|
GETRPCBYNAME(3NSL) |
Networking Services Library Functions |
GETRPCBYNAME(3NSL) |
NAME
getrpcbyname, getrpcbyname_r, getrpcbynumber, getrpcbynumber_r, getrpcent, getrpcent_r, setrpcent, endrpcent - get RPC entry
SYNOPSIS
cc [
flag ... ]
file ...
-lnsl [
library ... ]
#include <rpc/rpcent.h>
struct rpcent *getrpcbyname(
const char *name);
struct rpcent *getrpcbyname_r(
const char *name,
struct rpcent *result,
char *buffer,
int buflen);
struct rpcent *getrpcbynumber(
const int number);
struct rpcent *getrpcbynumber_r(
const int number,
struct rpcent *result,
char *buffer,
int buflen);
struct rpcent *getrpcent(
void);
struct rpcent *getrpcent_r(
struct rpcent *result,
char *buffer,
int buflen);
void setrpcent(
const int stayopen);
void endrpcent(
void);
DESCRIPTION
These functions are used to obtain entries for RPC (Remote Procedure Call) services. An entry may come from any of the sources for
rpc specified in the
/etc/nsswitch.conf file (see
nsswitch.conf(4)).
getrpcbyname() searches for an entry with the RPC service name specified by the parameter
name.
getrpcbynumber() searches for an entry with the RPC program number
number.
The functions
setrpcent(),
getrpcent(), and
endrpcent() are used to enumerate RPC entries from the database.
setrpcent() sets (or resets) the enumeration to the beginning of the set of RPC entries. This function should be called before the first call to
getrpcent(). Calls to
getrpcbyname() and
getrpcbynumber() leave the enumeration position in an indeterminate state. If the
stayopen flag is non-zero, the system may keep allocated resources such as open file descriptors until a subsequent call to
endrpcent().
Successive calls to
getrpcent() return either successive entries or
NULL, indicating the end of the enumeration.
endrpcent() may be called to indicate that the caller expects to do no further RPC entry retrieval operations; the system may then deallocate resources it was using. It is still allowed, but possibly less efficient, for the process to call more RPC entry retrieval functions after calling
endrpcent().
Reentrant Interfaces
The functions
getrpcbyname(),
getrpcbynumber(), and
getrpcent() use static storage that is re-used in each call, making these routines unsafe for use in multithreaded applications.
The functions
getrpcbyname_r(),
getrpcbynumber_r(), and
getrpcent_r() provide reentrant interfaces for these operations.
Each reentrant interface performs the same operation as its non-reentrant counterpart, named by removing the ``
_r'' suffix. The reentrant interfaces, however, use buffers supplied by the caller to store returned results, and are safe for use in both single-threaded and multithreaded applications.
Each reentrant interface takes the same parameters as its non-reentrant counterpart, as well as the following additional parameters. The parameter
result must be a pointer to a
struct rpcent structure allocated by the caller. On successful completion, the function returns the RPC entry in this structure. The parameter
buffer must be a pointer to a buffer supplied by the caller. This buffer is used as storage space for the RPC entry data. All of the pointers within the returned
struct rpcent result point to data stored within this buffer (see
RETURN VALUES). The buffer must be large enough to hold all of the data associated with the RPC entry. The parameter
buflen should give the size in bytes of the buffer indicated by
buffer.
For enumeration in multithreaded applications, the position within the enumeration is a process-wide property shared by all threads.
setrpcent() may be used in a multithreaded application but resets the enumeration position for all threads. If multiple threads interleave calls to
getrpcent_r(), the threads will enumerate disjoint subsets of the RPC entry database.
Like their non-reentrant counterparts,
getrpcbyname_r() and
getrpcbynumber_r() leave the enumeration position in an indeterminate state.
RETURN VALUES
RPC entries are represented by the
struct rpcent structure defined in
<rpc/rpcent.h>:
struct rpcent {
char *r_name; /* name of this rpc service
char **r_aliases; /* zero-terminated list of alternate names */
int r_number; /* rpc program number */
};
The functions
getrpcbyname(),
getrpcbyname_r(),
getrpcbynumber(), and
getrpcbynumber_r() each return a pointer to a
struct rpcent if they successfully locate the requested entry; otherwise they return
NULL.
The functions
getrpcent() and
getrpcent_r() each return a pointer to a
struct rpcent if they successfully enumerate an entry; otherwise they return
NULL, indicating the end of the enumeration.
The functions
getrpcbyname(),
getrpcbynumber(), and
getrpcent() use static storage, so returned data must be copied before a subsequent call to any of these functions if the data is to be saved.
When the pointer returned by the reentrant functions
getrpcbyname_r(),
getrpcbynumber_r(), and
getrpcent_r() is non-NULL, it is always equal to the
result pointer that was supplied by the caller.
ERRORS
The reentrant functions getrpcbyname_r(), getrpcbynumber_r() and getrpcent_r() will return NULL and set errno to ERANGE if the length of the buffer supplied by caller is not large enough to store the result. See Intro(2) for the proper usage and interpretation of errno in multithreaded applications.
FILES
/etc/rpc
/etc/nsswitch.conf
ATTRIBUTES
See
attributes(5) for descriptions of the following attributes:
|
ATTRIBUTE TYPE |
ATTRIBUTE VALUE |
|
|
|
MT-Level |
See "Reentrant Interfaces" in DESCRIPTION. |
SEE ALSO
rpcinfo(1M), rpc(3NSL), nsswitch.conf(4), rpc(4), attributes(5)
WARNINGS
The reentrant interfaces getrpcbyname_r(), getrpcbynumber_r(), and getrpcent_r() are included in this release on an uncommitted basis only, and are subject to change or removal in future minor releases.
NOTES
When compiling multithreaded applications, see
Intro(3),
Notes On Multithreaded Applications, for information about the use of the
_REENTRANT flag.
Use of the enumeration interfaces
getrpcent() and
getrpcent_r() is discouraged; enumeration may not be supported for all database sources. The semantics of enumeration are discussed further in
nsswitch.conf(4).