Add libpq new API lo_import_with_oid() which is similar to lo_import()

except that lob's oid can be specified.

4 files changed, 53 insertions, 2 deletions

diff --git a/doc/src/sgml/lobj.sgml b/doc/src/sgml/lobj.sgml
index dbabd75e1d..68cb257c7e 100644
--- a/doc/src/sgml/lobj.sgml
+++ b/doc/src/sgml/lobj.sgml
@@ -161,6 +161,28 @@ Oid lo_import(PGconn *conn, const char *filename);
      the server; so it must exist in the client file system and be readable
      by the client application.
     </para>
+
+    <para>
+     The function
+<synopsis>
+Oid lo_import_with_oid(PGconn *conn, const char *filename, Oid lobjId);
+</synopsis>
+     <indexterm><primary>lo_import_with_oid</></>
+     also imports a new large object.  The OID to be assigned can be
+     specified by <replaceable class="parameter">lobjId</replaceable>;
+     if so, failure occurs if that OID is already in use for some large
+     object.  If <replaceable class="parameter">lobjId</replaceable>
+     is <symbol>InvalidOid</symbol> (zero) then <function>lo_import_with_oid</> assigns an unused
+     OID (this is the same behavior as <function>lo_import</>).
+     The return value is the OID that was assigned to the new large object,
+     or <symbol>InvalidOid</symbol> (zero) on failure.
+    </para>
+
+    <para>
+     <function>lo_import_with_oid</> is new as of <productname>PostgreSQL</productname>
+     8.4 and uses <function>lo_create</function> internally which is new in 8.1; if this function is run against 8.0 or before, it will
+     fail and return <symbol>InvalidOid</symbol>.
+    </para>
    </sect2>
 
    <sect2>
diff --git a/src/interfaces/libpq/exports.txt b/src/interfaces/libpq/exports.txt
index d9951b2650..b8bd30098e 100644
--- a/src/interfaces/libpq/exports.txt
+++ b/src/interfaces/libpq/exports.txt
@@ -140,3 +140,4 @@ lo_truncate               137
 PQconnectionUsedPassword  138
 pg_valid_server_encoding_id 139
 PQconnectionNeedsPassword 140
+lo_import_with_oid		  141
diff --git a/src/interfaces/libpq/fe-lobj.c b/src/interfaces/libpq/fe-lobj.c
index e14c9d659f..5609cf03e2 100644
--- a/src/interfaces/libpq/fe-lobj.c
+++ b/src/interfaces/libpq/fe-lobj.c
@@ -41,6 +41,8 @@
 
 static int	lo_initialize(PGconn *conn);
 
+static Oid
+lo_import_internal(PGconn *conn, const char *filename, const Oid oid);
 
 /*
  * lo_open
@@ -484,6 +486,27 @@ lo_unlink(PGconn *conn, Oid lobjId)
 Oid
 lo_import(PGconn *conn, const char *filename)
 {
+	return lo_import_internal(conn, filename, InvalidOid);
+}
+
+/*
+ * lo_import_with_oid -
+ *	  imports a file as an (inversion) large object.
+ *	  large object id can be specified.
+ *
+ * returns the oid of that object upon success,
+ * returns InvalidOid upon failure
+ */
+
+Oid
+lo_import_with_oid(PGconn *conn, const char *filename, Oid lobjId)
+{
+	return lo_import_internal(conn, filename, lobjId);
+}
+
+static Oid
+lo_import_internal(PGconn *conn, const char *filename, Oid oid)
+{
 	int			fd;
 	int			nbytes,
 				tmp;
@@ -507,10 +530,14 @@ lo_import(PGconn *conn, const char *filename)
 	/*
 	 * create an inversion object
 	 */
-	lobjOid = lo_creat(conn, INV_READ | INV_WRITE);
+	if (oid == InvalidOid)
+		lobjOid = lo_creat(conn, INV_READ | INV_WRITE);
+	else
+		lobjOid = lo_create(conn, oid);
+
 	if (lobjOid == InvalidOid)
 	{
-		/* we assume lo_creat() already set a suitable error message */
+		/* we assume lo_create() already set a suitable error message */
 		(void) close(fd);
 		return InvalidOid;
 	}
diff --git a/src/interfaces/libpq/libpq-fe.h b/src/interfaces/libpq/libpq-fe.h
index 0d33488615..d7eca2fa23 100644
--- a/src/interfaces/libpq/libpq-fe.h
+++ b/src/interfaces/libpq/libpq-fe.h
@@ -495,6 +495,7 @@ extern int	lo_tell(PGconn *conn, int fd);
 extern int	lo_truncate(PGconn *conn, int fd, size_t len);
 extern int	lo_unlink(PGconn *conn, Oid lobjId);
 extern Oid	lo_import(PGconn *conn, const char *filename);
+extern Oid	lo_import_with_oid(PGconn *conn, const char *filename, Oid lobjId);
 extern int	lo_export(PGconn *conn, Oid lobjId, const char *filename);
 
 /* === in fe-misc.c === */