lxccontainer: simplify partial file creation

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
index 1a5567aa90e33752f407c7ad8e6bcfecc2a83e36..0011e52921b4fd1be817e37c751845e0a4746371 100644 (file)
--- a/src/lxc/lxccontainer.c
+++ b/src/lxc/lxccontainer.c
@@ -170,27 +170,15 @@ static int ongoing_create(struct lxc_container *c)
        return LXC_CREATE_INCOMPLETE;
 }
 
-static int create_partial(struct lxc_container *c)
+static int create_partial(int fd_rootfs, struct lxc_container *c)
 {
-       __do_free char *path = NULL;
        __do_close int fd_partial = -EBADF;
        int ret;
-       size_t len;
        struct flock lk = {0};
 
-       /* $lxcpath + '/' + $name + '/partial' + \0 */
-       len = strlen(c->config_path) + 1 + strlen(c->name) + 1 + strlen(LXC_PARTIAL_FNAME) + 1;
-       path = malloc(len);
-       if (!path)
-               return ret_errno(ENOMEM);
-
-       ret = strnprintf(path, len, "%s/%s/%s", c->config_path, c->name, LXC_PARTIAL_FNAME);
-       if (ret < 0)
-               return -errno;
-
-       fd_partial = open(path, O_RDWR | O_CREAT | O_EXCL | O_CLOEXEC, 0000);
+       fd_partial = openat(fd_rootfs, LXC_PARTIAL_FNAME, O_RDWR | O_CREAT | O_EXCL | O_CLOEXEC, 0000);
        if (fd_partial < 0)
-               return syserror("Failed to create \"%s\" to mark container as partially created", path);
+               return syserror("errno(%d) - Failed to create \"%d/" LXC_PARTIAL_FNAME "\" to mark container as partially created", errno, fd_rootfs);
 
        lk.l_type = F_WRLCK;
        lk.l_whence = SEEK_SET;
@@ -203,10 +191,10 @@ static int create_partial(struct lxc_container *c)
                                return move_fd(fd_partial);
                }
 
-               return syserror("Failed to lock partial file %s", path);
+               return syserror("Failed to lock partial file \"%d/" LXC_PARTIAL_FNAME"\"", fd_rootfs);
        }
 
-       TRACE("Created \"%s\" to mark container as partially created", path);
+       TRACE("Created \"%d/" LXC_PARTIAL_FNAME "\" to mark container as partially created", fd_rootfs);
        return move_fd(fd_partial);
 }
 
@@ -1206,32 +1194,31 @@ WRAP_API(bool, lxcapi_stop)
 
 static int do_create_container_dir(const char *path, struct lxc_conf *conf)
 {
-       int lasterr;
+       __do_close int fd_rootfs = -EBADF;
        int ret = -1;
 
        mode_t mask = umask(0002);
        ret = mkdir(path, 0770);
-       lasterr = errno;
        umask(mask);
-       errno = lasterr;
-       if (ret) {
-               if (errno != EEXIST)
-                       return -1;
+       if (ret < 0 && errno != EEXIST)
+               return -errno;
 
-               ret = 0;
-       }
+       fd_rootfs = open_at(-EBADF, path, O_DIRECTORY | O_CLOEXEC, PROTECT_LOOKUP_ABSOLUTE_WITH_SYMLINKS, 0);
+       if (fd_rootfs < 0)
+               return syserror("Failed to open container directory \"%d(%s)\"", fd_rootfs, path);
 
-       if (!list_empty(&conf->id_map)) {
-               ret = chown_mapped_root(path, conf);
-               if (ret < 0)
-                       ret = -1;
-       }
+       if (list_empty(&conf->id_map))
+               return move_fd(fd_rootfs);
 
-       return ret;
+       ret = userns_exec_mapped_root(NULL, fd_rootfs, conf);
+       if (ret < 0)
+               return syserror_ret(-1, "Failed to chown rootfs \"%s\"", path);
+
+       return move_fd(fd_rootfs);
 }
 
 /* Create the standard expected container dir. */
-static bool create_container_dir(struct lxc_container *c)
+static int create_container_dir(struct lxc_container *c)
 {
        __do_free char *s = NULL;
        int ret;
@@ -1240,13 +1227,13 @@ static bool create_container_dir(struct lxc_container *c)
        len = strlen(c->config_path) + strlen(c->name) + 2;
        s = malloc(len);
        if (!s)
-               return false;
+               return ret_errno(ENOMEM);
 
        ret = strnprintf(s, len, "%s/%s", c->config_path, c->name);
        if (ret < 0)
-               return false;
+               return -errno;
 
-       return do_create_container_dir(s, c->lxc_conf) == 0;
+       return do_create_container_dir(s, c->lxc_conf);
 }
 
 /* do_storage_create: thin wrapper around storage_create(). Like
@@ -1776,6 +1763,7 @@ static bool do_lxcapi_create(struct lxc_container *c, const char *t,
                             const char *bdevtype, struct bdev_specs *specs,
                             int flags, char *const argv[])
 {
+       __do_close int fd_rootfs = -EBADF;
        __do_free char *path_template = NULL;
        int partial_fd;
        mode_t mask;
@@ -1805,7 +1793,8 @@ static bool do_lxcapi_create(struct lxc_container *c, const char *t,
                return log_error(false, "Failed to load default configuration file %s",
                                 lxc_global_config_value("lxc.default_config"));
 
-       if (!create_container_dir(c))
+       fd_rootfs = create_container_dir(c);
+       if (fd_rootfs < 0)
                return log_error(false, "Failed to create container %s", c->name);
 
        if (c->lxc_conf->rootfs.path)
@@ -1844,7 +1833,7 @@ static bool do_lxcapi_create(struct lxc_container *c, const char *t,
        }
 
        /* Mark that this container as being created */
-       partial_fd = create_partial(c);
+       partial_fd = create_partial(fd_rootfs, c);
        if (partial_fd < 0) {
                SYSERROR("Failed to mark container as being partially created");
                goto out;
@@ -2614,7 +2603,7 @@ WRAP_API_3(int, lxcapi_get_keys, const char *, char *, int)
 
 static bool do_lxcapi_save_config(struct lxc_container *c, const char *alt_file)
 {
-       __do_close int fd_config = -EBADF;
+       __do_close int fd_config = -EBADF, fd_rootfs = -EBADF;
        int lret = -1;
        bool bret = false, need_disklock = false;
 
@@ -2632,7 +2621,8 @@ static bool do_lxcapi_save_config(struct lxc_container *c, const char *alt_file)
                }
        }
 
-       if (!create_container_dir(c))
+       fd_rootfs = create_container_dir(c);
+       if (fd_rootfs < 0)
                return log_error(false, "Failed to create container directory");
 
        /* If we're writing to the container's config file, take the disk lock.
@@ -3753,17 +3743,18 @@ only rootfs gets converted (copied/snapshotted) on clone.
 
 static int create_file_dirname(char *path, struct lxc_conf *conf)
 {
-       char *p = strrchr(path, '/');
-       int ret = -1;
+       __do_close int fd_rootfs = -EBADF;
+       char *p;
 
+       p = strrchr(path, '/');
        if (!p)
                return -1;
 
        *p = '\0';
-       ret = do_create_container_dir(path, conf);
+       fd_rootfs = do_create_container_dir(path, conf);
        *p = '/';
 
-       return ret;
+       return fd_rootfs >= 0;
 }
 
 static struct lxc_container *do_lxcapi_clone(struct lxc_container *c, const char *newname,