On 10/6/2017 10:18 AM, Jeff King wrote:
On Fri, Oct 06, 2017 at 09:52:31AM -0400, Derrick Stolee wrote:
A common mistake when writing binary search is to allow possible
integer overflow by using the simple average:
mid = (min + max) / 2;
Instead, use the overflow-safe version:
mid = min + (max - min) / 2;
Great, thank you for picking this up!
The included changes were found using the following two greps:
grep "/ 2;" *.c
grep "/ 2;" */*.c
grep "/2;" */*.c
You can use[1]:
git grep '/ 2;' '*.c'
to have Git expand the wildcard. That catches a few extra cases in
compat/regex/*.c. Even though it's imported code, it might be
nice to cover those, too (since it's a possible bug, and also as a good
example).
[1] I'd actually write:
git grep '/ *2;' '*.c'
to do it all in one grep. :)
Thanks for the grep lesson! I knew there would be a simpler way to do
what I wanted.
---
builtin/index-pack.c | 4 ++--
builtin/pack-objects.c | 2 +-
builtin/unpack-objects.c | 2 +-
cache-tree.c | 2 +-
packfile.c | 2 +-
sha1-lookup.c| 2 +-
sha1_name.c | 2 +-
string-list.c| 2 +-
utf8.c | 2 +-
xdiff/xpatience.c| 2 +-
10 files changed, 11 insertions(+), 11 deletions(-)
These all look good to me (really the only way the conversion could be
bad is if "min" was higher than "max", and each case is just inside a
loop condition which makes sure that is not the case).
-Peff
I thought this should be simple enough. When we are all happy with the
idea of this cleanup, I'll re-roll with the missed examples.
Thanks,
-Stolee
