fix possible invalid read (reproducible only on big-endian machines)

diff --git a/main/SAPI.c b/main/SAPI.c
index fe55a2ae98e862539af07211a589c27a5fb17f52..f3eb0d9398e53747cebc8cc6bdaeb048ae6bb3d1 100644 (file)
--- a/main/SAPI.c
+++ b/main/SAPI.c
@@ -591,7 +591,7 @@ SAPI_API int sapi_header_op(sapi_header_op_enum op, void *arg TSRMLS_DC)
        header_line = estrndup(header_line, header_line_len);
 
        /* cut of trailing spaces, linefeeds and carriage-returns */
-       while(isspace(header_line[header_line_len-1])) 
+       while(header_line_len && isspace(header_line[header_line_len-1])) 
                  header_line[--header_line_len]='\0';
        
        /* new line safety check */