[lxc-devel] [PATCH 1/1] lxc-clone: don't s/oldname/newname in the config file and hooks
Serge Hallyn
serge.hallyn at ubuntu.com
Mon Aug 5 20:34:11 UTC 2013
1. container hooks should use lxcpath and lxcname from the environment.
2. the utsname now gets separately updated
3. the rootfs path gets updated by the bdev backend.
4. the fstab mount targets should be relative
5. the fstab source directories could be separately updated if needed.
This leaves one definate bug: the lxc.logfile does not get updated.
This made me wonder why it was in the configuration file to begin with.
Digging deeper, I realized that whatever '-o outfile' you give
lxc-create gets set in log.c and gets used by the lxc_container object
we create at write_config(). So if you say
lxc-create -t cirros -n c1 -o /tmp/out1
then /var/lib/lxc/c1/config will have lxc.logfile=/tmp/out1 - which is
clearly wrong. Therefore I leave fixing that for later.
I'm looking for candidates for $p/$n expansion. Note we can't expand
these at config_utsname() etc, because then lxc-clone would see the
expanded variable. So we want to read $p/$n verbatim at config_*(),
and expand them only when they are used. lxc.logfile is an obvious
good use case. lxc.utsname can do it too, in case you want container
c1 to be called "c1-whatever". I'm not sure that's worth it though.
Are there any others, or is that it?
Signed-off-by: Serge Hallyn <serge.hallyn at ubuntu.com>
---
src/lxc/lxccontainer.c | 191 +++++++------------------------------------------
1 file changed, 24 insertions(+), 167 deletions(-)
diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
index b0695bc..3affe22 100644
--- a/src/lxc/lxccontainer.c
+++ b/src/lxc/lxccontainer.c
@@ -1423,11 +1423,23 @@ out:
return ret;
}
+static bool set_config_item_locked(struct lxc_container *c, const char *key, const char *v)
+{
+ struct lxc_config_t *config;
+
+ if (!c->lxc_conf)
+ c->lxc_conf = lxc_conf_init();
+ if (!c->lxc_conf)
+ return false;
+ config = lxc_getconfig(key);
+ if (!config)
+ return false;
+ return (0 == config->cb(key, v, c->lxc_conf));
+}
+
static bool lxcapi_set_config_item(struct lxc_container *c, const char *key, const char *v)
{
- int ret;
bool b = false;
- struct lxc_config_t *config;
if (!c)
return false;
@@ -1435,18 +1447,8 @@ static bool lxcapi_set_config_item(struct lxc_container *c, const char *key, con
if (container_mem_lock(c))
return false;
- if (!c->lxc_conf)
- c->lxc_conf = lxc_conf_init();
- if (!c->lxc_conf)
- goto err;
- config = lxc_getconfig(key);
- if (!config)
- goto err;
- ret = config->cb(key, v, c->lxc_conf);
- if (!ret)
- b = true;
+ b = set_config_item_locked(c, key, v);
-err:
container_mem_unlock(c);
return b;
}
@@ -1658,153 +1660,6 @@ err:
return -1;
}
-/*
- * we're being passed result of two strstrs(x, y). We want to write
- * all data up to the first found string, or to end of the string if
- * neither string was found.
- * This function will return the earliest found string if any, or else
- * NULL
- */
-static const char *lowest_nonnull(const char *p1, const char *p2)
-{
- if (!p1)
- return p2;
- if (!p2)
- return p1;
- return p1 < p2 ? p1 : p2;
-}
-
-static int is_word_sep(char c)
-{
- switch(c) {
- case '\0':
- case '\n':
- case '\r':
- case '\t':
- case ' ':
- case '=':
- case '.':
- case ',':
- case '_':
- case '-':
- case '/':
- return 1;
- default: return 0;
- }
-}
-
-static const char *find_first_wholeword(const char *p0, const char *word)
-{
- const char *p = p0;
-
- if (!p)
- return NULL;
-
- while ((p = strstr(p, word)) != NULL) {
- if ((p == p0 || is_word_sep(*(p-1))) &&
- is_word_sep(p[strlen(word)]))
- return p;
- p++;
- }
- return NULL;
-}
-
-static int update_name_and_paths(const char *path, struct lxc_container *oldc,
- const char *newname, const char *newpath)
-{
- FILE *f;
- long flen;
- char *contents;
- const char *p0, *p1, *p2, *end;
- const char *oldpath = oldc->get_config_path(oldc);
- const char *oldname = oldc->name;
-
- f = fopen(path, "r");
- if (!f) {
- SYSERROR("opening old config");
- return -1;
- }
- if (fseek(f, 0, SEEK_END) < 0) {
- SYSERROR("seeking to end of old config");
- fclose(f);
- return -1;
- }
- flen = ftell(f);
- if (flen < 0) {
- SYSERROR("telling size of old config");
- fclose(f);
- return -1;
- }
- if (fseek(f, 0, SEEK_SET) < 0) {
- SYSERROR("rewinding old config");
- fclose(f);
- return -1;
- }
- contents = malloc(flen+1);
- if (!contents) {
- SYSERROR("out of memory");
- fclose(f);
- return -1;
- }
- if (fread(contents, 1, flen, f) != flen) {
- SYSERROR("reading old config");
- free(contents);
- fclose(f);
- return -1;
- }
- contents[flen] = '\0';
- if (fclose(f) < 0) {
- SYSERROR("closing old config");
- free(contents);
- return -1;
- }
-
- f = fopen(path, "w");
- if (!f) {
- SYSERROR("reopening config");
- free(contents);
- return -1;
- }
-
- p0 = contents;
- end = contents + flen;
- while (1) {
- p1 = find_first_wholeword(p0, oldpath);
- p2 = find_first_wholeword(p0, oldname);
- if (!p1 && !p2) {
- // write the rest and be done
- if (fwrite(p0, 1, (end-p0), f) != (end-p0)) {
- SYSERROR("writing new config");
- free(contents);
- fclose(f);
- return -1;
- }
- free(contents);
- fclose(f);
- // success
- return 0;
- } else {
- const char *p = lowest_nonnull(p1, p2);
- const char *new = (p == p2) ? newname : newpath;
- if (fwrite(p0, 1, (p-p0), f) != (p-p0)) {
- SYSERROR("writing new config");
- free(contents);
- fclose(f);
- return -1;
- }
- p0 = p;
- // now write the newpath or newname
- if (fwrite(new, 1, strlen(new), f) != strlen(new)) {
- SYSERROR("writing new name or path in new config");
- free(contents);
- fclose(f);
- return -1;
- }
- p0 += (p == p2) ? strlen(oldname) : strlen(oldpath);
- }
- }
-}
-
static int copyhooks(struct lxc_container *oldc, struct lxc_container *c)
{
int i;
@@ -1832,7 +1687,6 @@ static int copyhooks(struct lxc_container *oldc, struct lxc_container *c)
ERROR("out of memory copying hook path");
return -1;
}
- update_name_and_paths(it->elem, oldc, c->name, c->get_config_path(c));
}
}
@@ -2063,7 +1917,8 @@ struct lxc_container *lxcapi_clone(struct lxc_container *c, const char *newname,
goto out;
}
- if (create_file_dirname(newpath) < 0) {
+ ret = create_file_dirname(newpath);
+ if (ret < 0 && errno != EEXIST) {
ERROR("Error creating container dir for %s", newpath);
goto out;
}
@@ -2077,11 +1932,6 @@ struct lxc_container *lxcapi_clone(struct lxc_container *c, const char *newname,
write_config(fout, c->lxc_conf);
fclose(fout);
- if (update_name_and_paths(newpath, c, n, l) < 0) {
- ERROR("Error updating name in cloned config");
- goto out;
- }
-
sprintf(newpath, "%s/%s/rootfs", l, n);
if (mkdir(newpath, 0755) < 0) {
SYSERROR("error creating %s", newpath);
@@ -2094,6 +1944,13 @@ struct lxc_container *lxcapi_clone(struct lxc_container *c, const char *newname,
goto out;
}
+ // update utsname
+ if (!set_config_item_locked(c2, "lxc.utsname", newname)) {
+ ERROR("Error setting new hostname");
+ goto out;
+ }
+
+
// copy hooks if requested
if (flags & LXC_CLONE_COPYHOOKS) {
ret = copyhooks(c, c2);
--
1.8.1.2
More information about the lxc-devel
mailing list