path: root/Utilities/cmlibarchive/tar/write.c

/*-
 * Copyright (c) 2003-2007 Tim Kientzle
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 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 "bsdtar_platform.h"
__FBSDID("$FreeBSD: src/usr.bin/tar/write.c,v 1.79 2008/11/27 05:49:52 kientzle Exp $");

#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#endif
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#ifdef 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_LIMITS_H
#include <limits.h>
#endif
#ifdef HAVE_LINUX_FS_H
#include <linux/fs.h>   /* for Linux file flags */
#endif
/*
 * Some Linux distributions have both linux/ext2_fs.h and ext2fs/ext2_fs.h.
 * As the include guards don't agree, the order of include is important.
 */
#ifdef HAVE_LINUX_EXT2_FS_H
#include <linux/ext2_fs.h>  /* for Linux file flags */
#endif
#if defined(HAVE_EXT2FS_EXT2_FS_H) && !defined(__CYGWIN__)
/* This header exists but is broken on Cygwin. */
#include <ext2fs/ext2_fs.h>
#endif
#ifdef HAVE_PWD_H
#include <pwd.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
#ifdef HAVE_WINDOWS_H
#include <windows.h>
#endif

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

/* Size of buffer for holding file data prior to writing. */
#define FILEDATABUFLEN  65536

/* Fixed size of uname/gname caches. */
#define name_cache_size 101

static const char * const NO_NAME = "(noname)";

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;
};

struct name_cache {
    int probes;
    int hits;
    size_t  size;
    struct {
        id_t id;
        const char *name;
    } cache[name_cache_size];
};

static void      add_dir_list(struct bsdtar *bsdtar, const char *path,
                 time_t mtime_sec, int mtime_nsec);
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(struct bsdtar *, struct archive *a,
                 struct archive *ina, struct archive_entry *);
static int       new_enough(struct bsdtar *, const char *path,
                 const struct stat *);
static void      report_write(struct bsdtar *, struct archive *,
                 struct archive_entry *, int64_t progress);
static void      test_for_append(struct bsdtar *);
static void      write_archive(struct archive *, struct bsdtar *);
static void      write_entry_backend(struct bsdtar *, struct archive *,
                 struct archive_entry *);
static int       write_file_data(struct bsdtar *, struct archive *,
                 struct archive_entry *, int fd);
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
#define lseek seek_file
#endif

void
tar_mode_c(struct bsdtar *bsdtar)
{
    struct archive *a;
    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 (bsdtar->create_format == NULL) {
        r = archive_write_set_format_pax_restricted(a);
        bsdtar->create_format = "pax restricted";
    } else {
        r = archive_write_set_format_by_name(a, bsdtar->create_format);
    }
    if (r != ARCHIVE_OK) {
        fprintf(stderr, "Can't use format %s: %s\n",
            bsdtar->create_format,
            archive_error_string(a));
        usage();
    }

    /*
     * If user explicitly set the block size, then assume they
     * want the last block padded as well.  Otherwise, use the
     * default block size and accept archive_write_open_file()'s
     * default padding decisions.
     */
    if (bsdtar->bytes_per_block != 0) {
        archive_write_set_bytes_per_block(a, bsdtar->bytes_per_block);
        archive_write_set_bytes_in_last_block(a,
            bsdtar->bytes_per_block);
    } else
        archive_write_set_bytes_per_block(a, DEFAULT_BYTES_PER_BLOCK);

    if (bsdtar->compress_program) {
        archive_write_set_compression_program(a, bsdtar->compress_program);
    } else {
        switch (bsdtar->create_compression) {
        case 0:
            r = archive_write_set_compression_none(a);
            break;
        case 'j': case 'y':
            r = archive_write_set_compression_bzip2(a);
            break;
        case 'J':
            r = archive_write_set_compression_xz(a);
            break;
        case OPTION_LZMA:
            archive_write_set_compression_lzma(a);
            break;
        case 'z':
            r = archive_write_set_compression_gzip(a);
            break;
        case 'Z':
            r = archive_write_set_compression_compress(a);
            break;
        default:
            lafe_errc(1, 0,
                "Unrecognized compression option -%c",
                bsdtar->create_compression);
        }
        if (r != ARCHIVE_OK) {
            lafe_errc(1, 0,
                "Unsupported compression option -%c",
                bsdtar->create_compression);
        }
    }

    if (ARCHIVE_OK != archive_write_set_options(a, bsdtar->option_options))
        lafe_errc(1, 0, archive_error_string(a));
    if (ARCHIVE_OK != archive_write_open_file(a, bsdtar->filename))
        lafe_errc(1, 0, 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;

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

    a = archive_read_new();
    archive_read_support_compression_all(a);
    archive_read_support_format_tar(a);
    archive_read_support_format_gnutar(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_compression(a) != ARCHIVE_COMPRESSION_NONE) {
            archive_read_finish(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_finish(a);

    /* Re-open archive for writing */
    a = archive_write_new();
    archive_write_set_compression_none(a);
    /*
     * 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 (bsdtar->create_format != NULL) {
        /* If the user requested a format, use that, but ... */
        archive_write_set_format_by_name(a,
            bsdtar->create_format);
        /* ... 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.",
                bsdtar->create_format, bsdtar->filename);
        }
    } else {
        /*
         * Just preserve the current format, with a little care
         * for formats that libarchive can't write.
         */
        if (format == ARCHIVE_FORMAT_TAR_GNUTAR)
            /* TODO: When gtar supports pax, use pax restricted. */
            format = ARCHIVE_FORMAT_TAR_USTAR;
        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");
    if (ARCHIVE_OK != archive_write_set_options(a, bsdtar->option_options))
        lafe_errc(1, 0, archive_error_string(a));
    if (ARCHIVE_OK != archive_write_open_fd(a, bsdtar->fd))
        lafe_errc(1, 0, 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);
    if (bsdtar->fd < 0)
        lafe_errc(1, errno,
            "Cannot open %s", bsdtar->filename);

    a = archive_read_new();
    archive_read_support_compression_all(a);
    archive_read_support_format_tar(a);
    archive_read_support_format_gnutar(a);
    if (archive_read_open_fd(a, bsdtar->fd,
        bsdtar->bytes_per_block != 0 ? bsdtar->bytes_per_block :
        DEFAULT_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_compression(a) != ARCHIVE_COMPRESSION_NONE) {
            archive_read_finish(a);
            close(bsdtar->fd);
            lafe_errc(1, 0,
                "Cannot append to compressed archive.");
        }
        add_dir_list(bsdtar, archive_entry_pathname(entry),
            archive_entry_mtime(entry),
            archive_entry_mtime_nsec(entry));
        /* 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_finish(a);

    /* Re-open archive for writing. */
    a = archive_write_new();
    archive_write_set_compression_none(a);
    /*
     * Set format to same one auto-detected above, except that
     * we don't write GNU tar format, so use ustar instead.
     */
    if (format == ARCHIVE_FORMAT_TAR_GNUTAR)
        format = ARCHIVE_FORMAT_TAR_USTAR;
    archive_write_set_format(a, format);
    if (bsdtar->bytes_per_block != 0) {
        archive_write_set_bytes_per_block(a, bsdtar->bytes_per_block);
        archive_write_set_bytes_in_last_block(a,
            bsdtar->bytes_per_block);
    } else
        archive_write_set_bytes_per_block(a, DEFAULT_BYTES_PER_BLOCK);
    if (lseek(bsdtar->fd, end_offset, SEEK_SET) < 0)
        lafe_errc(1, errno, "Could not seek to archive end");
    if (ARCHIVE_OK != archive_write_set_options(a, bsdtar->option_options))
        lafe_errc(1, 0, archive_error_string(a));
    if (ARCHIVE_OK != archive_write_open_fd(a, bsdtar->fd))
        lafe_errc(1, 0, 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;

    /* Allocate a buffer for file data. */
    if ((bsdtar->buff = malloc(FILEDATABUFLEN)) == 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));
    if ((bsdtar->diskreader = archive_read_disk_new()) == NULL)
        lafe_errc(1, 0, "Cannot create read_disk object");
    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(1, 0,
                        "Missing argument for -C");
                    bsdtar->return_value = 1;
                    goto cleanup;
                }
            }
            set_chdir(bsdtar, arg);
        } else {
            if (*arg != '/' && (arg[0] != '@' || arg[1] != '/'))
                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++;
    }

    entry = NULL;
    archive_entry_linkify(bsdtar->resolver, &entry, &sparse_entry);
    while (entry != NULL) {
        write_entry_backend(bsdtar, a, 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_finish(bsdtar->diskreader);
    bsdtar->diskreader = NULL;

    if (bsdtar->option_totals) {
        fprintf(stderr, "Total bytes written: " BSDTAR_FILESIZE_PRINTF "\n",
            (BSDTAR_FILESIZE_TYPE)archive_position_compressed(a));
    }

    archive_write_finish(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.
 */
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->option_null);
    while ((line = lafe_line_reader_next(lr)) != NULL) {
        if (bsdtar->next_line_is_dir) {
            set_chdir(bsdtar, line);
            bsdtar->next_line_is_dir = 0;
        } else if (!bsdtar->option_null && 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 *filename)
{
    struct archive *ina;
    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_compression_all(ina);
    if (archive_read_open_file(ina, filename, 10240)) {
        lafe_warnc(0, "%s", archive_error_string(ina));
        bsdtar->return_value = 1;
        return (0);
    }

    rc = append_archive(bsdtar, a, ina);

    if (archive_errno(ina)) {
        lafe_warnc(0, "Error reading archive %s: %s",
            filename, archive_error_string(ina));
        bsdtar->return_value = 1;
    }
    archive_read_finish(ina);

    return (rc);
}

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

    while (0 == archive_read_next_header(ina, &in_entry)) {
        if (!new_enough(bsdtar, archive_entry_pathname(in_entry),
            archive_entry_stat(in_entry)))
            continue;
        if (lafe_excluded(bsdtar->matching, archive_entry_pathname(in_entry)))
            continue;
        if (bsdtar->option_interactive &&
            !yes("copy '%s'", archive_entry_pathname(in_entry)))
            continue;
        if (bsdtar->verbose)
            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(bsdtar, a, ina, in_entry))
                exit(1);
        }

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

    /* Note: If we got here, we saw no write errors, so return success. */
    return (0);
}

/* Helper function to copy data between archives. */
static int
copy_file_data(struct bsdtar *bsdtar, struct archive *a,
    struct archive *ina, struct archive_entry *entry)
{
    ssize_t bytes_read;
    ssize_t bytes_written;
    int64_t progress = 0;

    bytes_read = archive_read_data(ina, bsdtar->buff, FILEDATABUFLEN);
    while (bytes_read > 0) {
        if (need_report())
            report_write(bsdtar, a, entry, progress);

        bytes_written = archive_write_data(a, bsdtar->buff,
            bytes_read);
        if (bytes_written < bytes_read) {
            lafe_warnc(0, "%s", archive_error_string(a));
            return (-1);
        }
        progress += bytes_written;
        bytes_read = archive_read_data(ina, bsdtar->buff,
            FILEDATABUFLEN);
    }

    return (0);
}

/*
 * 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_entry *entry = NULL, *spare_entry = NULL;
    struct tree *tree;
    char symlink_mode = bsdtar->symlink_mode;
    dev_t first_dev = 0;
    int dev_recorded = 0;
    int tree_ret;

    tree = tree_open(path);

    if (!tree) {
        lafe_warnc(errno, "%s: Cannot open", path);
        bsdtar->return_value = 1;
        return;
    }

    while ((tree_ret = tree_next(tree))) {
        int r;
        const char *name = tree_current_path(tree);
        const struct stat *st = NULL; /* info to use for this entry */
        const struct stat *lst = NULL; /* lstat() information */
        int descend;

        if (tree_ret == TREE_ERROR_FATAL)
            lafe_errc(1, tree_errno(tree),
                "%s: Unable to continue traversing directory tree",
                name);
        if (tree_ret == TREE_ERROR_DIR) {
            lafe_warnc(errno,
                "%s: Couldn't visit directory", name);
            bsdtar->return_value = 1;
        }
        if (tree_ret != TREE_REGULAR)
            continue;

        /*
         * If this file/dir is excluded by a filename
         * pattern, skip it.
         */
        if (lafe_excluded(bsdtar->matching, name))
            continue;

        /*
         * Get lstat() info from the tree library.
         */
        lst = tree_current_lstat(tree);
        if (lst == NULL) {
            /* Couldn't lstat(); must not exist. */
            lafe_warnc(errno, "%s: Cannot stat", name);
            /* Return error if files disappear during traverse. */
            bsdtar->return_value = 1;
            continue;
        }

        /*
         * Distinguish 'L'/'P'/'H' symlink following.
         */
        switch(symlink_mode) {
        case 'H':
            /* 'H': After the first item, rest like 'P'. */
            symlink_mode = 'P';
            /* 'H': First item (from command line) like 'L'. */
            /* FALLTHROUGH */
        case 'L':
            /* 'L': Do descend through a symlink to dir. */
            descend = tree_current_is_dir(tree);
            /* 'L': Follow symlinks to files. */
            archive_read_disk_set_symlink_logical(bsdtar->diskreader);
            /* 'L': Archive symlinks as targets, if we can. */
            st = tree_current_stat(tree);
            if (st != NULL)
                break;
            /* If stat fails, we have a broken symlink;
             * in that case, don't follow the link. */
            /* FALLTHROUGH */
        default:
            /* 'P': Don't descend through a symlink to dir. */
            descend = tree_current_is_physical_dir(tree);
            /* 'P': Don't follow symlinks to files. */
            archive_read_disk_set_symlink_physical(bsdtar->diskreader);
            /* 'P': Archive symlinks as symlinks. */
            st = lst;
            break;
        }

        /*
         * Are we about to cross to a new filesystem?
         */
        if (!dev_recorded) {
            /* This is the initial file system. */
            first_dev = lst->st_dev;
            dev_recorded = 1;
        } else if (lst->st_dev == first_dev) {
            /* The starting file system is always acceptable. */
        } else if (descend == 0) {
            /* We're not descending, so no need to check. */
        } else if (bsdtar->option_dont_traverse_mounts) {
            /* User has asked us not to cross mount points. */
            descend = 0;
        } else {
            /* We're prepared to cross a mount point. */

            /* 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.
             *
             * This is going to be heavily OS dependent:
             * FreeBSD's statfs() in conjunction with getvfsbyname()
             * provides all of this; NetBSD's statvfs() does
             * most of it; other systems will vary.
             */
        }

        /*
         * In -u mode, check that the file is newer than what's
         * already in the archive; in all modes, obey --newerXXX flags.
         */
        if (!new_enough(bsdtar, name, st))
            continue;

        archive_entry_free(entry);
        entry = archive_entry_new();

        archive_entry_set_pathname(entry, name);
        archive_entry_copy_sourcepath(entry,
            tree_current_access_path(tree));

        /* Populate the archive_entry with metadata from the disk. */
        /* XXX TODO: Arrange to open a regular file before
         * calling this so we can pass in an fd and shorten
         * the race to query metadata.  The linkify dance
         * makes this more complex than it might sound. */
#if defined(_WIN32) && !defined(__CYGWIN__)
        /* TODO: tree.c uses stat(), which is badly broken
         * on Windows.  To fix this, we should
         * deprecate tree_current_stat() and provide a new
         * call tree_populate_entry(t, entry).  This call
         * would use stat() internally on POSIX and
         * GetInfoByFileHandle() internally on Windows.
         * This would be another step towards a tree-walker
         * that can be integrated deep into libarchive.
         * For now, just set st to NULL on Windows;
         * archive_read_disk_entry_from_file() should
         * be smart enough to use platform-appropriate
         * ways to probe file information.
         */
        st = NULL;
#endif
        r = archive_read_disk_entry_from_file(bsdtar->diskreader,
            entry, -1, st);
        if (r != ARCHIVE_OK)
            lafe_warnc(archive_errno(bsdtar->diskreader),
                archive_error_string(bsdtar->diskreader));
        if (r < ARCHIVE_WARN)
            continue;

        /* XXX TODO: Just use flag data from entry; avoid the
         * duplicate check here. */

        /*
         * If this file/dir is flagged "nodump" and we're
         * honoring such flags, skip this file/dir.
         */
#ifdef HAVE_STRUCT_STAT_ST_FLAGS
        /* BSD systems store flags in struct stat */
        if (bsdtar->option_honor_nodump &&
            (lst->st_flags & UF_NODUMP))
            continue;
#endif

#if defined(EXT2_IOC_GETFLAGS) && defined(EXT2_NODUMP_FL)
        /* Linux uses ioctl to read flags. */
        if (bsdtar->option_honor_nodump) {
            int fd = open(name, O_RDONLY | O_NONBLOCK);
            if (fd >= 0) {
                unsigned long fflags;
                int r = ioctl(fd, EXT2_IOC_GETFLAGS, &fflags);
                close(fd);
                if (r >= 0 && (fflags & EXT2_NODUMP_FL))
                    continue;
            }
        }
#endif

        /*
         * 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->option_interactive &&
            !yes("add '%s'", name))
            continue;

        /* Note: if user vetoes, we won't descend. */
        if (descend && !bsdtar->option_no_subdirs)
            tree_descend(tree);

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

        /* Display entry as we process it.
         * This format is required by SUSv2. */
        if (bsdtar->verbose)
            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_entry_backend(bsdtar, a, entry);
            archive_entry_free(entry);
            entry = spare_entry;
            spare_entry = NULL;
        }

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

/*
 * Backend for write_entry.
 */
static void
write_entry_backend(struct bsdtar *bsdtar, struct archive *a,
    struct archive_entry *entry)
{
    int fd = -1;
    int e;

    if (archive_entry_size(entry) > 0) {
        const char *pathname = archive_entry_sourcepath(entry);
        fd = open(pathname, O_RDONLY);
        if (fd == -1) {
            if (!bsdtar->verbose)
                lafe_warnc(errno,
                    "%s: could not open file", pathname);
            else
                fprintf(stderr, ": %s", strerror(errno));
            return;
        }
    }

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

    /*
     * If we opened a file, close it now even if there was an error
     * which made us decide not to write the archive body.
     */
    if (fd >= 0)
        close(fd);
}

static void
report_write(struct bsdtar *bsdtar, struct archive *a,
    struct archive_entry *entry, int64_t progress)
{
    uintmax_t comp, uncomp;
    if (bsdtar->verbose)
        fprintf(stderr, "\n");
    comp = archive_position_compressed(a);
    uncomp = archive_position_uncompressed(a);
    fprintf(stderr, "In: %d files, %ju bytes;",
        archive_file_count(a), uncomp);
    fprintf(stderr,
        " Out: %ju bytes, compression %d%%\n",
        comp, (int)((uncomp - comp) * 100 / uncomp));
    safe_fprintf(stderr, "Current: %s (%ju/%ju bytes)",
        archive_entry_pathname(entry),
        (uintmax_t)progress,
        (uintmax_t)archive_entry_size(entry));
    fprintf(stderr, "\n");
}


/* Helper function to copy file to archive. */
static int
write_file_data(struct bsdtar *bsdtar, struct archive *a,
    struct archive_entry *entry, int fd)
{
    ssize_t bytes_read;
    ssize_t bytes_written;
    int64_t progress = 0;

    bytes_read = read(fd, bsdtar->buff, FILEDATABUFLEN);
    while (bytes_read > 0) {
        if (need_report())
            report_write(bsdtar, a, entry, progress);

        bytes_written = archive_write_data(a, bsdtar->buff,
            bytes_read);
        if (bytes_written < 0) {
            /* Write failed; this is bad */
            lafe_warnc(0, "%s", archive_error_string(a));
            return (-1);
        }
        if (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;
        bytes_read = read(fd, bsdtar->buff, FILEDATABUFLEN);
    }
    return 0;
}

/*
 * Test if the specified file is new enough to include in the archive.
 */
int
new_enough(struct bsdtar *bsdtar, const char *path, const struct stat *st)
{
    struct archive_dir_entry *p;

    /*
     * If this file/dir is excluded by a time comparison, skip it.
     */
    if (bsdtar->newer_ctime_sec > 0) {
        if (st->st_ctime < bsdtar->newer_ctime_sec)
            return (0); /* Too old, skip it. */
        if (st->st_ctime == bsdtar->newer_ctime_sec
            && ARCHIVE_STAT_CTIME_NANOS(st)
            <= bsdtar->newer_ctime_nsec)
            return (0); /* Too old, skip it. */
    }
    if (bsdtar->newer_mtime_sec > 0) {
        if (st->st_mtime < bsdtar->newer_mtime_sec)
            return (0); /* Too old, skip it. */
        if (st->st_mtime == bsdtar->newer_mtime_sec
            && ARCHIVE_STAT_MTIME_NANOS(st)
            <= bsdtar->newer_mtime_nsec)
            return (0); /* Too old, skip it. */
    }

    /*
     * In -u mode, we only write an entry if it's newer than
     * what was already in the archive.
     */
    if (bsdtar->archive_dir != NULL &&
        bsdtar->archive_dir->head != NULL) {
        for (p = bsdtar->archive_dir->head; p != NULL; p = p->next) {
            if (pathcmp(path, p->name)==0)
                return (p->mtime_sec < st->st_mtime ||
                    (p->mtime_sec == st->st_mtime &&
                    p->mtime_nsec
                    < ARCHIVE_STAT_MTIME_NANOS(st)));
        }
    }

    /* If the file wasn't rejected, include it. */
    return (1);
}

/*
 * Add an entry to the dir list for 'u' mode.
 *
 * XXX TODO: Make this fast.
 */
static void
add_dir_list(struct bsdtar *bsdtar, const char *path,
    time_t mtime_sec, int mtime_nsec)
{
    struct archive_dir_entry    *p;

    /*
     * Search entire list to see if this file has appeared before.
     * If it has, override the timestamp data.
     */
    p = bsdtar->archive_dir->head;
    while (p != NULL) {
        if (strcmp(path, p->name)==0) {
            p->mtime_sec = mtime_sec;
            p->mtime_nsec = mtime_nsec;
            return;
        }
        p = p->next;
    }

    p = malloc(sizeof(*p));
    if (p == NULL)
        lafe_errc(1, ENOMEM, "Can't read archive directory");

    p->name = strdup(path);
    if (p->name == NULL)
        lafe_errc(1, ENOMEM, "Can't read archive directory");
    p->mtime_sec = mtime_sec;
    p->mtime_nsec = mtime_nsec;
    p->next = NULL;
    if (bsdtar->archive_dir->tail == NULL) {
        bsdtar->archive_dir->head = bsdtar->archive_dir->tail = p;
    } else {
        bsdtar->archive_dir->tail->next = p;
        bsdtar->archive_dir->tail = p;
    }
}

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 (bsdtar->create_compression != 0)
        lafe_errc(1, 0,
            "Cannot append to %s with compression", bsdtar->filename);

    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");
*/

}