NAME

endprotoent, getprotobyname, getprotobynumber, getprotoent, setprotoent — network protocol database functions

SYNOPSIS

#include <netdb.h>

void endprotoent(void);
struct protoent *getprotobyname(const char *name);
struct protoent *getprotobynumber(int proto);
struct protoent *getprotoent(void);
void setprotoent(int stayopen);


DESCRIPTION

These functions shall retrieve information about protocols. This information is considered to be stored in a database that can be accessed sequentially or randomly. The implementation of this database is unspecified.

The setprotoent() function shall open a connection to the database, and set the next entry to the first entry. If the stayopen argument is non-zero, the connection to the network protocol database shall not be closed after each call to getprotoent() (either directly, or indirectly through one of the other getproto*() functions), and the implementation may maintain an open file descriptor for the database. If a file descriptor is used, the FD_CLOEXEC flag shall be set; see <fcntl.h>.

The getprotobyname() function shall search the database from the beginning and find the first entry for which the protocol name specified by name matches the p_name member, opening and closing a connection to the database as necessary.

The getprotobynumber() function shall search the database from the beginning and find the first entry for which the protocol number specified by proto matches the p_proto member, opening and closing a connection to the database as necessary.

The getprotoent() function shall read the next entry of the database, opening and closing a connection to the database as necessary.

The getprotobyname(), getprotobynumber(), and getprotoent() functions shall each return a pointer to a protoent structure, the members of which shall contain the fields of an entry in the network protocol database.

The endprotoent() function shall close the connection to the database, releasing any open file descriptor.

These functions need not be thread-safe.

RETURN VALUE

Upon successful completion, getprotobyname(), getprotobynumber(), and getprotoent() return a pointer to a protoent structure if the requested entry was found, and a null pointer if the end of the database was reached or the requested entry was not found. Otherwise, a null pointer is returned.

The application shall not modify the structure to which the return value points, nor any storage areas pointed to by pointers within the structure. The returned pointer, and pointers within the structure, might be invalidated or the structure or the storage areas might be overwritten by a subsequent call to getprotobyname(), getprotobynumber(), or getprotoent(). The returned pointer, and pointers within the structure, might also be invalidated if the calling thread is terminated.

ERRORS

The getprotobyname(), getprotobynumber(), getprotoent(), and setprotoent() functions may fail if:

[EMFILE]

All file descriptors available to the process are currently open.

[ENFILE]

The maximum allowable number of files is currently open in the system.

EXAMPLES

None.

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

XBD <fcntl.h>, <netdb.h>

CHANGE HISTORY

First released in Issue 6. Derived from the XNS, Issue 5.2 specification.

Issue 7

Austin Group Interpretation 1003.1-2001 #156 is applied.

POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0085 [75] and XSH/TC1-2008/0086 [75] are applied.

POSIX.1-2008, Technical Corrigendum 2, XSH/TC2-2008/0091 [656] is applied.

Issue 8

Austin Group Defect 368 is applied, adding a requirement for FD_CLOEXEC to be set if a file descriptor is used, and adding the [EMFILE] and [ENFILE] errors.