Add support for hash chaining to detect modifications in postings

The following details of a posting contribute to its hash:

  fullname of account
  string representation of amount

Each posting hashes contributes to the transaction hash, which is compromised
of:

  previous transaction’s hash (as encountered in parsing order)
  actual date
  optional auxiliary date
  optional code
  payee
  hashes of all postings

Note that this means that changes in the “code” or any of the comments

1 files changed, 2 insertions, 2 deletions

diff --git a/src/journal.h b/src/journal.h
index 06bcbd4f..d68618bf 100644
--- a/src/journal.h
+++ b/src/journal.h
@@ -184,7 +184,7 @@ public:
     return period_xacts.end();
   }
 
-  std::size_t read(parse_context_stack_t& context);
+  std::size_t read(parse_context_stack_t& context, bool store_hashes);
 
   bool has_xdata();
   void clear_xdata();
@@ -193,7 +193,7 @@ public:
 
 private:
 
-  std::size_t read_textual(parse_context_stack_t& context);
+  std::size_t read_textual(parse_context_stack_t& context, bool store_hashes);
 
   bool        should_check_payees();
   bool        payee_not_registered(const string& name);