1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
|
.\" gd_alter_encoding.3.in. The gd_alter_encoding man page.
.\"
.\" @configure_input@
.\"
.\" Copyright (C) 2008, 2009, 2010, 2014, 2016 D. V. Wiebe
.\"
.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
.\"
.\" This file is part of the GetData project.
.\"
.\" Permission is granted to copy, distribute and/or modify this document
.\" under the terms of the GNU Free Documentation License, Version 1.2 or
.\" any later version published by the Free Software Foundation; with no
.\" Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
.\" Texts. A copy of the license is included in the `COPYING.DOC' file
.\" as part of this distribution.
.\"
.TH gd_alter_encoding 3 "25 December 2016" "Version 0.10.0" "GETDATA"
.SH NAME
gd_alter_encoding \(em modify the binary encoding of data in a Dirfile
.SH SYNOPSIS
.SC
.B #include <getdata.h>
.HP
.BI "int gd_alter_encoding(DIRFILE *" dirfile ", unsigned int " encoding ,
.BI "int " fragment_index ", int " recode );
.EC
.SH DESCRIPTION
The
.FN gd_alter_encoding
function sets the binary encoding of the format specification fragment given by
.ARG fragment_index
to the encoding specified by
.ARG encoding
in the dirfile(5) database specified by
.ARG dirfile .
The binary encoding of a fragment indicate the encoding of data stored in binary
files associated with
.B RAW
fields defined in the specified fragment. The binary encoding of a fragment containing
no
.B RAW
fields is ignored.
The
.ARG encoding
argument should be one of the following symbols:
.IP
.SC
.BR GD_UNENCODED ,
.BR GD_BZIP2_ENCODED ,
.BR GD_FLAC_ENCODED ,
.BR GD_GZIP_ENCODED ,
.BR GD_LZMA_ENCODED ,
.BR GD_SLIM_ENCODED ,
.BR GD_SIE_ENCODED ,
.BR GD_TEXT_ENCODED .
.EC
.PP
See
.F3 gd_open
and dirfile-encoding(5) for the meanings of these symbols and details on the
supported encoding schemes.
.PP
In addition to being simply a valid fragment index,
.ARG fragment_index
may also be the special value
.BR GD_ALL_FRAGMENTS ,
which indicates that the encoding of all fragments in the database should
be changed.
If the
.ARG recode
argument is non-zero, this call will recode the binary data of affected
.B RAW
fields to account for the change in binary encoding. If the encoding of the
fragment is encoding insensitive, or if the data type is only one byte in
size, no change is made. The I/O pointer of all affected
.B RAW
fields is reset to the beginning-of-frame.
If
.ARG recode
is zero, affected binary files are left untouched.
.SH RETURN VALUE
Upon successful completion,
.FN gd_alter_encoding
returns zero. On error, it returns a negative-valued error code. Possible
error codes are:
.DD GD_E_ACCMODE
The specified dirfile was opened read-only.
.DD GD_E_ALLOC
The library was unable to allocate memory.
.DD GD_E_BAD_DIRFILE
The supplied dirfile was invalid.
.DD GD_E_BAD_INDEX
The supplied index was out of range.
.DD GD_E_IO
An I/O error occurred while attempting to recode a binary file.
.DD GD_E_PROTECTED
The metadata of the given format specification fragment was protected from
change, or the binary data of the fragment was protected from change and binary
file recoding was requested.
.DD GD_E_UNCLEAN_DB
An error occurred while moving the recoded file into place. As a result, the
database may be in an unclean state. See the
.B NOTES
section below for recovery instructions. In this case, the dirfile will be
flagged as invalid, to prevent further database corruption. It should be
immediately closed.
.DD GD_E_UNKNOWN_ENCODING
The encoding scheme of the fragment is unknown.
.DD GD_E_UNSUPPORTED
The encoding scheme of the fragment does not support binary file recoding.
.PP
The error code is also stored in the
.B DIRFILE
object and may be retrieved after this function returns by calling
.F3 gd_error .
A descriptive error string for the error may be obtained by calling
.F3 gd_error_string .
.SH NOTES
A binary file recoding occurs out-of-place. As a result, sufficient space
must be present on the filesystem for the binary files of all
.B RAW
fields in the fragment both before and after translation. If all fragments
are updated by specifying
.BR GD_ALL_FRAGMENTS ,
the recoding occurs one fragment at a time.
An error code of
.B GD_E_UNCLEAN_DB
indicates a system error occurred while moving the re-encoded binary data into
place or when deleting the old data. If this happens, the database may be left
in an unclean state. The caller should check the filesystem directly to
ascertain the state of the dirfile data before continuing. For recovery
instructions, see the file
@absolute_docdir@/unclean_database_recovery.txt.
.SH HISTORY
The function
.FN dirfile_alter_encoding
appeared in GetData-0.5.0.
In GetData-0.7.0, this function was renamed to
.FN gd_alter_encoding .
in GetData-0.10.0, the error return from this function changed from -1 to
a negative-valued error code.
.SH SEE ALSO
.F3 gd_error ,
.F3 gd_error_string ,
.F3 gd_encoding ,
.F3 gd_open ,
dirfile(5),
dirfile-format(5)
|
