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<title>Berkeley DB: DB_ENV->log_archive</title>
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<h1>DB_ENV->log_archive</h1>
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<h3><pre>
#include <db.h>
<p>
int
DB_ENV->log_archive(DB_ENV *env, char *(*listp)[], u_int32_t flags);
</pre></h3>
<h1>Description</h1>
<p>The DB_ENV->log_archive method
creates a NULL-terminated array of log or database filenames, and copies
a pointer to them into the user-specified memory location <b>listp</b>.
<p>By default, DB_ENV->log_archive returns the names of all of the log
files that are no longer in use (for example, that are no longer
involved in active transactions), and that may safely be archived for
catastrophic recovery and then removed from the system. If there are
no filenames to return,
the memory location to which <b>listp</b> refers will be set to NULL.
<p>Arrays of log filenames are created in allocated memory. If application-specific allocation
routines have been declared (see <a href="../api_c/env_set_alloc.html">DB_ENV->set_alloc</a> for more
information), they are used to allocate the memory; otherwise, the
library <b>malloc</b>(3) interface is used. The caller is
responsible for deallocating the memory. To deallocate the memory, free
the memory reference; references inside the returned memory need not be
individually freed.
<p>The <b>flags</b> value must be set to 0 or by bitwise inclusively <b>OR</b>'ing together one or
more of the following values:
<p><dl compact>
<p><dt><a name="DB_ARCH_ABS">DB_ARCH_ABS</a><dd>All pathnames are returned as absolute pathnames, instead of relative
to the database home directory.
<p><dt><a name="DB_ARCH_DATA">DB_ARCH_DATA</a><dd>Return the database files that need to be archived in order to recover
the database from catastrophic failure. If any of the database files
have not been accessed during the lifetime of the current log files,
DB_ENV->log_archive will not include them in this list. It is also
possible that some of the files referred to by the log have since been
deleted from the system.
<p><dt><a name="DB_ARCH_LOG">DB_ARCH_LOG</a><dd>Return all the log filenames, regardless of whether or not they are in
use.
</dl>
<p>The DB_ARCH_DATA and DB_ARCH_LOG flags are mutually
exclusive.
<p>Log cursor handles (returned by the <a href="../api_c/log_cursor.html">DB_ENV->log_cursor</a> method) may have open
file descriptors for log files in the database environment. Also, the
Berkeley DB interfaces to the database environment logging subsystem (for
example, <a href="../api_c/log_put.html">DB_ENV->log_put</a> and <a href="../api_c/txn_abort.html">DB_TXN->abort</a>) may allocate log cursors
and have open file descriptors for log files as well. On operating
systems where filesystem related system calls (for example, rename and
unlink on Windows/NT) can fail if a process has an open file descriptor
for the affected file, attempting to move or remove the log files listed
by DB_ENV->log_archive may fail. All Berkeley DB internal use of log cursors
operates on active log files only and furthermore, is short-lived in
nature. So, an application seeing such a failure should be restructured
to close any open log cursors it may have, and otherwise to retry the
operation until it succeeds. (Although the latter is not likely to be
necessary; it is hard to imagine a reason to move or rename a log file
in which transactions are being logged or aborted.)
<p>See the <a href="../utility/db_archive.html">db_archive</a> manual page for more information on database
archival procedures.
<p>The DB_ENV->log_archive method is the underlying interface used by the <a href="../utility/db_archive.html">db_archive</a> utility.
See the <a href="../utility/db_archive.html">db_archive</a> utility source code for an example of using DB_ENV->log_archive
in a IEEE/ANSI Std 1003.1 (POSIX) environment.
<p>The DB_ENV->log_archive method returns a non-zero error value on failure and 0 on success.
<h1>Errors</h1>
<p>The DB_ENV->log_archive method may fail and return a non-zero error for the following conditions:
<p><dl compact>
<p><dt>EINVAL<dd>An invalid flag value or parameter was specified.
<p>The log was corrupted.
</dl>
<p>The DB_ENV->log_archive method may fail and return a non-zero error for errors specified for other Berkeley DB and C library or system functions.
If a catastrophic error has occurred, the DB_ENV->log_archive method may fail and
return <a href="../ref/program/errorret.html#DB_RUNRECOVERY">DB_RUNRECOVERY</a>,
in which case all subsequent Berkeley DB calls will fail in the same way.
<h1>Class</h1>
<a href="../api_c/env_class.html">DB_ENV</a>, <a href="../api_c/logc_class.html">DB_LOGC</a>, <a href="../api_c/lsn_class.html">DB_LSN</a>
<h1>See Also</h1>
<a href="../api_c/log_list.html">Logging Subsystem and Related Methods</a>
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