test/internal/mountinfo: move from sandbox

This also improves its API.

Signed-off-by: Ophestra <cat@gensokyo.uk>

3 files changed, 338 insertions, 0 deletions

diff --git a/test/internal/mountinfo/mountinfo.go b/test/internal/mountinfo/mountinfo.go
new file mode 100644
index 00000000..19892cd2
--- /dev/null
+++ b/test/internal/mountinfo/mountinfo.go
@@ -0,0 +1,177 @@
+// Package mountinfo provides util-linux bindings for parsing
+// proc_pid_mountinfo(5).
+//
+// This package must never be used outside integration tests, a much better
+// implementation can be found in package vfs.
+//
+// Attempting to import this package outside testing causes the resulting
+// program to panic.
+package mountinfo
+
+/*
+#cgo linux pkg-config: --static mount
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <libmount.h>
+
+const char *HAKUREI_MOUNTINFO_PATH = "/proc/self/mountinfo";
+*/
+import "C"
+
+import (
+	"errors"
+	"fmt"
+	"runtime"
+	"unsafe"
+)
+
+var (
+	// ErrParse is returned by [Open] when encountering a bad record.
+	ErrParse = errors.New("invalid mountinfo record")
+	// ErrIter is returned by [Open] if an iterator cannot be allocated.
+	ErrIter = errors.New("cannot allocate iterator")
+	// ErrIterAdvance is stored when the iterator is unable to advance.
+	ErrIterAdvance = errors.New("unable to advance iterator")
+)
+
+type (
+	// Iter refers to libmnt iterator state.
+	Iter struct {
+		// Last stored error.
+		err error
+		// Whether iteration has concluded.
+		ok bool
+		// Whether Close had already been called.
+		closed bool
+
+		tb  *C.struct_libmnt_table
+		itr *C.struct_libmnt_iter
+
+		fs *C.struct_libmnt_fs
+	}
+
+	// Entry represents deterministic mountinfo parts of a libmnt_fs entry.
+	Entry struct {
+		// mount ID: a unique ID for the mount (may be reused after umount(2)).
+		ID int `json:"id"`
+		// parent ID: the ID of the parent mount (or of self for the root of
+		// this mount namespace's mount tree).
+		Parent int `json:"parent"`
+		// root: the pathname of the directory in the filesystem which forms the
+		// root of this mount.
+		Root string `json:"root"`
+		// mount point: the pathname of the mount point relative to the
+		// process's root directory.
+		Target string `json:"target"`
+		// mount options: per-mount options (see mount(2)).
+		VfsOptstr string `json:"vfs_optstr"`
+		// filesystem type: the filesystem type in the form "type[.subtype]".
+		FsType string `json:"fstype"`
+		// mount source: filesystem-specific information or "none".
+		Source string `json:"source"`
+		// super options: per-superblock options (see mount(2)).
+		FsOptstr string `json:"fs_optstr"`
+	}
+)
+
+// Copy populates v with the current record.
+func (m *Iter) Copy(v *Entry) {
+	if m.fs == nil {
+		panic("invalid entry")
+	}
+	v.ID = int(C.mnt_fs_get_id(m.fs))
+	v.Parent = int(C.mnt_fs_get_parent_id(m.fs))
+	v.Root = C.GoString(C.mnt_fs_get_root(m.fs))
+	v.Target = C.GoString(C.mnt_fs_get_target(m.fs))
+	v.VfsOptstr = C.GoString(C.mnt_fs_get_vfs_options(m.fs))
+	v.FsType = C.GoString(C.mnt_fs_get_fstype(m.fs))
+	v.Source = C.GoString(C.mnt_fs_get_source(m.fs))
+	v.FsOptstr = C.GoString(C.mnt_fs_get_fs_options(m.fs))
+}
+
+// Err returns the saved iterator error.
+func (m *Iter) Err() error { return m.err }
+
+// Open opens a mountinfo document. If name is an empty string, the mountinfo
+// document of the current process is opened instead.
+func Open(name string) (*Iter, error) {
+	var m Iter
+	if name == "" {
+		m.tb = C.mnt_new_table_from_file(C.HAKUREI_MOUNTINFO_PATH)
+	} else {
+		_name := C.CString(name)
+		m.tb = C.mnt_new_table_from_file(_name)
+		C.free(unsafe.Pointer(_name))
+	}
+	if m.tb == nil {
+		return nil, ErrParse
+	}
+	m.itr = C.mnt_new_iter(C.MNT_ITER_FORWARD)
+	if m.itr == nil {
+		C.mnt_unref_table(m.tb)
+		return nil, ErrIter
+	}
+	m.ok = true
+
+	runtime.SetFinalizer(&m, (*Iter).Close)
+	return &m, nil
+}
+
+// Close frees the iterator.
+func (m *Iter) Close() {
+	if m.closed {
+		return
+	}
+	if m.tb == nil {
+		panic("unref called before open")
+	}
+
+	C.mnt_unref_table(m.tb)
+	C.mnt_free_iter(m.itr)
+	m.closed = true
+	runtime.SetFinalizer(m, nil)
+}
+
+// Reset resets the iterator to the first record for reuse.
+func (m *Iter) Reset() {
+	if m.err != nil {
+		panic("attempting to reset a faulted iterator")
+	}
+	m.ok = true
+	C.mnt_reset_iter(m.itr, -1)
+}
+
+// Next advances the iterator to the next record. The record may be copied if
+// Next returns true.
+func (m *Iter) Next() bool {
+	if !m.ok || m.err != nil {
+		return false
+	}
+
+	r := C.mnt_table_next_fs(m.tb, m.itr, &m.fs)
+	if r < 0 {
+		m.err = ErrIterAdvance
+	}
+	m.ok = r == 0
+	return m.ok
+}
+
+// EqualWithIgnore compares e with want, ignoring fields with the specified
+// ignore value.
+func (e *Entry) EqualWithIgnore(want *Entry, ignore string) bool {
+	return (e.ID == want.ID || want.ID == -1) &&
+		(e.Parent == want.Parent || want.Parent == -1) &&
+		(e.Root == want.Root || want.Root == ignore) &&
+		(e.Target == want.Target || want.Target == ignore) &&
+		(e.VfsOptstr == want.VfsOptstr || want.VfsOptstr == ignore) &&
+		(e.FsType == want.FsType || want.FsType == ignore) &&
+		(e.Source == want.Source || want.Source == ignore) &&
+		(e.FsOptstr == want.FsOptstr || want.FsOptstr == ignore)
+}
+
+// String returns a text representation of e loosely following the kernel format.
+func (e *Entry) String() string {
+	return fmt.Sprintf("%d %d %s %s %s %s %s %s",
+		e.ID, e.Parent, e.Root, e.Target, e.VfsOptstr, e.FsType, e.Source, e.FsOptstr)
+}
diff --git a/test/internal/mountinfo/mountinfo_guard.go b/test/internal/mountinfo/mountinfo_guard.go
new file mode 100644
index 00000000..aaf63ac4
--- /dev/null
+++ b/test/internal/mountinfo/mountinfo_guard.go
@@ -0,0 +1,15 @@
+//go:build !testsuite && !tester
+
+package mountinfo
+
+import (
+	"os"
+	"testing"
+)
+
+func init() {
+	if !testing.Testing() {
+		println("package mountinfo imported in non-testsuite program")
+		os.Exit(1)
+	}
+}
diff --git a/test/internal/mountinfo/mountinfo_test.go b/test/internal/mountinfo/mountinfo_test.go
new file mode 100644
index 00000000..45cfdf5f
--- /dev/null
+++ b/test/internal/mountinfo/mountinfo_test.go
@@ -0,0 +1,146 @@
+package mountinfo_test
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"hakurei.app/test/internal/mountinfo"
+)
+
+func TestMountinfo(t *testing.T) {
+	testCases := []struct {
+		name string
+
+		sample string
+		want   []*mountinfo.Entry
+	}{
+		{"util-linux", `15 20 0:3 / /proc rw,relatime - proc /proc rw
+16 20 0:15 / /sys rw,relatime - sysfs /sys rw
+17 20 0:5 / /dev rw,relatime - devtmpfs udev rw,size=1983516k,nr_inodes=495879,mode=755
+18 17 0:10 / /dev/pts rw,relatime - devpts devpts rw,gid=5,mode=620,ptmxmode=000
+19 17 0:16 / /dev/shm rw,relatime - tmpfs tmpfs rw
+20 1 8:4 / / rw,noatime - ext3 /dev/sda4 rw,errors=continue,user_xattr,acl,barrier=0,data=ordered
+21 16 0:17 / /sys/fs/cgroup rw,nosuid,nodev,noexec,relatime - tmpfs tmpfs rw,mode=755
+22 21 0:18 / /sys/fs/cgroup/systemd rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd
+23 21 0:19 / /sys/fs/cgroup/cpuset rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,cpuset
+24 21 0:20 / /sys/fs/cgroup/ns rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,ns
+25 21 0:21 / /sys/fs/cgroup/cpu rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,cpu
+26 21 0:22 / /sys/fs/cgroup/cpuacct rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,cpuacct
+27 21 0:23 / /sys/fs/cgroup/memory rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,memory
+28 21 0:24 / /sys/fs/cgroup/devices rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,devices
+29 21 0:25 / /sys/fs/cgroup/freezer rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,freezer
+30 21 0:26 / /sys/fs/cgroup/net_cls rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,net_cls
+31 21 0:27 / /sys/fs/cgroup/blkio rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,blkio
+32 16 0:28 / /sys/kernel/security rw,relatime - autofs systemd-1 rw,fd=22,pgrp=1,timeout=300,minproto=5,maxproto=5,direct
+33 17 0:29 / /dev/hugepages rw,relatime - autofs systemd-1 rw,fd=23,pgrp=1,timeout=300,minproto=5,maxproto=5,direct
+34 16 0:30 / /sys/kernel/debug rw,relatime - autofs systemd-1 rw,fd=24,pgrp=1,timeout=300,minproto=5,maxproto=5,direct
+35 15 0:31 / /proc/sys/fs/binfmt_misc rw,relatime - autofs systemd-1 rw,fd=25,pgrp=1,timeout=300,minproto=5,maxproto=5,direct
+36 17 0:32 / /dev/mqueue rw,relatime - autofs systemd-1 rw,fd=26,pgrp=1,timeout=300,minproto=5,maxproto=5,direct
+37 15 0:14 / /proc/bus/usb rw,relatime - usbfs /proc/bus/usb rw
+38 33 0:33 / /dev/hugepages rw,relatime - hugetlbfs hugetlbfs rw
+39 36 0:12 / /dev/mqueue rw,relatime - mqueue mqueue rw
+40 20 8:6 / /boot rw,noatime - ext3 /dev/sda6 rw,errors=continue,barrier=0,data=ordered
+41 20 253:0 / /home/kzak rw,noatime - ext4 /dev/mapper/kzak-home rw,barrier=1,data=ordered
+42 35 0:34 / /proc/sys/fs/binfmt_misc rw,relatime - binfmt_misc none rw
+43 16 0:35 / /sys/fs/fuse/connections rw,relatime - fusectl fusectl rw
+44 41 0:36 / /home/kzak/.gvfs rw,nosuid,nodev,relatime - fuse.gvfs-fuse-daemon gvfs-fuse-daemon rw,user_id=500,group_id=500
+45 20 0:37 / /var/lib/nfs/rpc_pipefs rw,relatime - rpc_pipefs sunrpc rw
+47 20 0:38 / /mnt/sounds rw,relatime - cifs //foo.home/bar/ rw,unc=\\foo.home\bar,username=kzak,domain=SRGROUP,uid=0,noforceuid,gid=0,noforcegid,addr=192.168.111.1,posixpaths,serverino,acl,rsize=16384,wsize=57344
+49 20 0:56 / /mnt/test/foobar rw,relatime,nosymfollow shared:323 - tmpfs tmpfs rw`, []*mountinfo.Entry{
+			e(15, 20, "/", "/proc", "rw,relatime", "proc", "/proc", "rw"),
+			e(16, 20, "/", "/sys", "rw,relatime", "sysfs", "/sys", "rw"),
+			e(17, 20, "/", "/dev", "rw,relatime", "devtmpfs", "udev", "rw,size=1983516k,nr_inodes=495879,mode=755"),
+			e(18, 17, "/", "/dev/pts", "rw,relatime", "devpts", "devpts", "rw,gid=5,mode=620,ptmxmode=000"),
+			e(19, 17, "/", "/dev/shm", "rw,relatime", "tmpfs", "tmpfs", "rw"),
+			e(20, 1, "/", "/", "rw,noatime", "ext3", "/dev/sda4", "rw,errors=continue,user_xattr,acl,barrier=0,data=ordered"),
+			e(21, 16, "/", "/sys/fs/cgroup", "rw,nosuid,nodev,noexec,relatime", "tmpfs", "tmpfs", "rw,mode=755"),
+			e(22, 21, "/", "/sys/fs/cgroup/systemd", "rw,nosuid,nodev,noexec,relatime", "cgroup", "cgroup", "rw,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd"),
+			e(23, 21, "/", "/sys/fs/cgroup/cpuset", "rw,nosuid,nodev,noexec,relatime", "cgroup", "cgroup", "rw,cpuset"),
+			e(24, 21, "/", "/sys/fs/cgroup/ns", "rw,nosuid,nodev,noexec,relatime", "cgroup", "cgroup", "rw,ns"),
+			e(25, 21, "/", "/sys/fs/cgroup/cpu", "rw,nosuid,nodev,noexec,relatime", "cgroup", "cgroup", "rw,cpu"),
+			e(26, 21, "/", "/sys/fs/cgroup/cpuacct", "rw,nosuid,nodev,noexec,relatime", "cgroup", "cgroup", "rw,cpuacct"),
+			e(27, 21, "/", "/sys/fs/cgroup/memory", "rw,nosuid,nodev,noexec,relatime", "cgroup", "cgroup", "rw,memory"),
+			e(28, 21, "/", "/sys/fs/cgroup/devices", "rw,nosuid,nodev,noexec,relatime", "cgroup", "cgroup", "rw,devices"),
+			e(29, 21, "/", "/sys/fs/cgroup/freezer", "rw,nosuid,nodev,noexec,relatime", "cgroup", "cgroup", "rw,freezer"),
+			e(30, 21, "/", "/sys/fs/cgroup/net_cls", "rw,nosuid,nodev,noexec,relatime", "cgroup", "cgroup", "rw,net_cls"),
+			e(31, 21, "/", "/sys/fs/cgroup/blkio", "rw,nosuid,nodev,noexec,relatime", "cgroup", "cgroup", "rw,blkio"),
+			e(32, 16, "/", "/sys/kernel/security", "rw,relatime", "autofs", "systemd-1", "rw,fd=22,pgrp=1,timeout=300,minproto=5,maxproto=5,direct"),
+			e(33, 17, "/", "/dev/hugepages", "rw,relatime", "autofs", "systemd-1", "rw,fd=23,pgrp=1,timeout=300,minproto=5,maxproto=5,direct"),
+			e(34, 16, "/", "/sys/kernel/debug", "rw,relatime", "autofs", "systemd-1", "rw,fd=24,pgrp=1,timeout=300,minproto=5,maxproto=5,direct"),
+			e(35, 15, "/", "/proc/sys/fs/binfmt_misc", "rw,relatime", "autofs", "systemd-1", "rw,fd=25,pgrp=1,timeout=300,minproto=5,maxproto=5,direct"),
+			e(36, 17, "/", "/dev/mqueue", "rw,relatime", "autofs", "systemd-1", "rw,fd=26,pgrp=1,timeout=300,minproto=5,maxproto=5,direct"),
+			e(37, 15, "/", "/proc/bus/usb", "rw,relatime", "usbfs", "/proc/bus/usb", "rw"),
+			e(38, 33, "/", "/dev/hugepages", "rw,relatime", "hugetlbfs", "hugetlbfs", "rw"),
+			e(39, 36, "/", "/dev/mqueue", "rw,relatime", "mqueue", "mqueue", "rw"),
+			e(40, 20, "/", "/boot", "rw,noatime", "ext3", "/dev/sda6", "rw,errors=continue,barrier=0,data=ordered"),
+			e(41, 20, "/", "/home/kzak", "rw,noatime", "ext4", "/dev/mapper/kzak-home", "rw,barrier=1,data=ordered"),
+			e(42, 35, "/", "/proc/sys/fs/binfmt_misc", "rw,relatime", "binfmt_misc", "none", "rw"),
+			e(43, 16, "/", "/sys/fs/fuse/connections", "rw,relatime", "fusectl", "fusectl", "rw"),
+			e(44, 41, "/", "/home/kzak/.gvfs", "rw,nosuid,nodev,relatime", "fuse.gvfs-fuse-daemon", "gvfs-fuse-daemon", "rw,user_id=500,group_id=500"),
+			e(45, 20, "/", "/var/lib/nfs/rpc_pipefs", "rw,relatime", "rpc_pipefs", "sunrpc", "rw"),
+			e(47, 20, "/", "/mnt/sounds", "rw,relatime", "cifs", "//foo.home/bar/", "rw,unc=\\\\foo.home\\bar,username=kzak,domain=SRGROUP,uid=0,noforceuid,gid=0,noforcegid,addr=192.168.111.1,posixpaths,serverino,acl,rsize=16384,wsize=57344"),
+			e(49, 20, "/", "/mnt/test/foobar", "rw,relatime,nosymfollow", "tmpfs", "tmpfs", "rw"),
+		}},
+	}
+
+	for _, tc := range testCases {
+		name := filepath.Join(t.TempDir(), "sample")
+		if err := os.WriteFile(name, []byte(tc.sample), 0400); err != nil {
+			t.Fatalf("cannot write sample: %v", err)
+		}
+
+		t.Run(tc.name, func(t *testing.T) {
+			m, err := mountinfo.Open(name)
+			if err != nil {
+				t.Fatalf("Open: error = %v", err)
+			}
+			t.Cleanup(m.Close)
+
+			i := 0
+			var ent mountinfo.Entry
+			for m.Next() {
+				m.Copy(&ent)
+
+				if i == len(tc.want) {
+					t.Errorf("Next: got more than %d entries", i)
+					t.FailNow()
+				}
+				if !ent.EqualWithIgnore(tc.want[i], "\x00") {
+					t.Errorf("Next: entry %d\n got: %#v\nwant: %#v", i,
+						ent, &tc.want[i])
+					t.FailNow()
+				} else {
+					t.Logf("%s", &ent)
+				}
+
+				i++
+			}
+
+			if err = m.Err(); err != nil {
+				t.Fatalf("Err: %v", err)
+			}
+		})
+
+		if err := os.Remove(name); err != nil {
+			t.Fatalf("cannot remove %q: %v", name, err)
+		}
+	}
+}
+
+func e(
+	id, parent int,
+	root, target, vfsOptstr string,
+	fsType, source, fsOptstr string,
+) *mountinfo.Entry {
+	return &mountinfo.Entry{
+		ID:        id,
+		Parent:    parent,
+		Root:      root,
+		Target:    target,
+		VfsOptstr: vfsOptstr,
+		FsType:    fsType,
+		Source:    source,
+		FsOptstr:  fsOptstr,
+	}
+}