endhostent, gethostent, sethostent: síťové hostitelské databázové funkce

Originální popis anglicky: endhostent, gethostent, sethostent - network host database functions

Návod, kniha: POSIX Programmer's Manual

STRUČNĚ

#include <netdb.h> void endhostent(void); struct hostent *gethostent(void); void sethostent(int stayopen);

POPIS / INSTRUKCE

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

Note:

In many cases this database is implemented by the Domain Name System, as documented in RFC 1034, RFC 1035, and RFC 1886.

 

The sethostent() function shall open a connection to the database and set the next entry for retrieval to the first entry in the database. If the stayopen argument is non-zero, the connection shall not be closed by a call to gethostent(), gethostbyname(), or gethostbyaddr(), and the implementation may maintain an open file descriptor. The gethostent() function shall read the next entry in the database, opening and closing a connection to the database as necessary. Entries shall be returned in hostent structures. Refer to gethostbyaddr() for a definition of the hostent structure. The endhostent() function shall close the connection to the database, releasing any open file descriptor. These functions need not be reentrant. A function that is not required to be reentrant is not required to be thread-safe.

NÁVRATOVÁ HODNOTA

Upon successful completion, the gethostent() function shall return a pointer to a hostent 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.

CHYBY / ERRORY

No errors are defined for endhostent(), gethostent(), and sethostent(). The following sections are informative.

PŘÍKLADY POUŽITÍ

None.

APPLICATION USAGE

The gethostent() function may return pointers to static data, which may be overwritten by subsequent calls to any of these functions.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SOUVISEJÍCÍ

endservent() , gethostbyaddr() , the Base Definitions volume of IEEE Std 1003.1-2001, <netdb.h>

COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .