make 'cat /proc/zaptel/1' not fail with ztdummy loaded (issue #5069)

git-svn-id: http://svn.digium.com/svn/zaptel/trunk@755 5390a7c7-147a-4af0-8ec9-7488f05a26cb

1 files changed, 5 insertions, 0 deletions

diff --git a/zaptel.c b/zaptel.c
index c35fed9..6ecca4d 100755
--- a/zaptel.c
+++ b/zaptel.c
@@ -571,6 +571,11 @@ static int zaptel_proc_read(char *page, char **start, off_t off, int count, int
 			}
 		}
 	}
+	if ( len <= off ) /* If everything printed so far is before beginning of request */
+	{
+		off -= len;
+		len = 0;
+	}
 	*start = page + off;
 	return len;
 }