getnetpath(3N)

getnetpath -- get netconfig entry corresponding to NETPATH component

Synopsis

cc [options] file -lnsl

#include <netconfig.h>

void *setnetpath(void);

struct netconfig *getnetpath(void *handlep);

int endnetpath(void *handlep);

void nc_perror (char *msg);

char *nc_sperror (void);

Description

The five routines described on this page are part of the UNIX System V Network Selection component. They provide application access to the system network configuration database, /etc/netconfig, as it is filtered by the NETPATH environment variable (see environ(5)). Network Selection also includes routines that access the network configuration database directly (see getnetconfig(3N)).

A call to setnetpath ``binds'' 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. setnetpath will fail if the netconfig database is not present. If NETPATH is unset, or if NETPATH is set but null, the set of visible networks constitutes a default NETPATH for use by setnetpath.

When first called, getnetpath returns a pointer to the netconfig database entry corresponding to the first valid NETPATH component. The netconfig entry is formatted as a netconfig structure. 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.

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'' NETPATH when processing is complete, releasing resources for reuse. Programmers should be aware, however, that endnetpath frees all memory allocated by setnetpath. endnetpath returns 0 on success and -1 on failure (for example, if setnetpath was not called previously).

nc_perror prints a message to the standard error indicating why any of the above routines failed. The message is prepended with string msg and a colon. A newline is appended at the end of the message.

nc_sperror is similar to nc_perror but instead of sending the message to the standard error indicating why the network selection routines failed, it returns a pointer to the message.

Files

/usr/lib/locale/locale/LC_MESSAGES/uxnsl

References

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

Notices

nc_sperror returns a pointer to static data that is overwritten on each call. For multi-threaded applications, each thread is allocated a separate message storage area.

Functions that provide successive entries in files on successive calls must be called from a single thread.