nbdkit_realpath3
Convert relative to absolute paths for nbdkit
Usage
#include <nbdkit-plugin.h>char *nbdkit_realpath (const char *filename);char *nbdkit_absolute_path (const char *filename);
Overview
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.imgmight 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