add dir detector

useful for blocking open for read of directories

ChangeLog

@@ -13,6 +13,7 @@
   VIPS_PIPE_READ_LIMIT
 - revise gifload to fix BACKGROUND and PREVIOUS dispose [alon-ne]
 - add subsample_mode, deprecate no_subsample in jpegsave [Elad-Laufer]
+- add vips_isdirf()
 
 31/1/19 started 8.9.2
 - fix a deadlock with --vips-leak [DarthSim]

libvips/foreign/foreign.c

@@ -535,7 +535,12 @@ vips_foreign_find_load( const char *name )
 	 */
 	if( !vips_existsf( "%s", filename ) ) {
 		vips_error( "VipsForeignLoad", 
-			_( "file \"%s\" not readable" ), name );
+			_( "file \"%s\" does not exist" ), name );
+		return( NULL );
+	}
+	if( vips_isdirf( "%s", filename ) ) {
+		vips_error( "VipsForeignLoad", 
+			_( "\"%s\" is a directory" ), name );
 		return( NULL );
 	}
 

libvips/include/vips/util.h

@@ -281,6 +281,8 @@ gint64 vips__seek( int fd, gint64 pos, int whence );
 int vips__ftruncate( int fd, gint64 pos );
 int vips_existsf( const char *name, ... )
 	__attribute__((format(printf, 1, 2)));
+int vips_isdirf( const char *name, ... )
+	__attribute__((format(printf, 1, 2)));
 int vips_mkdirf( const char *name, ... )
 	__attribute__((format(printf, 1, 2)));
 int vips_rmdirf( const char *name, ... )

libvips/iofuncs/util.c

@@ -1157,7 +1157,7 @@ vips__ftruncate( int fd, gint64 pos )
 	return( 0 );
 }
 
-/* TRUE if file exists and is not a directory.
+/* TRUE if file exists. True for directories as well.
  */
 gboolean
 vips_existsf( const char *name, ... )
@@ -1170,9 +1170,27 @@ vips_existsf( const char *name, ... )
 	path = g_strdup_vprintf( name, ap ); 
         va_end( ap );
 
-	/* A regular (not a directory) file.
-	 */
-	result = g_file_test( path, G_FILE_TEST_IS_REGULAR );
+	result = g_file_test( path, G_FILE_TEST_EXISTS );
+
+	g_free( path ); 
+
+	return( result ); 
+}
+
+/* TRUE if file exists and is a directory.
+ */
+gboolean
+vips_isdirf( const char *name, ... )
+{
+        va_list ap;
+	char *path; 
+        gboolean result; 
+
+        va_start( ap, name );
+	path = g_strdup_vprintf( name, ap ); 
+        va_end( ap );
+
+	result = g_file_test( path, G_FILE_TEST_IS_DIR );
 
 	g_free( path );