[PATCH 22/22] sequencer: refactor write_message()

[Johannes Schindelin <johannes.schindelin@xxxxxx>]

The write_message() function safely writes an strbuf to a file.
Sometimes this is inconvenient, though: the text to be written may not
be stored in a strbuf, or the strbuf should not be released after
writing.

Let's allow for such use cases by refactoring write_message() to allow
for a convenience function write_file_gently(). As some of the upcoming
callers of that new function will want to append a newline character,
let's just add a flag for that, too.

Signed-off-by: Johannes Schindelin <johannes.schindelin@xxxxxx>
---
 sequencer.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index 5efed2e..f5b5e5e 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -239,22 +239,37 @@ static void print_advice(int show_hint, struct replay_opts *opts)
 	}
 }
 
-static int write_message(struct strbuf *msgbuf, const char *filename)
+static int write_with_lock_file(const char *filename,
+				const void *buf, size_t len, int append_eol)
 {
 	static struct lock_file msg_file;
 
 	int msg_fd = hold_lock_file_for_update(&msg_file, filename, 0);
 	if (msg_fd < 0)
 		return error_errno(_("Could not lock '%s'"), filename);
-	if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
+	if (write_in_full(msg_fd, buf, len) < 0)
 		return error_errno(_("Could not write to %s"), filename);
-	strbuf_release(msgbuf);
+	if (append_eol && write(msg_fd, "\n", 1) < 0)
+		return error_errno(_("Could not write eol to %s"), filename);
 	if (commit_lock_file(&msg_file) < 0)
 		return error(_("Error wrapping up %s."), filename);
 
 	return 0;
 }
 
+static int write_message(struct strbuf *msgbuf, const char *filename)
+{
+	int res = write_with_lock_file(filename, msgbuf->buf, msgbuf->len, 0);
+	strbuf_release(msgbuf);
+	return res;
+}
+
+static int write_file_gently(const char *filename,
+			     const char *text, int append_eol)
+{
+	return write_with_lock_file(filename, text, strlen(text), append_eol);
+}
+
 /*
  * Reads a file that was presumably written by a shell script, i.e.
  * with an end-of-line marker that needs to be stripped.
-- 
2.10.0.rc1.114.g2bd6b38