Thread (218 messages) flat view 218 messages, 9 authors, 2016-11-06

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

From: Jakub Narębski <hidden>
Date: 2016-09-01 11:10:43

Hello Johannes,

W dniu 29.08.2016 o 10:06, Johannes Schindelin pisze:
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.
By "this" you mean "using strbuf", isn't it?  It is not very obvious,
and I think it would be better to say it explicitly.
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.
This paragraph feels a bit convoluted.

As I understand it, you 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().

Isn't it better / easier to understand?
quoted hunk ↗ jump to hunk
Signed-off-by: Johannes Schindelin <redacted>
---
 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);
You could have, for consistency, add quotes around filename (see previous
error_errno callsite), *while at it*:

  		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);
Same here, and it wouldn't even be 'while at it'

  +		return error_errno(_("Could not write eol to '%s'"), filename);

 	if (commit_lock_file(&msg_file) < 0)
 		return error(_("Error wrapping up %s."), filename);
Another "while at it"... though the one that can be safely postponed
(well, the make message easier to understand part, not the quote
filename part):

  		return error(_("Error wrapping up writing to '%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;
+}
Nice.
+
+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);
+}
Nice.  And it is static function, so we don't need to come up
with a better function name (to describe its function better).
+
 /*
  * Reads a file that was presumably written by a shell script, i.e.
  * with an end-of-line marker that needs to be stripped.
And thus we got to the last patch in this series.  I have skipped
patches that already got reviewed; are there some that you would
like to have second review of?  Is there patch series that needs
to be applied earlier that needs a review?

P.S. I'll try to respond to your comments later today.

Regards,
-- 
Jakub Narębski
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