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Add clone_update_unexp_ovl_paths() function

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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@gmail.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
This commit is contained in:
Christian Brauner 2015-11-02 23:20:35 +01:00 committed by Stéphane Graber
parent 16d08ae7e3
commit 329b36256a
2 changed files with 99 additions and 0 deletions
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96
src/lxc/confile.c
View File

@ -2598,6 +2598,102 @@ 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)
goto next;
p = strchr(lstart + strlen(key), '=');
if (!p)
goto next;
p++;
while (isblank(*p))
p++;
if (p >= lend)
goto next;
/* 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. (Checking q >= lend ensures that we
* only count matches in the current line.) */
if ((!(q = strstr(p, " overlay")) || q >= lend) && (!(q = strstr(p, " aufs")) || q >= lend))
goto next;
if (!(q = strstr(p, olddir)) || (q >= lend))
goto next;
/* 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;
}
} 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);
lend += diff;
}
next:
lstart = lend;
}
return true;
}
bool clone_update_unexp_hooks(struct lxc_conf *conf, const char *oldpath,
const char *newpath, const char *oldname, const char *newname)
{

3
src/lxc/confile.h
View File

@ -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