1 files changed, 6 insertions, 8 deletions

diff --git a/trace-cmd.c b/trace-cmd.c
index e1341bf..9965428 100644
--- a/trace-cmd.c
+++ b/trace-cmd.c
@@ -891,6 +891,11 @@ static void update_filter(const char *event_name, const char *field,
                 die("Can't read %s", path);
         close(fd);
 
+        if (ret >= BUFSIZ)
+                ret = BUFSIZ - 1;
+
+        buf[ret] = 0;
+
         /* append unless there is currently no filter */
         if (strncmp(buf, "none", 4) == 0) {
                 filter = malloc_or_die(strlen(pid) + strlen(field) +
@@ -902,14 +907,7 @@ static void update_filter(const char *event_name, const char *field,
                 sprintf(filter, "(%s)||(%s==%s)", buf, field, pid);
         }
 
-        fd = open(path, O_WRONLY);
-        if (fd < 0)
-                die("can't open %s", path);
-
-        ret = write(fd, filter, strlen(filter));
-        if (ret < 0)
-                warning("Can't write to %s", path);
-        close(fd);
+        write_filter(path, filter);
 
         free(filter);