When creating ephemeral containers that have the option lxc.ephemeral = 1 set
in their config, they will be destroyed on shutdown. As they are simple overlay
clones of an existing container they should be registered in the lxc_snapshots
file of the original container to stay consistent and adhere to the
expectancies of the users. Most of all, it ensure that we cannot remove a
container that has clones, even if they are just ephemeral snapshot-clones. The
function adds further consistency because remove_snapshots_entry() ensures that
ephemeral clone-snapshots deregister themselves from the lxc_snapshots file
when they are destroyed.
Signed-off-by: Christian Brauner <christianvanbrau...@gmail.com>
---
src/lxc/start.c | 43 ++++++++++++++++++++-----------------------
1 file changed, 20 insertions(+), 23 deletions(-)
diff --git a/src/lxc/start.c b/src/lxc/start.c
index 93c039c..f58d9a4 100644
--- a/src/lxc/start.c
+++ b/src/lxc/start.c
@@ -84,7 +84,7 @@ const struct ns_info ns_info[LXC_NS_MAX] = {
[LXC_NS_NET] = {"net", CLONE_NEWNET}
};
-static void update_clone_snapshots(struct lxc_handler *handler, const char
*name);
+static void remove_snapshot_entry(struct lxc_handler *handler, const char
*name);
static bool do_destroy_container(struct lxc_conf *conf);
static int lxc_rmdir_onedev_wrapper(void *data);
static void lxc_destroy_container_on_signal(struct lxc_handler *handler,
@@ -1324,7 +1324,7 @@ static void lxc_destroy_container_on_signal(struct
lxc_handler *handler,
return;
}
- update_clone_snapshots(handler, name);
+ remove_snapshot_entry(handler, name);
if (am_unpriv())
ret = userns_exec_1(handler->conf, lxc_rmdir_onedev_wrapper,
destroy);
@@ -1353,7 +1353,7 @@ static bool do_destroy_container(struct lxc_conf *conf) {
return bdev_destroy(conf);
}
-static void update_clone_snapshots(struct lxc_handler *handler, const char
*name)
+static void remove_snapshot_entry(struct lxc_handler *handler, const char
*name)
{
char rdepfile[MAXPATHLEN];
char path[MAXPATHLEN];
@@ -1365,9 +1365,9 @@ static void update_clone_snapshots(struct lxc_handler
*handler, const char *name
char *origpath = NULL;
char *origname = NULL;
int ret = 0;
+ int bytes = 0;
int fd = -1;
size_t len = 0;
- size_t difflen = 0;
struct stat fbuf;
ret = snprintf(rdepfile, MAXPATHLEN, "%s/%s/lxc_rdepends",
handler->lxcpath, name);
@@ -1435,7 +1435,13 @@ static void update_clone_snapshots(struct lxc_handler
*handler, const char *name
}
if (fbuf.st_size != 0) {
- buf = mmap(NULL, fbuf.st_size, PROT_READ | PROT_WRITE,
MAP_SHARED, fd, 0);
+ /* write terminating \0-byte to file */
+ if (pwrite(fd, "", 1, fbuf.st_size) <= 0) {
+ close(fd);
+ return;
+ }
+
+ buf = mmap(NULL, fbuf.st_size + 1, PROT_READ | PROT_WRITE,
MAP_SHARED, fd, 0);
if (buf == MAP_FAILED) {
SYSERROR("Failed to create mapping %s", path);
close(fd);
@@ -1443,25 +1449,16 @@ static void update_clone_snapshots(struct lxc_handler
*handler, const char *name
}
len = strlen(newpath);
+ while ((del = strstr((char *)buf, newpath))) {
+ memmove(del, del + len, strlen(del) - len + 1);
+ bytes += len;
+ }
- /* mmap()ed memory is only \0-terminated when it is not
- * a multiple of a pagesize. Hence, we'll use memmem(). */
- if ((del = memmem(buf, fbuf.st_size, newpath, len))) {
- /* remove container entry */
- if (del != buf + fbuf.st_size - len) {
- difflen = fbuf.st_size - (del - buf);
- memmove(del, del + len, strnlen(del, difflen) -
len);
- }
-
- munmap(buf, fbuf.st_size);
-
- if (ftruncate(fd, fbuf.st_size - len) < 0) {
- SYSERROR("Failed to truncate file %s", path);
- close(fd);
- return;
- }
- } else {
- munmap(buf, fbuf.st_size);
+ munmap(buf, fbuf.st_size + 1);
+ if (ftruncate(fd, fbuf.st_size - bytes) < 0) {
+ SYSERROR("Failed to truncate file %s", path);
+ close(fd);
+ return;
}
}
--
2.5.1
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