From 4cd2c4e818a1438bf63d1ca05a6cf134f39bc06b Mon Sep 17 00:00:00 2001
From: Paul Buetow <paul@buetow.org>
Date: Sun, 22 Feb 2026 22:31:35 +0200
Subject: Add copy_file_range support and tracepoint attach tests

---
 .../cmd/ioworkload/scenario_copy_file_range.go     | 78 ++++++++++++++++++++++
 integrationtests/cmd/ioworkload/scenarios.go       |  2 +
 2 files changed, 80 insertions(+)
 create mode 100644 integrationtests/cmd/ioworkload/scenario_copy_file_range.go

(limited to 'integrationtests/cmd')

diff --git a/integrationtests/cmd/ioworkload/scenario_copy_file_range.go b/integrationtests/cmd/ioworkload/scenario_copy_file_range.go
new file mode 100644
index 0000000..87531b0
--- /dev/null
+++ b/integrationtests/cmd/ioworkload/scenario_copy_file_range.go
@@ -0,0 +1,78 @@
+package main
+
+import (
+	"fmt"
+	"path/filepath"
+	"syscall"
+)
+
+// SYS_COPY_FILE_RANGE on x86_64 Linux.
+const sysCopyFileRange = 326
+
+// copyFileRangeBasic copies bytes from a source file to a destination file
+// using copy_file_range(2) with flags=0 as required by the manpage.
+func copyFileRangeBasic() error {
+	dir, cleanup, err := makeTempDir("copy-file-range-basic")
+	if err != nil {
+		return err
+	}
+	defer cleanup()
+
+	srcPath := filepath.Join(dir, "copyrangesrc.txt")
+	dstPath := filepath.Join(dir, "copyrangedst.txt")
+
+	srcFd, err := syscall.Open(srcPath, syscall.O_RDWR|syscall.O_CREAT|syscall.O_TRUNC, 0o644)
+	if err != nil {
+		return fmt.Errorf("open source: %w", err)
+	}
+	defer syscall.Close(srcFd)
+
+	dstFd, err := syscall.Open(dstPath, syscall.O_RDWR|syscall.O_CREAT|syscall.O_TRUNC, 0o644)
+	if err != nil {
+		return fmt.Errorf("open destination: %w", err)
+	}
+	defer syscall.Close(dstFd)
+
+	data := []byte("copy_file_range integration data")
+	if _, err := syscall.Write(srcFd, data); err != nil {
+		return fmt.Errorf("write source: %w", err)
+	}
+
+	n, _, errno := syscall.Syscall6(uintptr(sysCopyFileRange), uintptr(srcFd), 0, uintptr(dstFd), 0, uintptr(len(data)), 0)
+	if errno != 0 {
+		return fmt.Errorf("copy_file_range: %w", errno)
+	}
+	if n == 0 {
+		return fmt.Errorf("copy_file_range copied 0 bytes")
+	}
+
+	return nil
+}
+
+// copyFileRangeBadDstFd calls copy_file_range(2) with an invalid destination fd.
+// The syscall should fail with EBADF, while still emitting the enter tracepoint.
+func copyFileRangeBadDstFd() error {
+	dir, cleanup, err := makeTempDir("copy-file-range-bad-dst")
+	if err != nil {
+		return err
+	}
+	defer cleanup()
+
+	srcPath := filepath.Join(dir, "copyrangeebadfsrc.txt")
+	srcFd, err := syscall.Open(srcPath, syscall.O_RDWR|syscall.O_CREAT|syscall.O_TRUNC, 0o644)
+	if err != nil {
+		return fmt.Errorf("open source: %w", err)
+	}
+	defer syscall.Close(srcFd)
+
+	if _, err := syscall.Write(srcFd, []byte("copy_file_range ebadf data")); err != nil {
+		return fmt.Errorf("write source: %w", err)
+	}
+
+	_, _, errno := syscall.Syscall6(uintptr(sysCopyFileRange), uintptr(srcFd), 0, uintptr(99999), 0, uintptr(16), 0)
+	if errno != syscall.EBADF {
+		return fmt.Errorf("expected EBADF from copy_file_range with invalid dst fd, got %v", errno)
+	}
+
+	return nil
+}
diff --git a/integrationtests/cmd/ioworkload/scenarios.go b/integrationtests/cmd/ioworkload/scenarios.go
index d99b584..f9a8e47 100644
--- a/integrationtests/cmd/ioworkload/scenarios.go
+++ b/integrationtests/cmd/ioworkload/scenarios.go
@@ -85,6 +85,8 @@ var scenarios = map[string]func() error{
 	"mmap-basic":                  mmapBasic,
 	"mmap-msync-sync":             mmapMsyncSync,
 	"mmap-msync-invalid-flags":    mmapMsyncInvalidFlags,
+	"copy-file-range-basic":       copyFileRangeBasic,
+	"copy-file-range-bad-dst-fd":  copyFileRangeBadDstFd,
 	"truncate-basic":              truncateBasic,
 	"truncate-ftruncate":          truncateFtruncate,
 	"truncate-enoent":             truncateEnoent,
-- 
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