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;
+ }
+
+ /* replace the olddir with newdir */
+ if (olddirlen >= newdirlen) {
+ size_t diff = olddirlen - newdirlen;
+ memcpy(q, newdir, newdirlen);
+ if (olddirlen != newdirlen) {
+ memmove(q + newdirlen, q + newdirlen + diff,
+ strlen(q) - newdirlen - diff + 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 + 1);
+ if (!new) {
+ ERROR("Out of memory");
+ return false;
+ }
+ conf->unexpanded_len = newlen;
+ conf->unexpanded_alloced = newlen + 1;
+ new[newlen - 1] = '\0';
+ lend = new + (lend - conf->unexpanded_config);
+ /* move over the remainder to make room for the newdir
*/
+ memmove(new + poffset + newdirlen,
+ new + poffset + olddirlen,
+ oldlen - poffset - olddirlen + 1);
+ conf->unexpanded_config = new;
+ memcpy(new + poffset, newdir, newdirlen);
+ lstart = lend + diff;
+ }
+ }
+ return true;
+}
+
bool clone_update_unexp_hooks(struct lxc_conf *conf, const char *oldpath,
const char *newpath, const char *oldname, const char *newname)
{
diff --git a/src/lxc/confile.h b/src/lxc/confile.h
index 8da3699..12ffd3c 100644
--- a/src/lxc/confile.h
+++ b/src/lxc/confile.h
@@ -61,5 +61,8 @@ extern bool do_append_unexp_config_line(struct lxc_conf
*conf, const char *key,
extern void clear_unexp_config_line(struct lxc_conf *conf, const char *key,
bool rm_subkeys);
extern bool clone_update_unexp_hooks(struct lxc_conf *conf, const char
*oldpath,
const char *newpath, const char *oldname, const char *newmame);
+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);
extern bool network_new_hwaddrs(struct lxc_conf *conf);
#endif
--
2.6.2
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