open_memstream on non-linux?

[Miika Turkia]

On Wed, Mar 13, 2013 at 11:08 AM, Martin Gysel <me at bearsh.org> wrote:
> Am 12.03.2013 20:24, schrieb Miika Turkia:
>> On Tue, Mar 12, 2013 at 2:48 PM, Lubomir I. Ivanov <neolit123 at gmail.com> wrote:
>>> On 12 March 2013 14:45, Lubomir I. Ivanov <neolit123 at gmail.com> wrote:
>>>> On 12 March 2013 10:35, Martin Gysel <me at bearsh.org> wrote:
>>>>> Am 11.03.2013 18:09, schrieb Lubomir I. Ivanov:
>>>>>> On 11 March 2013 18:19, Dirk Hohndel <dirk at hohndel.org> wrote:
>>>>>>> There is some discussion and code on working around that here…
>>>>>>>
>>>>>>> http://stackoverflow.com/questions/10305095/can-i-replace-a-call-to-open-memstream-with-a-malloc-and-an-implicit-cast
>>>>>>>
>>>>>>> which looks way overkill to me.
>>>>>>>
>>>>>>> Miika - any way you could reimplement this differently? :-)
>>>>>>
>>>>>> here is my attempt for miika's reference.
>>>>>>
>>>>>> it also now, uses ./ for the temp zip file, since obviously /tmp/
>>>>>> isn't portable to non-UNIX OS. instead i would write the temp file in
>>>>>> the home directory, which we should retrieve in a OS specific way
>>>>>> using e.g. subsurface_get_home_path().
>>>>>
>>>>> For me it seems to be a bad idea to create a tmp file in the home
>>>>> directory, just image, if subsurface crashes once a tmp file has been
>>>>> created, it will never get deleted again. there's a reason places like
>>>>> /tmp are there.
>>>>>
>>>>
>>>> that's certainly true.
>>>>
>>>>> looking through the glib's documentation I found
>>>>> g_mkstemp() or g_file_open_tmp().
>>>>> g_file_open_tmp() for example takes a filename template (no directory)
>>>>> creates and opens a tmp file in the appropriate location. it also gives
>>>>> you the actual name of the file based on the template. there's no
>>>>> mention that this doesn't work on windows...
>>>>>
>>>>
>>>> yep, g_file_open_tmp() should do it, given g_file_open_tmp() succeeds.
>>>>
>>>
>>> i meant g_get_tmp_dir(), which searches for the temp directory...
>>
>> Here is a version (on top of Lubomir's patch) that uses
>> g_get_tmp_dir() and g_build_filename() to create the temporary file
>> name.
>>
>> miika
>>
>
> maybe it is a little bit nip-picking...
>
> from your patch:
>
>         struct zip_source *s[dive_table.nr];
>         struct zip *zip;
> +       const gchar *tmpdir = g_get_tmp_dir();
>
>         /*
>          * Creating a temporary .DLD file to be eventually uploaded to
>          * divelogs.de. I wonder if this could be done in-memory.
>          */
>
> -       template = strdup("./export.DLD-XXXXXX");
> +       template = g_build_filename(tmpdir, "export.DLD-XXXXXX", NULL);
>         tempfile = (char *)mktemp(template);
>
> just wondering why you call g_get_tmp_dir() followed by
> g_build_filename() followed by mktemp() and not just simple use
> g_file_open_tmp()? supposing the glib guys did a good job it seems to be
> less error prone to me...

I did consider the g_file_open_tmp, but it opens the temp file as well
as returns the name for the generated file. Thus I would have to close
the file and give the string for zip_open. Not ideal for our purpose.
So I just chose to create the full temporary file name  manually and
give that to open_zip (not ideal either).

miika