On Thu, Oct 22, 2015 at 02:15:18PM +0000, Serge Hallyn wrote: > Quoting Christian Brauner (christianvanbrau...@gmail.com): > > On Thu, Oct 22, 2015 at 01:13:35PM +0000, Serge Hallyn wrote: > > > Quoting Christian Brauner (christianvanbrau...@gmail.com): > > > > On Tue, Oct 20, 2015 at 04:17:18PM +0000, Serge Hallyn wrote: > > > > > Quoting Christian Brauner (christianvanbrau...@gmail.com): <snip> > > > > > > > > > > Alternate suggestion. How about using clear_unexp_config_line() to > > > > > remove all > > > > > lxc.mount.entry lines from unexpanded config first, then run through > > > > > this loop > > > > > and simply add the new ones? > > > > > > > > > > The lxc_string_replace approach feels problematic. > > > > > > > > I thought so too, but clear_unexp_config_line() will not just clear > > > > mount > > > > entries from the containers config but also entries from files like > > > > common.conf > > > > which are also present in lxc_conf->mount_list e.g.: > > > > > > Hm, might be the other way around, but yeah we can't do that. > > > > > > But if the config file has say a commented version of the line before > > > the real line, you'll update only the comment right? > > > > > > So can you do lik eclear_unexp_config_line() does and make sure you > > > are looking for only lines beginning with "lxc.mount.entry += +" > > > and then have the mnt_entry? I guess that should do. > > > > > > > I'll test that and get back with an updated patch. I *try* to think of > > something > > smarter... Do you want me to avoid lxc_string_replace()? > > Not because of lxc_string_replace itself, but because it won't confine > itself to one ^.*$ line. So if you cna make it work, that's fine with me, > but it feels like a wrecking ball in our unexpanded_config china shop.
Ok, we are clear that we need to update both, the lxc_conf->mount_list and the
lxc_conf->unexpanded_config. I suggest we split this into separate functions.
For updating lxc_conf->unexpanded_config we could add a function to confile.c
which is similar to clone_update_unexp_hooks(). It would look like this:
bool clone_update_unexp_ovl_dir(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) +
1 + 1;
size_t olddirlen = strlen(ovldir) + strlen(oldpath) + strlen(oldname) +
1 + 1;
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)
return true;
/* Should we check that when an lxc.mount.entry is found the
* substrings "overlay" or "aufs" are actually present before we
* try to update the line? This seems like a bit more safety. We
* can check for " overlay " and " aufs " since both substrings
* need to have at least one space before and after them. When
* the space before or after is missing it is very likely that
* these substrings are part of a path or something else. So we
* shouldn't bother to do any further work...
*/
if (!strstr(p, " overlay ") && !strstr(p, " aufs "))
continue;
if (!(q = strstr(p, olddir))) {
lstart = lend;
continue;
}
/* replace the olddir with newdir */
if (olddirlen >= newdirlen) {
size_t diff = olddirlen - newdirlen;
memcpy(q, newdir, newdirlen);
if (olddirlen != newdirlen) {
memmove(lend-diff, lend, strlen(lend)+1);
lend -= diff;
conf->unexpanded_len -= diff;
}
lstart = lend;
} else {
char *new;
size_t diff = newdirlen - olddirlen;
size_t oldlen = conf->unexpanded_len;
size_t newlen = oldlen + diff;
size_t poffset = q - conf->unexpanded_config;
new = realloc(conf->unexpanded_config, newlen);
if (!new) {
ERROR("Out of memory");
return false;
}
conf->unexpanded_len = newlen;
new[newlen-1] = '\0';
lend = new + (lend - conf->unexpanded_config);
/* move over the remainder, /$hookname\n$rest */
memmove(new+poffset+newdirlen,
new+poffset+olddirlen,
oldlen-poffset-olddirlen);
conf->unexpanded_config = new;
memcpy(new+poffset, newdir, newdirlen);
lstart = lend + diff;
}
}
return true;
}
If you agree with this approach we can put another function in lxccontainer.c
which updates lxc_conf->mount_list and which calls clone_update_unexp_ovl_dir().
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