write.c

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2003-2007 Tim Kientzle
 * Copyright (c) 2012 Michihiro NAKAJIMA
 * All rights reserved.
 */

#include "bsdtar_platform.h"

#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#if HAVE_SYS_XATTR_H
#include <sys/xattr.h>
#elif HAVE_ATTR_XATTR_H
#include <attr/xattr.h>
#endif
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#ifdef HAVE_GRP_H
#include <grp.h>
#endif
#ifdef HAVE_IO_H
#include <io.h>
#endif
#ifdef HAVE_LIBGEN_H
#include <libgen.h>
#endif
#ifdef HAVE_LIMITS_H
#include <limits.h>
#endif
#ifdef HAVE_PATHS_H
#include <paths.h>
#endif
#ifdef HAVE_PWD_H
#include <pwd.h>
#endif
#ifdef HAVE_STDINT_H
#include <stdint.h>
#endif
#include <stdio.h>
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include "bsdtar.h"
#include "err.h"
#include "line_reader.h"

#ifndef O_BINARY
#define	O_BINARY 0
#endif

struct archive_dir_entry {
	struct archive_dir_entry	*next;
	time_t			 mtime_sec;
	int			 mtime_nsec;
	char			*name;
};

struct archive_dir {
	struct archive_dir_entry *head, *tail;
};

static int		 append_archive(struct bsdtar *, struct archive *,
			     struct archive *ina);
static int		 append_archive_filename(struct bsdtar *,
			     struct archive *, const char *fname);
static void		 archive_names_from_file(struct bsdtar *bsdtar,
			     struct archive *a);
static int		 copy_file_data_block(struct bsdtar *,
			     struct archive *a, struct archive *,
			     struct archive_entry *);
static void		 excluded_callback(struct archive *, void *,
			     struct archive_entry *);
static void		 report_write(struct bsdtar *, struct archive *,
			     struct archive_entry *, int64_t progress);
static void		 test_for_append(struct bsdtar *);
static int		 metadata_filter(struct archive *, void *,
			     struct archive_entry *);
static void		 write_archive(struct archive *, struct bsdtar *);
static void		 write_entry(struct bsdtar *, struct archive *,
			     struct archive_entry *);
static void		 write_file(struct bsdtar *, struct archive *,
			     struct archive_entry *);
static void		 write_hierarchy(struct bsdtar *, struct archive *,
			     const char *);

#if defined(_WIN32) && !defined(__CYGWIN__)
/* Not a full lseek() emulation, but enough for our needs here. */
static int
seek_file(int fd, int64_t offset, int whence)
{
	LARGE_INTEGER distance;
	(void)whence; /* UNUSED */
	distance.QuadPart = offset;
	return (SetFilePointerEx((HANDLE)_get_osfhandle(fd),
		distance, NULL, FILE_BEGIN) ? 1 : -1);
}
#define	open _open
#define	close _close
#define	read _read
#ifdef lseek
#undef lseek
#endif
#define	lseek seek_file
#endif

static void
set_writer_options(struct bsdtar *bsdtar, struct archive *a)
{
	const char *writer_options;
	int r;

	writer_options = getenv(ENV_WRITER_OPTIONS);
	if (writer_options != NULL) {
		size_t module_len = sizeof(IGNORE_WRONG_MODULE_NAME) - 1;
		size_t opt_len = strlen(writer_options) + 1;
		char *p;
		/* Set default write options. */
		if ((p = malloc(module_len + opt_len)) == NULL)
			lafe_errc(1, errno, "Out of memory");
		/* Prepend magic code to ignore options for
		 * a format or filters which are not added to
		 * the archive write object. */
		memcpy(p, IGNORE_WRONG_MODULE_NAME, module_len);
		memcpy(p, writer_options, opt_len);
		r = archive_write_set_options(a, p);
		free(p);
		if (r < ARCHIVE_WARN)
			lafe_errc(1, 0, "%s", archive_error_string(a));
		else
			archive_clear_error(a);
	}
	if (ARCHIVE_OK != archive_write_set_options(a, bsdtar->option_options))
		lafe_errc(1, 0, "%s", archive_error_string(a));
}

static void
set_reader_options(struct bsdtar *bsdtar, struct archive *a)
{
	const char *reader_options;
	int r;

	(void)bsdtar; /* UNUSED */

	reader_options = getenv(ENV_READER_OPTIONS);
	if (reader_options != NULL) {
		size_t module_len = sizeof(IGNORE_WRONG_MODULE_NAME) - 1;
		size_t opt_len = strlen(reader_options) + 1;
		char *p;
		/* Set default write options. */
		if ((p = malloc(module_len + opt_len)) == NULL)
		if (p == NULL)
			lafe_errc(1, errno, "Out of memory");
		/* Prepend magic code to ignore options for
		 * a format or filters which are not added to
		 * the archive write object. */
		memcpy(p, IGNORE_WRONG_MODULE_NAME, module_len);
		memcpy(p, reader_options, opt_len);
		r = archive_read_set_options(a, p);
		free(p);
		if (r < ARCHIVE_WARN)
			lafe_errc(1, 0, "%s", archive_error_string(a));
		else
			archive_clear_error(a);
	}
	if (bsdtar->flags & OPTFLAG_IGNORE_ZEROS)
		if (archive_read_set_options(a,
		    "read_concatenated_archives") != ARCHIVE_OK)
			lafe_errc(1, 0, "%s", archive_error_string(a));
}

void
tar_mode_c(struct bsdtar *bsdtar)
{
	struct archive *a;
	const void *filter_name;
	int r;

	if (*bsdtar->argv == NULL && bsdtar->names_from_file == NULL)
		lafe_errc(1, 0, "no files or directories specified");

	a = archive_write_new();

	/* Support any format that the library supports. */
	if (cset_get_format(bsdtar->cset) == NULL) {
		r = archive_write_set_format_pax_restricted(a);
		cset_set_format(bsdtar->cset, "pax restricted");
	} else {
		r = archive_write_set_format_by_name(a,
			cset_get_format(bsdtar->cset));
	}
	if (r != ARCHIVE_OK) {
		fprintf(stderr, "Can't use format %s: %s\n",
		    cset_get_format(bsdtar->cset),
		    archive_error_string(a));
		usage();
	}

	archive_write_set_bytes_per_block(a, bsdtar->bytes_per_block);
	archive_write_set_bytes_in_last_block(a, bsdtar->bytes_in_last_block);

	r = cset_write_add_filters(bsdtar->cset, a, &filter_name);
	if (r < ARCHIVE_WARN) {
		lafe_errc(1, 0, "Unsupported compression option --%s",
		    (const char *)filter_name);
	}

	set_writer_options(bsdtar, a);
	if (bsdtar->passphrase != NULL)
		r = archive_write_set_passphrase(a, bsdtar->passphrase);
	else
		r = archive_write_set_passphrase_callback(a, bsdtar,
			&passphrase_callback);
	if (r != ARCHIVE_OK)
		lafe_errc(1, 0, "%s", archive_error_string(a));
	if (ARCHIVE_OK != archive_write_open_filename(a, bsdtar->filename))
		lafe_errc(1, 0, "%s", archive_error_string(a));
	write_archive(a, bsdtar);
}

/*
 * Same as 'c', except we only support tar or empty formats in
 * uncompressed files on disk.
 */
void
tar_mode_r(struct bsdtar *bsdtar)
{
	int64_t	end_offset;
	int	format;
	struct archive *a;
	struct archive_entry *entry;
	int	r;

	/* Sanity-test some arguments and the file. */
	test_for_append(bsdtar);

	format = ARCHIVE_FORMAT_TAR_PAX_RESTRICTED;

#if defined(__BORLANDC__)
	bsdtar->fd = open(bsdtar->filename, O_RDWR | O_CREAT | O_BINARY);
#else
	bsdtar->fd = open(bsdtar->filename, O_RDWR | O_CREAT | O_BINARY, 0666);
#endif
	if (bsdtar->fd < 0)
		lafe_errc(1, errno,
		    "Cannot open %s", bsdtar->filename);

	a = archive_read_new();
	archive_read_support_filter_all(a);
	archive_read_support_format_empty(a);
	archive_read_support_format_tar(a);
	archive_read_support_format_gnutar(a);
	set_reader_options(bsdtar, a);
	r = archive_read_open_fd(a, bsdtar->fd, 10240);
	if (r != ARCHIVE_OK)
		lafe_errc(1, archive_errno(a),
		    "Can't read archive %s: %s", bsdtar->filename,
		    archive_error_string(a));
	while (0 == archive_read_next_header(a, &entry)) {
		if (archive_filter_code(a, 0) != ARCHIVE_FILTER_NONE) {
			archive_read_free(a);
			close(bsdtar->fd);
			lafe_errc(1, 0,
			    "Cannot append to compressed archive.");
		}
		/* Keep going until we hit end-of-archive */
		format = archive_format(a);
	}

	end_offset = archive_read_header_position(a);
	archive_read_free(a);

	/* Re-open archive for writing */
	a = archive_write_new();
	/*
	 * Set the format to be used for writing.  To allow people to
	 * extend empty files, we need to allow them to specify the format,
	 * which opens the possibility that they will specify a format that
	 * doesn't match the existing format.  Hence, the following bit
	 * of arcane ugliness.
	 */

	if (cset_get_format(bsdtar->cset) != NULL) {
		/* If the user requested a format, use that, but ... */
		archive_write_set_format_by_name(a,
		    cset_get_format(bsdtar->cset));
		/* ... complain if it's not compatible. */
		format &= ARCHIVE_FORMAT_BASE_MASK;
		if (format != (int)(archive_format(a) & ARCHIVE_FORMAT_BASE_MASK)
		    && format != ARCHIVE_FORMAT_EMPTY) {
			lafe_errc(1, 0,
			    "Format %s is incompatible with the archive %s.",
			    cset_get_format(bsdtar->cset), bsdtar->filename);
		}
	} else {
		/*
		 * Just preserve the current format, with a little care
		 * for formats that libarchive can't write.
		 */
		if (format == ARCHIVE_FORMAT_EMPTY)
			format = ARCHIVE_FORMAT_TAR_PAX_RESTRICTED;
		archive_write_set_format(a, format);
	}
	if (lseek(bsdtar->fd, end_offset, SEEK_SET) < 0)
		lafe_errc(1, errno, "Could not seek to archive end");
	set_writer_options(bsdtar, a);
	if (ARCHIVE_OK != archive_write_open_fd(a, bsdtar->fd))
		lafe_errc(1, 0, "%s", archive_error_string(a));

	write_archive(a, bsdtar); /* XXX check return val XXX */

	close(bsdtar->fd);
	bsdtar->fd = -1;
}

void
tar_mode_u(struct bsdtar *bsdtar)
{
	int64_t			 end_offset;
	struct archive		*a;
	struct archive_entry	*entry;
	int			 format;
	struct archive_dir_entry	*p;
	struct archive_dir	 archive_dir;

	bsdtar->archive_dir = &archive_dir;
	memset(&archive_dir, 0, sizeof(archive_dir));

	format = ARCHIVE_FORMAT_TAR_PAX_RESTRICTED;

	/* Sanity-test some arguments and the file. */
	test_for_append(bsdtar);

	bsdtar->fd = open(bsdtar->filename, O_RDWR | O_BINARY);
	if (bsdtar->fd < 0)
		lafe_errc(1, errno,
		    "Cannot open %s", bsdtar->filename);

	a = archive_read_new();
	archive_read_support_filter_all(a);
	archive_read_support_format_tar(a);
	archive_read_support_format_gnutar(a);
	set_reader_options(bsdtar, a);
	if (archive_read_open_fd(a, bsdtar->fd, bsdtar->bytes_per_block)
	    != ARCHIVE_OK) {
		lafe_errc(1, 0,
		    "Can't open %s: %s", bsdtar->filename,
		    archive_error_string(a));
	}

	/* Build a list of all entries and their recorded mod times. */
	while (0 == archive_read_next_header(a, &entry)) {
		if (archive_filter_code(a, 0) != ARCHIVE_FILTER_NONE) {
			archive_read_free(a);
			close(bsdtar->fd);
			lafe_errc(1, 0,
			    "Cannot append to compressed archive.");
		}
		if (archive_match_exclude_entry(bsdtar->matching,
		    ARCHIVE_MATCH_MTIME | ARCHIVE_MATCH_OLDER |
		    ARCHIVE_MATCH_EQUAL, entry) != ARCHIVE_OK)
			lafe_errc(1, 0, "Error : %s",
			    archive_error_string(bsdtar->matching));
		/* Record the last format determination we see */
		format = archive_format(a);
		/* Keep going until we hit end-of-archive */
	}

	end_offset = archive_read_header_position(a);
	archive_read_free(a);

	/* Re-open archive for writing. */
	a = archive_write_new();
	/*
	 * Set format to same one auto-detected above.
	 */
	archive_write_set_format(a, format);
	archive_write_set_bytes_per_block(a, bsdtar->bytes_per_block);
	archive_write_set_bytes_in_last_block(a, bsdtar->bytes_in_last_block);

	if (lseek(bsdtar->fd, end_offset, SEEK_SET) < 0)
		lafe_errc(1, errno, "Could not seek to archive end");
	set_writer_options(bsdtar, a);
	if (ARCHIVE_OK != archive_write_open_fd(a, bsdtar->fd))
		lafe_errc(1, 0, "%s", archive_error_string(a));

	write_archive(a, bsdtar);

	close(bsdtar->fd);
	bsdtar->fd = -1;

	while (bsdtar->archive_dir->head != NULL) {
		p = bsdtar->archive_dir->head->next;
		free(bsdtar->archive_dir->head->name);
		free(bsdtar->archive_dir->head);
		bsdtar->archive_dir->head = p;
	}
	bsdtar->archive_dir->tail = NULL;
}


/*
 * Write user-specified files/dirs to opened archive.
 */
static void
write_archive(struct archive *a, struct bsdtar *bsdtar)
{
	const char *arg;
	struct archive_entry *entry, *sparse_entry;

	/* Choose a suitable copy buffer size */
	bsdtar->buff_size = 64 * 1024;
	while (bsdtar->buff_size < (size_t)bsdtar->bytes_per_block)
	  bsdtar->buff_size *= 2;
	/* Try to compensate for space we'll lose to alignment. */
	bsdtar->buff_size += 16 * 1024;

	/* Allocate a buffer for file data. */
	if ((bsdtar->buff = malloc(bsdtar->buff_size)) == NULL)
		lafe_errc(1, 0, "cannot allocate memory");

	if ((bsdtar->resolver = archive_entry_linkresolver_new()) == NULL)
		lafe_errc(1, 0, "cannot create link resolver");
	archive_entry_linkresolver_set_strategy(bsdtar->resolver,
	    archive_format(a));

	/* Create a read_disk object. */
	if ((bsdtar->diskreader = archive_read_disk_new()) == NULL)
		lafe_errc(1, 0, "Cannot create read_disk object");
	/* Tell the read_disk how handle symlink. */
	switch (bsdtar->symlink_mode) {
	case 'H':
		archive_read_disk_set_symlink_hybrid(bsdtar->diskreader);
		break;
	case 'L':
		archive_read_disk_set_symlink_logical(bsdtar->diskreader);
		break;
	default:
		archive_read_disk_set_symlink_physical(bsdtar->diskreader);
		break;
	}
	/* Register entry filters. */
	archive_read_disk_set_matching(bsdtar->diskreader,
	    bsdtar->matching, excluded_callback, bsdtar);
	archive_read_disk_set_metadata_filter_callback(
	    bsdtar->diskreader, metadata_filter, bsdtar);
	/* Set the behavior of archive_read_disk. */
	archive_read_disk_set_behavior(bsdtar->diskreader,
	    bsdtar->readdisk_flags);
	archive_read_disk_set_standard_lookup(bsdtar->diskreader);

	if (bsdtar->names_from_file != NULL)
		archive_names_from_file(bsdtar, a);

	while (*bsdtar->argv) {
		arg = *bsdtar->argv;
		if (arg[0] == '-' && arg[1] == 'C') {
			arg += 2;
			if (*arg == '\0') {
				bsdtar->argv++;
				arg = *bsdtar->argv;
				if (arg == NULL) {
					lafe_warnc(0, "%s",
					    "Missing argument for -C");
					bsdtar->return_value = 1;
					goto cleanup;
				}
				if (*arg == '\0') {
					lafe_warnc(0,
					    "Meaningless argument for -C: ''");
					bsdtar->return_value = 1;
					goto cleanup;
				}
			}
			set_chdir(bsdtar, arg);
		} else {
			if (*arg != '/')
				do_chdir(bsdtar); /* Handle a deferred -C */
			if (*arg == '@') {
				if (append_archive_filename(bsdtar, a,
				    arg + 1) != 0)
					break;
			} else
				write_hierarchy(bsdtar, a, arg);
		}
		bsdtar->argv++;
	}

	archive_read_disk_set_matching(bsdtar->diskreader, NULL, NULL, NULL);
	archive_read_disk_set_metadata_filter_callback(
	    bsdtar->diskreader, NULL, NULL);
	entry = NULL;
	archive_entry_linkify(bsdtar->resolver, &entry, &sparse_entry);
	while (entry != NULL) {
		int r;
		struct archive_entry *entry2;
		struct archive *disk = bsdtar->diskreader;

		/*
		 * This tricky code here is to correctly read the contents
		 * of the entry because the disk reader bsdtar->diskreader
		 * is pointing at does not have any information about the
		 * entry by this time and using archive_read_data_block()
		 * with the disk reader consequently must fail. And we
		 * have to re-open the entry to read the contents.
		 */
		/* TODO: Work with -C option as well. */
		r = archive_read_disk_open(disk,
			archive_entry_sourcepath(entry));
		if (r != ARCHIVE_OK) {
			lafe_warnc(archive_errno(disk),
			    "%s", archive_error_string(disk));
			bsdtar->return_value = 1;
			goto next_entry;
		}

		/*
		 * Invoke archive_read_next_header2() to work
		 * archive_read_data_block(), which is called via write_file(),
		 * without failure.
		 */
		entry2 = archive_entry_new();
		r = archive_read_next_header2(disk, entry2);
		archive_entry_free(entry2);
		if (r != ARCHIVE_OK) {
			lafe_warnc(archive_errno(disk),
			    "%s", archive_error_string(disk));
			if (r == ARCHIVE_FATAL)
				bsdtar->return_value = 1;
			archive_read_close(disk);
			goto next_entry;
		}

		write_file(bsdtar, a, entry);
		archive_read_close(disk);
next_entry:
		archive_entry_free(entry);
		entry = NULL;
		archive_entry_linkify(bsdtar->resolver, &entry, &sparse_entry);
	}

	if (archive_write_close(a)) {
		lafe_warnc(0, "%s", archive_error_string(a));
		bsdtar->return_value = 1;
	}

cleanup:
	/* Free file data buffer. */
	free(bsdtar->buff);
	archive_entry_linkresolver_free(bsdtar->resolver);
	bsdtar->resolver = NULL;
	archive_read_free(bsdtar->diskreader);
	bsdtar->diskreader = NULL;

	if (bsdtar->flags & OPTFLAG_TOTALS) {
		fprintf(stderr, "Total bytes written: %s\n",
		    tar_i64toa(archive_filter_bytes(a, -1)));
	}

	archive_write_free(a);
}

/*
 * Archive names specified in file.
 *
 * Unless --null was specified, a line containing exactly "-C" will
 * cause the next line to be a directory to pass to chdir().  If
 * --null is specified, then a line "-C" is just another filename.
 */
static void
archive_names_from_file(struct bsdtar *bsdtar, struct archive *a)
{
	struct lafe_line_reader *lr;
	const char *line;

	bsdtar->next_line_is_dir = 0;

	lr = lafe_line_reader(bsdtar->names_from_file,
	    (bsdtar->flags & OPTFLAG_NULL));
	while ((line = lafe_line_reader_next(lr)) != NULL) {
		if (bsdtar->next_line_is_dir) {
			if (*line != '\0')
				set_chdir(bsdtar, line);
			else {
				lafe_warnc(0,
				    "Meaningless argument for -C: ''");
				bsdtar->return_value = 1;
			}
			bsdtar->next_line_is_dir = 0;
		} else if (((bsdtar->flags & OPTFLAG_NULL) == 0) &&
		    strcmp(line, "-C") == 0)
			bsdtar->next_line_is_dir = 1;
		else {
			if (*line != '/')
				do_chdir(bsdtar); /* Handle a deferred -C */
			write_hierarchy(bsdtar, a, line);
		}
	}
	lafe_line_reader_free(lr);
	if (bsdtar->next_line_is_dir)
		lafe_errc(1, errno,
		    "Unexpected end of filename list; "
		    "directory expected after -C");
}

/*
 * Copy from specified archive to current archive.  Returns non-zero
 * for write errors (which force us to terminate the entire archiving
 * operation).  If there are errors reading the input archive, we set
 * bsdtar->return_value but return zero, so the overall archiving
 * operation will complete and return non-zero.
 */
static int
append_archive_filename(struct bsdtar *bsdtar, struct archive *a,
    const char *raw_filename)
{
	struct archive *ina;
	const char *filename = raw_filename;
	int rc;

	if (strcmp(filename, "-") == 0)
		filename = NULL; /* Library uses NULL for stdio. */

	ina = archive_read_new();
	archive_read_support_format_all(ina);
	archive_read_support_filter_all(ina);
	set_reader_options(bsdtar, ina);
	archive_read_set_options(ina, "mtree:checkfs");
	if (bsdtar->passphrase != NULL)
		rc = archive_read_add_passphrase(a, bsdtar->passphrase);
	else
		rc = archive_read_set_passphrase_callback(ina, bsdtar,
			&passphrase_callback);
	if (rc != ARCHIVE_OK)
		lafe_errc(1, 0, "%s", archive_error_string(a));
	if (archive_read_open_filename(ina, filename,
					bsdtar->bytes_per_block)) {
		lafe_warnc(0, "%s", archive_error_string(ina));
		bsdtar->return_value = 1;
		return (0);
	}

	rc = append_archive(bsdtar, a, ina);

	if (rc != ARCHIVE_OK) {
		lafe_warnc(0, "Error reading archive %s: %s",
		    raw_filename, archive_error_string(ina));
		bsdtar->return_value = 1;
	}
	archive_read_free(ina);

	return (rc);
}

static int
append_archive(struct bsdtar *bsdtar, struct archive *a, struct archive *ina)
{
	struct archive_entry *in_entry;
	int e;

	while (ARCHIVE_OK == (e = archive_read_next_header(ina, &in_entry))) {
		if (archive_match_excluded(bsdtar->matching, in_entry))
			continue;
		if(edit_pathname(bsdtar, in_entry))
			continue;
		if ((bsdtar->flags & OPTFLAG_INTERACTIVE) &&
		    !yes("copy '%s'", archive_entry_pathname(in_entry)))
			continue;
		edit_mtime(bsdtar, in_entry);
		if (bsdtar->verbose > 1) {
			safe_fprintf(stderr, "a ");
			list_item_verbose(bsdtar, stderr, in_entry);
		} else if (bsdtar->verbose > 0)
			safe_fprintf(stderr, "a %s",
			    archive_entry_pathname(in_entry));
		if (need_report())
			report_write(bsdtar, a, in_entry, 0);

		e = archive_write_header(a, in_entry);
		if (e != ARCHIVE_OK) {
			if (!bsdtar->verbose)
				lafe_warnc(0, "%s: %s",
				    archive_entry_pathname(in_entry),
				    archive_error_string(a));
			else
				fprintf(stderr, ": %s", archive_error_string(a));
		}
		if (e == ARCHIVE_FATAL)
			exit(1);

		if (e >= ARCHIVE_WARN) {
			if (archive_entry_size(in_entry) == 0)
				archive_read_data_skip(ina);
			else if (copy_file_data_block(bsdtar, a, ina, in_entry))
				exit(1);
		}

		if (bsdtar->verbose)
			fprintf(stderr, "\n");
	}

	return (e == ARCHIVE_EOF ? ARCHIVE_OK : e);
}

/* Helper function to copy file to archive. */
static int
copy_file_data_block(struct bsdtar *bsdtar, struct archive *a,
    struct archive *in_a, struct archive_entry *entry)
{
	size_t	bytes_read;
	ssize_t	bytes_written;
	int64_t	offset, progress = 0;
	char *null_buff = NULL;
	const void *buff;
	int r;

	while ((r = archive_read_data_block(in_a, &buff,
	    &bytes_read, &offset)) == ARCHIVE_OK) {
		if (need_report())
			report_write(bsdtar, a, entry, progress);

		if (offset > progress) {
			int64_t sparse = offset - progress;
			size_t ns;

			if (null_buff == NULL) {
				null_buff = bsdtar->buff;
				memset(null_buff, 0, bsdtar->buff_size);
			}

			while (sparse > 0) {
				if (sparse > (int64_t)bsdtar->buff_size)
					ns = bsdtar->buff_size;
				else
					ns = (size_t)sparse;
				bytes_written =
				    archive_write_data(a, null_buff, ns);
				if (bytes_written < 0) {
					/* Write failed; this is bad */
					lafe_warnc(0, "%s",
					     archive_error_string(a));
					return (-1);
				}
				if ((size_t)bytes_written < ns) {
					/* Write was truncated; warn but
					 * continue. */
					lafe_warnc(0,
					    "%s: Truncated write; file may "
					    "have grown while being archived.",
					    archive_entry_pathname(entry));
					return (0);
				}
				progress += bytes_written;
				sparse -= bytes_written;
			}
		}

		bytes_written = archive_write_data(a, buff, bytes_read);
		if (bytes_written < 0) {
			/* Write failed; this is bad */
			lafe_warnc(0, "%s", archive_error_string(a));
			return (-1);
		}
		if ((size_t)bytes_written < bytes_read) {
			/* Write was truncated; warn but continue. */
			lafe_warnc(0,
			    "%s: Truncated write; file may have grown "
			    "while being archived.",
			    archive_entry_pathname(entry));
			return (0);
		}
		progress += bytes_written;
	}
	if (r < ARCHIVE_WARN) {
		lafe_warnc(archive_errno(a), "%s", archive_error_string(a));
		return (-1);
	}
	return (0);
}

static void
excluded_callback(struct archive *a, void *_data, struct archive_entry *entry)
{
	struct bsdtar *bsdtar = (struct bsdtar *)_data;

	if (bsdtar->flags & OPTFLAG_NO_SUBDIRS)
		return;
	if (!archive_read_disk_can_descend(a))
		return;
	if ((bsdtar->flags & OPTFLAG_INTERACTIVE) &&
	    !yes("add '%s'", archive_entry_pathname(entry)))
		return;
	archive_read_disk_descend(a);
}

static int
metadata_filter(struct archive *a, void *_data, struct archive_entry *entry)
{
	struct bsdtar *bsdtar = (struct bsdtar *)_data;

	/* XXX TODO: check whether this filesystem is
	 * synthetic and/or local.  Add a new
	 * --local-only option to skip non-local
	 * filesystems.  Skip synthetic filesystems
	 * regardless.
	 *
	 * The results should be cached, since
	 * tree.c doesn't usually visit a directory
	 * and the directory contents together.  A simple
	 * move-to-front list should perform quite well.
	 *
	 * Use archive_read_disk_current_filesystem_is_remote().
	 */

	/*
	 * If the user vetoes this file/directory, skip it.
	 * We want this to be fairly late; if some other
	 * check would veto this file, we shouldn't bother
	 * the user with it.
	 */
	if ((bsdtar->flags & OPTFLAG_INTERACTIVE) &&
	    !yes("add '%s'", archive_entry_pathname(entry)))
		return (0);

	/* Note: if user vetoes, we won't descend. */
	if (((bsdtar->flags & OPTFLAG_NO_SUBDIRS) == 0) &&
	    archive_read_disk_can_descend(a))
		archive_read_disk_descend(a);

	return (1);
}

/*
 * Add the file or dir hierarchy named by 'path' to the archive
 */
static void
write_hierarchy(struct bsdtar *bsdtar, struct archive *a, const char *path)
{
	struct archive *disk = bsdtar->diskreader;
	struct archive_entry *entry = NULL, *spare_entry = NULL;
	int r;

	r = archive_read_disk_open(disk, path);
	if (r != ARCHIVE_OK) {
		lafe_warnc(archive_errno(disk),
		    "%s", archive_error_string(disk));
		bsdtar->return_value = 1;
		return;
	}
	bsdtar->first_fs = -1;

	for (;;) {
		archive_entry_free(entry);
		entry = archive_entry_new();
		r = archive_read_next_header2(disk, entry);
		if (r == ARCHIVE_EOF)
			break;
		else if (r != ARCHIVE_OK) {
			lafe_warnc(archive_errno(disk),
			    "%s", archive_error_string(disk));
			if (r == ARCHIVE_FATAL || r == ARCHIVE_FAILED) {
				bsdtar->return_value = 1;
				archive_entry_free(entry);
				archive_read_close(disk);
				return;
			} else if (r < ARCHIVE_WARN)
				continue;
		}

		if (bsdtar->uid >= 0) {
			archive_entry_set_uid(entry, bsdtar->uid);
			if (!bsdtar->uname)
				archive_entry_set_uname(entry,
				    archive_read_disk_uname(bsdtar->diskreader,
					bsdtar->uid));
		}
		if (bsdtar->gid >= 0) {
			archive_entry_set_gid(entry, bsdtar->gid);
			if (!bsdtar->gname)
				archive_entry_set_gname(entry,
				    archive_read_disk_gname(bsdtar->diskreader,
					bsdtar->gid));
		}
		if (bsdtar->uname)
			archive_entry_set_uname(entry, bsdtar->uname);
		if (bsdtar->gname)
			archive_entry_set_gname(entry, bsdtar->gname);

		/*
		 * Rewrite the pathname to be archived.  If rewrite
		 * fails, skip the entry.
		 */
		if (edit_pathname(bsdtar, entry))
			continue;

		/* Rewrite the mtime. */
		edit_mtime(bsdtar, entry);

		/* Display entry as we process it. */
		if (bsdtar->verbose > 1) {
			safe_fprintf(stderr, "a ");
			list_item_verbose(bsdtar, stderr, entry);
		} else if (bsdtar->verbose > 0) {
		/* This format is required by SUSv2. */
			safe_fprintf(stderr, "a %s",
			    archive_entry_pathname(entry));
		}

		/* Non-regular files get archived with zero size. */
		if (archive_entry_filetype(entry) != AE_IFREG)
			archive_entry_set_size(entry, 0);

		archive_entry_linkify(bsdtar->resolver, &entry, &spare_entry);

		while (entry != NULL) {
			write_file(bsdtar, a, entry);
			if (entry != spare_entry) {
				archive_entry_free(entry);
			}
			entry = spare_entry;
			spare_entry = NULL;
		}

		if (bsdtar->verbose)
			fprintf(stderr, "\n");
	}
	archive_entry_free(entry);
	archive_read_close(disk);
}

/*
 * Write a single file (or directory or other filesystem object) to
 * the archive.
 */
static void
write_file(struct bsdtar *bsdtar, struct archive *a,
    struct archive_entry *entry)
{
	write_entry(bsdtar, a, entry);
}

/*
 * Write a single entry to the archive.
 */
static void
write_entry(struct bsdtar *bsdtar, struct archive *a,
    struct archive_entry *entry)
{
	int e;

	e = archive_write_header(a, entry);
	if (e != ARCHIVE_OK) {
		if (bsdtar->verbose > 1) {
			safe_fprintf(stderr, "a ");
			list_item_verbose(bsdtar, stderr, entry);
			lafe_warnc(0, ": %s", archive_error_string(a));
		} else {
			lafe_warnc(0, "%s: %s",
			    archive_entry_pathname(entry),
			    archive_error_string(a));
		}
	}

	if (e == ARCHIVE_FATAL)
		exit(1);

	/*
	 * If we opened a file earlier, write it out now.  Note that
	 * the format handler might have reset the size field to zero
	 * to inform us that the archive body won't get stored.  In
	 * that case, just skip the write.
	 */
	if (e >= ARCHIVE_WARN && archive_entry_size(entry) > 0) {
		if (copy_file_data_block(bsdtar, a, bsdtar->diskreader, entry))
			exit(1);
	}
}

static void
report_write(struct bsdtar *bsdtar, struct archive *a,
    struct archive_entry *entry, int64_t progress)
{
	uint64_t comp, uncomp;
	int compression;

	if (bsdtar->verbose)
		fprintf(stderr, "\n");
	comp = archive_filter_bytes(a, -1);
	uncomp = archive_filter_bytes(a, 0);
	fprintf(stderr, "In: %d files, %s bytes;",
	    archive_file_count(a), tar_i64toa(uncomp));
	if (comp >= uncomp)
		compression = 0;
	else
		compression = (int)((uncomp - comp) * 100 / uncomp);
	fprintf(stderr,
	    " Out: %s bytes, compression %d%%\n",
	    tar_i64toa(comp), compression);
	/* Can't have two calls to tar_i64toa() pending, so split the output. */
	safe_fprintf(stderr, "Current: %s (%s",
	    archive_entry_pathname(entry),
	    tar_i64toa(progress));
	fprintf(stderr, "/%s bytes)\n",
	    tar_i64toa(archive_entry_size(entry)));
}

static void
test_for_append(struct bsdtar *bsdtar)
{
	struct stat s;

	if (*bsdtar->argv == NULL && bsdtar->names_from_file == NULL)
		lafe_errc(1, 0, "no files or directories specified");
	if (bsdtar->filename == NULL)
		lafe_errc(1, 0, "Cannot append to stdout.");

	if (stat(bsdtar->filename, &s) != 0)
		return;

	if (!S_ISREG(s.st_mode) && !S_ISBLK(s.st_mode))
		lafe_errc(1, 0,
		    "Cannot append to %s: not a regular file.",
		    bsdtar->filename);

/* Is this an appropriate check here on Windows? */
/*
	if (GetFileType(handle) != FILE_TYPE_DISK)
		lafe_errc(1, 0, "Cannot append");
*/

}