diff options
Diffstat (limited to 'pkg/sentry/kernel')
-rw-r--r-- | pkg/sentry/kernel/pipe/buffer.go | 25 | ||||
-rw-r--r-- | pkg/sentry/kernel/pipe/pipe.go | 82 | ||||
-rw-r--r-- | pkg/sentry/kernel/pipe/reader_writer.go | 76 |
3 files changed, 166 insertions, 17 deletions
diff --git a/pkg/sentry/kernel/pipe/buffer.go b/pkg/sentry/kernel/pipe/buffer.go index 69ef2a720..95bee2d37 100644 --- a/pkg/sentry/kernel/pipe/buffer.go +++ b/pkg/sentry/kernel/pipe/buffer.go @@ -15,6 +15,7 @@ package pipe import ( + "io" "sync" "gvisor.dev/gvisor/pkg/sentry/safemem" @@ -67,6 +68,17 @@ func (b *buffer) WriteFromBlocks(srcs safemem.BlockSeq) (uint64, error) { return n, err } +// WriteFromReader writes to the buffer from an io.Reader. +func (b *buffer) WriteFromReader(r io.Reader, count int64) (int64, error) { + dst := b.data[b.write:] + if count < int64(len(dst)) { + dst = b.data[b.write:][:count] + } + n, err := r.Read(dst) + b.write += n + return int64(n), err +} + // ReadToBlocks implements safemem.Reader.ReadToBlocks. func (b *buffer) ReadToBlocks(dsts safemem.BlockSeq) (uint64, error) { src := safemem.BlockSeqOf(safemem.BlockFromSafeSlice(b.data[b.read:b.write])) @@ -75,6 +87,19 @@ func (b *buffer) ReadToBlocks(dsts safemem.BlockSeq) (uint64, error) { return n, err } +// ReadToWriter reads from the buffer into an io.Writer. +func (b *buffer) ReadToWriter(w io.Writer, count int64, dup bool) (int64, error) { + src := b.data[b.read:b.write] + if count < int64(len(src)) { + src = b.data[b.read:][:count] + } + n, err := w.Write(src) + if !dup { + b.read += n + } + return int64(n), err +} + // bufferPool is a pool for buffers. var bufferPool = sync.Pool{ New: func() interface{} { diff --git a/pkg/sentry/kernel/pipe/pipe.go b/pkg/sentry/kernel/pipe/pipe.go index 247e2928e..93b50669f 100644 --- a/pkg/sentry/kernel/pipe/pipe.go +++ b/pkg/sentry/kernel/pipe/pipe.go @@ -23,7 +23,6 @@ import ( "gvisor.dev/gvisor/pkg/sentry/context" "gvisor.dev/gvisor/pkg/sentry/fs" - "gvisor.dev/gvisor/pkg/sentry/usermem" "gvisor.dev/gvisor/pkg/syserror" "gvisor.dev/gvisor/pkg/waiter" ) @@ -173,13 +172,24 @@ func (p *Pipe) Open(ctx context.Context, d *fs.Dirent, flags fs.FileFlags) *fs.F } } +type readOps struct { + // left returns the bytes remaining. + left func() int64 + + // limit limits subsequence reads. + limit func(int64) + + // read performs the actual read operation. + read func(*buffer) (int64, error) +} + // read reads data from the pipe into dst and returns the number of bytes // read, or returns ErrWouldBlock if the pipe is empty. // // Precondition: this pipe must have readers. -func (p *Pipe) read(ctx context.Context, dst usermem.IOSequence) (int64, error) { +func (p *Pipe) read(ctx context.Context, ops readOps) (int64, error) { // Don't block for a zero-length read even if the pipe is empty. - if dst.NumBytes() == 0 { + if ops.left() == 0 { return 0, nil } @@ -196,12 +206,12 @@ func (p *Pipe) read(ctx context.Context, dst usermem.IOSequence) (int64, error) } // Limit how much we consume. - if dst.NumBytes() > p.size { - dst = dst.TakeFirst64(p.size) + if ops.left() > p.size { + ops.limit(p.size) } done := int64(0) - for dst.NumBytes() > 0 { + for ops.left() > 0 { // Pop the first buffer. first := p.data.Front() if first == nil { @@ -209,10 +219,9 @@ func (p *Pipe) read(ctx context.Context, dst usermem.IOSequence) (int64, error) } // Copy user data. - n, err := dst.CopyOutFrom(ctx, first) + n, err := ops.read(first) done += int64(n) p.size -= n - dst = dst.DropFirst64(n) // Empty buffer? if first.Empty() { @@ -230,12 +239,57 @@ func (p *Pipe) read(ctx context.Context, dst usermem.IOSequence) (int64, error) return done, nil } +// dup duplicates all data from this pipe into the given writer. +// +// There is no blocking behavior implemented here. The writer may propagate +// some blocking error. All the writes must be complete writes. +func (p *Pipe) dup(ctx context.Context, ops readOps) (int64, error) { + p.mu.Lock() + defer p.mu.Unlock() + + // Is the pipe empty? + if p.size == 0 { + if !p.HasWriters() { + // See above. + return 0, nil + } + return 0, syserror.ErrWouldBlock + } + + // Limit how much we consume. + if ops.left() > p.size { + ops.limit(p.size) + } + + done := int64(0) + for buf := p.data.Front(); buf != nil; buf = buf.Next() { + n, err := ops.read(buf) + done += n + if err != nil { + return done, err + } + } + + return done, nil +} + +type writeOps struct { + // left returns the bytes remaining. + left func() int64 + + // limit should limit subsequent writes. + limit func(int64) + + // write should write to the provided buffer. + write func(*buffer) (int64, error) +} + // write writes data from sv into the pipe and returns the number of bytes // written. If no bytes are written because the pipe is full (or has less than // atomicIOBytes free capacity), write returns ErrWouldBlock. // // Precondition: this pipe must have writers. -func (p *Pipe) write(ctx context.Context, src usermem.IOSequence) (int64, error) { +func (p *Pipe) write(ctx context.Context, ops writeOps) (int64, error) { p.mu.Lock() defer p.mu.Unlock() @@ -246,17 +300,16 @@ func (p *Pipe) write(ctx context.Context, src usermem.IOSequence) (int64, error) // POSIX requires that a write smaller than atomicIOBytes (PIPE_BUF) be // atomic, but requires no atomicity for writes larger than this. - wanted := src.NumBytes() + wanted := ops.left() if avail := p.max - p.size; wanted > avail { if wanted <= p.atomicIOBytes { return 0, syserror.ErrWouldBlock } - // Limit to the available capacity. - src = src.TakeFirst64(avail) + ops.limit(avail) } done := int64(0) - for src.NumBytes() > 0 { + for ops.left() > 0 { // Need a new buffer? last := p.data.Back() if last == nil || last.Full() { @@ -266,10 +319,9 @@ func (p *Pipe) write(ctx context.Context, src usermem.IOSequence) (int64, error) } // Copy user data. - n, err := src.CopyInTo(ctx, last) + n, err := ops.write(last) done += int64(n) p.size += n - src = src.DropFirst64(n) // Handle errors. if err != nil { diff --git a/pkg/sentry/kernel/pipe/reader_writer.go b/pkg/sentry/kernel/pipe/reader_writer.go index f69dbf27b..7c307f013 100644 --- a/pkg/sentry/kernel/pipe/reader_writer.go +++ b/pkg/sentry/kernel/pipe/reader_writer.go @@ -15,6 +15,7 @@ package pipe import ( + "io" "math" "syscall" @@ -55,7 +56,45 @@ func (rw *ReaderWriter) Release() { // Read implements fs.FileOperations.Read. func (rw *ReaderWriter) Read(ctx context.Context, _ *fs.File, dst usermem.IOSequence, _ int64) (int64, error) { - n, err := rw.Pipe.read(ctx, dst) + n, err := rw.Pipe.read(ctx, readOps{ + left: func() int64 { + return dst.NumBytes() + }, + limit: func(l int64) { + dst = dst.TakeFirst64(l) + }, + read: func(buf *buffer) (int64, error) { + n, err := dst.CopyOutFrom(ctx, buf) + dst = dst.DropFirst64(n) + return n, err + }, + }) + if n > 0 { + rw.Pipe.Notify(waiter.EventOut) + } + return n, err +} + +// WriteTo implements fs.FileOperations.WriteTo. +func (rw *ReaderWriter) WriteTo(ctx context.Context, _ *fs.File, w io.Writer, count int64, dup bool) (int64, error) { + ops := readOps{ + left: func() int64 { + return count + }, + limit: func(l int64) { + count = l + }, + read: func(buf *buffer) (int64, error) { + n, err := buf.ReadToWriter(w, count, dup) + count -= n + return n, err + }, + } + if dup { + // There is no notification for dup operations. + return rw.Pipe.dup(ctx, ops) + } + n, err := rw.Pipe.read(ctx, ops) if n > 0 { rw.Pipe.Notify(waiter.EventOut) } @@ -64,7 +103,40 @@ func (rw *ReaderWriter) Read(ctx context.Context, _ *fs.File, dst usermem.IOSequ // Write implements fs.FileOperations.Write. func (rw *ReaderWriter) Write(ctx context.Context, _ *fs.File, src usermem.IOSequence, _ int64) (int64, error) { - n, err := rw.Pipe.write(ctx, src) + n, err := rw.Pipe.write(ctx, writeOps{ + left: func() int64 { + return src.NumBytes() + }, + limit: func(l int64) { + src = src.TakeFirst64(l) + }, + write: func(buf *buffer) (int64, error) { + n, err := src.CopyInTo(ctx, buf) + src = src.DropFirst64(n) + return n, err + }, + }) + if n > 0 { + rw.Pipe.Notify(waiter.EventIn) + } + return n, err +} + +// ReadFrom implements fs.FileOperations.WriteTo. +func (rw *ReaderWriter) ReadFrom(ctx context.Context, _ *fs.File, r io.Reader, count int64) (int64, error) { + n, err := rw.Pipe.write(ctx, writeOps{ + left: func() int64 { + return count + }, + limit: func(l int64) { + count = l + }, + write: func(buf *buffer) (int64, error) { + n, err := buf.WriteFromReader(r, count) + count -= n + return n, err + }, + }) if n > 0 { rw.Pipe.Notify(waiter.EventIn) } |