NAME

     archive_clear_error, archive_compression, archive_compression_name, archive_copy_error,
     archive_errno, archive_error_string, archive_file_count, archive_filter_code,
     archive_filter_count, archive_filter_name, archive_format, archive_format_name,
     archive_position, archive_set_error — libarchive utility functions

LIBRARY

     Streaming Archive Library (libarchive, -larchive)

SYNOPSIS

     #include <archive.h>

     void
     archive_clear_error(struct archive *);

     int
     archive_compression(struct archive *);

     const char *
     archive_compression_name(struct archive *);

     void
     archive_copy_error(struct archive *, struct archive *);

     int
     archive_errno(struct archive *);

     const char *
     archive_error_string(struct archive *);

     int
     archive_file_count(struct archive *);

     int
     archive_filter_code(struct archive *, int);

     int
     archive_filter_count(struct archive *, int);

     const char *
     archive_filter_name(struct archive *, int);

     int
     archive_format(struct archive *);

     const char *
     archive_format_name(struct archive *);

     int64_t
     archive_position(struct archive *, int);

     void
     archive_set_error(struct archive *, int error_code, const char *fmt, ...);

DESCRIPTION

     These functions provide access to various information about the struct archive object used
     in the libarchive(3) library.
     archive_clear_error()
             Clears any error information left over from a previous call.  Not generally used in
             client code.
     archive_compression()
             Synonym for archive_filter_code(a,(0)).
     archive_compression_name()
             Synonym for archive_filter_name(a,(0)).
     archive_copy_error()
             Copies error information from one archive to another.
     archive_errno()
             Returns a numeric error code (see errno(2)) indicating the reason for the most
             recent error return.  Note that this can not be reliably used to detect whether an
             error has occurred.  It should be used only after another libarchive function has
             returned an error status.
     archive_error_string()
             Returns a textual error message suitable for display.  The error message here is
             usually more specific than that obtained from passing the result of archive_errno()
             to strerror(3).
     archive_file_count()
             Returns a count of the number of files processed by this archive object.  The count
             is incremented by calls to archive_write_header(3) or archive_read_next_header(3).
     archive_filter_code()
             Returns a numeric code identifying the indicated filter.  See archive_filter_count()
             for details of the numbering.
     archive_filter_count()
             Returns the number of filters in the current pipeline.  For read archive handles,
             these filters are added automatically by the automatic format detection.  For write
             archive handles, these filters are added by calls to the various
             archive_write_add_filter_XXX() functions.  Filters in the resulting pipeline are
             numbered so that filter 0 is the filter closest to the format handler.  As a
             convenience, functions that expect a filter number will accept -1 as a synonym for
             the highest-numbered filter.

             For example, when reading a uuencoded gzipped tar archive, there are three filters:
             filter 0 is the gunzip filter, filter 1 is the uudecode filter, and filter 2 is the
             pseudo-filter that wraps the archive read functions.  In this case, requesting
             archive_position(a,(-1)) would be a synonym for archive_position(a,(2)) which would
             return the number of bytes currently read from the archive, while
             archive_position(a,(1)) would return the number of bytes after uudecoding, and
             archive_position(a,(0)) would return the number of bytes after decompression.
     archive_filter_name()
             Returns a textual name identifying the indicated filter.  See archive_filter_count()
             for details of the numbering.
     archive_format()
             Returns a numeric code indicating the format of the current archive entry.  This
             value is set by a successful call to archive_read_next_header().  Note that it is
             common for this value to change from entry to entry.  For example, a tar archive
             might have several entries that utilize GNU tar extensions and several entries that
             do not.  These entries will have different format codes.
     archive_format_name()
             A textual description of the format of the current entry.
     archive_position()
             Returns the number of bytes read from or written to the indicated filter.  In
             particular, archive_position(a,(0)) returns the number of bytes read or written by
             the format handler, while archive_position(a,(-1)) returns the number of bytes read
             or written to the archive.  See archive_filter_count() for details of the numbering
             here.
     archive_set_error()
             Sets the numeric error code and error description that will be returned by
             archive_errno() and archive_error_string().  This function should be used within I/O
             callbacks to set system-specific error codes and error descriptions.  This function
             accepts a printf-like format string and arguments.  However, you should be careful
             to use only the following printf format specifiers: “%c”, “%d”, “%jd”, “%jo”, “%ju”,
             “%jx”, “%ld”, “%lo”, “%lu”, “%lx”, “%o”, “%u”, “%s”, “%x”, “%%”.  Field-width
             specifiers and other printf features are not uniformly supported and should not be
             used.

SEE ALSO

     archive_read(3), archive_write(3), libarchive(3), printf(3)

HISTORY

     The libarchive library first appeared in FreeBSD 5.3.

AUTHORS

     The libarchive library was written by Tim Kientzle <kientzle@acm.org>.