encoding: better DECODE_START_LEGACY_COMPAT_LEN

- let you specify whether to decode compat and/or len
- put the argument order in the macro name so you know when you get it
  wrong

This is useful for FileJournal::header_t.

Signed-off-by: Sage Weil <sage.weil@dreamhost.com>

diff --git a/src/include/encoding.h b/src/include/encoding.h
index 123a8d310b698d06222c5fae5ac478239bcccdca..36fc040fbaba182c5016cf5da1dff4fb712acddf 100644 (file)
--- a/src/include/encoding.h
+++ b/src/include/encoding.h
@@ -669,25 +669,31 @@ inline void decode(std::deque<T>& ls, bufferlist::iterator& p)
     throw buffer::malformed_input(DECODE_ERR_VERSION(__PRETTY_FUNCTION__, v)); \
   __u32 struct_len;                                                    \
   ::decode(struct_len, bl);                                            \
+  if (struct_len > bl.get_remaining())                                 \
+    throw buffer::malformed_input(DECODE_ERR_PAST(__PRETTY_FUNCTION__)); \
   unsigned struct_end = bl.get_off() + struct_len;                     \
   do {
 
-#define DECODE_START_LEGACY(v, lencompat, bl)                          \
+#define DECODE_START_LEGACY_COMPAT_LEN(v, compatv, lenv, bl)           \
   __u8 struct_v;                                                       \
   ::decode(struct_v, bl);                                              \
-  unsigned struct_end = 0;                                             \
-  if (struct_v >= lencompat) {                                         \
+  if (struct_v >= compatv) {                                           \
     __u8 struct_compat;                                                        \
     ::decode(struct_compat, bl);                                       \
-    if (v < struct_compat)                                     \
+    if (v < struct_compat)                                             \
       throw buffer::malformed_input(DECODE_ERR_VERSION(__PRETTY_FUNCTION__, v)); \
+  }                                                                    \
+  unsigned struct_end = 0;                                             \
+  if (struct_v >= lenv) {                                              \
     __u32 struct_len;                                                  \
     ::decode(struct_len, bl);                                          \
+    if (struct_len > bl.get_remaining())                               \
+      throw buffer::malformed_input(DECODE_ERR_PAST(__PRETTY_FUNCTION__)); \
     struct_end = bl.get_off() + struct_len;                            \
   }                                                                    \
   do {
 
-#define DECODE_FINISH(bl)                                                      \
+#define DECODE_FINISH(bl)                                              \
   } while (false);                                                     \
   if (struct_end) {                                                    \
     if (bl.get_off() > struct_end)                                     \