extern int read_index_from(struct index_state *, const char *path);
extern int is_index_unborn(struct index_state *);
extern int read_index_unmerged(struct index_state *);
+
+/* For use with `write_locked_index()`. */
#define COMMIT_LOCK (1 << 0)
-#define CLOSE_LOCK (1 << 1)
+
+/*
+ * Write the index while holding an already-taken lock. Close the lock,
+ * and if `COMMIT_LOCK` is given, commit it.
+ *
+ * Unless a split index is in use, write the index into the lockfile.
+ *
+ * With a split index, write the shared index to a temporary file,
+ * adjust its permissions and rename it into place, then write the
+ * split index to the lockfile. If the temporary file for the shared
+ * index cannot be created, fall back to the behavior described in
+ * the previous paragraph.
+ *
+ * With `COMMIT_LOCK`, the lock is always committed or rolled back.
+ * Without it, the lock is closed, but neither committed nor rolled
+ * back.
+ */
extern int write_locked_index(struct index_state *, struct lock_file *lock, unsigned flags);
+
extern int discard_index(struct index_state *);
extern void move_index_extensions(struct index_state *dst, struct index_state *src);
extern int unmerged_index(const struct index_state *);
extern int refresh_index(struct index_state *, unsigned int flags, const struct pathspec *pathspec, char *seen, const char *header_msg);
extern struct cache_entry *refresh_cache_entry(struct cache_entry *, unsigned int);
+/*
+ * Opportunistically update the index but do not complain if we can't.
+ * The lockfile is always committed or rolled back.
+ */
extern void update_index_if_able(struct index_state *, struct lock_file *);
extern int hold_locked_index(struct lock_file *, int);