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
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