mirror of
https://github.com/netbirdio/gvisor.git
synced 2026-05-22 17:12:49 -07:00
Ayush Ranjan
980de72deb
dup(2) man page specifies:
If the file descriptor newfd was previously open, it is closed
before being reused; the close is performed silently (i.e., any
errors during the close are not reported by dup2()).
Even though we were DecRef-ing and hence releasing the replaced FD, we were
not calling OnClose(). Compare fs/file.c:do_dup2() -> filp_close(tofree), which
in turn calls filp_flush(). In gVisor, FileDescription.OnClose() analogously
does such flush operations.
in turn
PiperOrigin-RevId: 583147682
360 lines
11 KiB
Go
360 lines
11 KiB
Go
// Copyright 2018 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package kernel
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import (
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"runtime"
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"testing"
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"gvisor.dev/gvisor/pkg/context"
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"gvisor.dev/gvisor/pkg/sentry/contexttest"
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"gvisor.dev/gvisor/pkg/sentry/limits"
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"gvisor.dev/gvisor/pkg/sentry/vfs"
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"gvisor.dev/gvisor/pkg/sync"
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)
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const (
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// maxFD is the maximum FD to try to create in the map.
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//
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// This number of open files has been seen in the wild.
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maxFD = 2 * 1024
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)
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// testFD is a read-only FileDescriptionImpl representing a regular file.
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type testFD struct {
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vfsfd vfs.FileDescription
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vfs.FileDescriptionDefaultImpl
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vfs.DentryMetadataFileDescriptionImpl
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vfs.NoLockFD
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}
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// Release implements FileDescriptionImpl.Release.
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func (fd *testFD) Release(context.Context) {}
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func newTestFD(ctx context.Context, vfsObj *vfs.VirtualFilesystem) *vfs.FileDescription {
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vd := vfsObj.NewAnonVirtualDentry("testFD")
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defer vd.DecRef(ctx)
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var fd testFD
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fd.vfsfd.Init(&fd, 0 /* flags */, vd.Mount(), vd.Dentry(), &vfs.FileDescriptionOptions{})
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return &fd.vfsfd
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}
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func runTest(t testing.TB, fn func(ctx context.Context, fdTable *FDTable, fd *vfs.FileDescription, limitSet *limits.LimitSet)) {
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t.Helper() // Don't show in stacks.
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// Create the limits and context.
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limitSet := limits.NewLimitSet()
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limitSet.Set(limits.NumberOfFiles, limits.Limit{maxFD, maxFD}, true)
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ctx := contexttest.WithLimitSet(contexttest.Context(t), limitSet)
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vfsObj := &vfs.VirtualFilesystem{}
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if err := vfsObj.Init(ctx); err != nil {
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t.Fatalf("VFS init: %v", err)
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}
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fd := newTestFD(ctx, vfsObj)
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defer fd.DecRef(ctx)
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// Create the table.
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fdTable := new(FDTable)
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fdTable.k = &Kernel{}
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fdTable.k.MaxFDLimit.Store(MaxFdLimit)
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fdTable.init()
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// Run the test.
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fn(ctx, fdTable, fd, limitSet)
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}
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// TestFDTableMany allocates maxFD FDs, i.e. maxes out the FDTable, until there
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// is no room, then makes sure that NewFDAt works and also that if we remove
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// one and add one that works too.
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func TestFDTableMany(t *testing.T) {
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runTest(t, func(ctx context.Context, fdTable *FDTable, fd *vfs.FileDescription, _ *limits.LimitSet) {
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for i := 0; i < maxFD; i++ {
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if _, err := fdTable.NewFDs(ctx, 0, []*vfs.FileDescription{fd}, FDFlags{}); err != nil {
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t.Fatalf("Allocated %v FDs but wanted to allocate %v", i, maxFD)
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}
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}
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if _, err := fdTable.NewFDs(ctx, 0, []*vfs.FileDescription{fd}, FDFlags{}); err == nil {
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t.Fatalf("fdTable.NewFDs(0, r) in full map: got nil, wanted error")
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}
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if df, err := fdTable.NewFDAt(ctx, 1, fd, FDFlags{}); err != nil {
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t.Fatalf("fdTable.NewFDAt(1, r, FDFlags{}): got %v, wanted nil", err)
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} else if df != nil {
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t.Fatalf("fdTable.NewFDAt(1, r, FDFlags{}) displaced FD")
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}
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i := int32(2)
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fdTable.Remove(ctx, i)
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if fds, err := fdTable.NewFDs(ctx, 0, []*vfs.FileDescription{fd}, FDFlags{}); err != nil || fds[0] != i {
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t.Fatalf("Allocated %v FDs but wanted to allocate %v: %v", i, maxFD, err)
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}
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})
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}
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func TestFDTableOverLimit(t *testing.T) {
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runTest(t, func(ctx context.Context, fdTable *FDTable, fd *vfs.FileDescription, _ *limits.LimitSet) {
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if _, err := fdTable.NewFDs(ctx, maxFD, []*vfs.FileDescription{fd}, FDFlags{}); err == nil {
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t.Fatalf("fdTable.NewFDs(maxFD, f): got nil, wanted error")
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}
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if _, err := fdTable.NewFDs(ctx, maxFD-2, []*vfs.FileDescription{fd, fd, fd}, FDFlags{}); err == nil {
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t.Fatalf("fdTable.NewFDs(maxFD-2, {f,f,f}): got nil, wanted error")
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}
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if fds, err := fdTable.NewFDs(ctx, maxFD-3, []*vfs.FileDescription{fd, fd, fd}, FDFlags{}); err != nil {
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t.Fatalf("fdTable.NewFDs(maxFD-3, {f,f,f}): got %v, wanted nil", err)
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} else {
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for _, fd := range fds {
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fdTable.Remove(ctx, fd)
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}
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}
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if fds, err := fdTable.NewFDs(ctx, maxFD-1, []*vfs.FileDescription{fd}, FDFlags{}); err != nil || fds[0] != maxFD-1 {
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t.Fatalf("fdTable.NewFDAt(1, r, FDFlags{}): got %v, wanted nil", err)
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}
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if fds, err := fdTable.NewFDs(ctx, 0, []*vfs.FileDescription{fd}, FDFlags{}); err != nil {
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t.Fatalf("Adding an FD to a resized map: got %v, want nil", err)
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} else if len(fds) != 1 || fds[0] != 0 {
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t.Fatalf("Added an FD to a resized map: got %v, want {1}", fds)
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}
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})
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}
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// TestFDTable does a set of simple tests to make sure simple adds, removes,
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// GetRefs, and DecRefs work. The ordering is just weird enough that a
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// table-driven approach seemed clumsy.
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func TestFDTable(t *testing.T) {
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runTest(t, func(ctx context.Context, fdTable *FDTable, fd *vfs.FileDescription, limitSet *limits.LimitSet) {
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// Cap the limit at one.
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limitSet.Set(limits.NumberOfFiles, limits.Limit{1, maxFD}, true)
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if _, err := fdTable.NewFDs(ctx, 0, []*vfs.FileDescription{fd}, FDFlags{}); err != nil {
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t.Fatalf("Adding an FD to an empty 1-size map: got %v, want nil", err)
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}
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if _, err := fdTable.NewFDs(ctx, 0, []*vfs.FileDescription{fd}, FDFlags{}); err == nil {
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t.Fatalf("Adding an FD to a filled 1-size map: got nil, wanted an error")
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}
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// Remove the previous limit.
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limitSet.Set(limits.NumberOfFiles, limits.Limit{maxFD, maxFD}, true)
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if fds, err := fdTable.NewFDs(ctx, 0, []*vfs.FileDescription{fd}, FDFlags{}); err != nil {
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t.Fatalf("Adding an FD to a resized map: got %v, want nil", err)
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} else if len(fds) != 1 || fds[0] != 1 {
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t.Fatalf("Added an FD to a resized map: got %v, want {1}", fds)
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}
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if df, err := fdTable.NewFDAt(ctx, 1, fd, FDFlags{}); err != nil {
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t.Fatalf("Replacing FD 1 via fdTable.NewFDAt(1, r, FDFlags{}): got %v, wanted nil", err)
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} else if df != nil {
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t.Fatalf("fdTable.NewFDAt(1, r, FDFlags{}) displaced FD")
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}
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if _, err := fdTable.NewFDAt(ctx, maxFD+1, fd, FDFlags{}); err == nil {
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t.Fatalf("Using an FD that was too large via fdTable.NewFDAt(%v, r, FDFlags{}): got nil, wanted an error", maxFD+1)
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}
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if ref, _ := fdTable.Get(1); ref == nil {
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t.Fatalf("fdTable.Get(1): got nil, wanted %v", fd)
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}
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if ref, _ := fdTable.Get(2); ref != nil {
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t.Fatalf("fdTable.Get(2): got a %v, wanted nil", ref)
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}
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ref := fdTable.Remove(ctx, 1)
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if ref == nil {
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t.Fatalf("fdTable.Remove(1) for an existing FD: failed, want success")
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}
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ref.DecRef(ctx)
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if ref := fdTable.Remove(ctx, 1); ref != nil {
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t.Fatalf("r.Remove(1) for a removed FD: got success, want failure")
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}
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})
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}
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func TestDescriptorFlags(t *testing.T) {
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runTest(t, func(ctx context.Context, fdTable *FDTable, fd *vfs.FileDescription, _ *limits.LimitSet) {
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if df, err := fdTable.NewFDAt(ctx, 2, fd, FDFlags{CloseOnExec: true}); err != nil {
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t.Fatalf("fdTable.NewFDAt(2, r, FDFlags{}): got %v, wanted nil", err)
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} else if df != nil {
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t.Fatalf("fdTable.NewFDAt(2, r, FDFlags{}) displaced FD")
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}
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newFile, flags := fdTable.Get(2)
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if newFile == nil {
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t.Fatalf("fdTable.Get(2): got a %v, wanted nil", newFile)
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}
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if !flags.CloseOnExec {
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t.Fatalf("new File flags %v don't match original %d\n", flags, 0)
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}
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})
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}
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func BenchmarkFDLookupAndDecRef(b *testing.B) {
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b.StopTimer() // Setup.
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runTest(b, func(ctx context.Context, fdTable *FDTable, fd *vfs.FileDescription, _ *limits.LimitSet) {
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fds, err := fdTable.NewFDs(ctx, 0, []*vfs.FileDescription{fd, fd, fd, fd, fd}, FDFlags{})
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if err != nil {
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b.Fatalf("fdTable.NewFDs: got %v, wanted nil", err)
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}
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b.StartTimer() // Benchmark.
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for i := 0; i < b.N; i++ {
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tf, _ := fdTable.Get(fds[i%len(fds)])
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tf.DecRef(ctx)
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}
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})
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}
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func BenchmarkNewFDAt(b *testing.B) {
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const maxLimit = 1 << 31
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b.StopTimer() // Setup.
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runTest(b, func(ctx context.Context, fdTable *FDTable, fd *vfs.FileDescription, limitSet *limits.LimitSet) {
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// Remove the previous limit.
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limitSet.Set(limits.NumberOfFiles, limits.Limit{maxLimit, maxLimit}, true)
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b.StartTimer() // Benchmark.
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for i := 0; i < b.N; i++ {
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_, err := fdTable.NewFDAt(ctx, int32(i%maxLimit), fd, FDFlags{})
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if err != nil {
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b.Fatalf("fdTable.NewFDAt: got %v, wanted nil", err)
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}
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}
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})
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}
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func BenchmarkFork(b *testing.B) {
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b.StopTimer() // Setup.
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runTest(b, func(ctx context.Context, fdTable *FDTable, fd *vfs.FileDescription, limitSet *limits.LimitSet) {
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for i := 0; i < maxFD; i++ {
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_, err := fdTable.NewFDAt(ctx, int32(i), fd, FDFlags{})
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if err != nil {
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b.Fatalf("fdTable.NewFDs: got %v, wanted nil", err)
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}
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}
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b.StartTimer() // Benchmark.
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for i := 0; i < b.N; i++ {
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t := fdTable.Fork(ctx, maxFD)
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t.DecRef(ctx)
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}
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})
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}
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func BenchmarkCreateWithMaxFD(b *testing.B) {
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const maxLimit = 1 << 31
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runTest(b, func(ctx context.Context, _ *FDTable, fd *vfs.FileDescription, limitSet *limits.LimitSet) {
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// Remove the previous limit.
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limitSet.Set(limits.NumberOfFiles, limits.Limit{maxLimit, maxLimit}, true)
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for i := 0; i < b.N; i++ {
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fdTable := new(FDTable)
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fdTable.init()
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_, err := fdTable.NewFDAt(ctx, maxLimit-1, fd, FDFlags{})
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if err != nil {
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b.Fatalf("fdTable.NewFDs: got %v, wanted nil", err)
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}
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fdTable.DecRef(ctx)
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}
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})
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}
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func BenchmarkFDLookupAndDecRefConcurrent(b *testing.B) {
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b.StopTimer() // Setup.
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runTest(b, func(ctx context.Context, fdTable *FDTable, fd *vfs.FileDescription, _ *limits.LimitSet) {
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fds, err := fdTable.NewFDs(ctx, 0, []*vfs.FileDescription{fd, fd, fd, fd, fd}, FDFlags{})
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if err != nil {
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b.Fatalf("fdTable.NewFDs: got %v, wanted nil", err)
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}
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concurrency := runtime.GOMAXPROCS(0)
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if concurrency < 4 {
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concurrency = 4
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}
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each := b.N / concurrency
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b.StartTimer() // Benchmark.
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var wg sync.WaitGroup
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for i := 0; i < concurrency; i++ {
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wg.Add(1)
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go func() {
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defer wg.Done()
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for i := 0; i < each; i++ {
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tf, _ := fdTable.Get(fds[i%len(fds)])
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tf.DecRef(ctx)
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}
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}()
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}
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wg.Wait()
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})
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}
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func TestSetFlagsForRange(t *testing.T) {
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type testCase struct {
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name string
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startFd int32
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endFd int32
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wantErr bool
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}
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testCases := []testCase{
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{"negative ranges", -100, -10, true},
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{"inverted positive ranges", 100, 10, true},
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{"good range", maxFD / 4, maxFD / 2, false},
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}
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for _, test := range testCases {
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runTest(t, func(ctx context.Context, fdTable *FDTable, fd *vfs.FileDescription, _ *limits.LimitSet) {
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for i := 0; i < maxFD; i++ {
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if _, err := fdTable.NewFDs(ctx, 0, []*vfs.FileDescription{fd}, FDFlags{}); err != nil {
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t.Fatalf("testCase: %v\nfdTable.NewFDs(_, 0, %+v, FDFlags{}): %d, want: nil", test, []*vfs.FileDescription{fd}, err)
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}
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}
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newFlags := FDFlags{CloseOnExec: true}
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if err := fdTable.SetFlagsForRange(ctx, test.startFd, test.endFd, newFlags); (err == nil) == test.wantErr {
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t.Fatalf("testCase: %v\nfdTable.SetFlagsForRange(_, %d, %d, %v): %v, waf: %t", test, test.startFd, test.endFd, newFlags, err, test.wantErr)
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}
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if test.wantErr {
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return
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}
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testRangeFlags := func(start int32, end int32, expected FDFlags) {
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for i := start; i <= end; i++ {
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file, flags := fdTable.Get(i)
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if file == nil || flags != expected {
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t.Fatalf("testCase: %v\nfdTable.Get(%d): (%v, %v), wanted (non-nil, %v)", test, i, file, flags, expected)
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}
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}
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}
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testRangeFlags(0, test.startFd-1, FDFlags{})
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testRangeFlags(test.startFd, test.endFd, newFlags)
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testRangeFlags(test.endFd+1, maxFD-1, FDFlags{})
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})
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}
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}
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