NAME

       nbdkit_realpath, nbdkit_absolute_path - convert relative to absolute paths for nbdkit

SYNOPSIS

        #include <nbdkit-plugin.h>

        char *nbdkit_realpath (const char *filename);
        char *nbdkit_absolute_path (const char *filename);

DESCRIPTION

       nbdkit(1) usually (not always) changes directory to / 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 /disk.img instead of the file in the user's current directory.

       To avoid this problem, you can:

       •   convert relative paths to absolute paths using one of the functions described here, or

       •   open the file at configure time and store the file descriptor.

   nbdkit_realpath
       The utility function "nbdkit_realpath" converts any path to an absolute path, resolving
       symlinks.  Under the hood it uses the 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 only when used in the ".config", ".config_complete" and ".get_ready"
       callbacks.

   nbdkit_absolute_path
       The utility function "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 "nbdkit_realpath", this function does not check that the file exists.

       This function works only when used in the ".config", ".config_complete" and ".get_ready"
       callbacks.

RETURN VALUE

       On success these functions return a newly allocated string.  The returned string must be
       freed by the caller.

       On error these call nbdkit_error(3) and return "NULL".

LANGUAGE BINDINGS

       In nbdkit-ocaml-plugin(3):

        NBDKit.realpath : string -> string

HISTORY

       "nbdkit_absolute_path" was present in nbdkit 0.1.0.

       "nbdkit_realpath" was added in nbdkit 1.4.

SEE ALSO

       nbdkit(1), nbdkit-plugin(3), nbdkit-filter(3).

AUTHORS

       Richard W.M. Jones

COPYRIGHT

       Copyright Red Hat

LICENSE

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