[sysprof] libsysprof: add trailing empty kernel node

[Christian Hergert <chergert src gnome org>]

commit 649dcf3aac7fec50c38e42b57ae450607a294d49
Author: Christian Hergert <chergert redhat com>
Date:   Tue May 28 13:54:14 2019 -0700

    libsysprof: add trailing empty kernel node
    
    This can be used so that we always know a symbol will be after the returned
    symbol (so we can look for peer address).

 src/libsysprof/sysprof-kernel-symbol.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)
---
diff --git a/src/libsysprof/sysprof-kernel-symbol.c b/src/libsysprof/sysprof-kernel-symbol.c
index 3213c8b..98d5f7b 100644
--- a/src/libsysprof/sysprof-kernel-symbol.c
+++ b/src/libsysprof/sysprof-kernel-symbol.c
@@ -111,6 +111,7 @@ do_shared_init (void)
 SysprofKernelSymbols *
 _sysprof_kernel_symbols_new_from_kallsyms (SysprofKallsyms *kallsyms)
 {
+  static const SysprofKernelSymbol empty = {0};
   SysprofKernelSymbols *self;
   const gchar *name;
   guint64 addr;
@@ -123,6 +124,7 @@ _sysprof_kernel_symbols_new_from_kallsyms (SysprofKallsyms *kallsyms)
   self = g_array_new (FALSE, FALSE, sizeof (SysprofKernelSymbol));
 
   G_LOCK (kernel_lock);
+
   while (sysprof_kallsyms_next (kallsyms, &name, &addr, &type))
     {
       if (!type_is_ignored (type))
@@ -135,10 +137,14 @@ _sysprof_kernel_symbols_new_from_kallsyms (SysprofKallsyms *kallsyms)
           g_array_append_val (self, sym);
         }
     }
-  G_UNLOCK (kernel_lock);
 
   g_array_sort (self, sysprof_kernel_symbol_compare);
 
+  /* Always add a trailing node */
+  g_array_append_val (self, empty);
+
+  G_UNLOCK (kernel_lock);
+
   return g_steal_pointer (&self);
 }
 
@@ -224,7 +230,8 @@ _sysprof_kernel_symbols_lookup (const SysprofKernelSymbols *self,
   ret = sysprof_kernel_symbol_lookup ((SysprofKernelSymbol *)(gpointer)self->data,
                                       address,
                                       0,
-                                      self->len - 1);
+                                      /* 1 for right-most, 1 for empty node */
+                                      self->len - 2);
 
   /* We resolve all symbols, including ignored symbols so that we
    * don't give back the wrong function juxtapose an ignored func.