retro-imager/dependencies/libarchive-3.5.2/doc/text/archive_util.3.txt

ARCHIVE_UTIL(3) 	 BSD Library Functions Manual	       ARCHIVE_UTIL(3)

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 re‐
	     liably 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 au‐
	     tomatic format detection.	For write archive handles, these fil‐
	     ters are added by calls to the various
	     archive_write_add_filter_XXX() functions.	Filters in the result‐
	     ing 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-num‐
	     bered 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 de‐
	     compression.
     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 ar‐
	     chive 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 writ‐
	     ten 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-spe‐
	     cific 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>.

BSD			       February 2, 2012 			   BSD