Re: [PATCH v7 1/5] unpack-objects.c: add dry_run mode for get_data()

>
> On Tue, Dec 21 2021, Han Xin wrote:
>
>> From: Han Xin <hanxin.hx@alibaba-inc.com>
>>
>> In dry_run mode, "get_data()" is used to verify the inflation of data,
>> and the returned buffer will not be used at all and will be freed
>> immediately. Even in dry_run mode, it is dangerous to allocate a
>> full-size buffer for a large blob object. Therefore, only allocate a
>> low memory footprint when calling "get_data()" in dry_run mode.
>>
>> Suggested-by: Jiang Xin <zhiyou.jx@alibaba-inc.com>
>> Signed-off-by: Han Xin <hanxin.hx@alibaba-inc.com>
>> ---
>>  builtin/unpack-objects.c            | 23 +++++++++---
>>  t/t5590-unpack-non-delta-objects.sh | 57 +++++++++++++++++++++++++++++
>>  2 files changed, 74 insertions(+), 6 deletions(-)
>>  create mode 100755 t/t5590-unpack-non-delta-objects.sh
>>
>> diff --git a/builtin/unpack-objects.c b/builtin/unpack-objects.c
>> index 4a9466295b..9104eb48da 100644
>> --- a/builtin/unpack-objects.c
>> +++ b/builtin/unpack-objects.c
>> @@ -96,15 +96,21 @@ static void use(int bytes)
>>  	display_throughput(progress, consumed_bytes);
>>  }
>>
>> -static void *get_data(unsigned long size)
>> +static void *get_data(size_t size, int dry_run)
>>  {
>>  	git_zstream stream;
>> -	void *buf = xmallocz(size);
>> +	size_t bufsize;
>> +	void *buf;
>>
>>  	memset(&stream, 0, sizeof(stream));
>> +	if (dry_run && size > 8192)
>> +		bufsize = 8192;
>> +	else
>> +		bufsize = size;
>> +	buf = xmallocz(bufsize);
>
> Maybe I'm misunderstanding this, but the commit message says it would be
> dangerous to allocate a very larger buffer, but here we only limit the
> size under "dry_run".