[lxc-devel] [PATCH 1/2 v3] Add clone_update_unexp_ovl_paths() function
Christian Brauner
christianvanbrauner at gmail.com
Mon Nov 2 14:43:55 UTC 2015
On Mon, Nov 02, 2015 at 02:38:16PM +0000, Serge Hallyn wrote:
> Quoting Christian Brauner (christianvanbrauner at gmail.com):
> > This functions updates absolute paths for overlay upper- and workdirs so users
> > can simply clone and start new containers without worrying about absolute paths
> > in lxc.mount.entry overlay entries.
> >
> > Signed-off-by: Christian Brauner <christianvanbrauner at gmail.com>
> > ---
> > src/lxc/confile.c | 102 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> > src/lxc/confile.h | 3 ++
> > 2 files changed, 105 insertions(+)
> >
> > diff --git a/src/lxc/confile.c b/src/lxc/confile.c
> > index f7d6814..47b0b8b 100644
> > --- a/src/lxc/confile.c
> > +++ b/src/lxc/confile.c
> > @@ -2598,6 +2598,108 @@ void clear_unexp_config_line(struct lxc_conf *conf, const char *key, bool rm_sub
> > }
> > }
> >
> > +bool clone_update_unexp_ovl_paths(struct lxc_conf *conf, const char *oldpath,
> > + const char *newpath, const char *oldname,
> > + const char *newname, const char *ovldir)
> > +{
> > + const char *key = "lxc.mount.entry";
> > + int ret;
> > + char *lstart = conf->unexpanded_config;
> > + char *lend;
> > + char *p;
> > + char *q;
> > + size_t newdirlen = strlen(ovldir) + strlen(newpath) + strlen(newname) + 2;
> > + size_t olddirlen = strlen(ovldir) + strlen(oldpath) + strlen(oldname) + 2;
> > + char *olddir = alloca(olddirlen + 1);
> > + char *newdir = alloca(newdirlen + 1);
> > +
> > + ret = snprintf(olddir, olddirlen + 1, "%s=%s/%s", ovldir, oldpath, oldname);
> > + if (ret < 0 || ret >= olddirlen + 1) {
> > + ERROR("Bug in %s", __func__);
> > + return false;
> > + }
> > + ret = snprintf(newdir, newdirlen + 1, "%s=%s/%s", ovldir, newpath, newname);
> > + if (ret < 0 || ret >= newdirlen + 1) {
> > + ERROR("Bug in %s", __func__);
> > + return false;
> > + }
> > + if (!conf->unexpanded_config)
> > + return true;
> > + while (*lstart) {
> > + lend = strchr(lstart, '\n');
> > + if (!lend)
> > + lend = lstart + strlen(lstart);
> > + else
> > + lend++;
> > + if (strncmp(lstart, key, strlen(key)) != 0) {
> > + lstart = lend;
> > + continue;
> > + }
> > + p = strchr(lstart + strlen(key), '=');
> > + if (!p) {
> > + lstart = lend;
> > + continue;
> > + }
> > + p++;
> > + while (isblank(*p))
> > + p++;
> > + if (p >= lend)
> > + continue;
> > + /* Whenever an lxc.mount.entry entry is found in a line we check
> > + * if the substring " overlay" or the substring " aufs" is
> > + * present before doing any further work. We check for "
> > + * overlay" and " aufs" since both substrings need to have at
> > + * least one space before them in a valid overlay
> > + * lxc.mount.entry (/A B overlay). When the space before is
> > + * missing it is very likely that these substrings are part of a
> > + * path or something else. */
> > + if (!strstr(p, " overlay") && !strstr(p, " aufs")) {
> > + lstart = lend;
> > + continue;
> > + }
> > + if (!(q = strstr(p, olddir))) {
> > + lstart = lend;
> > + continue;
> > + }
>
> You're still not doing anything to ensure that 'overlays'/'aufs' and the
> olddir are actually occurring on this same line. So they could be showing
> up in a comment or just later line. Temporarily turning lend into '\0' is
> the easiest way, but you could also do something like
>
> if (!(q = strstr(p, " overlay")) && !(q=strstr(p, " aufs")))
> goto next;
> if (q >= lend)
> goto next;
>
> if (!(q = strstr(p, olddir)) || q >= lend)
> goto next;
>
> ...
>
> break;
> next:
> lstart = lend;
> continue;
Ah, I didn't get what you wanted me to do the first time.
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