Alessandro Bonazzi 5c7aa8c1c0 Patch level : 12.0 no-patch
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Aggiunta documentazione di sqlite 3
2020-11-29 00:32:36 +01:00

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<a href="intro.html"><h2>SQLite C Interface</h2></a>
<h2>Create and Destroy VFS Filenames</h2>
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<blockquote><pre>
char *sqlite3_create_filename(
const char *zDatabase,
const char *zJournal,
const char *zWal,
int nParam,
const char **azParam
);
void sqlite3_free_filename(char*);
</pre></blockquote>
<p>
These interfces are provided for use by <a href="../vfs.html#shim">VFS shim</a> implementations and
are not useful outside of that context.</p>
<p>The sqlite3_create_filename(D,J,W,N,P) allocates memory to hold a version of
database filename D with corresponding journal file J and WAL file W and
with N URI parameters key/values pairs in the array P. The result from
sqlite3_create_filename(D,J,W,N,P) is a pointer to a database filename that
is safe to pass to routines like:
<ul>
<li> <a href="../c3ref/uri_boolean.html">sqlite3_uri_parameter()</a>,
<li> <a href="../c3ref/uri_boolean.html">sqlite3_uri_boolean()</a>,
<li> <a href="../c3ref/uri_boolean.html">sqlite3_uri_int64()</a>,
<li> <a href="../c3ref/uri_boolean.html">sqlite3_uri_key()</a>,
<li> <a href="../c3ref/filename_database.html">sqlite3_filename_database()</a>,
<li> <a href="../c3ref/filename_database.html">sqlite3_filename_journal()</a>, or
<li> <a href="../c3ref/filename_database.html">sqlite3_filename_wal()</a>.
</ul>
If a memory allocation error occurs, sqlite3_create_filename() might
return a NULL pointer. The memory obtained from sqlite3_create_filename(X)
must be released by a corresponding call to sqlite3_free_filename(Y).</p>
<p>The P parameter in sqlite3_create_filename(D,J,W,N,P) should be an array
of 2*N pointers to strings. Each pair of pointers in this array corresponds
to a key and value for a query parameter. The P parameter may be a NULL
pointer if N is zero. None of the 2*N pointers in the P array may be
NULL pointers and key pointers should not be empty strings.
None of the D, J, or W parameters to sqlite3_create_filename(D,J,W,N,P) may
be NULL pointers, though they can be empty strings.</p>
<p>The sqlite3_free_filename(Y) routine releases a memory allocation
previously obtained from sqlite3_create_filename(). Invoking
sqlite3_free_filename(Y) where Y is a NULL pointer is a harmless no-op.</p>
<p>If the Y parameter to sqlite3_free_filename(Y) is anything other
than a NULL pointer or a pointer previously acquired from
sqlite3_create_filename(), then bad things such as heap
corruption or segfaults may occur. The value Y should be
used again after sqlite3_free_filename(Y) has been called. This means
that if the <a href="../c3ref/vfs.html#sqlite3vfsxopen">sqlite3_vfs.xOpen()</a> method of a VFS has been called using Y,
then the corresponding [sqlite3_module.xClose() method should also be
invoked prior to calling sqlite3_free_filename(Y).
</p><p>See also lists of
<a href="objlist.html">Objects</a>,
<a href="constlist.html">Constants</a>, and
<a href="funclist.html">Functions</a>.</p>