Initial import of libarchive.

What it is:
   A library for reading and writing various streaming archive
   formats, especially tar and cpio.  Being a library, it should
   be easy to incorporate into pkg_* tools, sysinstall, and any
   other place that needs to read or write such archives.

Features:
  * Full automatic detection of both compression and archive format.
  * Extensible internal architecture to make it easy to add new formats.
  * Support for "pax interchange format," a new POSIX-standard tar format
    that eliminates essentially all of the restrictions of historic formats.
  * BSD license

Thanks to: jkh for pushing me to start this work, gordon for
  encouraging me to commit it, bde for answering endless style
  questions, and many others for feedback and encouragement.

Status: Pretty good overall, though there are still a few rough edges and
  the library could always use more testing.  Feedback eagerly solicited.

1 files changed, 694 insertions, 0 deletions

diff --git a/lib/libarchive/archive_write_set_format_pax.c b/lib/libarchive/archive_write_set_format_pax.c
new file mode 100644
index 0000000..bee95d3
--- /dev/null
+++ b/lib/libarchive/archive_write_set_format_pax.c
@@ -0,0 +1,694 @@
+/*-
+ * Copyright (c) 2003-2004 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
+ *    in this position and unchanged.
+ * 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 <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/stat.h>
+#include <errno.h>
+#ifdef DMALLOC
+#include <dmalloc.h>
+#endif
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "archive.h"
+#include "archive_entry.h"
+#include "archive_private.h"
+
+struct pax {
+	uint64_t	entry_bytes_remaining;
+	uint64_t	entry_padding;
+	struct archive_string	pax_header;
+	char		written;
+};
+
+static void		 add_pax_attr(struct archive_string *, const char *key,
+			     const char *value);
+static void		 add_pax_attr_int(struct archive_string *,
+			     const char *key, int64_t value);
+static void		 add_pax_attr_time(struct archive_string *,
+			     const char *key, int64_t sec,
+			     unsigned long nanos);
+static int		 archive_write_pax_data(struct archive *,
+			     const void *, size_t);
+static int		 archive_write_pax_finish(struct archive *);
+static int		 archive_write_pax_finish_entry(struct archive *);
+static int		 archive_write_pax_header(struct archive *,
+			     struct archive_entry *);
+static char		*build_pax_attribute_name(const char *abbreviated,
+			     struct archive_string *work);
+static char		*build_ustar_entry_name(char *dest, const char *src);
+static char		*format_int(char *dest, int64_t);
+static int		 write_nulls(struct archive *, size_t);
+
+/*
+ * Set output format to 'restricted pax' format.
+ *
+ * This is the same as normal 'pax', but tries to suppress
+ * the pax header whenever possible.  This is the default for
+ * bsdtar, for instance.
+ */
+int
+archive_write_set_format_pax_restricted(struct archive *a)
+{
+	int r;
+	r = archive_write_set_format_pax(a);
+	a->archive_format = ARCHIVE_FORMAT_TAR_PAX_RESTRICTED;
+	a->archive_format_name = "restricted POSIX pax interchange";
+	return (r);
+}
+
+/*
+ * Set output format to 'pax' format.
+ */
+int
+archive_write_set_format_pax(struct archive *a)
+{
+	struct pax *pax;
+
+	if (a->format_finish != NULL)
+		(a->format_finish)(a);
+
+	pax = malloc(sizeof(*pax));
+	if (pax == NULL) {
+		archive_set_error(a, ENOMEM, "Can't allocate pax data");
+		return (ARCHIVE_FATAL);
+	}
+	memset(pax, 0, sizeof(*pax));
+	a->format_data = pax;
+
+	a->pad_uncompressed = 1;
+	a->format_write_header = archive_write_pax_header;
+	a->format_write_data = archive_write_pax_data;
+	a->format_finish = archive_write_pax_finish;
+	a->format_finish_entry = archive_write_pax_finish_entry;
+	a->archive_format = ARCHIVE_FORMAT_TAR_PAX_INTERCHANGE;
+	a->archive_format_name = "POSIX pax interchange";
+	return (ARCHIVE_OK);
+}
+
+/*
+ * Note: This code assumes that 'nanos' has the same sign as 'sec',
+ * which implies that sec=-1, nanos=200000000 represents -1.2 seconds
+ * and not -0.8 seconds.  This is a pretty pedantic point, as we're
+ * unlikely to encounter many real files created before Jan 1, 1970,
+ * much less ones with timestamps recorded to sub-second resolution.
+ */
+static void
+add_pax_attr_time(struct archive_string *as, const char *key,
+    int64_t sec, unsigned long nanos)
+{
+	int digit, i;
+	char *t;
+	/*
+	 * Note that each byte contributes fewer than 3 base-10
+	 * digits, so this will always be big enough.
+	 */
+	char tmp[1 + 3*sizeof(sec) + 1 + 3*sizeof(nanos)];
+
+	tmp[sizeof(tmp) - 1] = 0;
+	t = tmp + sizeof(tmp) - 1;
+
+	/* Skip trailing zeros in the fractional part. */
+	for(digit = 0, i = 10; i > 0 && digit == 0; i--) {
+		digit = nanos % 10;
+		nanos /= 10;
+	}
+
+	/* Only format the fraction if it's non-zero. */
+	if (i > 0) {
+		while (i > 0) {
+			*--t = "0123456789"[digit];
+			digit = nanos % 10;
+			nanos /= 10;
+			i--;
+		}
+		*--t = '.';
+	}
+	t = format_int(t, sec);
+
+	add_pax_attr(as, key, t);
+}
+
+static char *
+format_int(char *t, int64_t i)
+{
+	int sign;
+
+	if (i < 0) {
+		sign = -1;
+		i = -i;
+	} else
+		sign = 1;
+
+	do {
+		*--t = "0123456789"[i % 10];
+	} while (i /= 10);
+	if (sign < 0)
+		*--t = '-';
+	return (t);
+}
+
+static void
+add_pax_attr_int(struct archive_string *as, const char *key, int64_t value)
+{
+	char tmp[1 + 3 * sizeof(value)];
+
+	tmp[sizeof(tmp) - 1] = 0;
+	add_pax_attr(as, key, format_int(tmp + sizeof(tmp) - 1, value));
+}
+
+/*
+ * Add a key/value attribute to the pax header.  This function handles
+ * the length field and various other syntactic requirements.
+ */
+static void
+add_pax_attr(struct archive_string *as, const char *key, const char *value)
+{
+	int digits, i, len, next_ten;
+	char tmp[1 + 3 * sizeof(int)];	/* < 3 base-10 digits per byte */
+
+	/*-
+	 * PAX attributes have the following layout:
+	 *     <len> <space> <key> <=> <value> <nl>
+	 */
+	len = 1 + strlen(key) + 1 + strlen(value) + 1;
+
+	/*
+	 * The <len> field includes the length of the <len> field, so
+	 * computing the correct length is tricky.  I start by
+	 * counting the number of base-10 digits in 'len' and
+	 * computing the next higher power of 10.
+	 */
+	next_ten = 1;
+	digits = 0;
+	i = len;
+	while (i > 0) {
+		i = i / 10;
+		digits++;
+		next_ten = next_ten * 10;
+	}
+	/*
+	 * For example, if string without the length field is 99
+	 * chars, then adding the 2 digit length "99" will force the
+	 * total length past 100, requiring an extra digit.  The next
+	 * statement adjusts for this effect.
+	 */
+	if (len + digits >= next_ten)
+		digits++;
+
+	/* Now, we have the right length so we can build the line. */
+	tmp[sizeof(tmp) - 1] = 0;	/* Null-terminate the work area. */
+	archive_strcat(as, format_int(tmp + sizeof(tmp) - 1, len + digits));
+	archive_strappend_char(as, ' ');
+	archive_strcat(as, key);
+	archive_strappend_char(as, '=');
+	archive_strcat(as, value);
+	archive_strappend_char(as, '\n');
+}
+
+/*
+ * TODO: Consider adding 'comment' and 'charset' fields to
+ * archive_entry so that clients can specify them.  Also, consider
+ * adding generic key/value tags so clients can add arbitrary
+ * key/value data.
+ */
+static int
+archive_write_pax_header(struct archive *a,
+    struct archive_entry *entry_original)
+{
+	struct archive_entry *entry_main;
+	const char *linkname, *name_start, *p;
+	int need_extension, oldstate, r, ret;
+	struct pax *pax;
+	const struct stat *st_main, *st_original;
+
+	struct archive_string pax_entry_name = EMPTY_ARCHIVE_STRING;
+	char paxbuff[512];
+	char ustarbuff[512];
+	char ustar_entry_name[256];
+
+	need_extension = 0;
+	pax = a->format_data;
+	pax->written = 1;
+
+	st_original = archive_entry_stat(entry_original);
+
+	/* Make sure this is a type of entry that we can handle here */
+	if (!archive_entry_hardlink(entry_original)) {
+		switch (st_original->st_mode & S_IFMT) {
+		case S_IFREG:
+		case S_IFLNK:
+		case S_IFCHR:
+		case S_IFBLK:
+		case S_IFDIR:
+		case S_IFIFO:
+			break;
+		case S_IFSOCK:
+			archive_set_error(a, -1,
+			    "tar format cannot archive socket");
+			return (ARCHIVE_WARN);
+		default:
+			archive_set_error(a, -1,
+			    "tar format cannot archive this");
+			return (ARCHIVE_WARN);
+		}
+	}
+
+	/* Copy entry so we can modify it as needed. */
+	entry_main = archive_entry_dup(entry_original);
+	archive_string_empty(&(pax->pax_header)); /* Blank our work area. */
+	st_main = archive_entry_stat(entry_main);
+
+	/*
+	 * Determining whether or not the name is too big is ugly
+	 * because of the rules for dividing names between 'name' and
+	 * 'prefix' fields.  Here, I pick out the longest possible
+	 * suffix, then test whether the remaining prefix is too long.
+	 */
+	p = archive_entry_pathname(entry_main);
+	if (strlen(p) <= 100)	/* Short enough for just 'name' field */
+		name_start = p;	/* Record a zero-length prefix */
+	else {
+		/* Find the largest suffix that fits in 'name' field. */
+		name_start = strchr(p + strlen(p) - 100 - 1, '/');
+		if (name_start == NULL)  /* No feasible break point. */
+			name_start =  p + strlen(p);
+	}
+
+	/* If name is too long, add 'path' to pax extended attrs. */
+	if (name_start - p > 155) {
+		add_pax_attr(&(pax->pax_header), "path", p);
+		archive_entry_set_pathname(entry_main,
+		    build_ustar_entry_name(ustar_entry_name, p));
+		need_extension = 1;
+	}
+
+	/* If link name is too long, add 'linkpath' to pax extended attrs. */
+	linkname = archive_entry_hardlink(entry_main);
+	if (linkname == NULL)
+		linkname = archive_entry_symlink(entry_main);
+
+	if (linkname != NULL && strlen(linkname) > 100) {
+		add_pax_attr(&(pax->pax_header), "linkpath", linkname);
+		if (archive_entry_hardlink(entry_main))
+			archive_entry_set_hardlink(entry_main,
+			    "././@LongHardLink");
+		else
+			archive_entry_set_symlink(entry_main,
+			    "././@LongSymLink");
+		need_extension = 1;
+	}
+
+	/* If file size is too large, add 'size' to pax extended attrs. */
+	if (st_main->st_size >= (1 << 30)) {
+		add_pax_attr_int(&(pax->pax_header), "size", st_main->st_size);
+		need_extension = 1;
+	}
+
+	/* If numeric GID is too large, add 'gid' to pax extended attrs. */
+	if (st_main->st_gid >= (1 << 20)) {
+		add_pax_attr_int(&(pax->pax_header), "gid", st_main->st_gid);
+		need_extension = 1;
+	}
+
+	/* If group name is too large, add 'gname' to pax extended attrs. */
+	/* TODO: If gname has non-ASCII characters, use pax attribute. */
+	p = archive_entry_gname(entry_main);
+	if (p != NULL && strlen(p) > 31) {
+		add_pax_attr(&(pax->pax_header), "gname", p);
+		archive_entry_set_gname(entry_main, NULL);
+		need_extension = 1;
+	}
+
+	/* If numeric UID is too large, add 'uid' to pax extended attrs. */
+	if (st_main->st_uid >= (1 << 20)) {
+		add_pax_attr_int(&(pax->pax_header), "uid", st_main->st_uid);
+		need_extension = 1;
+	}
+
+	/* If user name is too large, add 'uname' to pax extended attrs. */
+	/* TODO: If uname has non-ASCII characters, use pax attribute. */
+	p = archive_entry_uname(entry_main);
+	if (p != NULL && strlen(p) > 31) {
+		add_pax_attr(&(pax->pax_header), "uname", p);
+		archive_entry_set_uname(entry_main, NULL);
+		need_extension = 1;
+	}
+
+	/*
+	 * POSIX/SUSv3 doesn't provide a standard key for large device
+	 * numbers.  I use the same keys here that Joerg Schilling used for
+	 * 'star.'  No doubt, other implementations use other keys.  Note that
+	 * there's no reason we can't write the same information into a number
+	 * of different keys.
+	 *
+	 * Of course, this is only needed for block or char device entries.
+	 */
+	if (S_ISBLK(st_main->st_mode) ||
+	    S_ISCHR(st_main->st_mode)) {
+		/*
+		 * If devmajor is too large, add 'SCHILY.devmajor' to
+		 * extended attributes.
+		 */
+		dev_t devmajor, devminor;
+		devmajor = major(st_main->st_rdev);
+		devminor = minor(st_main->st_rdev);
+		if (devmajor >= (1 << 18)) {
+			add_pax_attr_int(&(pax->pax_header), "SCHILY.devmajor",
+			    devmajor);
+			archive_entry_set_devmajor(entry_main, (1 << 18) - 1);
+			need_extension = 1;
+		}
+
+		/*
+		 * If devminor is too large, add 'SCHILY.devminor' to
+		 * extended attributes.
+		 */
+		if (devminor >= (1 << 18)) {
+			add_pax_attr_int(&(pax->pax_header), "SCHILY.devminor",
+			    devminor);
+			archive_entry_set_devminor(entry_main, (1 << 18) - 1);
+			need_extension = 1;
+		}
+	}
+
+	/*
+	 * Technically, the mtime field in the ustar header can
+	 * support 33 bits, but many platforms use signed 32-bit time
+	 * values.  The cutoff of 0x7fffffff here is a compromise.
+	 * Yes, this check is duplicated just below; this helps to
+	 * avoid writing an mtime attribute just to handle a
+	 * high-resolution timestamp in "restricted pax" mode.
+	 */
+	if ((st_main->st_mtime < 0) || (st_main->st_mtime >= 0x7fffffff))
+		need_extension = 1;
+
+	/*
+	 * The following items are handled differently in "pax
+	 * restricted" format.  In particular, in "pax restricted"
+	 * format they won't be added unless need_extension is
+	 * already set (we're already generated an extended header, so
+	 * may as well include these).
+	 */
+	if (a->archive_format != ARCHIVE_FORMAT_TAR_PAX_RESTRICTED ||
+	    need_extension) {
+
+		if (st_main->st_mtime < 0  ||
+		    st_main->st_mtime >= 0x7fffffff  ||
+		    st_main->st_mtimespec.tv_nsec != 0)
+			add_pax_attr_time(&(pax->pax_header), "mtime",
+			    st_main->st_mtime, st_main->st_mtimespec.tv_nsec);
+
+		if (st_main->st_ctimespec.tv_nsec != 0 ||
+		    st_main->st_ctime != 0)
+			add_pax_attr_time(&(pax->pax_header), "ctime",
+			    st_main->st_ctime, st_main->st_ctimespec.tv_nsec);
+
+		if (st_main->st_atimespec.tv_nsec != 0 ||
+		    st_main->st_atime != 0)
+			add_pax_attr_time(&(pax->pax_header), "atime",
+			    st_main->st_atime, st_main->st_atimespec.tv_nsec);
+
+		/* I use a star-compatible file flag attribute. */
+		p = archive_entry_fflags(entry_main);
+		if (p != NULL  &&  *p != '\0')
+			add_pax_attr(&(pax->pax_header), "SCHILY.fflags", p);
+
+		/* I use star-compatible ACL attributes. */
+		p = archive_entry_acl(entry_main);
+		if (p != NULL && *p != '\0')
+			add_pax_attr(&(pax->pax_header), "SCHILY.acl.access", p);
+		p = archive_entry_acl_default(entry_main);
+		if (p != NULL && *p != '\0')
+			add_pax_attr(&(pax->pax_header), "SCHILY.acl.default",
+			    p);
+
+		/* Include star-compatible metadata info. */
+		add_pax_attr_int(&(pax->pax_header), "SCHILY.dev",
+		    st_main->st_dev);
+		add_pax_attr_int(&(pax->pax_header), "SCHILY.ino",
+		    st_main->st_ino);
+		add_pax_attr_int(&(pax->pax_header), "SCHILY.nlink",
+		    st_main->st_nlink);
+	}
+
+	/* Format 'ustar' header for main entry. */
+	/* We don't care if this returns an error. */
+	__archive_write_format_header_ustar(a, ustarbuff, entry_main);
+
+	/* If we built any extended attributes, write that entry first. */
+	ret = 0;
+	if (archive_strlen(&(pax->pax_header)) > 0) {
+		struct stat st;
+		struct archive_entry *pax_attr_entry;
+		const char *pax_attr_name;
+
+		memset(&st, 0, sizeof(st));
+		pax_attr_entry = archive_entry_new();
+		p = archive_entry_pathname(entry_main);
+		pax_attr_name = build_pax_attribute_name(p, &pax_entry_name);
+
+		archive_entry_set_tartype(pax_attr_entry, 'x');
+		archive_entry_set_pathname(pax_attr_entry, pax_attr_name);
+		st.st_size = archive_strlen(&(pax->pax_header));
+		st.st_uid = st_main->st_uid;
+		st.st_gid = st_main->st_gid;
+		st.st_mode = st_main->st_mode;
+		archive_entry_copy_stat(pax_attr_entry, &st);
+
+		archive_entry_set_uname(pax_attr_entry,
+		    archive_entry_uname(entry_main));
+		archive_entry_set_gname(pax_attr_entry,
+		    archive_entry_gname(entry_main));
+
+		ret = __archive_write_format_header_ustar(a, paxbuff,
+		    pax_attr_entry);
+
+		archive_entry_free(pax_attr_entry);
+		free(pax_entry_name.s);
+
+		/* Note that the 'x' header shouldn't ever fail to format */
+		if (ret != 0) {
+			const char *msg = "archive_write_header_pax: "
+			    "'x' header failed?!  This can't happen.\n";
+			write(2, msg, strlen(msg));
+			exit(1);
+		}
+		r = (a->compression_write)(a, paxbuff, 512);
+		if (r < 512) {
+			pax->entry_bytes_remaining = 0;
+			pax->entry_padding = 0;
+			return (ARCHIVE_FATAL);
+		}
+
+		pax->entry_bytes_remaining = archive_strlen(&(pax->pax_header));
+		pax->entry_padding = 0x1ff & (- pax->entry_bytes_remaining);
+
+		oldstate = a->state;
+		a->state = ARCHIVE_STATE_DATA;
+		r = archive_write_data(a, pax->pax_header.s,
+		    archive_strlen(&(pax->pax_header)));
+		a->state = oldstate;
+		if (r < (int)archive_strlen(&(pax->pax_header))) {
+			/* If a write fails, we're pretty much toast. */
+			return (ARCHIVE_FATAL);
+		}
+
+		archive_write_pax_finish_entry(a);
+	}
+
+	/* Write the header for main entry. */
+	r = (a->compression_write)(a, ustarbuff, 512);
+	if (ret != ARCHIVE_OK)
+		ret = (r < 512) ? ARCHIVE_FATAL : ARCHIVE_OK;
+
+	/* Only regular files have data.  Note that pax, unlike ustar,
+	 * does permit a hardlink to have data associated with it. */
+	if (!S_ISREG(archive_entry_mode(entry_main)))
+		pax->entry_bytes_remaining = 0;
+	else
+		pax->entry_bytes_remaining = archive_entry_size(entry_main);
+
+	pax->entry_padding = 0x1ff & (- pax->entry_bytes_remaining);
+	archive_entry_free(entry_main);
+
+	return (ret);
+}
+
+/*
+ * We need a valid name for the regular 'ustar' entry.  This routine
+ * tries to hack something more-or-less reasonable.
+ */
+static char *
+build_ustar_entry_name(char *dest, const char *src)
+{
+	const char *basename, *break_point, *prefix;
+	int basename_length, dirname_length, prefix_length;
+
+	prefix = src;
+	basename = strrchr(src, '/');
+	if (basename == NULL) {
+		basename = src;
+		prefix_length = 0;
+		basename_length = strlen(basename);
+		if (basename_length > 100)
+			basename_length = 100;
+	} else {
+		basename_length = strlen(basename);
+		if (basename_length > 100)
+			basename_length = 100;
+		dirname_length = basename - src;
+
+		break_point =
+		    strchr(src + dirname_length + basename_length - 101, '/');
+		prefix_length = break_point - prefix - 1;
+		while (prefix_length > 155) {
+			prefix = strchr(prefix, '/') + 1; /* Drop 1st dir. */
+			prefix_length = break_point - prefix - 1;
+		}
+	}
+
+	strlcpy(dest, prefix, basename - prefix + 1 + basename_length);
+
+	return (dest);
+}
+
+/*
+ * The ustar header for the pax extended attributes must have a
+ * reasonable name:  SUSv3 suggests 'dirname'/PaxHeaders/'basename'
+ *
+ * Joerg Schiling has argued that this is unnecessary because, in practice,
+ * if the pax extended attributes get extracted as regular files, noone is
+ * going to bother reading those attributes to manually restore them.
+ * This is a tempting argument, but I'm not entirely convinced.
+ *
+ * Of course, adding "PaxHeaders/" might force the name to be too big.
+ * Here, I start from the (possibly already-trimmed) name used in the
+ * main ustar header and delete some additional early path elements to
+ * fit in the extra "PaxHeader/" part.
+ */
+static char *
+build_pax_attribute_name(const char *abbreviated, /* ustar-compat name */
+    struct archive_string *work)
+{
+	const char *basename, *break_point, *prefix;
+	int prefix_length, suffix_length;
+
+	/*
+	 * This is much simpler because I know that "abbreviated" is
+	 * already small enough; I just need to determine if it needs
+	 * any further trimming to fit the "PaxHeader/" portion.
+	 */
+
+	/* Identify the final prefix and suffix portions. */
+	prefix = abbreviated;	/* First guess: prefix starts at beginning */
+	if (strlen(abbreviated) > 100) {
+		break_point = strchr(prefix + strlen(prefix) - 101, '/');
+		prefix_length = break_point - prefix - 1;
+		suffix_length = strlen(break_point + 1);
+		/*
+		 * The next loop keeps trimming until "/PaxHeader/" can
+		 * be added to either the prefix or the suffix.
+		 */
+		while (prefix_length > 144 && suffix_length > 89) {
+			prefix = strchr(prefix, '/') + 1; /* Drop 1st dir. */
+			prefix_length = break_point - prefix - 1;
+		}
+	}
+
+	archive_string_empty(work);
+	basename = strrchr(prefix, '/');
+	if (basename == NULL) {
+		archive_strcpy(work, "PaxHeader/");
+		archive_strcat(work, prefix);
+	} else {
+		basename++;
+		archive_strncpy(work, prefix, basename - prefix);
+		archive_strcat(work, "PaxHeader/");
+		archive_strcat(work, basename);
+	}
+
+	return (work->s);
+}
+
+/* Write two null blocks for the end of archive */
+static int
+archive_write_pax_finish(struct archive *a)
+{
+	struct pax *pax;
+	pax = a->format_data;
+	if (pax->written && a->compression_write != NULL)
+		return (write_nulls(a, 512 * 2));
+	free(pax);
+	a->format_data = NULL;
+	return (ARCHIVE_OK);
+}
+
+static int
+archive_write_pax_finish_entry(struct archive *a)
+{
+	struct pax *pax;
+	int ret;
+
+	pax = a->format_data;
+	ret = write_nulls(a, pax->entry_bytes_remaining + pax->entry_padding);
+	pax->entry_bytes_remaining = pax->entry_padding = 0;
+	return (ret);
+}
+
+static int
+write_nulls(struct archive *a, size_t padding)
+{
+	int ret, to_write;
+
+	while (padding > 0) {
+		to_write = padding < a->null_length ? padding : a->null_length;
+		ret = (a->compression_write)(a, a->nulls, to_write);
+		if (ret <= 0)
+			return (ARCHIVE_FATAL);
+		padding -= ret;
+	}
+	return (ARCHIVE_OK);
+}
+
+static int
+archive_write_pax_data(struct archive *a, const void *buff, size_t s)
+{
+	struct pax *pax;
+	int ret;
+
+	pax = a->format_data;
+	pax->written = 1;
+	if (s > pax->entry_bytes_remaining)
+		s = pax->entry_bytes_remaining;
+
+	ret = (a->compression_write)(a, buff, s);
+	pax->entry_bytes_remaining -= s;
+	return (ret);
+}