👷 gucc: add mtab parser

.github/workflows/build.yml

@@ -38,6 +38,7 @@ jobs:
           cd ${{github.workspace}}/build
           ./gucc/tests/test-initcpio
           ./gucc/tests/test-pacmanconf
+          ./gucc/tests/test-mtab
           ./gucc/tests/test-fstab_gen
           ./gucc/tests/test-crypttab_gen
           ./gucc/tests/test-grub_config_gen
@@ -85,6 +86,7 @@ jobs:
           cd ${{github.workspace}}/build
           ./gucc/tests/test-initcpio
           ./gucc/tests/test-pacmanconf
+          ./gucc/tests/test-mtab
           ./gucc/tests/test-fstab_gen
           ./gucc/tests/test-crypttab_gen
           ./gucc/tests/test-grub_config_gen

gucc/CMakeLists.txt

@@ -27,6 +27,7 @@ add_library(${PROJECT_NAME} SHARED
    src/bootloader.cpp include/gucc/bootloader.hpp
    src/systemd_services.cpp include/gucc/systemd_services.hpp
    src/autologin.cpp include/gucc/autologin.hpp
+   src/mtab.cpp include/gucc/mtab.hpp
    #src/chwd_profiles.cpp src/chwd_profiles.hpp
    #src/disk.cpp src/disk.hpp
    )

gucc/include/gucc/mtab.hpp

@@ -0,0 +1,24 @@
+#ifndef MTAB_HPP
+#define MTAB_HPP
+
+#include <optional>     // for optional
+#include <string>       // for string
+#include <string_view>  // for string_view
+#include <vector>       // for vector
+
+namespace gucc::mtab {
+
+struct MTabEntry {
+    std::string device{};
+    std::string mountpoint{};
+};
+
+// Parse mtab
+auto parse_mtab(std::string_view root_mountpoint) noexcept -> std::optional<std::vector<MTabEntry>>;
+
+// Parse mtab content
+auto parse_mtab_content(std::string_view mtab_content, std::string_view root_mountpoint) noexcept -> std::vector<MTabEntry>;
+
+}  // namespace gucc::mtab
+
+#endif  // MTAB_HPP

gucc/meson.build

@@ -17,6 +17,7 @@ gucc_lib = library('gucc',
         'src/bootloader.cpp',
         'src/systemd_services.cpp',
         'src/autologin.cpp',
+        'src/mtab.cpp',
     ],
     include_directories : [include_directories('include')],
     dependencies: deps

gucc/src/mtab.cpp

@@ -0,0 +1,40 @@
+#include "gucc/mtab.hpp"
+#include "gucc/file_utils.hpp"
+#include "gucc/string_utils.hpp"
+
+using namespace std::string_view_literals;
+
+namespace gucc::mtab {
+
+auto parse_mtab_content(std::string_view mtab_content, std::string_view root_mountpoint) noexcept -> std::vector<MTabEntry> {
+    std::vector<MTabEntry> entries{};
+
+    auto&& file_content_lines = utils::make_split_view(mtab_content);
+    for (auto&& line : file_content_lines) {
+        if (line.empty() || line.starts_with('#')) {
+            continue;
+        }
+
+        auto&& line_split = utils::make_split_view(line, ' ');
+        auto&& device     = *utils::index_viewable_range(line_split, 0);
+        if (utils::size_viewable_range(line_split) >= 3 && !device.starts_with('#')) {
+            // e.g format: <device> <mountpoint> <fstype> <options>
+            auto&& mountpoint = *utils::index_viewable_range(line_split, 1);
+            if (mountpoint.starts_with(root_mountpoint)) {
+                entries.emplace_back(MTabEntry{.device = std::string{device}, .mountpoint = std::string{mountpoint}});
+            }
+        }
+    }
+    return entries;
+}
+
+auto parse_mtab(std::string_view root_mountpoint) noexcept -> std::optional<std::vector<MTabEntry>> {
+    static constexpr auto mtab_path = "/etc/mtab"sv;
+    auto&& file_content             = file_utils::read_whole_file(mtab_path);
+    if (file_content.empty()) {
+        return std::nullopt;
+    }
+    return mtab::parse_mtab_content(file_content, root_mountpoint);
+}
+
+}  // namespace gucc::mtab

gucc/tests/meson.build

@@ -37,3 +37,11 @@ executable(
   link_with: [gucc_lib],
   include_directories: [include_directories('../include')],
   install: false)
+
+executable(
+  'test-mtab',
+  files('unit-mtab.cpp'),
+  dependencies: deps,
+  link_with: [gucc_lib],
+  include_directories: [include_directories('../include')],
+  install: false)

gucc/tests/unit-mtab.cpp

@@ -0,0 +1,60 @@
+#include "gucc/mtab.hpp"
+
+#include <cassert>
+
+#include <string_view>
+
+using namespace std::string_view_literals;
+
+static constexpr auto MTAB_RUNNING_SYSTEM_TEST = R"(
+proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0
+
+sys /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
+dev /dev devtmpfs rw,nosuid,relatime,size=8104116k,nr_inodes=2026029,mode=755,inode64 0 0
+run /run tmpfs rw,nosuid,nodev,relatime,mode=755,inode64 0 0
+efivarfs /sys/firmware/efi/efivars efivarfs rw,nosuid,nodev,noexec,relatime 0 0
+# test string
+/dev/nvme0n1p3 /mnt btrfs rw,relatime,compress=zstd:3,ssd,discard=async,space_cache,subvolid=5,subvol=/ 0 0
+securityfs /sys/kernel/security securityfs rw,nosuid,nodev,noexec,relatime 0 0
+tmpfs /dev/shm tmpfs rw,nosuid,nodev,inode64 0 0
+devpts /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
+cgroup2 /sys/fs/cgroup cgroup2 rw,nosuid,nodev,noexec,relatime,nsdelegate,memory_recursiveprot 0 0
+ # test something
+pstore /sys/fs/pstore pstore rw,nosuid,nodev,noexec,relatime 0 0
+bpf /sys/fs/bpf bpf rw,nosuid,nodev,noexec,relatime,mode=700 0 0
+systemd-1 /proc/sys/fs/binfmt_misc autofs rw,relatime,fd=39,pgrp=1,timeout=0,minproto=5,maxproto=5,direct,pipe_ino=4748 0 0
+debugfs /sys/kernel/debug debugfs rw,nosuid,nodev,noexec,relatime 0 0
+mqueue /dev/mqueue mqueue rw,nosuid,nodev,noexec,relatime 0 0
+hugetlbfs /dev/hugepages hugetlbfs rw,nosuid,nodev,relatime,pagesize=2M 0 0
+tracefs /sys/kernel/tracing tracefs rw,nosuid,nodev,noexec,relatime 0 0
+tmpfs /run/credentials/systemd-journald.service tmpfs ro,nosuid,nodev,noexec,relatime,nosymfollow,size=1024k,nr_inodes=1024,mode=700,inode64,noswap 0 0
+tmpfs /run/credentials/systemd-udev-load-credentials.service tmpfs ro,nosuid,nodev,noexec,relatime,nosymfollow,size=1024k,nr_inodes=1024,mode=700,inode64,noswap 0 0
+fusectl /sys/fs/fuse/connections fusectl rw,nosuid,nodev,noexec,relatime 0 0
+tmpfs /run/credentials/systemd-tmpfiles-setup-dev-early.service tmpfs ro,nosuid,nodev,noexec,relatime,nosymfollow,size=1024k,nr_inodes=1024,mode=700,inode64,noswap 0 0
+configfs /sys/kernel/config configfs rw,nosuid,nodev,noexec,relatime 0 0
+tmpfs /run/credentials/systemd-sysctl.service tmpfs ro,nosuid,nodev,noexec,relatime,nosymfollow,size=1024k,nr_inodes=1024,mode=700,inode64,noswap 0 0
+tmpfs /run/credentials/systemd-tmpfiles-setup-dev.service tmpfs ro,nosuid,nodev,noexec,relatime,nosymfollow,size=1024k,nr_inodes=1024,mode=700,inode64,noswap 0 0
+tmpfs /tmp tmpfs rw,nosuid,nodev,nr_inodes=1048576,inode64 0 0
+/dev/nvme0n1p1 /mnt/boot vfat rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=ascii,shortname=mixed,utf8,errors=remount-ro 0 0
+tmpfs /run/credentials/systemd-tmpfiles-setup.service tmpfs ro,nosuid,nodev,noexec,relatime,nosymfollow,size=1024k,nr_inodes=1024,mode=700,inode64,noswap 0 0
+binfmt_misc /proc/sys/fs/binfmt_misc binfmt_misc rw,nosuid,nodev,noexec,relatime 0 0
+tmpfs /run/credentials/systemd-vconsole-setup.service tmpfs ro,nosuid,nodev,noexec,relatime,nosymfollow,size=1024k,nr_inodes=1024,mode=700,inode64,noswap 0 0
+tmpfs /run/credentials/getty@tty1.service tmpfs ro,nosuid,nodev,noexec,relatime,nosymfollow,size=1024k,nr_inodes=1024,mode=700,inode64,noswap 0 0
+tmpfs /run/user/1000 tmpfs rw,nosuid,nodev,relatime,size=1632224k,nr_inodes=408056,mode=700,uid=1000,gid=984,inode64 0 0
+portal /run/user/1000/doc fuse.portal rw,nosuid,nodev,relatime,user_id=1000,group_id=984 0 0
+run /run/firejail/dbus tmpfs rw,nosuid,nodev,noexec,relatime,mode=755,inode64 0 0
+run /run/firejail/firejail.ro.dir tmpfs ro,nosuid,nodev,relatime,mode=755,inode64 0 0
+run /run/firejail/firejail.ro.file tmpfs ro,nosuid,nodev,relatime,mode=755,inode64 0 0
+)"sv;
+
+int main() {
+    // running system
+    {
+        const auto& mtab_entries = gucc::mtab::parse_mtab_content(MTAB_RUNNING_SYSTEM_TEST, "/mnt"sv);
+        assert(mtab_entries.size() == 2);
+        assert(mtab_entries[0].device == "/dev/nvme0n1p3");
+        assert(mtab_entries[0].mountpoint == "/mnt");
+        assert(mtab_entries[1].device == "/dev/nvme0n1p1");
+        assert(mtab_entries[1].mountpoint == "/mnt/boot");
+    }
+}