I tried to build this with Meson, but pathrs depends on thiserror, which tries to read OUT_DIR, and support for setting that isn't currently in a Meson release, and requires nightly Rust, so build with Cargo for now and we can revisit that later. Link: https://github.com/mesonbuild/meson/pull/15148 Link: https://github.com/rust-lang/rust/issues/118372 Signed-off-by: Alyssa Ross <hi@alyssa.is> --- v4: • Open a root for the Flatpak installation to limit scope • Update usage • Call open_tree with AT_SYMLINK_NOFOLLOW • Add comment explaining purpose and directory structure • Set MS_SLAVE on the final mount • Cast non-pointer syscall arguments to long v3: https://spectrum-os.org/lists/archives/spectrum-devel/20251127202311.42422-2... LICENSES/MPL-2.0.txt | 373 +++++++++++++++++++++++++ pkgs/default.nix | 1 + tools/mount-flatpak/Cargo.lock | 238 ++++++++++++++++ tools/mount-flatpak/Cargo.lock.license | 2 + tools/mount-flatpak/Cargo.toml | 11 + tools/mount-flatpak/config | 7 + tools/mount-flatpak/default.nix | 25 ++ tools/mount-flatpak/src/keyfile.rs | 189 +++++++++++++ tools/mount-flatpak/src/main.rs | 296 ++++++++++++++++++++ tools/mount-flatpak/src/metadata.rs | 19 ++ 10 files changed, 1161 insertions(+) create mode 100644 LICENSES/MPL-2.0.txt create mode 100644 tools/mount-flatpak/Cargo.lock create mode 100644 tools/mount-flatpak/Cargo.lock.license create mode 100644 tools/mount-flatpak/Cargo.toml create mode 100644 tools/mount-flatpak/config create mode 100644 tools/mount-flatpak/default.nix create mode 100644 tools/mount-flatpak/src/keyfile.rs create mode 100644 tools/mount-flatpak/src/main.rs create mode 100644 tools/mount-flatpak/src/metadata.rs 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/pkgs/default.nix b/pkgs/default.nix index bc25420..29fefb4 100644 --- a/pkgs/default.nix +++ b/pkgs/default.nix @@ -36,6 +36,7 @@ let path: (import path { inherit (self) callPackage; }).override; rootfs = self.callSpectrumPackage ../host/rootfs {}; + mount-flatpak = self.callSpectrumPackage ../tools/mount-flatpak {}; spectrum-build-tools = self.callSpectrumPackage ../tools { appSupport = false; buildSupport = true; diff --git a/tools/mount-flatpak/Cargo.lock b/tools/mount-flatpak/Cargo.lock new file mode 100644 index 0000000..8cb5663 --- /dev/null +++ b/tools/mount-flatpak/Cargo.lock @@ -0,0 +1,238 @@ +# This file is automatically @generated by Cargo. +# It is not intended for manual editing. +version = 4 + +[[package]] +name = "bitflags" +version = "2.10.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "812e12b5285cc515a9c72a5c1d3b6d46a19dac5acfef5265968c166106e31dd3" + +[[package]] +name = "cfg-if" +version = "1.0.4" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801" + +[[package]] +name = "either" +version = "1.15.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "48c757948c5ede0e46177b7add2e67155f70e33c07fea8284df6576da70b3719" + 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+source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "0562428422c63773dad2c345a1882263bbf4d65cf3f42e90921f787ef5ad58e7" +dependencies = [ + "wit-bindgen", +] + +[[package]] +name = "windows-link" +version = "0.2.1" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "f0805222e57f7521d6a62e36fa9163bc891acd422f971defe97d64e70d0a4fe5" + +[[package]] +name = "windows-sys" +version = "0.61.2" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "ae137229bcbd6cdf0f7b80a31df61766145077ddf49416a728b02cb3921ff3fc" +dependencies = [ + "windows-link", +] + +[[package]] +name = "wit-bindgen" +version = "0.46.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "f17a85883d4e6d00e8a97c586de764dabcc06133f7f1d55dce5cdc070ad7fe59" diff --git a/tools/mount-flatpak/Cargo.lock.license b/tools/mount-flatpak/Cargo.lock.license new file mode 100644 index 0000000..d705e97 --- /dev/null +++ b/tools/mount-flatpak/Cargo.lock.license @@ -0,0 +1,2 @@ +SPDX-License-Identifier: CC0-1.0 +SPDX-FileCopyrightText: 2024 Alyssa Ross <hi@alyssa.is> diff --git a/tools/mount-flatpak/Cargo.toml b/tools/mount-flatpak/Cargo.toml new file mode 100644 index 0000000..670be2f --- /dev/null +++ b/tools/mount-flatpak/Cargo.toml @@ -0,0 +1,11 @@ +# SPDX-License-Identifier: CC0-1.0 +# SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> + +[package] +name = "mount-flatpak" +edition = "2024" + +[dependencies] +libc = "0.2.177" +pathrs = "0.2.1" +rustix = "1.1.2" 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/default.nix b/tools/mount-flatpak/default.nix new file mode 100644 index 0000000..f364fd7 --- /dev/null +++ b/tools/mount-flatpak/default.nix @@ -0,0 +1,25 @@ +# SPDX-FileCopyrightText: 2024-2025 Alyssa Ross <hi@alyssa.is> +# SPDX-License-Identifier: MIT + +import ../../lib/call-package.nix ( +{ src, lib, rustPlatform }: + +rustPlatform.buildRustPackage { + name = "mount-flatpak"; + + src = lib.fileset.toSource { + root = ../..; + fileset = lib.fileset.intersection src ./.; + }; + sourceRoot = "source/tools/mount-flatpak"; + + cargoLock.lockFile = ./Cargo.lock; + + env = { + MOUNT_FLATPAK_CONFIG_PATH = "${placeholder "out"}/share/spectrum/flatpak-config"; + }; + + postInstall = '' + install -Dm 0755 config $MOUNT_FLATPAK_CONFIG_PATH + ''; +}) (_: {}) diff --git a/tools/mount-flatpak/src/keyfile.rs b/tools/mount-flatpak/src/keyfile.rs new file mode 100644 index 0000000..fa746b3 --- /dev/null +++ b/tools/mount-flatpak/src/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/src/main.rs b/tools/mount-flatpak/src/main.rs new file mode 100644 index 0000000..db246cd --- /dev/null +++ b/tools/mount-flatpak/src/main.rs @@ -0,0 +1,296 @@ +// SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> +// SPDX-License-Identifier: EUPL-1.2+ + +//! Flatpak installations look like this: +//! +//! ```text +//! flatpak/ +//! ├── app/ +//! │ └── org.gnome.TextEditor/ +//! │ ├── current -> x86_64/stable +//! │ └── x86_64/ +//! │ └── stable/ +//! │ ├── 0029140121b39f5b7cf4d44fd46b0708eee67f395b5e1291628612a0358fb909/ +//! │ │ └── … +//! │ └── active -> 0029140121b39f5b7cf4d44fd46b0708eee67f395b5e1291628612a0358fb909 +//! ├── db/ +//! ├── exports/ +//! │ └── … +//! ├── repo +//! │ ├── config +//! │ ├── objects +//! │ ├── tmp +//! │ │ └── cache +//! │ │ └── … +//! │ └── … +//! └── runtime +//! ├── org.gnome.Platform +//! │ └── x86_64 +//! │ └── 49 +//! │ ├── active -> bf6aa432cb310726f4ac0ec08cc88558619e1d4bd4b964e27e95187ecaad5400 +//! │ └── bf6aa432cb310726f4ac0ec08cc88558619e1d4bd4b964e27e95187ecaad5400 +//! │ └── … +//! └── … +//! ``` +//! +//! The purpose of this program is to use bind mounts to construct a +//! Flatpak installation containing only a single application and +//! runtime, which can be passed through to a VM without exposing +//! other installed applications. + +mod keyfile; +mod metadata; + +use std::borrow::Cow; +use std::env::{ArgsOs, args_os}; +use std::ffi::OsStr; +use std::io; +use std::os::unix::prelude::*; +use std::path::{Path, PathBuf}; +use std::process::exit; + +use pathrs::Root; +use pathrs::flags::{OpenFlags, ResolverFlags}; +use rustix::fs::{CWD, FileType, fstat}; +use rustix::mount::{MoveMountFlags, OpenTreeFlags, move_mount, open_tree}; + +use metadata::extract_runtime; + +fn ex_usage() -> ! { + eprintln!("Usage: mount-flatpak userdata installation app"); + exit(1); +} + +fn run(mut args: ArgsOs) -> Result<(), String> { + let Some(user_data_path) = args.next().map(PathBuf::from) else { + ex_usage(); + }; + let Some(installation_path) = args.next().map(PathBuf::from) else { + ex_usage(); + }; + let Some(app) = args.next() else { + ex_usage(); + }; + if args.next().is_some() { + ex_usage(); + } + + let mut user_data = + Root::open(&user_data_path).map_err(|e| format!("opening user data partition: {e}"))?; + user_data.set_resolver_flags(ResolverFlags::NO_SYMLINKS); + + let mut source_installation_dir = user_data + .open_subpath(&installation_path, OpenFlags::O_PATH) + .map(Root::from_fd) + .map_err(|e| format!("opening source flatpak installation: {e}"))?; + source_installation_dir.set_resolver_flags(ResolverFlags::NO_SYMLINKS); + + std::fs::create_dir("flatpak") + .map_err(|e| format!("creating target flatpak installation: {e}"))?; + + let target_installation_dir = open_tree( + CWD, + "flatpak", + OpenTreeFlags::OPEN_TREE_CLONE + | OpenTreeFlags::OPEN_TREE_CLOEXEC + | OpenTreeFlags::AT_RECURSIVE + | OpenTreeFlags::AT_SYMLINK_NOFOLLOW, + ) + .map_err(|e| format!("opening target flatpak installation: {e}"))?; + let mut target_installation_dir = Root::from_fd(target_installation_dir); + target_installation_dir.set_resolver_flags(ResolverFlags::NO_SYMLINKS); + + let mut full_app_path = installation_path.join("app"); + full_app_path.push(&app); + full_app_path.push("current"); + let arch_and_branch = source_installation_dir + .readlink(&full_app_path) + .map_err(|e| format!("reading current app arch and branch: {e}"))?; + let mut components = arch_and_branch.components(); + let arch = components.next().unwrap().as_os_str(); + let branch = components.as_path().as_os_str(); + if branch.is_empty() { + return Err("can't infer branch from \"current\" link".to_string()); + } + + full_app_path.pop(); + full_app_path.push(&arch_and_branch); + full_app_path.push("active"); + let commit = source_installation_dir + .readlink(&full_app_path) + .map_err(|e| format!("reading active app commit: {e}"))? + .into_os_string(); + + full_app_path.pop(); + full_app_path.push(&commit); + let source_app_dir = source_installation_dir + .resolve(&full_app_path) + .map_err(|e| format!("opening source app directory: {e}"))?; + + let metadata = source_installation_dir + .resolve(full_app_path.join("metadata")) + .map_err(|e| format!("resolving app metadata: {e}"))?; + + let metadata_stat = + fstat(&metadata).map_err(|e| format!("checking app metadata is a regular file: {e}"))?; + let metadata_type = FileType::from_raw_mode(metadata_stat.st_mode); + if !metadata_type.is_file() { + let e = format!("type of app metadata is {metadata_type:?}, not RegularFile"); + return Err(e); + } + let metadata = metadata + .reopen(OpenFlags::O_RDONLY) + .map_err(|e| format!("opening app metadata: {e}"))?; + + let runtime = + extract_runtime(metadata).map_err(|e| format!("reading runtime from metadata: {e}"))?; + + let mut full_runtime_path = installation_path.join("runtime"); + full_runtime_path.push(runtime); + full_runtime_path.push("active"); + let runtime_commit = source_installation_dir + .readlink(&full_runtime_path) + .map_err(|e| format!("reading active runtime commit: {e}"))? + .into_os_string(); + + full_runtime_path.pop(); + full_runtime_path.push(&runtime_commit); + let source_runtime_dir = source_installation_dir + .resolve(&full_runtime_path) + .map_err(|e| format!("opening source runtime directory: {e}"))?; + + let target_app_dir = target_installation_dir + .mkdir_all(&full_app_path, &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating target app directory: {e}"))?; + let target_runtime_dir = target_installation_dir + .mkdir_all(&full_runtime_path, &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating target runtime directory: {e}"))?; + + let source_app_tree = open_tree( + &source_app_dir, + "", + OpenTreeFlags::AT_EMPTY_PATH + | OpenTreeFlags::OPEN_TREE_CLONE + | OpenTreeFlags::OPEN_TREE_CLOEXEC + | OpenTreeFlags::AT_RECURSIVE, + ) + .map_err(|e| format!("cloning source app tree: {e}"))?; + let source_runtime_tree = open_tree( + &source_runtime_dir, + "", + OpenTreeFlags::AT_EMPTY_PATH + | OpenTreeFlags::OPEN_TREE_CLONE + | OpenTreeFlags::OPEN_TREE_CLOEXEC + | OpenTreeFlags::AT_RECURSIVE, + ) + .map_err(|e| format!("cloning source runtime tree: {e}"))?; + + move_mount( + source_app_tree, + "", + target_app_dir, + "", + MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH | MoveMountFlags::MOVE_MOUNT_T_EMPTY_PATH, + ) + .map_err(|e| format!("mounting app directory: {e}"))?; + move_mount( + source_runtime_tree, + "", + target_runtime_dir, + "", + MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH | MoveMountFlags::MOVE_MOUNT_T_EMPTY_PATH, + ) + .map_err(|e| format!("mounting runtime directory: {e}"))?; + + target_installation_dir + .mkdir_all("repo/objects", &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating repo/objects: {e}"))?; + target_installation_dir + .mkdir_all("repo/tmp/cache", &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating repo/tmp/cache: {e}"))?; + let config_target = target_installation_dir + .create_file( + "repo/config", + OpenFlags::O_WRONLY | OpenFlags::O_CLOEXEC, + &PermissionsExt::from_mode(0o700), + ) + .map_err(|e| format!("creating repo/config: {e}"))?; + let config_source_path = env!("MOUNT_FLATPAK_CONFIG_PATH"); + let config_source = open_tree( + CWD, + config_source_path, + OpenTreeFlags::OPEN_TREE_CLONE | OpenTreeFlags::OPEN_TREE_CLOEXEC, + ) + .map_err(|e| format!("opening {config_source_path}: {e}"))?; + move_mount( + config_source, + "", + config_target, + "", + MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH | MoveMountFlags::MOVE_MOUNT_T_EMPTY_PATH, + ) + .map_err(|e| format!("mounting config: {e}"))?; + + let mut attr = libc::mount_attr { + attr_clr: libc::MOUNT_ATTR_NOSYMFOLLOW, + attr_set: libc::MOUNT_ATTR_RDONLY | libc::MOUNT_ATTR_NODEV, + propagation: libc::MS_SLAVE, + userns_fd: 0, + }; + let empty = b"\0"; + // SAFETY: we pass a valid FD, and a valid mutable pointer with the correct size. + unsafe { + let r = libc::syscall( + libc::SYS_mount_setattr, + target_installation_dir.as_fd().as_raw_fd() as libc::c_long, + empty.as_ptr() as *const libc::c_char, + (libc::AT_EMPTY_PATH | libc::AT_RECURSIVE) as libc::c_long, + &mut attr as *mut libc::mount_attr, + size_of::<libc::mount_attr>() as libc::c_long, + ); + if r == -1 { + return Err(format!( + "setting target mount attributes: {}", + io::Error::last_os_error() + )); + } + } + move_mount( + target_installation_dir, + "", + CWD, + "flatpak", + MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH, + ) + .map_err(|e| format!("mounting target installation dir: {e}"))?; + + std::fs::create_dir("params").map_err(|e| format!("creating params directory: {e}"))?; + std::fs::write("params/id", app.as_bytes()).map_err(|e| format!("writing params/id: {e}"))?; + std::fs::write("params/commit", commit.as_bytes()) + .map_err(|e| format!("writing params/commit: {e}"))?; + std::fs::write("params/arch", arch.as_bytes()) + .map_err(|e| format!("writing params/arch: {e}"))?; + std::fs::write("params/branch", branch.as_bytes()) + .map_err(|e| format!("writing params/branch: {e}"))?; + std::fs::write("params/runtime-commit", runtime_commit.as_bytes()) + .map_err(|e| format!("writing params/runtime-commit: {e}"))?; + + Ok(()) +} + +fn main() { + let mut args = args_os(); + + let prog_name = args + .next() + .as_ref() + .map(Path::new) + .and_then(Path::file_name) + .map_or(Cow::Borrowed("mount-flatpak"), OsStr::to_string_lossy) + .into_owned(); + + if let Err(e) = run(args) { + eprintln!("{prog_name}: {e}"); + exit(1); + } +} diff --git a/tools/mount-flatpak/src/metadata.rs b/tools/mount-flatpak/src/metadata.rs new file mode 100644 index 0000000..dfc05b1 --- /dev/null +++ b/tools/mount-flatpak/src/metadata.rs @@ -0,0 +1,19 @@ +// SPDX-License-Identifier: EUPL-1.2+ +// SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> + +use std::fs::File; +use std::io::read_to_string; + +use crate::keyfile::parse; + +pub 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()) +} -- 2.51.0