getnetpath(3N)

DESCRIPTION

The routines described on this page are part of the Network Selection component. They provide the application access to the system network configuration database, /etc/netconfig, as it is "filtered" by the NETPATH environment variable (see environ(5)). See getnetconfig(3N) for other routines that also access the network configuration database directly. The NETPATH variable is a list of colon-separated network identifiers.

getnetpath() returns a pointer to the netconfig database entry corresponding to the first valid NETPATH component. The netconfig entry is formatted as a struct netconfig. On each subsequent call, getnetpath() returns a pointer to the netconfig entry that corresponds to the next valid NETPATH component. getnetpath() can thus be used to search the netconfig database for all networks included in the NETPATH variable. When NETPATH has been exhausted, getnetpath() returns NULL.

A call to setnetpath() "binds" to or "rewinds" NETPATH. setnetpath() must be called before the first call to getnetpath() and may be called at any other time. It returns a handle that is used by getnetpath().

getnetpath() silently ignores invalid NETPATH components. A NETPATH component is invalid if there is no corresponding entry in the netconfig database.

If the NETPATH variable is unset, getnetpath() behaves as if NETPATH were set to the sequence of "default" or "visible" networks in the netconfig database, in the order in which they are listed.

endnetpath() may be called to "unbind" from NETPATH when processing is complete, releasing resources for reuse. Programmers should be aware, however, that endnetpath() frees all memory allocated by getnetpath() for the struct netconfig data structure.

MULTITHREAD USAGE

These functions can be called safely in a multithreaded environment. They may be cancellation points in that they call functions that are cancel points.

In a multithreaded environment, these functions are not safe to be called by a child process after fork() and before exec(). These functions should not be called by a multithreaded application that supports asynchronous cancellation or asynchronous signals.

RETURN VALUES

setnetpath() returns a handle that is used by getnetpath(). In case of an error, setnetpath() returns NULL. nc_perror() or nc_sperror() can be used to print out the reason for failure. See getnetconfig(3N).

When first called, getnetpath() returns a pointer to the netconfig database entry corresponding to the first valid NETPATH component. When NETPATH has been exhausted, getnetpath() returns NULL.

endnetpath() returns 0 on success and -1 on failure (for example, if setnetpath() was not called previously).

SEE ALSO

getnetconfig(3N), netconfig(4), environ(5).