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<! "@(#)fd.so 10.10 (Sleepycat) 10/3/98">
<!Copyright 1997, 1998 by Sleepycat Software, Inc. All rights reserved.>
<html>
<body bgcolor=white>
<head>
<title>Berkeley DB: DB->fd</title>
<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit.">
<meta name="keywords" content="embedded,database,programmatic,toolkit,b+tree,btr
ee,hash,hashing,transaction,transactions,locking,logging,access method,access me
thods,java,C,C++">
</head>
<h1>DB->fd</h1>
<hr size=1 noshade>
<tt>
<h3>
<pre>
#include <db.h>
<p>
int
DB->fd(DB *db, int *fdp);
</pre>
</h3>
<h1>Description</h1>
<p>
The DB->fd function
copies a file descriptor representative of the underlying database into
the memory referenced by <b>fdp</b>. A file descriptor referencing the
same file will be returned to all processes that call <a href="../../api_c/Db/open.html">db_open</a> with
the same <b>file</b> argument. This file descriptor may be safely used
as an argument to the <b>fcntl</b>(2) and <b>flock</b>(2) locking
functions. The file descriptor is not necessarily associated with any of
the underlying files actually used by the access method.
<p>
The <b>Db_fd</b> function only supports a coarse-grained form of locking.
Applications should use the lock manager where possible.
<p>
The DB->fd
function returns the value of <b>errno</b> on failure, and 0 on success.
<p>
<h1>Errors</h1>
If a fatal error occurs in Berkeley DB, the DB->fd function may fail and return
DB_RUNRECOVERY, at which point all subsequent database calls will also
return DB_RUNRECOVERY.
<p>
The DB->fd
function may fail and return <b>errno</b>
for any of the errors specified for the following Berkeley DB and C library
functions:
DBmemp->pgin(3),
DBmemp->pgout(3),
abort(3),
close(3),
dbenv->db_paniccall(3),
fcntl(3),
fflush(3),
fprintf(3),
free(3),
fsync(3),
getenv(3),
getpid(3),
getuid(3),
isdigit(3),
<a href="../../api_c/DbLog/compare.html">log_compare</a>,
<a href="../../api_c/DbLog/flush.html">log_flush</a>,
lseek(3),
malloc(3),
memcpy(3),
memset(3),
open(3),
pread(3),
pwrite(3),
qsort(3),
read(3),
realloc(3),
sigfillset(3),
sigprocmask(3),
stat(3),
strerror(3),
strlen(3),
unlink(3),
vfprintf(3),
vsnprintf(3),
and
write(3).
<p>
<h1>See Also</h1>
<a href="../../api_c/DbEnv/appexit.html">db_appexit</a>,
<a href="../../api_c/DbEnv/appinit.html">db_appinit</a>,
<a href="../../api_c/DbEnv/version.html">db_version</a>,
<a href="../../api_c/Db/close.html">DB->close</a>,
<a href="../../api_c/Db/cursor.html">DB->cursor</a>,
<a href="../../api_c/Db/del.html">DB->del</a>,
DB->fd,
<a href="../../api_c/Db/get.html">DB->get</a>,
<a href="../../api_c/Db/join.html">DB->join</a>,
<a href="../../api_c/Db/open.html">db_open</a>,
<a href="../../api_c/Db/put.html">DB->put</a>,
<a href="../../api_c/Db/stat.html">DB->stat</a>,
<a href="../../api_c/Db/sync.html">DB->sync</a>,
<a href="../../api_c/Dbc/close.html">DBcursor->c_close</a>,
<a href="../../api_c/Dbc/del.html">DBcursor->c_del</a>,
<a href="../../api_c/Dbc/get.html">DBcursor->c_get</a>
and
<a href="../../api_c/Dbc/put.html">DBcursor->c_put</a>.
</tt>
</body>
</html>
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