Merge pull request #1875 from brauner/2017-10-27/tools_allow_undefined_containers

tools: allow lxc-attach to undefined containers

diff --git a/src/lxc/tools/lxc_attach.c b/src/lxc/tools/lxc_attach.c
index cab75ca765ed40243d708b7f194fed1a9d201916..56875fff6882b6cde65a59c4a2103d913d71237f 100644 (file)
--- a/src/lxc/tools/lxc_attach.c
+++ b/src/lxc/tools/lxc_attach.c
@@ -38,6 +38,7 @@
 #include "attach.h"
 #include "arguments.h"
 #include "caps.h"
+#include "conf.h"
 #include "confile.h"
 #include "console.h"
 #include "log.h"
@@ -279,20 +280,46 @@ static int get_pty_on_host_callback(void *p)
 
 static int get_pty_on_host(struct lxc_container *c, struct wrapargs *wrap, int *pid)
 {
-       int ret = -1;
-       struct wrapargs *args = wrap;
        struct lxc_epoll_descr descr;
        struct lxc_conf *conf;
        struct lxc_tty_state *ts;
+       int ret = -1;
+       struct wrapargs *args = wrap;
 
        INFO("Trying to allocate a pty on the host");
 
        if (!isatty(args->ptyfd)) {
-               ERROR("Standard file descriptor does not refer to a pty\n.");
+               ERROR("Standard file descriptor does not refer to a pty");
                return -1;
        }
 
-       conf = c->lxc_conf;
+       if (c->lxc_conf) {
+               conf = c->lxc_conf;
+       } else {
+               /* If the container is not defined and the user didn't specify a
+                * config file to load we will simply init a dummy config here.
+                */
+               conf = lxc_conf_init();
+               if (!conf) {
+                       ERROR("Failed to allocate dummy config file for the container");
+                       return -1;
+               }
+
+               /* We also need a dummy rootfs path otherwise
+                * lxc_console_create() will not let us create a console. Note,
+                * I don't want this change to make it into
+                * lxc_console_create()'s since this function will only be
+                * responsible for proper /dev/{console,tty<n>} devices.
+                * lxc-attach is just abusing it to also handle the pty case
+                * because it is very similar. However, with LXC 3.0 lxc-attach
+                * will need to move away from using lxc_console_create() since
+                * this is actually an internal symbol and we only want the
+                * tools to use the API with LXC 3.0.
+                */
+               conf->rootfs.path = strdup("dummy");
+               if (!conf->rootfs.path)
+                       return -1;
+       }
        free(conf->console.log_path);
        if (my_args.console_log)
                conf->console.log_path = strdup(my_args.console_log);
@@ -434,12 +461,6 @@ int main(int argc, char *argv[])
                exit(EXIT_FAILURE);
        }
 
-       if (!c->is_defined(c)) {
-               fprintf(stderr, "Error: container %s is not defined\n", c->name);
-               lxc_container_put(c);
-               exit(EXIT_FAILURE);
-       }
-
        if (remount_sys_proc)
                attach_options.attach_flags |= LXC_ATTACH_REMOUNT_PROC_SYS;
        if (elevated_privileges)
@@ -457,7 +478,7 @@ int main(int argc, char *argv[])
 
        struct wrapargs wrap = (struct wrapargs){
                .command = &command,
-                       .options = &attach_options
+               .options = &attach_options
        };
 
        wrap.ptyfd = stdfd_is_pty();