libarchive_changes man page

— changes in libarchive interface

Changes in Libarchive 3

This page describes user-visible changes in libarchive3, and lists public functions and other symbols changed, deprecated or removed in libarchive3, along with their replacements if any.

Multiple Filters

Libarchive2 permitted a single (input or output) filter active on an archive. Libarchive3 extends this into a variable-length stack. Where archive_write_set_compression_XXX() would replace any existing filter, archive_write_add_filter_XXX() extends the write pipeline with another filter.

Character Set Handling

Libarchive2 assumed that the local platform uses Unicode as the native wchar_t encoding, which is true on Windows, modern Linux, and a few other systems, but is certainly not universal. As a result, pax format archives were written incorrectly on some systems, since pax format requires UTF-8 and libarchive 2 incorrectly assumed that wchar_t strings can be easily converted to UTF-8.

Libarchive3 uses the standard iconv library to convert between character sets and is introducing the notion of a “default character set for the archive”. To support this, archive_entry objects can now be bound to a particular archive when they are created. The automatic character set conversions performed by archive_entry objects when reading and writing filenames, usernames, and other strings will now use an appropriate default character set:

If the archive_entry object is bound to an archive, it will use the default character set for that archive.

The platform default character encoding (as returned by nl_langinfo(CHARSET)) will be used if nothing else is specified.

Libarchive3 also introduces charset options to many of the archive readers and writers to control the character set that will be used for filenames written in those archives. When possible, this will be set automatically based on information in the archive itself. Combining this with the notion of a default character set for the archive should allow you to configure libarchive to read archives from other platforms and have the filenames and other information transparently converted to the character encoding suitable for your application.

Prototype Changes

These changes break binary compatibility; libarchive3 has a new shared library version to reflect these changes. The library now uses portable wide types such as int64_t instead of less-portable types such as off_t, gid_t, uid_t, and ino_t.

There are a few cases where these changes will affect your source code:

  • In some cases, libarchive's wider types will introduce the possibility of truncation: for example, on a system with a 16-bit uid_t, you risk having uid 65536 be truncated to uid 0, which can cause serious security problems.
  • Typedef function pointer types will be incompatible. For example, if you define custom skip callbacks, you may have to use code similar to the following if you want to support building against libarchive2 and libarchive3:

    #if ARCHIVE_VERSION_NUMBER < 3000000 
    typedef off_t myoff_t; 
    #else 
    typedef int64_t myoff_t; 
    #endif 
     
    myoff_t 
    my_skip_function(struct archive *a, void *v, myoff_t o) 
    { 
        ... implementation ... 
    }

Affected functions:

  • archive_entry_gid(), archive_entry_set_gid()
  • archive_entry_uid(), archive_entry_set_uid()
  • archive_entry_ino(), archive_entry_set_ino()
  • archive_read_data_block(), archive_write_data_block()
  • archive_read_disk_gname(), archive_read_disk_uname()
  • archive_read_disk_set_gname_lookup(), archive_read_disk_set_group_lookup(), archive_read_disk_set_uname_lookup(), archive_read_disk_set_user_lookup()
  • archive_skip_callback()
  • archive_read_extract_set_skip_file(), archive_write_disk_set_skip_file(), archive_write_set_skip_file()
  • archive_write_disk_set_group_lookup(), archive_write_disk_set_user_lookup()

Where these functions or their arguments took or returned gid_t, ino_t, off_t, or uid_t they now take or return int64_t or equivalent.

Deprecated Symbols

Symbols deprecated in libarchive3 will be removed in libarchive4. These symbols, along with their replacements if any, are listed below:

archive_position_compressed(), archive_position_uncompressed()
archive_filter_bytes()
archive_compression()
archive_filter_code()
archive_compression_name()
archive_filter_name()
archive_read_finish(), archive_write_finish()
archive_read_free(), archive_write_free()
archive_read_open_file(), archive_write_open_file()
archive_read_open_filename(), archive_write_open_filename()
archive_read_support_compression_all()
archive_read_support_filter_all()
archive_read_support_compression_bzip2()
archive_read_support_filter_bzip2()
archive_read_support_compression_compress()
archive_read_support_filter_compress()
archive_read_support_compression_gzip()
archive_read_support_filter_gzip()
archive_read_support_compression_lzip()
archive_read_support_filter_lzip()
archive_read_support_compression_lzma()
archive_read_support_filter_lzma()
archive_read_support_compression_none()
archive_read_support_filter_none()
archive_read_support_compression_program()
archive_read_support_filter_program()
archive_read_support_compression_program_signature()
archive_read_support_filter_program_signature()
archive_read_support_compression_rpm()
archive_read_support_filter_rpm()
archive_read_support_compression_uu()
archive_read_support_filter_uu()
archive_read_support_compression_xz()
archive_read_support_filter_xz()
archive_write_set_compression_bzip2()
archive_write_add_filter_bzip2()
archive_write_set_compression_compress()
archive_write_add_filter_compress()
archive_write_set_compression_gzip()
archive_write_add_filter_gzip()
archive_write_set_compression_lzip()
archive_write_add_filter_lzip()
archive_write_set_compression_lzma()
archive_write_add_filter_lzma()
archive_write_set_compression_none()
archive_write_add_filter_none()
archive_write_set_compression_program()
archive_write_add_filter_program()
archive_write_set_compression_filter()
archive_write_add_filter_filter()

Removed Symbols

These symbols, listed below along with their replacements if any, were deprecated in libarchive2, and are not part of libarchive3.

archive_api_feature()
archive_version_number()
archive_api_version()
archive_version_number()
archive_version()
archive_version_string()
archive_version_stamp()
archive_version_number()
archive_read_set_filter_options()
archive_read_set_options() or archive_read_set_filter_option()
archive_read_set_format_options()
archive_read_set_options() or archive_read_set_format_option()
archive_write_set_filter_options()
archive_write_set_options() or archive_write_set_filter_option()
archive_write_set_format_options()
archive_write_set_options() or archive_write_set_format_option()
ARCHIVE_API_FEATURE
ARCHIVE_VERSION_NUMBER
ARCHIVE_API_VERSION
ARCHIVE_VERSION_NUMBER
ARCHIVE_VERSION_STAMP
ARCHIVE_VERSION_NUMBER
ARCHIVE_LIBRARY_VERSION
ARCHIVE_VERSION_STRING
ARCHIVE_COMPRESSION_NONE
ARCHIVE_FILTER_NONE
ARCHIVE_COMPRESSION_GZIP
ARCHIVE_FILTER_GZIP
ARCHIVE_COMPRESSION_BZIP2
ARCHIVE_FILTER_BZIP2
ARCHIVE_COMPRESSION_COMPRESS
ARCHIVE_FILTER_COMPRESS
ARCHIVE_COMPRESSION_PROGRAM
ARCHIVE_FILTER_PROGRAM
ARCHIVE_COMPRESSION_LZMA
ARCHIVE_FILTER_LZMA
ARCHIVE_COMPRESSION_XZ
ARCHIVE_FILTER_XZ
ARCHIVE_COMPRESSION_UU
ARCHIVE_FILTER_UU
ARCHIVE_COMPRESSION_RPM
ARCHIVE_FILTER_RPM
ARCHIVE_COMPRESSION_LZIP
ARCHIVE_FILTER_LZIP
ARCHIVE_BYTES_PER_RECORD
512
ARCHIVE_DEFAULT_BYTES_PER_BLOCK
10240

See Also

libarchive(3), archive_read(3), archive_read_filter(3), archive_read_format(3), archive_read_set_options(3), archive_write(3), archive_write_filter(3), archive_write_format(3), archive_write_set_options(3), archive_util(3)

Info

December 23, 2011