threads / patch / 53055

patchbisect: remove root directory restriction for git bisect

Subject: [PATCH] bisect: remove root directory restriction for git bisect

## tl;dr

7 messages between Mar 22, 2020 and Mar 23, 2020. Diffs are folded; open one to read it.

replies: 6people: 5as markdown or json

Sheikh hamza via GitGitGadget· Mar 22, 2020, 09:15 UTC · lore
From: sheikh hamza <sheikhhamza012@gmail.com>
    according to the open issue #486 the git bisect
    command should be able to run from inside any
    subdirectory and in the same disscusion "dscho"
    gave the directions and those directions lead me
    the fix of adding SUBDIRECTORY_OK=Yes on L#34
    before sourcing git-sh-setup that made it work as
    in git-sh-setup there was a check on SUBDIRECTORY_OK
    that prevents it to run in sub directories if it is not
    set to "ok" as this file was also sourced in other commands
    that are required to only run from root one of such scripts
    is git-filter-branch
Signed-off-by: sheikh hamza <sheikhhamza012@gmail.com>
---
    bisect: remove root directory restriction for git bisect
    
    according to the open issue #486 the git bisect
    command should be able to run from inside any
    subdirectory and in the same disscusion "dscho"
    gave the directions and those directions lead me
    the fix of adding SUBDIRECTORY_OK=Yes on L#34
    before sourcing git-sh-setup that made it work as
    in git-sh-setup there was a check on SUBDIRECTORY_OK
    that prevents it to run in sub directories if it is not
    set to "ok" as this file was also sourced in other commands
    that are required to only run from root one of such scripts
    is git-filter-branch
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-736%2Fsheikhhamza012%2Fbisect_subdirectory_fix-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-736/sheikhhamza012/bisect_subdirectory_fix-v1
Pull-Request: https://github.com/git/git/pull/736
 git-bisect.sh            | 1 +
 t/perf/bisect_regression | 6 ++----
 2 files changed, 3 insertions(+), 4 deletions(-)
Show changes to 2 files +3 −4

git-bisect.sh, t/perf/bisect_regression

diff --git a/git-bisect.sh b/git-bisect.sh
index efee12b8b1e..8c1da200e41 100755
--- a/git-bisect.sh
+++ b/git-bisect.sh
@@ -31,6 +31,7 @@ git bisect run <cmd>...
 
 Please use "git help bisect" to get the full man page.'
 
+SUBDIRECTORY_OK=Yes
 OPTIONS_SPEC=
 . git-sh-setup
 
diff --git a/t/perf/bisect_regression b/t/perf/bisect_regression
index ce47e1662a9..d6b96f49e46 100755
--- a/t/perf/bisect_regression
+++ b/t/perf/bisect_regression
@@ -57,11 +57,9 @@ tmpdir=$(mktemp -d -t bisect_regression_XXXXXX) || die "Failed to create temp di
 echo "$oldtime" >"$tmpdir/oldtime" || die "Failed to write to '$tmpdir/oldtime'"
 echo "$newtime" >"$tmpdir/newtime" || die "Failed to write to '$tmpdir/newtime'"
 
-# Bisecting must be performed from the top level directory (even with --no-checkout)
-(
-	toplevel_dir=$(git rev-parse --show-toplevel) || die "Failed to find top level directory"
-	cd "$toplevel_dir" || die "Failed to cd into top level directory '$toplevel_dir'"
 
+(
+	 
 	git bisect start --no-checkout "$newrev" "$oldrev" || die "Failed to start bisecting"
 
 	git bisect run t/perf/bisect_run_script "$test_script" "$test_number" "$tmpdir"

base-commit: 98cedd0233ee88e69711f79d1126b6bd772ff5bd

-- 
gitgitgadget
SZEDER Gábor· Mar 22, 2020, 10:48 UTC · re: Sheikh hamza via GitGitGadget · lore

Re: [PATCH] bisect: remove root directory restriction for git bisect

On Sun, Mar 22, 2020 at 09:15:47AM +0000, Sheikh hamza via GitGitGadget wrote:
> From: sheikh hamza <sheikhhamza012@gmail.com>
> 
>     according to the open issue #486
What issue #486?  Where?  The Git project doesn't use issues.
> the git bisect
>     command should be able to run from inside any
>     subdirectory

Why should 'git bisect' be able to run from inside any subdirectory (of the working tree, I presume)?

In particular, what happens, if someone starts 'git bisect' from within 'subdir/', and 'git bisect' then checks out an old commit, where said 'subdir/' didn't exist? What happens, if the user runs 'git bisect run ./script' from within 'subdir/', and that 'subdir/' doesn't exist in that old commit? What happens, if 'subdir' does exists in that old commit, but it's a file, not a directory? What happens, if all this is on Windows?

Show 9 quoted lines
> and in the same disscusion "dscho"
>     gave the directions and those directions lead me
>     the fix of adding SUBDIRECTORY_OK=Yes on L#34
>     before sourcing git-sh-setup that made it work as
>     in git-sh-setup there was a check on SUBDIRECTORY_OK
>     that prevents it to run in sub directories if it is not
>     set to "ok" as this file was also sourced in other commands
>     that are required to only run from root one of such scripts
>     is git-filter-branch

Please don't indent the commit message and use punctuation to make it more readable.

Show 59 quoted lines
> 
> Signed-off-by: sheikh hamza <sheikhhamza012@gmail.com>
> ---
>     bisect: remove root directory restriction for git bisect
>     
>     according to the open issue #486 the git bisect
>     command should be able to run from inside any
>     subdirectory and in the same disscusion "dscho"
>     gave the directions and those directions lead me
>     the fix of adding SUBDIRECTORY_OK=Yes on L#34
>     before sourcing git-sh-setup that made it work as
>     in git-sh-setup there was a check on SUBDIRECTORY_OK
>     that prevents it to run in sub directories if it is not
>     set to "ok" as this file was also sourced in other commands
>     that are required to only run from root one of such scripts
>     is git-filter-branch
> 
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-736%2Fsheikhhamza012%2Fbisect_subdirectory_fix-v1
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-736/sheikhhamza012/bisect_subdirectory_fix-v1
> Pull-Request: https://github.com/git/git/pull/736
> 
>  git-bisect.sh            | 1 +
>  t/perf/bisect_regression | 6 ++----
>  2 files changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/git-bisect.sh b/git-bisect.sh
> index efee12b8b1e..8c1da200e41 100755
> --- a/git-bisect.sh
> +++ b/git-bisect.sh
> @@ -31,6 +31,7 @@ git bisect run <cmd>...
>  
>  Please use "git help bisect" to get the full man page.'
>  
> +SUBDIRECTORY_OK=Yes
>  OPTIONS_SPEC=
>  . git-sh-setup
>  
> diff --git a/t/perf/bisect_regression b/t/perf/bisect_regression
> index ce47e1662a9..d6b96f49e46 100755
> --- a/t/perf/bisect_regression
> +++ b/t/perf/bisect_regression
> @@ -57,11 +57,9 @@ tmpdir=$(mktemp -d -t bisect_regression_XXXXXX) || die "Failed to create temp di
>  echo "$oldtime" >"$tmpdir/oldtime" || die "Failed to write to '$tmpdir/oldtime'"
>  echo "$newtime" >"$tmpdir/newtime" || die "Failed to write to '$tmpdir/newtime'"
>  
> -# Bisecting must be performed from the top level directory (even with --no-checkout)
> -(
> -	toplevel_dir=$(git rev-parse --show-toplevel) || die "Failed to find top level directory"
> -	cd "$toplevel_dir" || die "Failed to cd into top level directory '$toplevel_dir'"
>  
> +(
> +	 
>  	git bisect start --no-checkout "$newrev" "$oldrev" || die "Failed to start bisecting"
>  
>  	git bisect run t/perf/bisect_run_script "$test_script" "$test_number" "$tmpdir"
> 
> base-commit: 98cedd0233ee88e69711f79d1126b6bd772ff5bd
> -- 
> gitgitgadget
sheikh hamza· Mar 22, 2020, 14:58 UTC · re: SZEDER Gábor · lore

Re: [PATCH] bisect: remove root directory restriction for git bisect

i apologize for empty mails, i was configuring the mailer,
by the issue i meant one of those mentioned on gigitgadget's
fork, there this was mentioned as a good entry point project
so thought of doing it as my GSoC microproject, do you think
it makes a good microproject should i continue to work on it ?
Johannes Schindelin· Mar 23, 2020, 16:02 UTC · re: SZEDER Gábor · lore

Re: [PATCH] bisect: remove root directory restriction for git bisect

Hi Gábor,
On Sun, 22 Mar 2020, SZEDER Gábor wrote:
Show 9 quoted lines
> On Sun, Mar 22, 2020 at 09:15:47AM +0000, Sheikh hamza via GitGitGadget wrote:
> > From: sheikh hamza <sheikhhamza012@gmail.com>
> >
> > the git bisect
> >     command should be able to run from inside any
> >     subdirectory
>
> Why should 'git bisect' be able to run from inside any subdirectory
> (of the working tree, I presume)?

Because other commands also allow the user to run in a subdirectory. For example, `git rebase`, `git checkout`, `git cherry-pick`, etc

Show 5 quoted lines
> In particular, what happens, if someone starts 'git bisect' from within
> 'subdir/', and 'git bisect' then checks out an old commit, where said
> 'subdir/' didn't exist?  What happens, if the user runs 'git bisect run
> ./script' from within 'subdir/', and that 'subdir/' doesn't exist in
> that old commit?

The same that happens if that situation arises in `git rebase` or `git checkout`: the directory is removed unless it is not empty (i.e. if there are untracked files in the directory, or submodules).

> What happens, if 'subdir' does exists in that old commit, but it's a
> file, not a directory?  What happens, if all this is on Windows?

On Windows, the directory is not deletable, of course, and the same thing happens as if an untracked file is still in that directory: it is not deleted.

> >  git-bisect.sh            | 1 +
> >  t/perf/bisect_regression | 6 ++----
> >  2 files changed, 3 insertions(+), 4 deletions(-)

The most obvious problem with this patch is that it is not accompanied by a regression test that documents and verifies the intended behavior.

Ciao, Dscho

Junio C Hamano· Mar 23, 2020, 16:17 UTC · re: SZEDER Gábor · lore

Re: [PATCH] bisect: remove root directory restriction for git bisect

SZEDER Gábor <szeder.dev@gmail.com> writes:
Show 21 quoted lines
> On Sun, Mar 22, 2020 at 09:15:47AM +0000, Sheikh hamza via GitGitGadget wrote:
>> From: sheikh hamza <sheikhhamza012@gmail.com>
>> 
>>     according to the open issue #486
>
> What issue #486?  Where?  The Git project doesn't use issues.
>
>> the git bisect
>>     command should be able to run from inside any
>>     subdirectory
>
> Why should 'git bisect' be able to run from inside any subdirectory
> (of the working tree, I presume)?
>
> In particular, what happens, if someone starts 'git bisect' from
> within 'subdir/', and 'git bisect' then checks out an old commit,
> where said 'subdir/' didn't exist?  What happens, if the user runs
> 'git bisect run ./script' from within 'subdir/', and that 'subdir/'
> doesn't exist in that old commit?  What happens, if 'subdir' does
> exists in that old commit, but it's a file, not a directory?  What
> happens, if all this is on Windows?

Hmm, I am of two minds. Most certainly, the bisection would break when the directory cannot be removed, and if it can be, then $pwd would become in a weird state and the iteration with the bisect machinery (be it interactive test before saying "bisect good/bad", or the command execution during "bisect run") would fail in a strange and unpredictable ways.

So from that perspective, it does make sense to forbid running "git bisect" from a subdirectory, and we should probably do so on the same principle for "git checkout", "git pull" and many other things.

But even then, it would not probably be foolproof. Another process that the end-user is not even aware of its execution (e.g. virus scanners?) may have a file open in the subdirectory on a filesystem that does not allow directories to be removed while there is an open file descriptor on a file it contains, and would cause the command to fail in a similar way.

So it probably is being too draconian to forbid these commands (not just "git bisect") from being run in a subdirectory for no good reason (i.e. being strict is not helping us much). What would help is to make sure we fail in an understandable way (i.e. "cannot remove directory /foo/bar/boz, so checkout of version v1.2.3 failed" is clearly conveyed to the end user, which we may be already doing in which case that is wonderful).

Show 12 quoted lines
>> and in the same disscusion "dscho"
>>     gave the directions and those directions lead me
>>     the fix of adding SUBDIRECTORY_OK=Yes on L#34
>>     before sourcing git-sh-setup that made it work as
>>     in git-sh-setup there was a check on SUBDIRECTORY_OK
>>     that prevents it to run in sub directories if it is not
>>     set to "ok" as this file was also sourced in other commands
>>     that are required to only run from root one of such scripts
>>     is git-filter-branch
>
> Please don't indent the commit message and use punctuation to make it
> more readable.
This is a good point.

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