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Merged
Zhihaoi merged 1 commit into from
May 25, 2026
Merged

feat: implement chmod/chown/utimens, fix access perms, add --allow-root #7

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33 changes: 33 additions & 0 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -121,6 +121,39 @@ cmake --build build --config Release -j
.\build\Release\agentvfs-ctl.exe --sock \\.\pipe\agentvfs-<hash> checkpoint baseline
```

### Self-hosting: build inside a ContextFS mount

ContextFS can build and install itself from within its own FUSE mount,
giving every checkout a self-contained build environment with checkpoint
and rollback for development experimentation.

Pass `--allow-root` to `agentvfs workspace start` (or `agentvfs workspace init`)
when root needs to access the FUSE mount — required for
`sudo cmake --install build` to write to system paths from inside the mount
(needs `user_allow_other` in `/etc/fuse.conf`, already set by the prebuilt
installer). The setting is persisted in `workspace.json` for subsequent starts.

```bash
# 1. Build and install agentvfs normally first
cd path/to/ContextFS
cmake -B build -DAGENTVFS_EBPF=OFF && cmake --build build -j
sudo cmake --install build

# 2. Start a workspace with allow_root on the source tree itself
agentvfs workspace init selfhost --from $(pwd) --allow-root
agentvfs workspace start selfhost --allow-root
# or via start.sh (pass --allow-root after workspace args):
# ./start.sh path/to/ContextFS
# agentvfs workspace start selfhost --allow-root

# 3. Rebuild and install from inside the mount
cd /run/user/$(id -u)/agentvfs/selfhost/mount
rm -rf build # fresh build dir inside the FUSE mount
cmake -B build -DAGENTVFS_EBPF=OFF
cmake --build build -j
sudo cmake --install build # allow_root enables sudo access
```

## License

Licensed under the Apache License, Version 2.0. See [LICENSE](LICENSE).
55 changes: 50 additions & 5 deletions src/cas/platform/linux/fuse_adapter.cpp
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Expand Up @@ -294,12 +294,13 @@ static int cas_access(const char* path, int mask) {
if (!entry) return -ENOENT;
if (mask == F_OK) return 0;

// Spec §FUSE callbacks: MVP checks only the "other" mode bits; owner
// uid/gid tracking is deferred. Single-agent scope makes this safe.
// getattr always sets st_uid/st_gid to the caller's own, so the
// caller is always the "owner" of the file in this FS's semantics.
// Check owner permission bits (0400/0200/0100), not other bits.
uint32_t m = entry->mode;
if ((mask & R_OK) && !(m & 0004)) return -EACCES;
if ((mask & W_OK) && !(m & 0002)) return -EACCES;
if ((mask & X_OK) && !(m & 0001)) return -EACCES;
if ((mask & R_OK) && !(m & 0400)) return -EACCES;
if ((mask & W_OK) && !(m & 0200)) return -EACCES;
if ((mask & X_OK) && !(m & 0100)) return -EACCES;
return 0;
}

Expand Down Expand Up @@ -396,6 +397,47 @@ static int cas_readlink(const char* path, char* buf, size_t size) {
return 0;
}

static int cas_utimens(const char* path, const struct timespec tv[2],
struct fuse_file_info* fi) {
(void)tv;
(void)fi;
Daemon* d = get_daemon();
if (Daemon::is_hidden(path)) return -ENOENT;
if (auto* bs = d->bootstrap()) bs->ensure_path(path);
auto br = resolve_branch(d);
auto entry = br->wt.lookup(path);
if (!entry) return -ENOENT;
return 0;
}

static int cas_chmod(const char* path, mode_t mode, struct fuse_file_info* fi) {
(void)fi;
Daemon* d = get_daemon();
if (Daemon::is_hidden(path)) return -ENOENT;
if (auto* bs = d->bootstrap()) bs->ensure_path(path);
auto br = resolve_branch(d);
std::lock_guard<std::mutex> lk(br->checkpoint_mu);
auto entry = br->wt.lookup(path);
if (!entry) return -ENOENT;
entry->mode = (entry->mode & S_IFMT) | (mode & 07777);
br->wt.insert(path, *entry);
return 0;
}

static int cas_chown(const char* path, uid_t uid, gid_t gid,
struct fuse_file_info* fi) {
(void)uid;
(void)gid;
(void)fi;
Daemon* d = get_daemon();
if (Daemon::is_hidden(path)) return -ENOENT;
if (auto* bs = d->bootstrap()) bs->ensure_path(path);
auto br = resolve_branch(d);
auto entry = br->wt.lookup(path);
if (!entry) return -ENOENT;
return 0;
}

static void fill_fuse_ops(struct fuse_operations& ops) {
ops.getattr = cas_getattr;
ops.open = cas_open;
Expand All @@ -415,6 +457,9 @@ static void fill_fuse_ops(struct fuse_operations& ops) {
ops.rename = cas_rename;
ops.symlink = cas_symlink;
ops.readlink = cas_readlink;
ops.utimens = cas_utimens;
ops.chmod = cas_chmod;
ops.chown = cas_chown;
}

int run_filesystem(Daemon& daemon, const MountOptions& opts) {
Expand Down
36 changes: 33 additions & 3 deletions src/cas/platform/macos/fuse_t_adapter.cpp
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Expand Up @@ -334,10 +334,13 @@ static int cas_access(const char* path, int mask) {
if (!entry) return -ENOENT;
if (mask == F_OK) return 0;

// getattr always sets st_uid/st_gid to the caller's own, so the
// caller is always the "owner" of the file in this FS's semantics.
// Check owner permission bits (0400/0200/0100), not other bits.
uint32_t m = entry->mode;
if ((mask & R_OK) && !(m & 0004)) return -EACCES;
if ((mask & W_OK) && !(m & 0002)) return -EACCES;
if ((mask & X_OK) && !(m & 0001)) return -EACCES;
if ((mask & R_OK) && !(m & 0400)) return -EACCES;
if ((mask & W_OK) && !(m & 0200)) return -EACCES;
if ((mask & X_OK) && !(m & 0100)) return -EACCES;
return 0;
}

Expand Down Expand Up @@ -430,6 +433,31 @@ static int cas_readlink(const char* path, char* buf, size_t size) {
return 0;
}

static int cas_chmod(const char* path, mode_t mode) {
Daemon* d = get_daemon();
if (Daemon::is_hidden(path) || is_appledouble(path)) return -ENOENT;
if (auto* bs = d->bootstrap()) bs->ensure_path(path);
auto br = resolve_branch(d);
std::lock_guard<std::mutex> lk(br->checkpoint_mu);
auto entry = br->wt.lookup(path);
if (!entry) return -ENOENT;
entry->mode = (entry->mode & S_IFMT) | (mode & 07777);
br->wt.insert(path, *entry);
return 0;
}

static int cas_chown(const char* path, uid_t uid, gid_t gid) {
(void)uid;
(void)gid;
Daemon* d = get_daemon();
if (Daemon::is_hidden(path) || is_appledouble(path)) return -ENOENT;
if (auto* bs = d->bootstrap()) bs->ensure_path(path);
auto br = resolve_branch(d);
auto entry = br->wt.lookup(path);
if (!entry) return -ENOENT;
return 0;
}

int run_filesystem(Daemon& daemon, const MountOptions& opts) {
struct fuse_operations ops{};
ops.getattr = cas_getattr;
Expand All @@ -451,6 +479,8 @@ int run_filesystem(Daemon& daemon, const MountOptions& opts) {
ops.rename = cas_rename;
ops.symlink = cas_symlink;
ops.readlink = cas_readlink;
ops.chmod = cas_chmod;
ops.chown = cas_chown;
// xattr callbacks left unset: libfuse returns -ENOSYS, which
// clients treat equivalently to ENOTSUP. Spec §"Semantic gaps".

Expand Down
77 changes: 62 additions & 15 deletions src/cas/workspace_cli.cpp
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Expand Up @@ -192,6 +192,24 @@ static bool json_get_long(const std::string& json,
return true;
}

static bool json_get_bool(const std::string& json,
const std::string& key,
bool& value) {
size_t p = 0;
if (!json_find_key(json, key, p)) return false;
while (p < json.size() && (json[p] == ' ' || json[p] == '\t')) p++;
std::string rest = json.substr(p);
if (rest.substr(0, 4) == "true") {
value = true;
return true;
}
if (rest.substr(0, 5) == "false") {
value = false;
return true;
}
return false;
}

std::string session_to_json(const SessionState& state) {
std::ostringstream out;
out << "{\n"
Expand Down Expand Up @@ -273,7 +291,8 @@ bool write_session_file(const std::string& path,
std::string workspace_config_to_json(const WorkspaceConfig& config) {
std::ostringstream out;
out << "{\n"
<< " \"mount_override\":\"" << json_escape(config.mount_override) << "\"\n"
<< " \"mount_override\":\"" << json_escape(config.mount_override) << "\",\n"
<< " \"allow_root\":" << (config.allow_root ? "true" : "false") << "\n"
<< "}\n";
return out.str();
}
Expand All @@ -300,15 +319,21 @@ bool parse_workspace_config_json(const std::string& json,
}

WorkspaceConfig parsed;
// mount_override is optional. Missing key is valid (forward-compat).
// Key present but value unparseable is an error.
// mount_override and allow_root are optional. Missing keys are valid
// (forward-compat). Keys present but unparseable is an error.
size_t after_colon = 0;
if (json_find_key(json, "mount_override", after_colon)) {
if (!json_get_string(json, "mount_override", parsed.mount_override)) {
error = "workspace.json: malformed mount_override value";
return false;
}
}
if (json_find_key(json, "allow_root", after_colon)) {
if (!json_get_bool(json, "allow_root", parsed.allow_root)) {
error = "workspace.json: malformed allow_root value";
return false;
}
}
config = parsed;
error.clear();
return true;
Expand Down Expand Up @@ -469,7 +494,7 @@ bool socket_responds(const std::string& socket_path) {

static int workspace_usage() {
std::cerr
<< "Usage: agentvfs workspace start [name] [--root <dir>] [--mount <dir>] [--telemetry auto|none|<csv>]\n"
<< "Usage: agentvfs workspace start [name] [--root <dir>] [--mount <dir>] [--telemetry auto|none|<csv>] [--allow-root]\n"
<< " agentvfs workspace init <name> --from <dir> [--root <dir>] [--mount <dir>]\n"
<< " agentvfs workspace status [name] [--root <dir>]\n"
<< " agentvfs workspace list [--root <dir>]\n"
Expand All @@ -488,6 +513,7 @@ struct ParsedCommon {
std::string target;
std::string from_dir; // for init
std::string mount_override; // for init/start
bool allow_root = false; // for init/start
};

static bool is_dir(const std::string& path) {
Expand Down Expand Up @@ -715,6 +741,8 @@ static bool parse_common_args(int argc,
return false;
}
out.mount_override = argv[i];
} else if (arg == "--allow-root" && (cmd == "init" || cmd == "start")) {
out.allow_root = true;
} else if (!arg.empty() && arg[0] == '-') {
std::cerr << "agentvfs: unknown option for workspace " << cmd << ": " << arg << "\n";
return false;
Expand Down Expand Up @@ -800,6 +828,7 @@ static bool acquire_start_lock(const WorkspacePaths& paths,
static pid_t spawn_daemon(const std::string& self_path,
const WorkspacePaths& paths,
const std::string& telemetry,
bool allow_root,
std::string& error) {
pid_t pid = fork();
if (pid < 0) {
Expand All @@ -823,6 +852,10 @@ static pid_t spawn_daemon(const std::string& self_path,
"--telemetry=" + telemetry,
"-f"
};
if (allow_root) {
args.push_back("-o");
args.push_back("allow_root");
}
std::vector<char*> cargs;
for (auto& a : args) cargs.push_back(const_cast<char*>(a.c_str()));
cargs.push_back(nullptr);
Expand Down Expand Up @@ -1061,17 +1094,22 @@ static int command_init(const ParsedCommon& opts) {
return 1;
}

if (!opts.mount_override.empty()) {
{
WorkspaceConfig config;
if (!make_absolute(opts.mount_override, config.mount_override, error)) {
std::cerr << "agentvfs: cannot resolve --mount " << opts.mount_override
<< ": " << error << "\n";
return 1;
if (!opts.mount_override.empty()) {
if (!make_absolute(opts.mount_override, config.mount_override, error)) {
std::cerr << "agentvfs: cannot resolve --mount " << opts.mount_override
<< ": " << error << "\n";
return 1;
}
}
std::string config_path = paths.root + "/workspace.json";
if (!write_workspace_config_file(config_path, config, error)) {
std::cerr << "agentvfs: " << error << "\n";
return 1;
config.allow_root = opts.allow_root;
if (!opts.mount_override.empty() || opts.allow_root) {
std::string config_path = paths.root + "/workspace.json";
if (!write_workspace_config_file(config_path, config, error)) {
std::cerr << "agentvfs: " << error << "\n";
return 1;
}
}
}

Expand Down Expand Up @@ -1210,11 +1248,20 @@ static int command_start(const ParsedCommon& opts, const std::string& self_path)
return 1;
}
paths.mount = resolve_mount_path(cli_override, config.mount_override, default_mount);
if (opts.allow_root) config.allow_root = true;

// Persist a CLI override so subsequent starts inherit it.
// Persist CLI overrides so subsequent starts inherit them.
if (!cli_override.empty() && cli_override != config.mount_override) {
WorkspaceConfig new_config = config;
new_config.mount_override = cli_override;
new_config.allow_root = config.allow_root || opts.allow_root;
if (!write_workspace_config_file(config_path, new_config, error)) {
std::cerr << "agentvfs: " << error << "\n";
return 1;
}
} else if (opts.allow_root && !config.allow_root) {
WorkspaceConfig new_config = config;
new_config.allow_root = true;
if (!write_workspace_config_file(config_path, new_config, error)) {
std::cerr << "agentvfs: " << error << "\n";
return 1;
Expand Down Expand Up @@ -1246,7 +1293,7 @@ static int command_start(const ParsedCommon& opts, const std::string& self_path)
telemetry = select_auto_telemetry(detect_telemetry_availability());
telemetry_warning = telemetry == "none";
}
pid_t pid = spawn_daemon(self_path, paths, telemetry, error);
pid_t pid = spawn_daemon(self_path, paths, telemetry, config.allow_root, error);
if (pid <= 0) {
std::cerr << "agentvfs: " << error << "\n";
return 1;
Expand Down
1 change: 1 addition & 0 deletions src/cas/workspace_cli.h
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Expand Up @@ -35,6 +35,7 @@ struct SessionState {
// Lives at <root>/<name>/workspace.json. Optional file: missing means defaults.
struct WorkspaceConfig {
std::string mount_override;
bool allow_root = false;
};

bool is_valid_workspace_name(const std::string& name);
Expand Down
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