1 files changed, 47 insertions, 1 deletions
diff --git a/vendor/github.com/cilium/ebpf/internal/io.go b/vendor/github.com/cilium/ebpf/internal/io.go
index fa7402782..30b6641f0 100644
--- a/vendor/github.com/cilium/ebpf/internal/io.go
+++ b/vendor/github.com/cilium/ebpf/internal/io.go
@@ -1,6 +1,35 @@
 package internal
 
-import "errors"
+import (
+	"bufio"
+	"compress/gzip"
+	"errors"
+	"io"
+	"os"
+)
+
+// NewBufferedSectionReader wraps an io.ReaderAt in an appropriately-sized
+// buffered reader. It is a convenience function for reading subsections of
+// ELF sections while minimizing the amount of read() syscalls made.
+//
+// Syscall overhead is non-negligible in continuous integration context
+// where ELFs might be accessed over virtual filesystems with poor random
+// access performance. Buffering reads makes sense because (sub)sections
+// end up being read completely anyway.
+//
+// Use instead of the r.Seek() + io.LimitReader() pattern.
+func NewBufferedSectionReader(ra io.ReaderAt, off, n int64) *bufio.Reader {
+	// Clamp the size of the buffer to one page to avoid slurping large parts
+	// of a file into memory. bufio.NewReader uses a hardcoded default buffer
+	// of 4096. Allow arches with larger pages to allocate more, but don't
+	// allocate a fixed 4k buffer if we only need to read a small segment.
+	buf := n
+	if ps := int64(os.Getpagesize()); n > ps {
+		buf = ps
+	}
+
+	return bufio.NewReaderSize(io.NewSectionReader(ra, off, n), int(buf))
+}
 
 // DiscardZeroes makes sure that all written bytes are zero
 // before discarding them.
@@ -14,3 +43,20 @@ func (DiscardZeroes) Write(p []byte) (int, error) {
 	}
 	return len(p), nil
 }
+
+// ReadAllCompressed decompresses a gzipped file into memory.
+func ReadAllCompressed(file string) ([]byte, error) {
+	fh, err := os.Open(file)
+	if err != nil {
+		return nil, err
+	}
+	defer fh.Close()
+
+	gz, err := gzip.NewReader(fh)
+	if err != nil {
+		return nil, err
+	}
+	defer gz.Close()
+
+	return io.ReadAll(gz)
+}