Make C++ compatible.

include/cdio/cdda.h

@@ -1,5 +1,5 @@
 /*
-  $Id: cdda.h,v 1.21 2005/04/30 07:15:51 rocky Exp $
+  $Id: cdda.h,v 1.22 2005/08/27 14:25:58 rocky Exp $
 
   Copyright (C) 2004, 2005 Rocky Bernstein <rocky@panix.com>
   Copyright (C) 2001 Xiph.org
@@ -32,6 +32,10 @@
 #include <cdio/cdio.h>
 #include <cdio/paranoia.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
 extern enum paranoia_cdda_enums {
   CDDA_MESSAGE_FORGETIT = 0,
   CDDA_MESSAGE_PRINTIT  = 1,
@@ -177,18 +181,19 @@ extern enum paranoia_jitter_enums {
 extern cdrom_drive_t *cdio_cddap_find_a_cdrom(int messagedest, 
 					      char **ppsz_message);
 
-/** Returns a paranoia CD-ROM drive object with a CD-DA in it.  
+/** Returns a paranoia CD-ROM drive object with a CD-DA in it or NULL
+    if there was an error.
     @see cdio_cddap_identify_cdio
  */
 extern cdrom_drive_t *cdio_cddap_identify(const char *psz_device, 
 					  int messagedest, 
 					  char **ppsz_message);
 
-/** Returns a paranoia CD-ROM drive object with a CD-DA in it.  In
-    contrast to cdio_cddap_identify, we start out with an initialized
-    p_cdio object. For example you may have used that for other
-    purposes such as to get CDDB/CD-Text information.  @see
-    cdio_cddap_identify
+/** Returns a paranoia CD-ROM drive object with a CD-DA in it or NULL
+    if there was an error.  In contrast to cdio_cddap_identify, we
+    start out with an initialized p_cdio object. For example you may
+    have used that for other purposes such as to get CDDB/CD-Text
+    information.  @see cdio_cddap_identify
  */
 cdrom_drive_t *cdio_cddap_identify_cdio(CdIo_t *p_cdio, 
 					int messagedest, char **ppsz_messages);
@@ -374,5 +379,9 @@ const char *strerror_tr[]={
 #define cdda_disc_lastsector    cdio_cddap_disc_lastsector
 #endif /*DO_NOT_WANT_PARANOIA_COMPATIBILITY*/
 
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+
 #endif /*_CDDA_INTERFACE_H_*/