Signed-off-by: Alyssa Ross <hi@alyssa.is> --- LICENSES/MPL-2.0.txt | 373 ++++++++++++++++++++++++++++ tools/default.nix | 7 +- tools/meson.build | 1 + tools/mount-flatpak/config | 7 + tools/mount-flatpak/keyfile.rs | 189 ++++++++++++++ tools/mount-flatpak/meson.build | 18 ++ tools/mount-flatpak/metadata.h | 4 + tools/mount-flatpak/metadata.rs | 47 ++++ tools/mount-flatpak/mount-flatpak.c | 294 ++++++++++++++++++++++ 9 files changed, 938 insertions(+), 2 deletions(-) create mode 100644 LICENSES/MPL-2.0.txt create mode 100644 tools/mount-flatpak/config create mode 100644 tools/mount-flatpak/keyfile.rs create mode 100644 tools/mount-flatpak/meson.build create mode 100644 tools/mount-flatpak/metadata.h create mode 100644 tools/mount-flatpak/metadata.rs create mode 100644 tools/mount-flatpak/mount-flatpak.c diff --git a/LICENSES/MPL-2.0.txt b/LICENSES/MPL-2.0.txt new file mode 100644 index 0000000..d0a1fa1 --- /dev/null +++ b/LICENSES/MPL-2.0.txt @@ -0,0 +1,373 @@ +Mozilla Public License Version 2.0 +================================== + +1. Definitions +-------------- + +1.1. "Contributor" + means each individual or legal entity that creates, contributes to + the creation of, or owns Covered Software. + +1.2. "Contributor Version" + means the combination of the Contributions of others (if any) used + by a Contributor and that particular Contributor's Contribution. + +1.3. "Contribution" + means Covered Software of a particular Contributor. + +1.4. "Covered Software" + means Source Code Form to which the initial Contributor has attached + the notice in Exhibit A, the Executable Form of such Source Code + Form, and Modifications of such Source Code Form, in each case + including portions thereof. + +1.5. "Incompatible With Secondary Licenses" + means + + (a) that the initial Contributor has attached the notice described + in Exhibit B to the Covered Software; or + + (b) that the Covered Software was made available under the terms of + version 1.1 or earlier of the License, but not also under the + terms of a Secondary License. + +1.6. "Executable Form" + means any form of the work other than Source Code Form. + +1.7. "Larger Work" + means a work that combines Covered Software with other material, in + a separate file or files, that is not Covered Software. + +1.8. "License" + means this document. + +1.9. "Licensable" + means having the right to grant, to the maximum extent possible, + whether at the time of the initial grant or subsequently, any and + all of the rights conveyed by this License. + +1.10. "Modifications" + means any of the following: + + (a) any file in Source Code Form that results from an addition to, + deletion from, or modification of the contents of Covered + Software; or + + (b) any new file in Source Code Form that contains any Covered + Software. + +1.11. "Patent Claims" of a Contributor + means any patent claim(s), including without limitation, method, + process, and apparatus claims, in any patent Licensable by such + Contributor that would be infringed, but for the grant of the + License, by the making, using, selling, offering for sale, having + made, import, or transfer of either its Contributions or its + Contributor Version. + +1.12. "Secondary License" + means either the GNU General Public License, Version 2.0, the GNU + Lesser General Public License, Version 2.1, the GNU Affero General + Public License, Version 3.0, or any later versions of those + licenses. + +1.13. "Source Code Form" + means the form of the work preferred for making modifications. + +1.14. "You" (or "Your") + means an individual or a legal entity exercising rights under this + License. For legal entities, "You" includes any entity that + controls, is controlled by, or is under common control with You. For + purposes of this definition, "control" means (a) the power, direct + or indirect, to cause the direction or management of such entity, + whether by contract or otherwise, or (b) ownership of more than + fifty percent (50%) of the outstanding shares or beneficial + ownership of such entity. + +2. License Grants and Conditions +-------------------------------- + +2.1. Grants + +Each Contributor hereby grants You a world-wide, royalty-free, +non-exclusive license: + +(a) under intellectual property rights (other than patent or trademark) + Licensable by such Contributor to use, reproduce, make available, + modify, display, perform, distribute, and otherwise exploit its + Contributions, either on an unmodified basis, with Modifications, or + as part of a Larger Work; and + +(b) under Patent Claims of such Contributor to make, use, sell, offer + for sale, have made, import, and otherwise transfer either its + Contributions or its Contributor Version. + +2.2. Effective Date + +The licenses granted in Section 2.1 with respect to any Contribution +become effective for each Contribution on the date the Contributor first +distributes such Contribution. + +2.3. Limitations on Grant Scope + +The licenses granted in this Section 2 are the only rights granted under +this License. No additional rights or licenses will be implied from the +distribution or licensing of Covered Software under this License. +Notwithstanding Section 2.1(b) above, no patent license is granted by a +Contributor: + +(a) for any code that a Contributor has removed from Covered Software; + or + +(b) for infringements caused by: (i) Your and any other third party's + modifications of Covered Software, or (ii) the combination of its + Contributions with other software (except as part of its Contributor + Version); or + +(c) under Patent Claims infringed by Covered Software in the absence of + its Contributions. + +This License does not grant any rights in the trademarks, service marks, +or logos of any Contributor (except as may be necessary to comply with +the notice requirements in Section 3.4). + +2.4. Subsequent Licenses + +No Contributor makes additional grants as a result of Your choice to +distribute the Covered Software under a subsequent version of this +License (see Section 10.2) or under the terms of a Secondary License (if +permitted under the terms of Section 3.3). + +2.5. Representation + +Each Contributor represents that the Contributor believes its +Contributions are its original creation(s) or it has sufficient rights +to grant the rights to its Contributions conveyed by this License. + +2.6. Fair Use + +This License is not intended to limit any rights You have under +applicable copyright doctrines of fair use, fair dealing, or other +equivalents. + +2.7. Conditions + +Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted +in Section 2.1. + +3. Responsibilities +------------------- + +3.1. Distribution of Source Form + +All distribution of Covered Software in Source Code Form, including any +Modifications that You create or to which You contribute, must be under +the terms of this License. You must inform recipients that the Source +Code Form of the Covered Software is governed by the terms of this +License, and how they can obtain a copy of this License. You may not +attempt to alter or restrict the recipients' rights in the Source Code +Form. + +3.2. Distribution of Executable Form + +If You distribute Covered Software in Executable Form then: + +(a) such Covered Software must also be made available in Source Code + Form, as described in Section 3.1, and You must inform recipients of + the Executable Form how they can obtain a copy of such Source Code + Form by reasonable means in a timely manner, at a charge no more + than the cost of distribution to the recipient; and + +(b) You may distribute such Executable Form under the terms of this + License, or sublicense it under different terms, provided that the + license for the Executable Form does not attempt to limit or alter + the recipients' rights in the Source Code Form under this License. + +3.3. Distribution of a Larger Work + +You may create and distribute a Larger Work under terms of Your choice, +provided that You also comply with the requirements of this License for +the Covered Software. If the Larger Work is a combination of Covered +Software with a work governed by one or more Secondary Licenses, and the +Covered Software is not Incompatible With Secondary Licenses, this +License permits You to additionally distribute such Covered Software +under the terms of such Secondary License(s), so that the recipient of +the Larger Work may, at their option, further distribute the Covered +Software under the terms of either this License or such Secondary +License(s). + +3.4. Notices + +You may not remove or alter the substance of any license notices +(including copyright notices, patent notices, disclaimers of warranty, +or limitations of liability) contained within the Source Code Form of +the Covered Software, except that You may alter any license notices to +the extent required to remedy known factual inaccuracies. + +3.5. Application of Additional Terms + +You may choose to offer, and to charge a fee for, warranty, support, +indemnity or liability obligations to one or more recipients of Covered +Software. However, You may do so only on Your own behalf, and not on +behalf of any Contributor. You must make it absolutely clear that any +such warranty, support, indemnity, or liability obligation is offered by +You alone, and You hereby agree to indemnify every Contributor for any +liability incurred by such Contributor as a result of warranty, support, +indemnity or liability terms You offer. You may include additional +disclaimers of warranty and limitations of liability specific to any +jurisdiction. + +4. Inability to Comply Due to Statute or Regulation +--------------------------------------------------- + +If it is impossible for You to comply with any of the terms of this +License with respect to some or all of the Covered Software due to +statute, judicial order, or regulation then You must: (a) comply with +the terms of this License to the maximum extent possible; and (b) +describe the limitations and the code they affect. Such description must +be placed in a text file included with all distributions of the Covered +Software under this License. Except to the extent prohibited by statute +or regulation, such description must be sufficiently detailed for a +recipient of ordinary skill to be able to understand it. + +5. Termination +-------------- + +5.1. The rights granted under this License will terminate automatically +if You fail to comply with any of its terms. However, if You become +compliant, then the rights granted under this License from a particular +Contributor are reinstated (a) provisionally, unless and until such +Contributor explicitly and finally terminates Your grants, and (b) on an +ongoing basis, if such Contributor fails to notify You of the +non-compliance by some reasonable means prior to 60 days after You have +come back into compliance. Moreover, Your grants from a particular +Contributor are reinstated on an ongoing basis if such Contributor +notifies You of the non-compliance by some reasonable means, this is the +first time You have received notice of non-compliance with this License +from such Contributor, and You become compliant prior to 30 days after +Your receipt of the notice. + +5.2. If You initiate litigation against any entity by asserting a patent +infringement claim (excluding declaratory judgment actions, +counter-claims, and cross-claims) alleging that a Contributor Version +directly or indirectly infringes any patent, then the rights granted to +You by any and all Contributors for the Covered Software under Section +2.1 of this License shall terminate. + +5.3. In the event of termination under Sections 5.1 or 5.2 above, all +end user license agreements (excluding distributors and resellers) which +have been validly granted by You or Your distributors under this License +prior to termination shall survive termination. + +************************************************************************ +* * +* 6. Disclaimer of Warranty * +* ------------------------- * +* * +* Covered Software is provided under this License on an "as is" * +* basis, without warranty of any kind, either expressed, implied, or * +* statutory, including, without limitation, warranties that the * +* Covered Software is free of defects, merchantable, fit for a * +* particular purpose or non-infringing. The entire risk as to the * +* quality and performance of the Covered Software is with You. * +* Should any Covered Software prove defective in any respect, You * +* (not any Contributor) assume the cost of any necessary servicing, * +* repair, or correction. This disclaimer of warranty constitutes an * +* essential part of this License. No use of any Covered Software is * +* authorized under this License except under this disclaimer. * +* * +************************************************************************ + +************************************************************************ +* * +* 7. Limitation of Liability * +* -------------------------- * +* * +* Under no circumstances and under no legal theory, whether tort * +* (including negligence), contract, or otherwise, shall any * +* Contributor, or anyone who distributes Covered Software as * +* permitted above, be liable to You for any direct, indirect, * +* special, incidental, or consequential damages of any character * +* including, without limitation, damages for lost profits, loss of * +* goodwill, work stoppage, computer failure or malfunction, or any * +* and all other commercial damages or losses, even if such party * +* shall have been informed of the possibility of such damages. This * +* limitation of liability shall not apply to liability for death or * +* personal injury resulting from such party's negligence to the * +* extent applicable law prohibits such limitation. Some * +* jurisdictions do not allow the exclusion or limitation of * +* incidental or consequential damages, so this exclusion and * +* limitation may not apply to You. * +* * +************************************************************************ + +8. Litigation +------------- + +Any litigation relating to this License may be brought only in the +courts of a jurisdiction where the defendant maintains its principal +place of business and such litigation shall be governed by laws of that +jurisdiction, without reference to its conflict-of-law provisions. +Nothing in this Section shall prevent a party's ability to bring +cross-claims or counter-claims. + +9. Miscellaneous +---------------- + +This License represents the complete agreement concerning the subject +matter hereof. If any provision of this License is held to be +unenforceable, such provision shall be reformed only to the extent +necessary to make it enforceable. Any law or regulation which provides +that the language of a contract shall be construed against the drafter +shall not be used to construe this License against a Contributor. + +10. Versions of the License +--------------------------- + +10.1. New Versions + +Mozilla Foundation is the license steward. Except as provided in Section +10.3, no one other than the license steward has the right to modify or +publish new versions of this License. Each version will be given a +distinguishing version number. + +10.2. Effect of New Versions + +You may distribute the Covered Software under the terms of the version +of the License under which You originally received the Covered Software, +or under the terms of any subsequent version published by the license +steward. + +10.3. Modified Versions + +If you create software not governed by this License, and you want to +create a new license for such software, you may create and use a +modified version of this License if you rename the license and remove +any references to the name of the license steward (except to note that +such modified license differs from this License). + +10.4. Distributing Source Code Form that is Incompatible With Secondary +Licenses + +If You choose to distribute Source Code Form that is Incompatible With +Secondary Licenses under the terms of this version of the License, the +notice described in Exhibit B of this License must be attached. + +Exhibit A - Source Code Form License Notice +------------------------------------------- + + This Source Code Form is subject to the terms of the Mozilla Public + License, v. 2.0. If a copy of the MPL was not distributed with this + file, You can obtain one at https://mozilla.org/MPL/2.0/. + +If it is not possible or desirable to put the notice in a particular +file, then You may include the notice in a location (such as a LICENSE +file in a relevant directory) where a recipient would be likely to look +for such a notice. + +You may add additional accurate notices of copyright ownership. + +Exhibit B - "Incompatible With Secondary Licenses" Notice +--------------------------------------------------------- + + This Source Code Form is "Incompatible With Secondary Licenses", as + defined by the Mozilla Public License, v. 2.0. diff --git a/tools/default.nix b/tools/default.nix index 27d4b82..27741b3 100644 --- a/tools/default.nix +++ b/tools/default.nix @@ -74,6 +74,7 @@ stdenv.mkDerivation (finalAttrs: { ./xdg-desktop-portal-spectrum ] ++ lib.optionals hostSupport [ ./lsvm + ./mount-flatpak ./sd-notify-adapter.c ./start-vmm ./subprojects @@ -88,8 +89,10 @@ stdenv.mkDerivation (finalAttrs: { ++ lib.optionals (appSupport || driverSupport) [ pkg-config ] ++ lib.optionals hostSupport [ rustc ] ++ lib.optionals driverSupport [ llvmPackages.clang-unwrapped ]; - buildInputs = lib.optionals appSupport [ dbus ] - ++ lib.optionals driverSupport [ libbpf linuxHeaders ]; + buildInputs = with stdenv.hostPlatform; lib.optionals appSupport [ dbus ] + ++ lib.optionals driverSupport [ libbpf linuxHeaders ] + # Workaround for <https://github.com/mesonbuild/meson/pull/15216>. + ++ lib.optionals (hostSupport && isMusl && isStatic) [ llvmPackages.libunwind ]; postPatch = lib.optionals hostSupport (lib.concatMapStringsSep "\n" (crate: '' mkdir -p subprojects/packagecache diff --git a/tools/meson.build b/tools/meson.build index d465e99..c024ca6 100644 --- a/tools/meson.build +++ b/tools/meson.build @@ -30,6 +30,7 @@ if get_option('host') install: true) subdir('lsvm') + subdir('mount-flatpak') subdir('start-vmm') endif diff --git a/tools/mount-flatpak/config b/tools/mount-flatpak/config new file mode 100644 index 0000000..b3c2bee --- /dev/null +++ b/tools/mount-flatpak/config @@ -0,0 +1,7 @@ +# SPDX-License-Identifier: CC0-1.0 +# SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> + +[core] +repo_version=1 +mode=bare-user-only +min-free-space-size=500MB diff --git a/tools/mount-flatpak/keyfile.rs b/tools/mount-flatpak/keyfile.rs new file mode 100644 index 0000000..fa746b3 --- /dev/null +++ b/tools/mount-flatpak/keyfile.rs @@ -0,0 +1,189 @@ +// Copyright 2021 System76 <info@system76.com> +// SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> +// SPDX-License-Identifier: MPL-2.0 + +// Adapted from freedesktop-desktop-entry 0.7.19. + +use std::collections::BTreeMap; +use std::fmt::{self, Display, Formatter}; + +type Group = BTreeMap<String, String>; + +#[derive(Debug)] +pub enum DecodeError { + KeyValueWithoutAGroup, + InvalidKey, + InvalidValue, +} + +impl Display for DecodeError { + fn fmt(&self, f: &mut Formatter) -> fmt::Result { + match self { + Self::KeyValueWithoutAGroup => write!(f, "key/value without a group"), + Self::InvalidKey => write!(f, "invalid key"), + Self::InvalidValue => write!(f, "invalid value"), + } + } +} + +pub fn parse(input: &str) -> Result<BTreeMap<String, Group>, DecodeError> { + let mut groups = BTreeMap::default(); + let mut active_group: Option<ActiveGroup> = None; + let mut active_keys: Option<ActiveKeys> = None; + + for line in input.lines() { + process_line(line, &mut groups, &mut active_group, &mut active_keys)?; + } + + if let Some(active_keys) = active_keys.take() { + match &mut active_group { + Some(active_group) => { + active_group + .group + .insert(active_keys.key_name, active_keys.value); + } + None => return Err(DecodeError::KeyValueWithoutAGroup), + } + } + + if let Some(mut group) = active_group.take() { + groups + .entry(group.group_name) + .or_default() + .append(&mut group.group); + } + + Ok(groups) +} + +struct ActiveGroup { + group_name: String, + group: Group, +} + +struct ActiveKeys { + key_name: String, + value: String, +} + +#[inline(never)] +fn process_line( + line: &str, + groups: &mut BTreeMap<String, Group>, + active_group: &mut Option<ActiveGroup>, + active_keys: &mut Option<ActiveKeys>, +) -> Result<(), DecodeError> { + if line.trim().is_empty() || line.starts_with('#') { + return Ok(()); + } + + let line_bytes = line.as_bytes(); + + // if group + if line_bytes[0] == b'[' { + if let Some(end) = line_bytes[1..].iter().rposition(|&b| b == b']') { + let group_name = &line[1..end + 1]; + + if let Some(active_keys) = active_keys.take() { + match active_group { + Some(active_group) => { + active_group + .group + .insert(active_keys.key_name, active_keys.value); + } + None => return Err(DecodeError::KeyValueWithoutAGroup), + } + } + + if let Some(mut group) = active_group.take() { + groups + .entry(group.group_name) + .or_default() + .append(&mut group.group); + } + + active_group.replace(ActiveGroup { + group_name: group_name.to_string(), + group: Group::default(), + }); + } + } + // else, if value + else if let Some(delimiter) = line_bytes.iter().position(|&b| b == b'=') { + let key = &line[..delimiter]; + let value = format_value(&line[delimiter + 1..])?; + + if key.is_empty() { + return Err(DecodeError::InvalidKey); + } + + if let Some(active_keys) = active_keys.take() { + match active_group { + Some(active_group) => { + active_group + .group + .insert(active_keys.key_name, active_keys.value); + } + None => return Err(DecodeError::KeyValueWithoutAGroup), + } + } + active_keys.replace(ActiveKeys { + key_name: key.trim().to_string(), + value, + }); + } + Ok(()) +} + +// https://specifications.freedesktop.org/desktop-entry-spec/latest/value-types... +#[inline] +fn format_value(input: &str) -> Result<String, DecodeError> { + let input = if let Some(input) = input.strip_prefix(" ") { + input + } else { + input + }; + + let mut res = String::with_capacity(input.len()); + + let mut last: usize = 0; + + for (i, v) in input.as_bytes().iter().enumerate() { + if *v != b'\\' { + continue; + } + + // edge case for // + if last > i { + continue; + } + + // when there is an \ at the end + if input.len() <= i + 1 { + return Err(DecodeError::InvalidValue); + } + + if last < i { + res.push_str(&input[last..i]); + } + + last = i + 2; + + match input.as_bytes()[i + 1] { + b's' => res.push(' '), + b'n' => res.push('\n'), + b't' => res.push('\t'), + b'r' => res.push('\r'), + b'\\' => res.push('\\'), + _ => { + return Err(DecodeError::InvalidValue); + } + } + } + + if last < input.len() { + res.push_str(&input[last..input.len()]); + } + + Ok(res) +} diff --git a/tools/mount-flatpak/meson.build b/tools/mount-flatpak/meson.build new file mode 100644 index 0000000..e0c0a85 --- /dev/null +++ b/tools/mount-flatpak/meson.build @@ -0,0 +1,18 @@ +# SPDX-License-Identifier: EUPL-1.2+ +# SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> + +rust_lib = static_library('metadata', 'metadata.rs', rust_abi : 'c') + +conf_data = configuration_data() +conf_data.set_quoted('CONFIG_PATH', + get_option('prefix') / get_option('datadir') / 'spectrum/flatpak-config') +configure_file(output : 'config.h', configuration : conf_data) + +executable('mount-flatpak', 'mount-flatpak.c', + c_args : '-D_GNU_SOURCE', + link_with : rust_lib, + install : true) + +install_data('config', + rename : 'flatpak-config', + install_dir : get_option('datadir') / 'spectrum') diff --git a/tools/mount-flatpak/metadata.h b/tools/mount-flatpak/metadata.h new file mode 100644 index 0000000..d6441b7 --- /dev/null +++ b/tools/mount-flatpak/metadata.h @@ -0,0 +1,4 @@ +// SPDX-License-Identifier: EUPL-1.2+ +// SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> + +void extract_runtime(int metadata, char *runtime); diff --git a/tools/mount-flatpak/metadata.rs b/tools/mount-flatpak/metadata.rs new file mode 100644 index 0000000..0398416 --- /dev/null +++ b/tools/mount-flatpak/metadata.rs @@ -0,0 +1,47 @@ +// SPDX-License-Identifier: EUPL-1.2+ +// SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> + +mod keyfile; + +use std::env::args_os; +use std::ffi::OsString; +use std::fs::File; +use std::io::{read_to_string, stderr, Write}; +use std::os::fd::OwnedFd; +use std::os::unix::prelude::*; +use std::process::exit; + +use keyfile::parse; + +fn extract_runtime(mut metadata: File) -> Result<String, String> { + let metadata = read_to_string(&mut metadata).map_err(|e| e.to_string())?; + let group = parse(&metadata).map_err(|e| e.to_string())?; + let application = group + .get("Application") + .ok_or_else(|| "Application group missing".to_string())?; + Ok(application + .get("runtime") + .ok_or_else(|| "runtime property missing".to_string())? + .clone()) +} + +// SAFETY: we do not expect "extract_runtime" to collide with another symbol. +#[unsafe(export_name = "extract_runtime")] +pub extern "C" fn extract_runtime_c(metadata: OwnedFd, out: &mut [u8; 256]) { + let error = match extract_runtime(metadata.into()) { + Err(e) => e, + Ok(runtime) if runtime.len() >= out.len() => "runtime name too long".to_string(), + Ok(runtime) => { + out[..runtime.len()].copy_from_slice(runtime.as_bytes()); + out[runtime.len()] = 0; + return; + } + }; + + let prog_name = args_os() + .next() + .unwrap_or_else(|| OsString::from("mount-flatpak")); + stderr().write_all(prog_name.as_bytes()).unwrap(); + eprintln!(": {error}"); + exit(1); +} diff --git a/tools/mount-flatpak/mount-flatpak.c b/tools/mount-flatpak/mount-flatpak.c new file mode 100644 index 0000000..8e09d1d --- /dev/null +++ b/tools/mount-flatpak/mount-flatpak.c @@ -0,0 +1,294 @@ +// SPDX-License-Identifier: EUPL-1.2+ +// SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> + +#include "config.h" +#include "metadata.h" + +#include <err.h> +#include <fcntl.h> +#include <stdlib.h> +#include <stdio.h> +#include <string.h> +#include <unistd.h> + +#include <sys/stat.h> +#include <sys/syscall.h> + +#include <linux/mount.h> +#include <linux/openat2.h> + +static void bind_mount(int source_fd, const char *source, + int target_fd, const char *target) +{ + int source_tree = syscall(SYS_open_tree, source_fd, source, + AT_EMPTY_PATH | OPEN_TREE_CLOEXEC | + OPEN_TREE_CLONE | AT_RECURSIVE); + + if (source_tree == -1) + err(EXIT_FAILURE, "open_tree %s", source); + if (syscall(SYS_move_mount, source_tree, "", target_fd, target, + MOVE_MOUNT_F_EMPTY_PATH | MOVE_MOUNT_T_EMPTY_PATH) == -1) + err(EXIT_FAILURE, "move_mount"); +} + +static int mkdir_openat(int dirfd, const char *path, mode_t mode) +{ + int fd; + if (mkdirat(dirfd, path, mode) == -1) + err(EXIT_FAILURE, "mkdirat %s", path); + if ((fd = openat(dirfd, path, O_PATH | O_DIRECTORY | O_CLOEXEC)) == -1) + err(EXIT_FAILURE, "openat %s", path); + return fd; +} + +// By failing on EEXIST when creating each directory, +// we can be sure we don't end up following .. components. +static int mkdirs_beneath(int root, const char *target) +{ + int last, fd = root; + size_t len = strlen(target); + char *end, *path = malloc(len + 1), *dir = path; + if (!dir) + err(EXIT_FAILURE, "malloc %zu", len + 1); + memcpy(dir, target, len + 1); + + do { + // Find next non-empty directory component + end = strchrnul(dir, '/'); + while (*(end + 1) == '/') + end++; + + // Replace path separator with string terminator. + *end = 0; + + // Update fd to a new child, and close the previous one + // unless it was the one provided by the caller. + last = fd; + fd = mkdir_openat(fd, dir, 0755); + if (last != root) + close(last); + + dir = end + 1; + } while (end != &path[len]); + + free(path); + return fd; +} + +static int openat_beneath(int dirfd, const char *path, int flags) +{ + struct open_how how = { + .flags = flags, + .resolve = RESOLVE_BENEATH | RESOLVE_NO_MAGICLINKS, + }; + int r = syscall(SYS_openat2, dirfd, path, &how, sizeof how); + if (r == -1) + err(EXIT_FAILURE, "openat2 %s", path); + return r; +} + +static int resolve_link(int dirfd, const char *path, char **target) +{ + int r; + struct stat sb; + if (fstatat(dirfd, path, &sb, AT_SYMLINK_NOFOLLOW) == -1) + err(EXIT_FAILURE, "fstatat %s", path); + if (!(*target = malloc(sb.st_size + 1))) + err(EXIT_FAILURE, "malloc %zu", sb.st_size + 1); + if ((r = readlinkat(dirfd, path, *target, sb.st_size + 1)) <= -1) + err(EXIT_FAILURE, "readlinkat %s", path); + if (r == sb.st_size + 1) + errx(EXIT_FAILURE, "symlink target lengthened"); + (*target)[r] = 0; // NOLINT(clang-analyzer-security.ArrayBound) + return openat_beneath(dirfd, *target, O_PATH | O_CLOEXEC | O_DIRECTORY); +} + +static void write_to(int dirfd, const char *path, const char *text) +{ + FILE *file; + size_t len = strlen(text); + int f = openat(dirfd, path, + O_WRONLY | O_CLOEXEC | O_NOFOLLOW | O_CREAT, 0644); + + if (f == -1) + err(EXIT_FAILURE, "openat %s", path); + if (!(file = fdopen(f, "w"))) + err(EXIT_FAILURE, "fdopen %s", path); + + if (fwrite(text, 1, len, file) != len) + err(EXIT_FAILURE, "fwrite"); + if (fclose(file) == EOF) + err(EXIT_FAILURE, "fclose"); +} + +static void set_up_app_dir(int source_commit_dir, int installation_dir, + const char *id, const char *arch, + const char *branch, const char *commit) +{ + int app_dir, id_dir, arch_dir, branch_dir; + + app_dir = mkdir_openat(installation_dir, "app", 0755); + + id_dir = mkdir_openat(app_dir, id, 0755); + close(app_dir); + + arch_dir = mkdir_openat(id_dir, arch, 0755); + close(id_dir); + + branch_dir = mkdir_openat(arch_dir, branch, 0755); + close(arch_dir); + + if (mkdirat(branch_dir, commit, 0755) == -1) + err(EXIT_FAILURE, "mkdirat %s", commit); + bind_mount(source_commit_dir, "", branch_dir, commit); + close(branch_dir); +} + +static int mount_app(int source_installation_dir, int target_installation_dir, + int params_dir, const char *id) +{ + char *arch_and_branch, *arch_end, *commit; + int app_dir, id_dir, branch_dir, commit_dir; + + app_dir = openat_beneath(source_installation_dir, "app", + O_PATH | O_CLOEXEC | O_DIRECTORY); + id_dir = openat_beneath(app_dir, id, O_PATH | O_CLOEXEC | O_DIRECTORY); + close(app_dir); + + branch_dir = resolve_link(id_dir, "current", &arch_and_branch); + close(id_dir); + + commit_dir = resolve_link(branch_dir, "active", &commit); + close(branch_dir); + + if (!(arch_end = strchr(arch_and_branch, '/'))) + errx(EXIT_FAILURE, "unexpected current format"); + *arch_end = 0; + + set_up_app_dir(commit_dir, target_installation_dir, id, + arch_and_branch, arch_end + 1, commit); + write_to(params_dir, "commit", commit); + write_to(params_dir, "arch", arch_and_branch); + write_to(params_dir, "branch", arch_end + 1); + + free(arch_and_branch); + free(commit); + return commit_dir; +} + +static void set_up_runtime_dir(int source_commit_dir, int installation_dir, + const char *ref, const char *commit) +{ + int runtime_dir, branch_dir; + + runtime_dir = mkdir_openat(installation_dir, "runtime", 0755); + + branch_dir = mkdirs_beneath(runtime_dir, ref); + close(runtime_dir); + + if (mkdirat(branch_dir, commit, 0755) == -1) + err(EXIT_FAILURE, "mkdirat %s", commit); + bind_mount(source_commit_dir, "", branch_dir, commit); + close(branch_dir); +} + +static void mount_runtime(int source_installation_dir, + int target_installation_dir, + int params_dir, int app_commit_dir) +{ + char runtime[256], *commit; + int runtime_dir, branch_dir, commit_dir; + int metadata = openat_beneath(app_commit_dir, "metadata", + O_RDONLY | O_CLOEXEC); + + extract_runtime(metadata, runtime); + + runtime_dir = openat_beneath(source_installation_dir, "runtime", + O_PATH | O_CLOEXEC | O_DIRECTORY); + + branch_dir = openat_beneath(runtime_dir, runtime, + O_PATH | O_CLOEXEC | O_DIRECTORY); + close(runtime_dir); + + commit_dir = resolve_link(branch_dir, "active", &commit); + close(branch_dir); + + set_up_runtime_dir(commit_dir, target_installation_dir, + runtime, commit); + write_to(params_dir, "runtime-commit", commit); + + free(commit); + close(commit_dir); +} + +static void set_up_repo(int target_installation_dir) +{ + int config; + + if (mkdirat(target_installation_dir, "repo", 0755) == -1) + err(EXIT_FAILURE, "mkdir repo"); + if (mkdirat(target_installation_dir, "repo/objects", 0755) == -1) + err(EXIT_FAILURE, "mkdir repo/objects"); + if (mkdirat(target_installation_dir, "repo/tmp", 0775) == -1) + err(EXIT_FAILURE, "mkdir repo/tmp"); + if (mkdirat(target_installation_dir, "repo/tmp/cache", 0775) == -1) + err(EXIT_FAILURE, "mkdir repo/tmp/cache"); + + if ((config = openat(target_installation_dir, "repo/config", + O_WRONLY | O_CLOEXEC | O_NOFOLLOW | O_CREAT, + 0644)) == -1) + err(EXIT_FAILURE, "openat repo/config"); + + bind_mount(AT_FDCWD, CONFIG_PATH, config, ""); + + close(config); +} + +int main(int, char **argv) +{ + char *installation_path, *id; + int params_dir, source_installation_dir, target_installation_dir, + app_commit_dir; + struct mount_attr attr = { + .attr_clr = MOUNT_ATTR_NOSYMFOLLOW, + .attr_set = MOUNT_ATTR_RDONLY | MOUNT_ATTR_NODEV, + }; + + if (!(installation_path = *++argv)) + errx(EXIT_FAILURE, "missing installation path"); + if (!(id = *++argv)) + errx(EXIT_FAILURE, "missing app ID"); + + if ((source_installation_dir = open(installation_path, + O_PATH | O_CLOEXEC | O_DIRECTORY)) == -1) + err(EXIT_FAILURE, "open %s", installation_path); + + params_dir = mkdir_openat(AT_FDCWD, "params", 0755); + write_to(params_dir, "id", id); + + if (mkdir("flatpak", 0755) == -1) + err(EXIT_FAILURE, "mkdir flatpak"); + if ((target_installation_dir = syscall(SYS_open_tree, AT_FDCWD, + "flatpak", + AT_EMPTY_PATH | OPEN_TREE_CLONE | + OPEN_TREE_CLOEXEC | + AT_RECURSIVE)) == -1) + err(EXIT_FAILURE, "open_tree flatpak"); + + app_commit_dir = mount_app(source_installation_dir, + target_installation_dir, params_dir, id); + mount_runtime(source_installation_dir, target_installation_dir, + params_dir, app_commit_dir); + close(source_installation_dir); + close(params_dir); + + set_up_repo(target_installation_dir); + + if (syscall(SYS_mount_setattr, target_installation_dir, "", + AT_EMPTY_PATH | AT_RECURSIVE, &attr, sizeof attr) == -1) + err(EXIT_FAILURE, "mount_setattr flatpak"); + if (syscall(SYS_move_mount, target_installation_dir, "", + AT_FDCWD, "flatpak", MOVE_MOUNT_F_EMPTY_PATH) == -1) + err(EXIT_FAILURE, "move_mount flatpak flatpak"); + close(target_installation_dir); +} base-commit: 4b89596e112d26c4bd60bc46bb45c5d9a0875314 -- 2.51.0