Re: [PATCH 2/2] read-cache: use time_t instead of unsigned long

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

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Hi,

On Mon, 12 Nov 2018, Junio C Hamano wrote:

> Carlo Marcelo Arenas Belón  <carenas@gmail.com> writes:
> 
> > b968372279 ("read-cache: unlink old sharedindex files", 2017-03-06)
> > introduced get_shared_index_expire_date using unsigned long to track
> > the modification times of a shared index.
> >
> > dddbad728c ("timestamp_t: a new data type for timestamps", 2017-04-26)
> > shows why that might problematic so move to time_t instead.
> >
> > Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
> > ---
> >  read-cache.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/read-cache.c b/read-cache.c
> > index 7b1354d759..5525d8e679 100644
> > --- a/read-cache.c
> > +++ b/read-cache.c
> > @@ -2625,9 +2625,9 @@ static int write_split_index(struct index_state *istate,
> >  
> >  static const char *shared_index_expire = "2.weeks.ago";
> >  
> > -static unsigned long get_shared_index_expire_date(void)
> > +static time_t get_shared_index_expire_date(void)
> >  {
> > -	static unsigned long shared_index_expire_date;
> > +	static time_t shared_index_expire_date;
> >  	static int shared_index_expire_date_prepared;
> >  
> >  	if (!shared_index_expire_date_prepared) {
> 
> After this line, the post-context reads like this:
> 
> 		git_config_get_expiry("splitindex.sharedindexexpire",
> 				      &shared_index_expire);
> 		shared_index_expire_date = approxidate(shared_index_expire);
> 		shared_index_expire_date_prepared = 1;
> 	}
> 
> 	return shared_index_expire_date;
> 
> Given that the function returns the value obtained from
> approxidate(), which is approxidate_careful() in disguise, time_t is
> not as appropriate as timestamp_t, no?
> 
> IOW, what if time_t were narrower than timestamp_t?

Riiiight. From the patch, I had assumed that the return type of
`approxidate()` is `time_t`, but it is `timestamp_t`.

Ciao,
Johannes

> 
> 
> > @@ -2643,7 +2643,7 @@ static unsigned long get_shared_index_expire_date(void)
> >  static int should_delete_shared_index(const char *shared_index_path)
> >  {
> >  	struct stat st;
> > -	unsigned long expiration;
> > +	time_t expiration;
> >  
> >  	/* Check timestamp */
> >  	expiration = get_shared_index_expire_date();
>