[xen staging] tools/xenstore: simplify and rename check_event_node()

[patchbot@xxxxxxx]

commit d3f8c086d23d886e2f5357b096bfefd5c8e5bcc4
Author:     Juergen Gross <jgross@xxxxxxxx>
AuthorDate: Tue Dec 15 13:34:42 2020 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Dec 15 13:34:42 2020 +0100

    tools/xenstore: simplify and rename check_event_node()
    
    There is no path which allows to call check_event_node() without a
    event name. So don't let the result depend on the name being NULL and
    add an assert() covering that case.
    
    Rename the function to check_special_event() to better match the
    semantics.
    
    This is part of XSA-115.
    
    Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
    Reviewed-by: Julien Grall <jgrall@xxxxxxxxxx>
    Reviewed-by: Paul Durrant <paul@xxxxxxx>
---
 tools/xenstore/xenstored_watch.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/tools/xenstore/xenstored_watch.c b/tools/xenstore/xenstored_watch.c
index 7dedca60df..f2f1bed47c 100644
--- a/tools/xenstore/xenstored_watch.c
+++ b/tools/xenstore/xenstored_watch.c
@@ -47,13 +47,11 @@ struct watch
        char *node;
 };
 
-static bool check_event_node(const char *node)
+static bool check_special_event(const char *name)
 {
-       if (!node || !strstarts(node, "@")) {
-               errno = EINVAL;
-               return false;
-       }
-       return true;
+       assert(name);
+
+       return strstarts(name, "@");
 }
 
 /* Is child a subnode of parent, or equal? */
@@ -87,7 +85,7 @@ static void add_event(struct connection *conn,
        unsigned int len;
        char *data;
 
-       if (!check_event_node(name)) {
+       if (!check_special_event(name)) {
                /* Can this conn load node, or see that it doesn't exist? */
                struct node *node = get_node(conn, ctx, name, XS_PERM_READ);
                /*
--
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