[RFC PATCH v2 2/7] migration/snapshot: Introduce qemu_ftell2() routine

[Andrey Gruzdev <andrey.gruzdev@virtuozzo.com>]

In qemu-snapshot it is needed to retrieve current QEMUFile offset as a
number of bytes read by qemu_get_byte()/qemu_get_buffer().

The existing qemu_ftell() routine would give read position as a number
of bytes fetched from underlying IOChannel which is not the same.

Signed-off-by: Andrey Gruzdev <andrey.gruzdev@virtuozzo.com>
---
 migration/qemu-file.c | 6 ++++++
 migration/qemu-file.h | 1 +
 2 files changed, 7 insertions(+)

diff --git a/migration/qemu-file.c b/migration/qemu-file.c
index d6e03dbc0e..66be5e6460 100644
--- a/migration/qemu-file.c
+++ b/migration/qemu-file.c
@@ -657,6 +657,12 @@ int64_t qemu_ftell(QEMUFile *f)
     return f->pos;
 }
 
+int64_t qemu_ftell2(QEMUFile *f)
+{
+    qemu_fflush(f);
+    return f->pos + f->buf_index - f->buf_size;
+}
+
 int qemu_file_rate_limit(QEMUFile *f)
 {
     if (f->shutdown) {
diff --git a/migration/qemu-file.h b/migration/qemu-file.h
index a9b6d6ccb7..bd1a6def02 100644
--- a/migration/qemu-file.h
+++ b/migration/qemu-file.h
@@ -124,6 +124,7 @@ void qemu_file_set_hooks(QEMUFile *f, const QEMUFileHooks *hooks);
 int qemu_get_fd(QEMUFile *f);
 int qemu_fclose(QEMUFile *f);
 int64_t qemu_ftell(QEMUFile *f);
+int64_t qemu_ftell2(QEMUFile *f);
 int64_t qemu_ftell_fast(QEMUFile *f);
 /*
  * put_buffer without copying the buffer.
-- 
2.27.0