Re: [PATCH v2 03/11] clone: add --sparse mode

From: Derrick Stolee <stolee@gmail.com>
Date: Oct 7, 2019, 13:56 UTC
Message-ID: <c57c71d3-ddd6-464d-a442-713707ee94f6@gmail.com>
In-Reply-To: <CABPp-BHaV+XX63Y46b8wHk0rHzdAbfDQDZAQe3pHcA63WerigA@mail.gmail.com>

On 10/5/2019 3:40 PM, Elijah Newren wrote:

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> On Thu, Sep 19, 2019 at 3:06 PM Derrick Stolee via GitGitGadget
> <gitgitgadget@gmail.com> wrote:
> 
>> During the 'git sparse-checkout init' call, we must first look
>> to see if HEAD is valid, or else we will fail while trying to
>> update the working directory. The first checkout will actually
>> update the working directory correctly.
> 
> This is new since the RFC series, but I'm not sure I understand.  Is
> the issue you're fixing here that a 'git init somerepo' would hit this
> codepath and print funny errors because HEAD doesn't exist yet and
> thus the whole `git read-tree -mu HEAD` stuff can't work?  Or that
> when the remote has HEAD pointing at a bad commit that you get error
> messages different than expected?

At the point where `git clone --sparse` calls `git sparse-checkout init`, there is no HEAD. We need to initialize the sparse-checkout before the clone operation populates the working directory and creates the HEAD ref. For that reason, `git read-tree -mu HEAD` wouldn't work. But that's fine, since there is nothing to do. The index update will happen later.

Show 25 quoted lines

> 
>> diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c
>> index 895479970d..656e6ebdd5 100644
>> --- a/builtin/sparse-checkout.c
>> +++ b/builtin/sparse-checkout.c
>> @@ -99,6 +99,7 @@ static int sparse_checkout_init(int argc, const char **argv)
>>         char *sparse_filename;
>>         FILE *fp;
>>         int res;
>> +       struct object_id oid;
>>
>>         if (sc_enable_config())
>>                 return 1;
>> @@ -120,6 +121,11 @@ static int sparse_checkout_init(int argc, const char **argv)
>>         fprintf(fp, "/*\n!/*/\n");
>>         fclose(fp);
>>
>> +       if (get_oid("HEAD", &oid)) {
>> +               /* assume we are in a fresh repo */
>> +               return 0;
>> +       }
>> +
>>  reset_dir:
>>         return update_working_directory();
>>  }