vendor: github.com/moby/buildkit v0.21.0-rc2

Signed-off-by: CrazyMax <1951866+crazy-max@users.noreply.github.com>

vendor/github.com/tonistiigi/fsutil/buffer.go

@@ -0,0 +1,44 @@
+package fsutil
+
+import (
+	"io"
+)
+
+const chunkSize = 32 * 1024
+
+type buffer struct {
+	chunks [][]byte
+}
+
+func (b *buffer) alloc(n int) []byte {
+	if n > chunkSize {
+		buf := make([]byte, n)
+		b.chunks = append(b.chunks, buf)
+		return buf
+	}
+
+	if len(b.chunks) != 0 {
+		lastChunk := b.chunks[len(b.chunks)-1]
+		l := len(lastChunk)
+		if l+n <= cap(lastChunk) {
+			lastChunk = lastChunk[:l+n]
+			b.chunks[len(b.chunks)-1] = lastChunk
+			return lastChunk[l : l+n]
+		}
+	}
+
+	buf := make([]byte, n, chunkSize)
+	b.chunks = append(b.chunks, buf)
+	return buf
+}
+
+func (b *buffer) WriteTo(w io.Writer) (n int64, err error) {
+	for _, c := range b.chunks {
+		m, err := w.Write(c)
+		n += int64(m)
+		if err != nil {
+			return n, err
+		}
+	}
+	return n, nil
+}