chore(kernel): add custom pretty printer for std::string

Kernel/gdb_printers.py

@@ -0,0 +1,51 @@
+import gdb
+
+class BasicStringPrinter:
+    def __init__(self, val):
+        self.val = val
+
+    def to_string(self):
+        try:
+            data = self.val['_data']
+            size = int(self.val['_size'])
+            capacity = int(self.val['_capacity'])
+            if int(data) == 0:
+                return '<null>'
+            content = data.string(length=size)
+            return f"'{content}' (size={size}, cap={capacity})"
+        except gdb.error:
+            return '<invalid string>'
+
+    def children(self):
+        try:
+            data = self.val['_data']
+            size = int(self.val['_size'])
+            if int(data) == 0:
+                return
+            for i in range(size):
+                yield (f'[{i}]', (data + i).dereference())
+        except gdb.error:
+            return
+
+    def display_hint(self):
+        return 'array'
+
+def lookup_fennix_string(val):
+    try:
+        typename = str(val.type.strip_typedefs())
+        fields = val.type.fields()
+        field_names = [f.name for f in fields]
+        if '_data' in field_names and '_size' in field_names and '_capacity' in field_names:
+            return BasicStringPrinter(val)
+    except:
+        pass
+    return None
+
+gdb.pretty_printers.append(lookup_fennix_string)
+
+def build_pretty_printers():
+    pp = gdb.printing.RegexpCollectionPrettyPrinter("fennix")
+    pp.add_printer('std::string', '^std::string$', BasicStringPrinter)
+    return pp
+
+gdb.printing.register_pretty_printer(None, build_pretty_printers(), replace=True)