Re: [PATCH v4] merge-recursive: check GIT_MERGE_VERBOSITY only once

Andrey Okoshkin [off-list ref] writes:

I think, the main benefits are:
* Code is more readable, no duplicated calls with the same constant string
argument.
* Code is potentially safer, the second getenv() call may return another
pointer value which could be NULL (and yes, this is an arguable point as it
can be done only artificially).

quoted

For the sake of fairness, I would say that the resulting code may be
easier to follow and has one less instance of a constant string that
the compiler cannot statically check if we made a typo.  That's the
only benefit in this patch as far as I can see.

The original makes a call to see if the result is NULL, and then
makes the same call, expecting that we get the same result (not just
that it is not NULL, but it is the same verbosity request the end
user made via the environment as the one we checked earlier), and I
can understand that it feels a bit redundant and ugly.

Yes, you absolutely right.

I am absolutely right when I say your "code is potentially safer" is
total BS.  The result from first getenv() call may be pointing at an
invalid piece of memory by the time it is used, if you are in a
situation in which not having the second getenv() matters
(i.e. somebody else is also mucking with getenv() at the same time).

So please update the log message so that the patch is not sold on
that basis.

Thanks.

Get rid of the duplicated getenv('GIT_MERGE_VERBOSITY') calls with the same
constant string argument. This makes code more readable and prevents typo in
the further development.

Signed-off-by: Andrey Okoshkin <redacted>
Reviewed-by: Stefan Beller <redacted>
---
Commit message is reworked according to the feedback.
 merge-recursive.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index 1494ffdb8..60084e3a0 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c

@@ -2163,6 +2163,7 @@ static void merge_recursive_config(struct merge_options *o)
 
 void init_merge_options(struct merge_options *o)
 {
+	const char *merge_verbosity;
 	memset(o, 0, sizeof(struct merge_options));
 	o->verbosity = 2;
 	o->buffer_output = 1;

@@ -2171,9 +2172,9 @@ void init_merge_options(struct merge_options *o)
 	o->renormalize = 0;
 	o->detect_rename = 1;
 	merge_recursive_config(o);
-	if (getenv("GIT_MERGE_VERBOSITY"))
-		o->verbosity =
-			strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
+	merge_verbosity = getenv("GIT_MERGE_VERBOSITY");
+	if (merge_verbosity)
+		o->verbosity = strtol(merge_verbosity, NULL, 10);
 	if (o->verbosity >= 5)
 		o->buffer_output = 0;
 	strbuf_init(&o->obuf, 0);

-- 
2.14.3