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

Let's refactor "safely writing string to a file" into
write_with_lock_file(), and make write_message() use it. The new
function makes it easy to create new convenience function
write_file_gently(); as some of the upcoming callers of this new
function would want to append a newline character, add a flag for it in
write_file_gently(), and thus in write_with_lock_file().

Signed-off-by: Johannes Schindelin <>
 sequencer.c | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index 5e5d113..aa949d4 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -242,22 +242,37 @@ 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)
-               return error_errno(_("Could not write to %s"), filename);
-       strbuf_release(msgbuf);
+       if (write_in_full(msg_fd, buf, len) < 0)
+               return error_errno(_("Could not write to '%s'"), filename);
+       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.

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