diff mbox series

[v2] rerere-train: two fixes to the use of "git show -s"

Message ID 20220227220924.2144325-1-gitster@pobox.com (mailing list archive)
State Accepted
Commit 2587df669bff9daeb7d2a66cfce6b1ce28af2ef3
Headers show
Series [v2] rerere-train: two fixes to the use of "git show -s" | expand

Commit Message

Junio C Hamano Feb. 27, 2022, 10:09 p.m. UTC
The script uses "git show -s" to display the title of the merge
commit being studied, without explicitly disabling the pager, which
is not a safe thing to do in a script.

For example, when the pager is set to "less" with "-SF" options (-S
tells the pager not to fold lines but allow horizontal scrolling to
show the overly long lines, -F tells the pager not to wait if the
output in its entirety is shown on a single page), and the title of
the merge commit is longer than the width of the terminal, the pager
will wait until the end-user tells it to quit after showing the
single line.

Explicitly disable the pager with this "git show" invocation to fix
this.

The command uses the "--pretty=format:..." format, which adds LF in
between each pair of commits it outputs, which means that the label
for the merge being learned from will be followed by the next
message on the same line.  "--pretty=tformat:..." is what we should
instead, which adds LF after each commit, or a more modern way to
spell it, i.e. "--format=...".  This existing breakage becomes
easier to see, now we no longer use the pager.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---

 * Relative to the initial version, the "--no-merges" change has
   been removed because the end user can still give --merges from
   the command line and the filtering of merges done by the script
   is still needed for correctness.

 contrib/rerere-train.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Johannes Altmanninger Feb. 28, 2022, 5:33 a.m. UTC | #1
On Sun, Feb 27, 2022 at 02:09:24PM -0800, Junio C Hamano wrote:
> The script uses "git show -s" to display the title of the merge
> commit being studied, without explicitly disabling the pager, which
> is not a safe thing to do in a script.
> 
> For example, when the pager is set to "less" with "-SF" options (-S
> tells the pager not to fold lines but allow horizontal scrolling to
> show the overly long lines, -F tells the pager not to wait if the
> output in its entirety is shown on a single page), and the title of
> the merge commit is longer than the width of the terminal, the pager
> will wait until the end-user tells it to quit after showing the
> single line.
> 
> Explicitly disable the pager with this "git show" invocation to fix
> this.
> 
> The command uses the "--pretty=format:..." format, which adds LF in
> between each pair of commits it outputs, which means that the label
> for the merge being learned from will be followed by the next
> message on the same line.  "--pretty=tformat:..." is what we should
> instead, which adds LF after each commit, or a more modern way to
> spell it, i.e. "--format=...".  This existing breakage becomes
> easier to see, now we no longer use the pager.

Sounds good (definitely better than two separate commits).

> 
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
> 
>  * Relative to the initial version, the "--no-merges" change has

it was "--merges", not "--no-merges"

>    been removed because the end user can still give --merges from
>    the command line and the filtering of merges done by the script
>    is still needed for correctness.

You probably mean that the user can pass "--no-merges HEAD"
but that would just make the effective command

	git rev-list --merges --no-merges HEAD

which outputs nothing. I don't think `git rev-list --merges "$@"` will
ever output non-merge commits, so the filtering should not be necessary.

> 
>  contrib/rerere-train.sh | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/contrib/rerere-train.sh b/contrib/rerere-train.sh
> index 75125d6ae0..26b724c8c6 100755
> --- a/contrib/rerere-train.sh
> +++ b/contrib/rerere-train.sh
> @@ -86,7 +86,7 @@ do
>  	fi
>  	if test -s "$GIT_DIR/MERGE_RR"
>  	then
> -		git show -s --pretty=format:"Learning from %h %s" "$commit"
> +		git --no-pager show -s --format="Learning from %h %s" "$commit"
>  		git rerere
>  		git checkout -q $commit -- .
>  		git rerere
> -- 
> 2.35.1-354-g715d08a9e5
>
diff mbox series

Patch

diff --git a/contrib/rerere-train.sh b/contrib/rerere-train.sh
index 75125d6ae0..26b724c8c6 100755
--- a/contrib/rerere-train.sh
+++ b/contrib/rerere-train.sh
@@ -86,7 +86,7 @@  do
 	fi
 	if test -s "$GIT_DIR/MERGE_RR"
 	then
-		git show -s --pretty=format:"Learning from %h %s" "$commit"
+		git --no-pager show -s --format="Learning from %h %s" "$commit"
 		git rerere
 		git checkout -q $commit -- .
 		git rerere