cpp: Add gpgme_data_rewind to cpp API

* lang/cpp/src/data.h, lang/cpp/src/data.cpp (Data::rewind): New.
* lang/qt/tests/t-various.cpp (testDataRewind): Test it.

--
The advantage of this convieniance function in GPGME is that
it avoids the messiness that are declarations with off_t.

GnuPG-Bug-Id: T3996

2 files changed, 8 insertions, 0 deletions

diff --git a/lang/cpp/src/data.cpp b/lang/cpp/src/data.cpp
index 52b8da24..2782aa79 100644
--- a/lang/cpp/src/data.cpp
+++ b/lang/cpp/src/data.cpp
@@ -232,6 +232,11 @@ off_t GpgME::Data::seek(off_t offset, int whence)
     return gpgme_data_seek(d->data, offset, whence);
 }
 
+GpgME::Error GpgME::Data::rewind()
+{
+    return Error(gpgme_data_rewind(d->data));
+}
+
 std::vector<GpgME::Key> GpgME::Data::toKeys(Protocol proto) const
 {
     std::vector<GpgME::Key> ret;
diff --git a/lang/cpp/src/data.h b/lang/cpp/src/data.h
index 446f6fa3..df8607e7 100644
--- a/lang/cpp/src/data.h
+++ b/lang/cpp/src/data.h
@@ -110,6 +110,9 @@ public:
     ssize_t write(const void *buffer, size_t length);
     off_t seek(off_t offset, int whence);
 
+    /* Convenience function to do a seek (0, SEEK_SET).  */
+    Error rewind();
+
     /** Try to parse the data to a key object using the
      * Protocol proto. Returns an empty list on error.*/
     std::vector<Key> toKeys(const Protocol proto = Protocol::OpenPGP) const;