setup_git_directory_gently contract question?

setup_git_directory_gently contract question?

[Ciprian Dorin Craciun]

    Is the function setup_git_directory_gently supposed to change the
current working directory, or should it keep the initial one?
    What is the meaning of nongit_ok?

    Because if I use nongit_ok != NULL, but *nongit_ok == 1, this
function changes the current working directory to the top of the
worktree directory.

    Thanks,
    Ciprian Craciun.

Re: setup_git_directory_gently contract question?

[Ciprian Dorin Craciun]

    Or another question: how can I obtain the git directory (.git)
(absolute) path without updating the current working directory?

    Thanks,
    Ciprian Craciun.


On Tue, May 27, 2008 at 5:10 PM, Ciprian Dorin Craciun
<ciprian.craciun@gmail.com> wrote:
>    Is the function setup_git_directory_gently supposed to change the
> current working directory, or should it keep the initial one?
>    What is the meaning of nongit_ok?
>
>    Because if I use nongit_ok != NULL, but *nongit_ok == 1, this
> function changes the current working directory to the top of the
> worktree directory.
>
>    Thanks,
>    Ciprian Craciun.

Re: setup_git_directory_gently contract question?

[Nguyen Thai Ngoc Duy]

On Tue, May 27, 2008 at 9:10 PM, Ciprian Dorin Craciun
<ciprian.craciun@gmail.com> wrote:
>    Is the function setup_git_directory_gently supposed to change the
> current working directory, or should it keep the initial one?

It will change if it finds a worktree.

>    What is the meaning of nongit_ok?

Setting it to a non null pointer prevents git from die() when no git
repository can be found.

>    Because if I use nongit_ok != NULL, but *nongit_ok == 1, this
> function changes the current working directory to the top of the
> worktree directory.

It returns a directory prefix so that you can still know the original
current working directory. You can do as following to have current
directory "unchanged"

prefix = setup_git_directory_gently(&nongit_ok);
if (prefix) chdir(prefix)

>    Thanks,
>    Ciprian Craciun.
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-- 
Duy

Re: setup_git_directory_gently contract question?

[Junio C Hamano]

"Ciprian Dorin Craciun" <ciprian.craciun@gmail.com> writes:

>     Is the function setup_git_directory_gently supposed to change the
> current working directory, or should it keep the initial one?
>     What is the meaning of nongit_ok?

Most commands that work from subdirectory use setup_git_directory()
interface, because major parts of the guts of the git internal want you to
be at the top of the work tree (e.g. so that you grab a path out of the
index, and be able to open(2) or lstat(2) that path).  A normal sequence
for a command is: (1) use setup_git_directory() to learn "prefix", (2) use
get_pathspec() and/or prefix_path() to add "prefix" to the paths given
from the command to make it a path relative to the work tree, (3) do its
thing.  setup_git_directory() chdir's up to the top of the work tree for
this reason.

Some commands can optionally work from even outside a git repository, but
they would want to operate the same way as other comands, when they are
started within a git repository.  In such a case, you use "gently"
variant, and give a pointer to int to store an additional return value to
signal you if you are inside a git repository or outside.

 * When NULL is given as nongit_ok to gently(), it does not behave gentle
   at all.  Outside a git repository it dies loudly.

 * If you are inside a git repository, it behaves pretty much the same as
   setup_git_directory().  "*nongit_ok" is set to zero to signal that you
   are inside a git repository.

 * If you are outside a git repository, *nongit_ok is set to non-zero so
   that the caller can tell that it is not in any git repository's work
   tree.  There is no need to chdir (nor a sensible place to chdir to) in
   this case, so it doesn't.

The caller thinks of the parameter as "are we operating in non-git mode?"
boolean, and the callee (i.e. setup_git_directory_gently()) thinks of it
as "is it ok to be called outside a git repository?" (if it is NULL, the
caller expects to be inside a repository and wants it to barf otherwise).
That is why caller's variable are often called "int nongit", and the
callee's parameter is called "int *nongit_ok".

Re: setup_git_directory_gently contract question?

[Ciprian Dorin Craciun]

On Wed, May 28, 2008 at 1:46 AM, Junio C Hamano <gitster@pobox.com> wrote:
> "Ciprian Dorin Craciun" <ciprian.craciun@gmail.com> writes:
>
>>     Is the function setup_git_directory_gently supposed to change the
>> current working directory, or should it keep the initial one?
>>     What is the meaning of nongit_ok?
>
> Most commands that work from subdirectory use setup_git_directory()
> interface, because major parts of the guts of the git internal want you to
> be at the top of the work tree (e.g. so that you grab a path out of the
> index, and be able to open(2) or lstat(2) that path).  A normal sequence
> for a command is: (1) use setup_git_directory() to learn "prefix", (2) use
> get_pathspec() and/or prefix_path() to add "prefix" to the paths given
> from the command to make it a path relative to the work tree, (3) do its
> thing.  setup_git_directory() chdir's up to the top of the work tree for
> this reason.
>
> Some commands can optionally work from even outside a git repository, but
> they would want to operate the same way as other comands, when they are
> started within a git repository.  In such a case, you use "gently"
> variant, and give a pointer to int to store an additional return value to
> signal you if you are inside a git repository or outside.
>
>  * When NULL is given as nongit_ok to gently(), it does not behave gentle
>   at all.  Outside a git repository it dies loudly.
>
>  * If you are inside a git repository, it behaves pretty much the same as
>   setup_git_directory().  "*nongit_ok" is set to zero to signal that you
>   are inside a git repository.
>
>  * If you are outside a git repository, *nongit_ok is set to non-zero so
>   that the caller can tell that it is not in any git repository's work
>   tree.  There is no need to chdir (nor a sensible place to chdir to) in
>   this case, so it doesn't.
>
> The caller thinks of the parameter as "are we operating in non-git mode?"
> boolean, and the callee (i.e. setup_git_directory_gently()) thinks of it
> as "is it ok to be called outside a git repository?" (if it is NULL, the
> caller expects to be inside a repository and wants it to barf otherwise).
> That is why caller's variable are often called "int nongit", and the
> callee's parameter is called "int *nongit_ok".

    Thank you for your complete answer.

    I would propose that these comments to be added to the
Documentation/technical/... directory, (or in the setup.c file), so
that further developers will have this information.

    Thanks again,
    Ciprian.