nlattr: introduce decode_nla_flags

Similar to decode_nla_xval.

* nlattr.c (decode_nla_flags): New function.
* nlattr.h: (DECL_NLA(flags)): New declaration.

2 files changed, 27 insertions, 0 deletions

diff --git a/nlattr.c b/nlattr.c
index f65d9cf6a..835cf25e5 100644
--- a/nlattr.c
+++ b/nlattr.c
@@ -296,6 +296,32 @@ decode_nla_ip_proto(struct tcb *const tcp,
 }
 
 bool
+decode_nla_flags(struct tcb *const tcp,
+		 const kernel_ulong_t addr,
+		 const unsigned int len,
+		 const void *const opaque_data)
+{
+	const struct decode_nla_xlat_opts * const opts = opaque_data;
+	union {
+		uint64_t flags;
+		uint8_t  bytes[sizeof(uint64_t)];
+	} data = { .flags = 0 };
+	const size_t bytes_offs = is_bigendian ? sizeof(data) - len : 0;
+
+	if (opts->xt == XT_INDEXED)
+		error_func_msg("indexed xlats are currently incompatible with "
+			       "printflags");
+
+	if (len > sizeof(data))
+		return false;
+	else if (!umoven_or_printaddr(tcp, addr, len, data.bytes + bytes_offs))
+		printflags_ex(data.flags, opts->dflt, opts->style, opts->xlat,
+			      NULL);
+
+	return true;
+}
+
+bool
 decode_nla_be16(struct tcb *const tcp,
 		const kernel_ulong_t addr,
 		const unsigned int len,
diff --git a/nlattr.h b/nlattr.h
index 765aba823..fc7a67d92 100644
--- a/nlattr.h
+++ b/nlattr.h
@@ -75,6 +75,7 @@ DECL_NLA(s64);
 DECL_NLA(be16);
 DECL_NLA(be64);
 DECL_NLA(xval);
+DECL_NLA(flags);
 DECL_NLA(str);
 DECL_NLA(strn);
 DECL_NLA(fd);