getprotoent(3N) getprotoent(3N)
NAME
getprotoent(), getprotoent_r(), getprotobynumber(),
getprotobynumber_r(), getprotobyname(), getprotobyname_r(),
setprotoent(), setprotoent_r(), endprotoent(), endprotoent_r() - get
protocol entry
SYNOPSIS
#include <netdb.h>
struct protoent *getprotoent(void);
int getprotoent_r(struct protoent *result,
struct protoent_data *buffer);
struct protoent *getprotobyname(const char *name);
int getprotobyname_r(const char *name,
struct protoent *result,
struct protoent_data *buffer);
struct protoent *getprotobynumber(int proto);
int getprotobynumber_r(int proto,
struct protoent *result,
struct protoent_data *buffer);
int setprotoent(int stayopen);
int setprotoent_r(int stayopen, struct protoent_data *buffer);
int endprotoent(void);
int endprotoent_r(struct protoent_data *buffer);
_XOPEN_SOURCE_EXTENDED only
void setprotoent(int stayopen);
void endprotoent(void);
DESCRIPTION
The getprotoent(), getprotobyname(), and getprotobynumber() functions
each return a pointer to a structure of type protoent containing the
broken-out fields of a line in the network protocol data base,
/etc/protocols.
The members of this structure are:
p_name The official name of the protocol.
p_aliases A null-terminated list of alternate names for the
protocol.
Hewlett-Packard Company - 1 - HP-UX Release 10.20: July 1996
getprotoent(3N) getprotoent(3N)
p_proto The protocol number.
Functions behave as follows:
getprotoent() Reads the next line of the file,
opening the file if necessary.
setprotoent() Opens and rewinds the file. If the
stayopen flag is non-zero, the protocol
data base is not closed after each call
to getprotoent() (either directly or
indirectly through one of the other
getproto* calls).
endprotoent() Closes the file.
getprotobyname()
getprotobynumber() Each sequentially searches from the
beginning of the file until a matching
protocol name (among either the
official names or the aliases) or
protocol number is found, or until EOF
is encountered.
If the system is running the Network Information Service (NIS)
services, getprotobyname() and getprotobynumber() get the
protocol information from the NIS server (see ypserv(1M) and
ypfiles(4)).
Reentrant Interfaces
getprotoent_r(), getprotobyname_r(), and getprotobynumber_r() expect
to be passed the address of a struct protoent and will store the
result at the supplied location. An additional parameter, a pointer
to a struct protoent_data, must also be supplied. This structure is
used to store data, to which fields in the struct protoent will point,
as well as state information such as open file descriptors. The
struct protoent_data is defined in the file <netdb.h>.
setprotoent_r() and endprotoent_r() are to be used only in conjunction
with getprotoent_r() and take the same pointer to a struct
protoent_data as a parameter. If the Network Information Service is
being used, setprotoent_r() initializes an internal database key. If
the /etc/protocols file is being used, setprotoent_r() opens or
rewinds the file. endprotoent_r() should always be called to ensure
that files are closed and internally allocated data structures are
released.
The stayopen parameter to setprotoent_r() currently has no effect.
However, setprotoent() can still be used to keep the /etc/protocols
file open when making calls to getprotobyname_r() and
getprotobynumber_r().
Hewlett-Packard Company - 2 - HP-UX Release 10.20: July 1996
getprotoent(3N) getprotoent(3N)
The proto_fp field in the struct protoent_data must be initialized to
NULL before it is passed to either getprotoent_r() or setprotoent_r()
for the first time. Thereafter it should not be modified in any way.
This is the only protoent_data field that should ever be explicitly
accessed.
Name Service Switch-Based Operation
The library routines, getprotobyname(), getprotobynumber(),
getprotoent(), and their reentrant counterparts, internally call the
name service switch to access the "protocols" database lookup policy
configured in the /etc/nsswitch.conf file (see switch(4)). The lookup
policy defines the order and the criteria of the supported name
services used to resolve protocol names and numbers.
RETURN VALUE
getprotoent(), getprotobyname(), and getprotobynumber() return a null
pointer (0) on EOF or when they are unable to open /etc/protocols.
For the reentrant (_r) versions of these routines, -1 will be returned
if the operation is unsuccessful or, in the case of getprotoent_r(),
if the end of the protocols list has been reached. 0 is returned
otherwise.
EXAMPLES
The following code excerpt counts the number of protocols entries:
int count = 0;
struct protoent protobuf;
struct protoent_data pdbuf;
pdbuf.proto_fp = NULL;
(void) setprotoent_r(0, &pdbuf);
while (getprotoent_r(&protobuf, &pdbuf) != -1)
count++;
(void) endprotoent_r(&pdbuf);
WARNINGS
In the non-reentrant versions of these routines, all information is
contained in a static area so it must be copied if it is to be saved.
getprotoent(), getprotobynumber(), getprotobyname(), setprotoent(),
and endprotoent() are unsafe in multi-thread applications.
getprotoent_r(), getprotobynumber_r(), getprotobyname_r(),
setprotoent_r(), and endprotoent_r() are MT-Safe and should be used
instead.
AUTHOR
getprotoent() was developed by the University of California, Berkeley.
FILES
/etc/protocols
Hewlett-Packard Company - 3 - HP-UX Release 10.20: July 1996
getprotoent(3N) getprotoent(3N)
SEE ALSO
ypserv(1M), protocols(4), ypfiles(4).
STANDARDS CONFORMANCE
getprotoent(): XPG4
Hewlett-Packard Company - 4 - HP-UX Release 10.20: July 1996