Add --list-volumes to list named volumes

Long-only (no free short letter left), lists each volume's name and host directory, tab-aligned the same way -l/--list-images already aligns name:tag output -- list_volumes_command() reuses that scheme. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Gv3s5jckJKzh6JkMoi2Akz
2026-08-21 13:15:28 +00:00
parent aac656be31
commit afca0f7ce3
3 changed files with 55 additions and 16 deletions
@@ -17,13 +17,15 @@ status); this file stays the dense, file-by-file reference. Still early-stage.
 Source layout (all under `src/`):
 - `main.cpp` — CLI entry point, dependency checks, orchestration (`mount_image()`,
  `run_container()`, `cleanup_image()`, `unmount_image()`, `list_images_command()`,
-  `create_volume_command()`). `run_container()` unconditionally calls
-  `read_oci_image_config()` and reuses the result for two independent defaults: the
-  command to run (`Entrypoint ++ Cmd`) when none is given on the command line, and,
-  when `--user` wasn't given, the sandboxed process's user/group (`config.User`,
-  split into `OciImageConfig::user`/`group`) — an explicit `--user`/`--group` on the
-  command line always takes precedence. `create_volume_command()` implements
-  `-v/--volume <name> <directory>`: see `config_file.{h,cpp}` below for what a
+  `create_volume_command()`, `list_volumes_command()`). `run_container()`
+  unconditionally calls `read_oci_image_config()` and reuses the result for two
+  independent defaults: the command to run (`Entrypoint ++ Cmd`) when none is given
+  on the command line, and, when `--user` wasn't given, the sandboxed process's
+  user/group (`config.User`, split into `OciImageConfig::user`/`group`) — an
+  explicit `--user`/`--group` on the command line always takes precedence.
+  `create_volume_command()` implements `-v/--volume <name> <directory>`;
+  `list_volumes_command()` implements `--list-volumes` (same tab-alignment scheme as
+  `list_images_command()`, reused as-is) — see `config_file.{h,cpp}` below for what a
  "volume" means here (a distinct concept from `OciImageConfig::volumes`).
 - `oci_image.{h,cpp}` — validates/parses the OCI Image Layout tar (libarchive +
  nlohmann_json) and extracts layer blobs. `list_oci_images()` scans a directory
@@ -152,8 +154,8 @@ Build directory is `buildDir/` (already configured).
  (see `priv_drop_helper.cpp` in "Project state")
 - Run the executable: `./buildDir/slocker-lite -m <image.tar>` (see `--help` for the
  full flag list: `-m/--mount`, `-r/--run`, `-u/--umount`, `-c/--cleanup`,
-  `-l/--list-images`, `-n/--no-nsenter`, `--user`, `--group`, `-t/--test`,
-  `--log-level`, `-h/--help`, `-V/--version`)
+  `-l/--list-images`, `-n/--no-nsenter`, `--user`, `--group`, `-v/--volume`,
+  `--list-volumes`, `-t/--test`, `--log-level`, `-h/--help`, `-V/--version`)
 - Run tests: `meson test -C buildDir`

 ## Code style
@@ -58,6 +58,7 @@ slocker-lite -u|--umount <layer-id>
 slocker-lite -c|--cleanup <layer-id>
 slocker-lite -l|--list-images <directory>
 slocker-lite -v|--volume <name> <directory>
+slocker-lite --list-volumes
 slocker-lite -t|--test
 slocker-lite -h|--help
 slocker-lite -V|--version
@@ -74,6 +75,7 @@ slocker-lite -V|--version
 | `--group <group>` | With `--user`, use this group (name or numeric gid) instead of the user's primary group. |
 | `-l, --list-images <dir>` | List OCI Image Layout tars (`*.tar`, `*.tar.*`) found directly in `<dir>`, with their `name:tag`. |
 | `-v, --volume <name> <dir>` | Create a named volume mapped to a host directory (created if missing), recorded in the config file's `volumes` section. Fails if the name or directory is already used by an existing volume. |
+| `--list-volumes` | List all named volumes (see `-v/--volume`) with their host directory. |
 | `-t, --test` | Print which `bwrap --unshare-xxx` namespaces the running kernel supports. |
 | `--log-level <level>` | Set log verbosity (`trace`, `debug`, `info`, `warn`, `error`, `critical`, `off`). |
 | `-h, --help` | Print usage and exit. |
@@ -99,6 +101,9 @@ sudo ./buildDir/slocker-lite -r myimage.tar --user git

 # Create a named volume backed by a host directory
 ./buildDir/slocker-lite -v mydata ~/slocker-volumes/mydata
+
+# List all named volumes
+./buildDir/slocker-lite --list-volumes
 ```

 ## Configuration
@@ -41,16 +41,18 @@ namespace {

 constexpr std::array<std::string_view, 2> kRequiredTools = {"containers-storage", "bwrap"};

-enum class Mode { kNone, kMount, kUnmount, kTest, kRun, kCleanup, kListImages, kVolume };
+enum class Mode { kNone, kMount, kUnmount, kTest, kRun, kCleanup, kListImages, kVolume, kListVolumes };

-// --log-level/--user/--group have no short form (--log-level's was freed up so -l
-// could become --list-images; -u is already --umount), so they need long-option
-// vals outside the printable-char range short options use.
+// --log-level/--user/--group/--list-volumes have no short form (--log-level's was
+// freed up so -l could become --list-images; -u is already --umount; --list-volumes
+// has no natural free letter left), so they need long-option vals outside the
+// printable-char range short options use.
 constexpr int kLogLevelOpt = 256;
 constexpr int kUserOpt = 257;
 constexpr int kGroupOpt = 258;
+constexpr int kListVolumesOpt = 259;

-constexpr std::array<struct option, 14> kLongOptions = {{
+constexpr std::array<struct option, 15> kLongOptions = {{
    {"help", no_argument, nullptr, 'h'},
    {"version", no_argument, nullptr, 'V'},
    {"test", no_argument, nullptr, 't'},
@@ -64,6 +66,7 @@ constexpr std::array<struct option, 14> kLongOptions = {{
    {"user", required_argument, nullptr, kUserOpt},
    {"group", required_argument, nullptr, kGroupOpt},
    {"volume", required_argument, nullptr, 'v'},
+    {"list-volumes", no_argument, nullptr, kListVolumesOpt},
    {nullptr, 0, nullptr, 0},
 }};

@@ -75,6 +78,7 @@ void print_usage(const char* prog) {
        "       {0} -c|--cleanup <layer-id>\n"
        "       {0} -l|--list-images <directory>\n"
        "       {0} -v|--volume <name> <directory>\n"
+        "       {0} --list-volumes\n"
        "       {0} -t|--test\n"
        "       {0} -h|--help\n"
        "       {0} -V|--version\n"
@@ -109,6 +113,8 @@ void print_usage(const char* prog) {
        "  -v, --volume <name> <dir> create a named volume mapped to a host directory\n"
        "                            (created if missing), recorded in the config\n"
        "                            file's volumes section\n"
+        "      --list-volumes        list all named volumes (see -v/--volume) with\n"
+        "                            their host directory\n"
        "  -t, --test                run the test suite\n"
        "      --log-level <level>   set log verbosity (trace, debug, info, warn,\n"
        "                            error, critical, off)\n"
@@ -300,6 +306,25 @@ int create_volume_command(const std::string& name, const std::string& directory,
    return 0;
 }

+int list_volumes_command(const AppConfig& config) {
+    size_t max_len = 0;
+    for (const auto& volume : config.volumes) {
+        max_len = std::max(max_len, volume.name.size());
+    }
+
+    // Same tab-alignment scheme as list_images_command(): pad each name to one
+    // 8-column tab stop past the longest one, however long that is.
+    constexpr size_t kTabWidth = 8;
+    size_t target_tabs = max_len / kTabWidth + 1;
+
+    for (const auto& volume : config.volumes) {
+        size_t tabs_used = volume.name.size() / kTabWidth;
+        size_t tabs_needed = target_tabs > tabs_used ? target_tabs - tabs_used : 1;
+        fmt::print("{}{}{}\n", volume.name, std::string(tabs_needed, '\t'), volume.directory);
+    }
+    return 0;
+}
+
 int run_container(const std::filesystem::path& image_tar,
                   const std::vector<std::string>& requested_command, bool use_nsenter,
                   const std::optional<std::string>& user, const std::optional<std::string>& group) {
@@ -387,7 +412,8 @@ int main(int argc, char* argv[]) {
            case 'r':
            case 'c':
            case 'l':
-            case 'v': {
+            case 'v':
+            case kListVolumesOpt: {
                Mode requested;
                switch (opt) {
                    case 't':
@@ -408,9 +434,12 @@ int main(int argc, char* argv[]) {
                    case 'l':
                        requested = Mode::kListImages;
                        break;
-                    default:
+                    case 'v':
                        requested = Mode::kVolume;
                        break;
+                    default:
+                        requested = Mode::kListVolumes;
+                        break;
                }
                if (mode != Mode::kNone && mode != requested) {
                    spdlog::error("multiple actions specified");
@@ -484,6 +513,9 @@ int main(int argc, char* argv[]) {
    if (mode == Mode::kVolume) {
        return create_volume_command(mode_arg, argv[optind], config_path, *config);
    }
+    if (mode == Mode::kListVolumes) {
+        return list_volumes_command(*config);
+    }
    if (mode == Mode::kRun) {
        std::vector<std::string> command(argv + optind, argv + argc);
        // As root, containers-storage mount doesn't need to reexec into a private