1ARCHIVE_UTIL(3)          BSD Library Functions Manual          ARCHIVE_UTIL(3)
2

NAME

4     archive_clear_error, archive_compression, archive_compression_name,
5     archive_copy_error, archive_errno, archive_error_string,
6     archive_file_count, archive_filter_code, archive_filter_count,
7     archive_filter_name, archive_format, archive_format_name,
8     archive_position, archive_set_error — libarchive utility functions
9

LIBRARY

11     Streaming Archive Library (libarchive, -larchive)
12

SYNOPSIS

14     #include <archive.h>
15
16     void
17     archive_clear_error(struct archive *);
18
19     int
20     archive_compression(struct archive *);
21
22     const char *
23     archive_compression_name(struct archive *);
24
25     void
26     archive_copy_error(struct archive *, struct archive *);
27
28     int
29     archive_errno(struct archive *);
30
31     const char *
32     archive_error_string(struct archive *);
33
34     int
35     archive_file_count(struct archive *);
36
37     int
38     archive_filter_code(struct archive *, int);
39
40     int
41     archive_filter_count(struct archive *, int);
42
43     const char *
44     archive_filter_name(struct archive *, int);
45
46     int
47     archive_format(struct archive *);
48
49     const char *
50     archive_format_name(struct archive *);
51
52     int64_t
53     archive_position(struct archive *, int);
54
55     void
56     archive_set_error(struct archive *, int error_code, const char *fmt,
57         ...);
58

DESCRIPTION

60     These functions provide access to various information about the struct
61     archive object used in the libarchive(3) library.
62     archive_clear_error()
63             Clears any error information left over from a previous call.  Not
64             generally used in client code.
65     archive_compression()
66             Synonym for archive_filter_code(a,(0)).
67     archive_compression_name()
68             Synonym for archive_filter_name(a,(0)).
69     archive_copy_error()
70             Copies error information from one archive to another.
71     archive_errno()
72             Returns a numeric error code (see errno(2)) indicating the reason
73             for the most recent error return.  Note that this can not be
74             reliably used to detect whether an error has occurred.  It should
75             be used only after another libarchive function has returned an
76             error status.
77     archive_error_string()
78             Returns a textual error message suitable for display.  The error
79             message here is usually more specific than that obtained from
80             passing the result of archive_errno() to strerror(3).
81     archive_file_count()
82             Returns a count of the number of files processed by this archive
83             object.  The count is incremented by calls to
84             archive_write_header(3) or archive_read_next_header(3).
85     archive_filter_code()
86             Returns a numeric code identifying the indicated filter.  See
87             archive_filter_count() for details of the numbering.
88     archive_filter_count()
89             Returns the number of filters in the current pipeline.  For read
90             archive handles, these filters are added automatically by the
91             automatic format detection.  For write archive handles, these
92             filters are added by calls to the various
93             archive_write_add_filter_XXX() functions.  Filters in the result‐
94             ing pipeline are numbered so that filter 0 is the filter closest
95             to the format handler.  As a convenience, functions that expect a
96             filter number will accept -1 as a synonym for the highest-num‐
97             bered filter.
98
99             For example, when reading a uuencoded gzipped tar archive, there
100             are three filters: filter 0 is the gunzip filter, filter 1 is the
101             uudecode filter, and filter 2 is the pseudo-filter that wraps the
102             archive read functions.  In this case, requesting
103             archive_position(a,(-1)) would be a synonym for
104             archive_position(a,(2)) which would return the number of bytes
105             currently read from the archive, while archive_position(a,(1))
106             would return the number of bytes after uudecoding, and
107             archive_position(a,(0)) would return the number of bytes after
108             decompression.
109     archive_filter_name()
110             Returns a textual name identifying the indicated filter.  See
111             archive_filter_count() for details of the numbering.
112     archive_format()
113             Returns a numeric code indicating the format of the current ar‐
114             chive entry.  This value is set by a successful call to
115             archive_read_next_header().  Note that it is common for this
116             value to change from entry to entry.  For example, a tar archive
117             might have several entries that utilize GNU tar extensions and
118             several entries that do not.  These entries will have different
119             format codes.
120     archive_format_name()
121             A textual description of the format of the current entry.
122     archive_position()
123             Returns the number of bytes read from or written to the indicated
124             filter.  In particular, archive_position(a,(0)) returns the num‐
125             ber of bytes read or written by the format handler, while
126             archive_position(a,(-1)) returns the number of bytes read or
127             written to the archive.  See archive_filter_count() for details
128             of the numbering here.
129     archive_set_error()
130             Sets the numeric error code and error description that will be
131             returned by archive_errno() and archive_error_string().  This
132             function should be used within I/O callbacks to set system-spe‐
133             cific error codes and error descriptions.  This function accepts
134             a printf-like format string and arguments.  However, you should
135             be careful to use only the following printf format specifiers:
136             “%c”, “%d”, “%jd”, “%jo”, “%ju”, “%jx”, “%ld”, “%lo”, “%lu”,
137             “%lx”, “%o”, “%u”, “%s”, “%x”, “%%”.  Field-width specifiers and
138             other printf features are not uniformly supported and should not
139             be used.
140

SEE ALSO

142     archive_read(3), archive_write(3), libarchive(3), printf(3)
143

HISTORY

145     The libarchive library first appeared in FreeBSD 5.3.
146

AUTHORS

148     The libarchive library was written by Tim Kientzle <kientzle@acm.org>.
149
150BSD                            February 2, 2012                            BSD
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