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

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

[Sheikh hamza via GitGitGadget]

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(-)

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

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

[SZEDER Gábor]

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?


> 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.

> 
> 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

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

[sheikh hamza]

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

[sheikh hamza]

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

[sheikh hamza]

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 ?

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

[Johannes Schindelin]

[-- Attachment #1: Type: text/plain, Size: 1664 bytes --]

Hi Gábor,

On Sun, 22 Mar 2020, SZEDER Gábor wrote:

> 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

> 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

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

[Junio C Hamano]

SZEDER Gábor <szeder.dev@gmail.com> writes:

> 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).

>> 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.