On Wed, Dec 07, 2022 at 05:05:47AM +0100, Ævar Arnfjörð Bjarmason wrote:
> Isn't the below squashed in better? I.e. just always pass the "path",
> but maybe pass a "fd=0", in which case the function might need to
> git_open() it.
>
> Then have map_loose_object() and loose_object_info() call
> open_loose_object(), and pass in the "path" and "fd".
I like this direction, though I'd give a few small suggestions. One is
to make it unconditional to pass in a valid "fd". These kind of magic
sentinel values sometimes lead to confusion or bugs, and it's easy
enough for the caller to use git_open() itself.
In fact, in the one caller who cares, it lets us produce a nicer
error message:
diff --git a/object-file.c b/object-file.c
index 24793e1b47..7c2a85132b 100644
--- a/object-file.c
+++ b/object-file.c
@@ -1219,9 +1219,6 @@ static void *map_loose_object_1(struct repository *r, const char *const path,
{
void *map;
- if (!fd)
- fd = git_open(path);
-
map = NULL;
if (fd >= 0) {
struct stat st;
@@ -2790,13 +2787,18 @@ int read_loose_object(const char *path,
struct object_info *oi)
{
int ret = -1;
+ int fd;
void *map = NULL;
unsigned long mapsize;
git_zstream stream;
char hdr[MAX_HEADER_LEN];
unsigned long *size = oi->sizep;
- map = map_loose_object_1(the_repository, path, 0, &mapsize);
+ fd = git_open(path);
+ if (fd < 0)
+ error_errno(_("unable to open %s"), path);
+
+ map = map_loose_object_1(the_repository, path, fd, &mapsize);
if (!map) {
error_errno(_("unable to mmap %s"), path);
goto out;
> +static void *map_loose_object_1(struct repository *r, const char *const path,
> + int fd, unsigned long *size)
> {
> void *map;
> - int fd;
>
> - if (path)
> + if (!fd)
> fd = git_open(path);
> - else
> - fd = open_loose_object(r, oid, &path);
> - if (mapped_path)
> - *mapped_path = xstrdup(path);
The other weird thing here is ownership of "fd". Now some callers pass
it in, but map_loose_object_1() always closes it. I think that's OK
(since we want it closed even on success), but definitely surprising
enough that we'd want to document that in a comment.
> @@ -1251,7 +1245,10 @@ void *map_loose_object(struct repository *r,
> const struct object_id *oid,
> unsigned long *size)
> {
> - return map_loose_object_1(r, NULL, oid, size, NULL);
> + const char *path;
> + int fd = open_loose_object(r, oid, &path);
> +
> + return map_loose_object_1(r, path,fd, size);
> }
It's also kind of weird that map_loose_object_1() is a noop on a
negative descriptor. That technically makes this correct, but I think it
would be much less surprising to always take a valid descriptor, and
this code should do:
if (fd)
return -1;
return map_loose_object_1(r, path, fd, size);
If we are going to make map_loose_object_1() less confusing (and I think
that is worth doing), let's go all the way.
-Peff
