Re: [PATCH 2/5] refs.c: do not die if locking fails in `write_pseudoref()`

[David Turner <novalis@novalis.org>]

Re making the lock static, I wonder about the following case:
          
      if (read_ref(pseudoref, &actual_old_oid))
                        
die("could not read ref '%s'", pseudoref);

I think this calls exit(), and then atexit tries to clean up the lock
files.  But since lock is no longer static, the stack may have been
destroyed (I don't actually know whether this is true, so maybe someone
else does).

On Sun, 2018-05-06 at 16:10 +0200, Martin Ågren wrote:
> If we could not take the lock, we add an error to the `strbuf err`
> and
> return. However, this code is dead. The reason is that we take the
> lock
> using `LOCK_DIE_ON_ERROR`. Drop the flag to allow our more gentle
> error-handling to actually kick in.
> 
> We could instead just drop the dead code and die here. But everything
> is
> prepared for gently propagating the error, so let's do that instead.
> 
> There is similar dead code in `delete_pseudoref()`, but let's save
> that
> for the next patch.
> 
> While at it, make the lock non-static.
> 
> Signed-off-by: Martin Ågren <martin.agren@gmail.com>
> ---
>  refs.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/refs.c b/refs.c
> index 8b7a77fe5e..8c50b8b139 100644
> --- a/refs.c
> +++ b/refs.c
> @@ -644,7 +644,7 @@ static int write_pseudoref(const char *pseudoref,
> const struct object_id *oid,
>  {
>  	const char *filename;
>  	int fd;
> -	static struct lock_file lock;
> +	struct lock_file lock = LOCK_INIT;
>  	struct strbuf buf = STRBUF_INIT;
>  	int ret = -1;
>  
> @@ -654,8 +654,7 @@ static int write_pseudoref(const char *pseudoref,
> const struct object_id *oid,
>  	strbuf_addf(&buf, "%s\n", oid_to_hex(oid));
>  
>  	filename = git_path("%s", pseudoref);
> -	fd = hold_lock_file_for_update_timeout(&lock, filename,
> -					       LOCK_DIE_ON_ERROR,
> +	fd = hold_lock_file_for_update_timeout(&lock, filename, 0,
>  					       get_files_ref_lock_ti
> meout_ms());
>  	if (fd < 0) {
>  		strbuf_addf(err, "could not open '%s' for writing:
> %s",