функции базы данных сетевого протокола (network protocol database functions)
Пролог (Prolog)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
Имя (Name)
endprotoent, getprotobyname, getprotobynumber, getprotoent,
setprotoent — network protocol database functions
Синопсис (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);
Описание (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.
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.
Возвращаемое значение (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.
Ошибки (Error)
No errors are defined.
The following sections are informative.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
None.
Обоснование (Rationale)
None.
Будущие направления (Future directions)
None.
Смотри также (See also)
The Base Definitions volume of POSIX.1‐2017, netdb.h(0p)
