[PATCH v7 31/40] environment: add set_index_file()

[Christian Couder <christian.couder@gmail.com>]

Introduce set_index_file() to be able to temporarily change the index file.

It should be used like this:

    /* Save current index file */
    old_index_file = get_index_file();
    set_index_file((char *)tmp_index_file);

    /* Do stuff that will use tmp_index_file as the index file */
    ...

    /* When finished reset the index file */
    set_index_file(old_index_file);

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 cache.h       |  1 +
 environment.c | 10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/cache.h b/cache.h
index 81d4ac3..28fc0bf 100644
--- a/cache.h
+++ b/cache.h
@@ -461,6 +461,7 @@ extern int is_inside_work_tree(void);
 extern const char *get_git_dir(void);
 extern const char *get_git_common_dir(void);
 extern char *get_object_directory(void);
+extern void set_index_file(char *index_file);
 extern char *get_index_file(void);
 extern char *get_graft_file(void);
 extern int set_git_dir(const char *path);
diff --git a/environment.c b/environment.c
index ca72464..7a53799 100644
--- a/environment.c
+++ b/environment.c
@@ -292,6 +292,16 @@ int odb_pack_keep(char *name, size_t namesz, const unsigned char *sha1)
 	return open(name, O_RDWR|O_CREAT|O_EXCL, 0600);
 }
 
+/*
+ * Temporarily change the index file.
+ * Please save the current index file using get_index_file() before changing
+ * the index file. And when finished, reset it to the saved value.
+ */
+void set_index_file(char *index_file)
+{
+	git_index_file = index_file;
+}
+
 char *get_index_file(void)
 {
 	if (!git_index_file)
-- 
2.9.0.rc2.411.g3e2ca28