machined/machinectl: add logic to show list of available images

This adds a new bus call to machined that enumerates /var/lib/container
and returns all trees stored in it, distuingishing three types:

        - GPT disk images, which are files suffixed with ".gpt"
        - directory trees
        - btrfs subvolumes

1 files changed, 239 insertions, 0 deletions

diff --git a/src/machine/image.c b/src/machine/image.c
new file mode 100644
index 0000000000..0ba9652497
--- /dev/null
+++ b/src/machine/image.c
@@ -0,0 +1,239 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2013 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <sys/statfs.h>
+
+#include "strv.h"
+#include "utf8.h"
+#include "btrfs-util.h"
+#include "image.h"
+#include "bus-label.h"
+
+Image *image_unref(Image *i) {
+        if (!i)
+                return NULL;
+
+        free(i->name);
+        free(i->path);
+        free(i);
+        return NULL;
+}
+
+static int add_image(
+                Hashmap *h,
+                ImageType t,
+                const char *name,
+                const char *path,
+                bool read_only,
+                usec_t mtime,
+                usec_t btime) {
+
+        _cleanup_(image_unrefp) Image *i = NULL;
+        int r;
+
+        assert(h);
+        assert(t >= 0);
+        assert(t < _IMAGE_TYPE_MAX);
+        assert(name);
+
+        i = new(Image, 1);
+        if (!i)
+                return -ENOMEM;
+
+        i->type = t;
+        i->read_only = read_only;
+        i->mtime = mtime;
+        i->btime = btime;
+
+        i->name = strdup(name);
+        if (!i->name)
+                return -ENOMEM;
+
+        if (path) {
+                i->path = strdup(path);
+                if (!i->path)
+                        return -ENOMEM;
+        }
+
+        r = hashmap_put(h, i->name, i);
+        if (r < 0)
+                return r;
+
+        i = NULL;
+        return 0;
+}
+
+int image_discover(Hashmap *h) {
+        const char *path;
+        int r;
+
+        assert(h);
+
+        FOREACH_STRING(path, "/var/lib/container", "/var/lib/machine") {
+                _cleanup_closedir_ DIR *d = NULL;
+                struct dirent *de;
+
+                d = opendir(path);
+                if (!d) {
+                        if (errno == ENOENT)
+                                return 0;
+
+                        return -errno;
+                }
+
+                FOREACH_DIRENT_ALL(de, d, return -errno) {
+                        struct stat st;
+
+                        if (STR_IN_SET(de->d_name, ".", ".."))
+                                continue;
+
+                        /* Temporary files for atomically creating new files */
+                        if (startswith(de->d_name, ".#"))
+                                continue;
+
+                        if (string_has_cc(de->d_name, NULL))
+                                continue;
+
+                        if (!utf8_is_valid(de->d_name))
+                                continue;
+
+                        if (hashmap_contains(h, de->d_name))
+                                continue;
+
+                        /* We explicitly *do* follow symlinks here,
+                         * since we want to allow symlinking trees
+                         * into /var/lib/container/, and treat them
+                         * normally. */
+                        if (fstatat(dirfd(d), de->d_name, &st, 0) < 0) {
+                                if (errno == ENOENT)
+                                        continue;
+
+                                return -errno;
+                        }
+
+                        if (S_ISDIR(st.st_mode)) {
+
+                                /* btrfs subvolumes have inode 256 */
+                                if (st.st_ino == 256) {
+                                        _cleanup_close_ int fd = -1;
+                                        struct statfs sfs;
+
+                                        fd = openat(dirfd(d), de->d_name, O_CLOEXEC|O_NOCTTY|O_DIRECTORY);
+                                        if (fd < 0) {
+                                                if (errno == ENOENT)
+                                                        continue;
+
+                                                return -errno;
+                                        }
+
+                                        if (fstatfs(fd, &sfs) < 0)
+                                                return -errno;
+
+                                        if (F_TYPE_EQUAL(sfs.f_type, BTRFS_SUPER_MAGIC)) {
+                                                usec_t btime = 0;
+                                                int ro;
+
+                                                /* It's a btrfs subvolume */
+
+                                                ro = btrfs_subvol_is_read_only_fd(fd);
+                                                if (ro < 0)
+                                                        return ro;
+
+                                                /* r = btrfs_subvol_get_btime(fd, &btime); */
+                                                /* if (r < 0) */
+                                                /*         return r; */
+
+                                                r = add_image(h,
+                                                              IMAGE_SUBVOLUME,
+                                                              de->d_name,
+                                                              path,
+                                                              ro,
+                                                              0,
+                                                              btime);
+
+                                                if (r < 0)
+                                                        return r;
+
+                                                continue;
+                                        }
+                                }
+
+                                /* It's just a normal directory. */
+
+                                r = add_image(h,
+                                              IMAGE_DIRECTORY,
+                                              de->d_name,
+                                              path,
+                                              false,
+                                              0,
+                                              0);
+                                if (r < 0)
+                                        return r;
+
+                        } else if (S_ISREG(st.st_mode) &&
+                                   endswith(de->d_name, ".gpt")) {
+
+                                /* It's a GPT block device */
+
+                                r = add_image(h,
+                                              IMAGE_GPT,
+                                              de->d_name,
+                                              path,
+                                              !!(st.st_mode & 0111),
+                                              timespec_load(&st.st_mtim),
+                                              0);
+                                if (r < 0)
+                                        return r;
+                        }
+                }
+        }
+
+        return 0;
+}
+
+void image_hashmap_free(Hashmap *map) {
+        Image *i;
+
+        while ((i = hashmap_steal_first(map)))
+                image_unref(i);
+
+        hashmap_free(map);
+}
+
+char *image_bus_path(const char *name) {
+        _cleanup_free_ char *e = NULL;
+
+        assert(name);
+
+        e = bus_label_escape(name);
+        if (!e)
+                return NULL;
+
+        return strappend("/org/freedesktop/machine1/image/", e);
+}
+
+static const char* const image_type_table[_IMAGE_TYPE_MAX] = {
+        [IMAGE_DIRECTORY] = "directory",
+        [IMAGE_SUBVOLUME] = "subvolume",
+        [IMAGE_GPT] = "gpt",
+};
+
+DEFINE_STRING_TABLE_LOOKUP(image_type, ImageType);