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
|
=head1 NAME
nbdkit_realpath,
nbdkit_absolute_path - convert relative to absolute paths for nbdkit
=head1 SYNOPSIS
#include <nbdkit-plugin.h>
char *nbdkit_realpath (const char *filename);
char *nbdkit_absolute_path (const char *filename);
=head1 DESCRIPTION
L<nbdkit(1)> usually (not always) changes directory to F</> before it
starts serving connections. This means that any relative paths passed
during configuration will not work when the server is running. In a
naive implementation of a plugin, a configuration like
nbdkit plugin file=disk.img
might attempt to open F</disk.img> instead of the file in the user's
current directory.
To avoid this problem, you can:
=over 4
=item *
convert relative paths to absolute paths using one of the functions
described here, or
=item *
open the file at configure time and store the file descriptor.
=back
=head2 nbdkit_realpath
The utility function C<nbdkit_realpath> converts any path to an
absolute path, resolving symlinks. Under the hood it uses the
L<realpath(3)> function, and thus it fails if the path does not exist,
or it is not possible to access components of the path.
This function works I<only> when used in the C<.config>,
C<.config_complete> and C<.get_ready> callbacks.
=head2 nbdkit_absolute_path
The utility function C<nbdkit_absolute_path> converts any path to an
absolute path: if it is relative, then all this function does is
prepend the current working directory to the path, with no extra
checks.
Unlike C<nbdkit_realpath>, this function does not check that the file
exists.
This function works I<only> when used in the C<.config>,
C<.config_complete> and C<.get_ready> callbacks.
=head1 RETURN VALUE
On success these functions return a newly allocated string. The
returned string must be freed by the caller.
On error these call L<nbdkit_error(3)> and return C<NULL>.
=head1 LANGUAGE BINDINGS
In L<nbdkit-ocaml-plugin(3)>:
NBDKit.realpath : string -> string
=head1 HISTORY
C<nbdkit_absolute_path> was present in nbdkit 0.1.0.
C<nbdkit_realpath> was added in nbdkit 1.4.
=head1 SEE ALSO
L<nbdkit(1)>,
L<nbdkit-plugin(3)>,
L<nbdkit-filter(3)>.
=head1 AUTHORS
Richard W.M. Jones
=head1 COPYRIGHT
Copyright Red Hat
|
