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// SPDX-License-Identifier: GPL-2.0-or-later
// shared backend selection and locking for uvol entry points
// (c) 2022 Daniel Golle <daniel@makrotopia.org>
let common_fs = require("fs");
let common_uci = require("uci");
include("/usr/lib/uvol/mount.uc");
let shell_quote = function(word) {
return "'" + replace(`${word}`, /'/g, "'\\''") + "'";
};
// volumes are taken down whether or not anything mounted them, so umount is
// expected to fail and stays quiet. That needs a shell, hence the quoting.
let umount_dev = function(dev) {
return system(sprintf("umount %s 2>/dev/null", shell_quote(sprintf("/dev/%s", dev))));
};
let lock_open = function(path) {
common_fs.mkdir("/tmp/run", 0755);
let lockfd = common_fs.open(path, "a");
if (lockfd)
lockfd.lock("x");
return lockfd;
};
uvol_common = {
// volume names reach tool arguments and lock file paths; anything outside
// this set is refused before it gets there. A leading '.' is reserved for
// internal volumes such as .meta, and a leading '-' would be taken for an
// option by the backend tools.
name_valid: function(name, allow_internal) {
if (type(name) != "string")
return false;
if (allow_internal && name == ".meta")
return true;
return !!match(name, /^[A-Za-z0-9_][A-Za-z0-9._-]*$/);
},
shell_quote: shell_quote,
ctx_init: function() {
let ctx = {};
ctx.cursor = common_uci ? common_uci.cursor() : null;
ctx.fs = common_fs;
ctx.register = uvol_mount.register;
ctx.unregister = uvol_mount.unregister;
ctx.shell_quote = shell_quote;
ctx.umount_dev = umount_dev;
return ctx;
},
backend_select: function(ctx) {
let backend = null;
let tried = [];
for (let plugin in common_fs.glob("/usr/lib/uvol/backends/*.uc")) {
let current_backend = {};
include(plugin, { backend: current_backend });
push(tried, current_backend.backend);
if (type(backend) == "object" &&
type(backend.priority) == "int" &&
type(current_backend.priority) == "int" &&
backend.priority > current_backend.priority)
continue;
if (type(current_backend.init) == "function" &&
current_backend.init(ctx)) {
backend = current_backend;
break;
}
}
return { backend: backend, tried: tried };
},
// released on process exit; the caller keeps the returned fd alive
lock_device: function() {
return lock_open("/tmp/run/uvol.lock");
},
lock_volume: function(vol_name) {
return lock_open(sprintf("/tmp/run/uvol.lock.%s", vol_name));
}
};
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