[PATCH/RFC/GSoC 07/17] rebase-common: implement refresh_and_write_cache()

[Paul Tan <pyokagan@gmail.com>]

In the upcoming git-rebase to C rewrite, it is a common operation to
refresh the index and write the resulting index.

builtin/am.c already implements refresh_and_write_cache(), which is what
we want. Move it to rebase-common.c, so that it can be shared with all
the rebase backends, including git-am.

Signed-off-by: Paul Tan <pyokagan@gmail.com>
---
 builtin/am.c    | 14 +-------------
 rebase-common.c | 11 +++++++++++
 rebase-common.h |  5 +++++
 3 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/builtin/am.c b/builtin/am.c
index d003939..504b604 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -28,6 +28,7 @@
 #include "rerere.h"
 #include "prompt.h"
 #include "mailinfo.h"
+#include "rebase-common.h"
 
 /**
  * Returns 1 if the file is empty or does not exist, 0 otherwise.
@@ -1125,19 +1126,6 @@ static const char *msgnum(const struct am_state *state)
 }
 
 /**
- * Refresh and write index.
- */
-static void refresh_and_write_cache(void)
-{
-	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
-
-	hold_locked_index(lock_file, 1);
-	refresh_cache(REFRESH_QUIET);
-	if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
-		die(_("unable to write index file"));
-}
-
-/**
  * Returns 1 if the index differs from HEAD, 0 otherwise. When on an unborn
  * branch, returns 1 if there are entries in the index, 0 otherwise. If an
  * strbuf is provided, the space-separated list of files that differ will be
diff --git a/rebase-common.c b/rebase-common.c
index 8169fb6..b07e1f1 100644
--- a/rebase-common.c
+++ b/rebase-common.c
@@ -3,6 +3,17 @@
 #include "dir.h"
 #include "run-command.h"
 #include "refs.h"
+#include "lockfile.h"
+
+void refresh_and_write_cache(void)
+{
+	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
+
+	hold_locked_index(lock_file, 1);
+	refresh_cache(REFRESH_QUIET);
+	if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
+		die(_("unable to write index file"));
+}
 
 void rebase_options_init(struct rebase_options *opts)
 {
diff --git a/rebase-common.h b/rebase-common.h
index 067ad0b..8620e8c 100644
--- a/rebase-common.h
+++ b/rebase-common.h
@@ -1,6 +1,11 @@
 #ifndef REBASE_COMMON_H
 #define REBASE_COMMON_H
 
+/**
+ * Refresh and write index.
+ */
+void refresh_and_write_cache(void);
+
 /* common rebase backend options */
 struct rebase_options {
 	struct object_id onto;
-- 
2.7.0