checkout: Add commentary around whiteout "quoting"

Signed-off-by: Colin Walters <walters@verbum.org>
This commit is contained in:
Colin Walters 2024-10-01 17:07:17 -04:00
parent 9ca8b4604d
commit fdfeb0ba7b

View File

@ -35,7 +35,13 @@
#define WHITEOUT_PREFIX ".wh."
#define OPAQUE_WHITEOUT_NAME ".wh..wh..opq"
#define OVERLAYFS_WHITEOUT_PREFIX ".ostree-wh."
// ostree doesn't have native support for devices. Whiteouts in overlayfs
// are a 0:0 character device, and in some cases people are copying docker/podman
// style overlayfs container storage directly into ostree commits. This
// adds special support for "quoting" the whiteout so it just appears as a regular
// file in the ostree commit, but can be converted back into a character device
// on checkout.
#define OSTREE_QUOTED_OVERLAYFS_WHITEOUT_PREFIX ".ostree-wh."
/* Per-checkout call state/caching */
typedef struct
@ -711,7 +717,8 @@ checkout_one_file_at (OstreeRepo *repo, OstreeRepoCheckoutAtOptions *options, Ch
const gboolean is_whiteout = (!is_symlink && options->process_whiteouts
&& g_str_has_prefix (destination_name, WHITEOUT_PREFIX));
const gboolean is_overlayfs_whiteout
= (!is_symlink && g_str_has_prefix (destination_name, OVERLAYFS_WHITEOUT_PREFIX));
= (!is_symlink
&& g_str_has_prefix (destination_name, OSTREE_QUOTED_OVERLAYFS_WHITEOUT_PREFIX));
const gboolean is_reg_zerosized = (!is_symlink && g_file_info_get_size (source_info) == 0);
const gboolean override_user_unreadable
= (options->mode == OSTREE_REPO_CHECKOUT_MODE_USER && is_unreadable);
@ -735,7 +742,7 @@ checkout_one_file_at (OstreeRepo *repo, OstreeRepoCheckoutAtOptions *options, Ch
}
else if (is_overlayfs_whiteout && options->process_passthrough_whiteouts)
{
const char *name = destination_name + (sizeof (OVERLAYFS_WHITEOUT_PREFIX) - 1);
const char *name = destination_name + (sizeof (OSTREE_QUOTED_OVERLAYFS_WHITEOUT_PREFIX) - 1);
if (!name[0])
return glnx_throw (error, "Invalid empty overlayfs whiteout '%s'", name);