length);

		if(ret < ARCHIVE_WARN)

			goto exit_write_header;

		/* Pad to multiple of 512 bytes. */

		ret = __archive_write_nulls(a, 0x1ff & (-(ssize_t)length));

		if (ret < ARCHIVE_WARN)

			goto exit_write_header;

	}

	if (archive_entry_hardlink(entry) != NULL) {

		tartype = '1';

	} else

		switch (archive_entry_filetype(entry)) {

		case AE_IFREG: tartype = '0' ; break;

		case AE_IFLNK: tartype = '2' ; break;

		case AE_IFCHR: tartype = '3' ; break;

		case AE_IFBLK: tartype = '4' ; break;

		case AE_IFDIR: tartype = '5' ; break;

		case AE_IFIFO: tartype = '6' ; break;

		case AE_IFSOCK:

			archive_set_error(&a->archive,

			    ARCHIVE_ERRNO_FILE_FORMAT,

			    "tar format cannot archive socket");

			ret = ARCHIVE_FAILED;

			goto exit_write_header;

		default:

			archive_set_error(&a->archive,

			    ARCHIVE_ERRNO_FILE_FORMAT,

			    "tar format cannot archive this (mode=0%lo)",

			    (unsigned long)archive_entry_mode(entry));

			ret = ARCHIVE_FAILED;

			goto exit_write_header;

		}

	ret = archive_format_gnutar_header(a, buff, entry, tartype);

	if (ret < ARCHIVE_WARN)

		goto exit_write_header;

	if (ret2 < ret)

		ret = ret2;

	ret2 = __archive_write_output(a, buff, 512);

	if (ret2 < ARCHIVE_WARN) {

		ret = ret2;

		goto exit_write_header;

	}

	if (ret2 < ret)

		ret = ret2;

	gnutar->entry_bytes_remaining = archive_entry_size(entry);

	gnutar->entry_padding = 0x1ff & (-(int64_t)gnutar->entry_bytes_remaining);

exit_write_header:

	if (entry_main)

		archive_entry_free(entry_main);

	return (ret);

}

static int

archive_format_gnutar_header(struct archive_write *a, char h[512],

    struct archive_entry *entry, int tartype)

{

	unsigned int checksum;

	int i, ret;

	size_t copy_length;

	const char *p;

	struct gnutar *gnutar;

	gnutar = (struct gnutar *)a->format_data;

	ret = 0;

	/*

	 * The "template header" already includes the signature,

	 * various end-of-field markers, and other required elements.

	 */

	memcpy(h, &template_header, 512);

	/*

	 * Because the block is already null-filled, and strings

	 * are allowed to exactly fill their destination (without null),

	 * I use memcpy(dest, src, strlen()) here a lot to copy strings.

	 */

	if (tartype == 'K' || tartype == 'L') {

		p = archive_entry_pathname(entry);

		copy_length = strlen(p);

	} else {

		p = gnutar->pathname;

		copy_length = gnutar->pathname_length;

	}

	if (copy_length > GNUTAR_name_size)

		copy_length = GNUTAR_name_size;

	memcpy(h + GNUTAR_name_offset, p, copy_length);

	if ((copy_length = gnutar->linkname_length) > 0) {

		if (copy_length > GNUTAR_linkname_size)

			copy_length = GNUTAR_linkname_size;

		memcpy(h + GNUTAR_linkname_offset, gnutar->linkname,

		    copy_length);

	}

	/* TODO: How does GNU tar handle unames longer than GNUTAR_uname_size? */

	if (tartype == 'K' || tartype == 'L') {

		p = archive_entry_uname(entry);

		copy_length = strlen(p);

	} else {

		p = gnutar->uname;

		copy_length = gnutar->uname_length;

	}

	if (copy_length > 0) {

		if (copy_length > GNUTAR_uname_size)

			copy_length = GNUTAR_uname_size;

		memcpy(h + GNUTAR_uname_offset, p, copy_length);

	}

	/* TODO: How does GNU tar handle gnames longer than GNUTAR_gname_size? */

	if (tartype == 'K' || tartype == 'L') {

		p = archive_entry_gname(entry);

		copy_length = strlen(p);

	} else {

		p = gnutar->gname;

		copy_length = gnutar->gname_length;

	}

	if (copy_length > 0) {

		if (strlen(p) > GNUTAR_gname_size)

			copy_length = GNUTAR_gname_size;

		memcpy(h + GNUTAR_gname_offset, p, copy_length);

	}

	/* By truncating the mode here, we ensure it always fits. */

	format_octal(archive_entry_mode(entry) & 07777,

	    h + GNUTAR_mode_offset, GNUTAR_mode_size);

	/* GNU tar supports base-256 here, so should never overflow. */

	if (format_number(archive_entry_uid(entry), h + GNUTAR_uid_offset,

		GNUTAR_uid_size, GNUTAR_uid_max_size)) {

		archive_set_error(&a->archive, ERANGE,

		    "Numeric user ID %jd too large",

		    (intmax_t)archive_entry_uid(entry));

		ret = ARCHIVE_FAILED;

	}

	/* GNU tar supports base-256 here, so should never overflow. */

	if (format_number(archive_entry_gid(entry), h + GNUTAR_gid_offset,

		GNUTAR_gid_size, GNUTAR_gid_max_size)) {

		archive_set_error(&a->archive, ERANGE,

		    "Numeric group ID %jd too large",

		    (intmax_t)archive_entry_gid(entry));

		ret = ARCHIVE_FAILED;

	}

	/* GNU tar supports base-256 here, so should never overflow. */

	if (format_number(archive_entry_size(entry), h + GNUTAR_size_offset,

		GNUTAR_size_size, GNUTAR_size_max_size)) {

		archive_set_error(&a->archive, ERANGE,

		    "File size out of range");

		ret = ARCHIVE_FAILED;

	}

	/* Shouldn't overflow before 2106, since mtime field is 33 bits. */

	format_octal(archive_entry_mtime(entry),

	    h + GNUTAR_mtime_offset, GNUTAR_mtime_size);

	if (archive_entry_filetype(entry) == AE_IFBLK

	    || archive_entry_filetype(entry) == AE_IFCHR) {

		if (format_octal(archive_entry_rdevmajor(entry),

		    h + GNUTAR_rdevmajor_offset,

			GNUTAR_rdevmajor_size)) {

			archive_set_error(&a->archive, ERANGE,

			    "Major device number too large");

			ret = ARCHIVE_FAILED;

		}

		if (format_octal(archive_entry_rdevminor(entry),

		    h + GNUTAR_rdevminor_offset,

			GNUTAR_rdevminor_size)) {

			archive_set_error(&a->archive, ERANGE,

			    "Minor device number too large");

			ret = ARCHIVE_FAILED;

		}

	}

	h[GNUTAR_typeflag_offset] = tartype;

	checksum = 0;

	for (i = 0; i < 512; i++)

		checksum += 255 & (unsigned int)h[i];

	h[GNUTAR_checksum_offset + 6] = '\0'; /* Can't be pre-set in the template. */

	/* h[GNUTAR_checksum_offset + 7] = ' '; */ /* This is pre-set in the template. */

	format_octal(checksum, h + GNUTAR_checksum_offset, 6);

	return (ret);

}

/*

 * Format a number into a field, falling back to base-256 if necessary.

 */

static int

format_number(int64_t v, char *p, int s, int maxsize)

{

	int64_t limit = ((int64_t)1 << (s*3));

	if (v < limit)

		return (format_octal(v, p, s));

	return (format_256(v, p, maxsize));

}

/*

 * Format a number into the specified field using base-256.

 */

static int

format_256(int64_t v, char *p, int s)

{

	p += s;

	while (s-- > 0) {

		*--p = (char)(v & 0xff);

		v >>= 8;

	}

	*p |= 0x80; /* Set the base-256 marker bit. */

	return (0);

}

/*

 * Format a number into the specified field using octal.

 */

static int

format_octal(int64_t v, char *p, int s)

{

	int len = s;

	/* Octal values can't be negative, so use 0. */

	if (v < 0)

		v = 0;

	p += s;		/* Start at the end and work backwards. */

	while (s-- > 0) {

		*--p = (char)('0' + (v & 7));

		v >>= 3;

	}

	if (v == 0)

		return (0);

	/* If it overflowed, fill field with max value. */

	while (len-- > 0)

		*p++ = '7';

	return (-1);

}