c/r: check for criu images in the checkpoint directory

CRIU can get confused if there are two dumps that are written to the same
directory, so we make some minimal effort to prevent people from doing this.
This is a better alternative than forcing liblxc to create the directory, since
it is mostly race free (and neither solution is bullet proof anyway if someone
rsyncs some bad images over the top of the good ones).

Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
index dbcee99ce990c500f62b71b1b242677931e10968..8999f44238619eb3ca863e2e56dda2e17c1a634a 100644 (file)
--- a/src/lxc/lxccontainer.c
+++ b/src/lxc/lxccontainer.c
@@ -3683,6 +3683,7 @@ static bool do_lxcapi_checkpoint(struct lxc_container *c, char *directory, bool
 {
        pid_t pid;
        int status;
+       char path[PATH_MAX];
 
        if (!criu_ok(c))
                return false;
@@ -3690,6 +3691,15 @@ static bool do_lxcapi_checkpoint(struct lxc_container *c, char *directory, bool
        if (mkdir(directory, 0700) < 0 && errno != EEXIST)
                return false;
 
+       status = snprintf(path, sizeof(path), "%s/inventory.img", directory);
+       if (status < 0 || status >= sizeof(path))
+               return false;
+
+       if (access(path, F_OK) == 0) {
+               ERROR("please use a fresh directory for the dump directory\n");
+               return false;
+       }
+
        if (!dump_net_info(c, directory))
                return false;