responsible for freeing *FILE_NAME. */
int make_unique_file_stream (FILE **fp, char **file_name) ;
+
+/* Prepares to atomically replace a (potentially) existing file
+ by a new file, by creating a temporary file with the given
+ PERMISSIONS bits in the same directory as *FILE_NAME.
+
+ Special files are an exception: they are not atomically
+ replaced but simply opened for writing.
+
+ If successful, stores the temporary file's name in *TMP_NAME
+ and a stream for it opened according to MODE (which should be
+ "w" or "wb") in *FP. Returns a ticket that can be used to
+ commit or abort the file replacement. If neither action has
+ yet been taken, program termination via signal will cause
+ *TMP_FILE to be unlinked.
+
+ The caller is responsible for closing *FP, but *TMP_NAME is
+ owned by the callee. */
+struct replace_file *replace_file_start (const char *file_name,
+ const char *mode, mode_t permissions,
+ FILE **fp, char **tmp_name);
+
+/* Commits or aborts the replacement of a (potentially) existing
+ file by a new file, using the ticket returned by
+ replace_file_start. Returns success. */
+bool replace_file_commit (struct replace_file *);
+bool replace_file_abort (struct replace_file *);
+
#endif /* make-file.h */