Quoting Christian Brauner (christianvanbrau...@gmail.com):
> On Mon, Nov 02, 2015 at 03:52:25PM +0100, Christian Brauner wrote:
> > On Mon, Nov 02, 2015 at 02:38:16PM +0000, Serge Hallyn wrote:
> > > Quoting Christian Brauner (christianvanbrau...@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 <christianvanbrau...@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.
>
> I don't think this is the case. At the beginning of the while() we search for
> a
> newline character and make lend point to the character immediately after it.
>
> lend = strchr(lstart, '\n');
> if (!lend)
> lend = lstart + strlen(lstart);
> else
> lend++;
>
> Then we check
>
> if (!strstr(p, " overlay") && !strstr(p, " aufs"))
strstr will not constrain it's search to values under lend (unless you
set *lend = '\0')
-serge
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