Quoting Christian Brauner ([email protected]):
> The mount_entry_overlay_dirs() and mount_entry_aufs_dirs() functions create
> workdirs and upperdirs for overlay and aufs lxc.mount.entry entries. They try
> to make sure that the workdirs and upperdirs can only be created under the
> containerdir (e.g. /path/to/the/container/CONTAINERNAME). In order to do this
> the right hand side of
>
> if ((strncmp(upperdir, lxcpath, dirlen) == 0) &&
> (strncmp(upperdir, rootfs->path, rootfslen) != 0))
>
> was thought to check if the rootfs->path is not present in the workdir and
> upperdir mount options. But the current check is bogus since it will be
> trivially true whenever the container is a block-dev or overlay or aufs backed
> since the rootfs->path will then have a form like e.g.
>
> overlayfs:/some/path:/some/other/path
>
> This patch adds the function ovl_get_rootfs_dir() which parses rootfs->path by
> searching backwards for the first occurrence of the delimiter pair ":/". We do
> not simply search for ":" since it might be used in path names. If ":/" is not
> found we assume the container is directory backed and simply return
> strdup(rootfs->path).
>
> Signed-off-by: Christian Brauner <[email protected]>
> ---
> src/lxc/conf.c | 115
> ++++++++++++++++++++++++++++++++++++++++++++-------------
> 1 file changed, 90 insertions(+), 25 deletions(-)
>
> diff --git a/src/lxc/conf.c b/src/lxc/conf.c
> index 16a62f8..301fe50 100644
> --- a/src/lxc/conf.c
> +++ b/src/lxc/conf.c
> @@ -1815,12 +1815,65 @@ static void cull_mntent_opt(struct mntent *mntent)
> }
> }
>
> +static char *ovl_get_rootfs_dir(const char *rootfs_path, size_t *rootfslen)
> +{
> + char *end = NULL;
> + char *s1 = NULL;
> + char *s2 = NULL;
> + char *rootfsdir = NULL;
> + char *tmp = NULL;
> + size_t len = 0;
> + size_t slen = 0;
> +
> + if (!rootfs_path || !rootfslen )
> + return NULL;
> +
> + *rootfslen = 0;
> +
> + s1 = strdup(rootfs_path);
> + if (!s1)
> + return NULL;
> +
> + s2 = malloc(strlen(rootfs_path) + 1);
> + if (!s2) {
> + free(s1);
> + return NULL;
> + }
> + end = stpcpy(s2, rootfs_path);
> +
> + /* If we find :/ in rootfs_path it means we either have a block-dev or
> + * overlay or aufs container. */
> + while ((tmp = strrchr(s1, ':'))) {
> + len = strlen(tmp);
> + *rootfslen += len;
If it is "overlay:/some/rootfs:/some/delta0", you will find the
delta0 and return it as rootfsdir?
(or am i misreading?)
> + if (strncmp(tmp, ":/", 2) == 0) {
> + rootfsdir = strdup(end - *rootfslen + 1);
> + break;
> + } else {
> + slen = strlen(s1);
> + s1[slen - len] = '\0';
> + }
> + }
> + free(s1);
> +
> + if (!*rootfslen && !tmp)
> + rootfsdir = s2;
> + else
> + free(s2);
> +
> + if (rootfsdir)
> + *rootfslen = strlen(rootfsdir);
> +
> + return rootfsdir;
> +}
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