From 3ec3c117bb280a377fea1a3eef84a70e2a3d4150 Mon Sep 17 00:00:00 2001 From: Paul Buetow Date: Sat, 21 Feb 2026 22:03:57 +0200 Subject: Split ioworkload scenarios.go into per-category files Split the 2494-line scenarios.go monolith into 14 focused files by syscall category: open, readwrite, close, dup, fcntl, rename, link, unlink, dir, stat, sync, truncate, iouring, plus the slimmed-down scenarios.go containing only the registry map, makeTempDir, and crash. Extracted rawLink, rawSymlink, rawReadlink helpers in scenario_link.go to reduce code duplication in linkBasic. Task: #349 (Go best practices: split oversized scenarios file) Amp-Thread-ID: https://ampcode.com/threads/T-019c81c6-e1b6-747a-9144-40f6be997e60 Co-authored-by: Amp --- integrationtests/cmd/ioworkload/scenario_close.go | 114 + integrationtests/cmd/ioworkload/scenario_dir.go | 186 ++ integrationtests/cmd/ioworkload/scenario_dup.go | 151 ++ integrationtests/cmd/ioworkload/scenario_fcntl.go | 129 ++ .../cmd/ioworkload/scenario_iouring.go | 129 ++ integrationtests/cmd/ioworkload/scenario_link.go | 385 ++++ integrationtests/cmd/ioworkload/scenario_open.go | 228 ++ .../cmd/ioworkload/scenario_readwrite.go | 263 +++ integrationtests/cmd/ioworkload/scenario_rename.go | 251 ++ integrationtests/cmd/ioworkload/scenario_stat.go | 274 +++ integrationtests/cmd/ioworkload/scenario_sync.go | 108 + .../cmd/ioworkload/scenario_truncate.go | 89 + integrationtests/cmd/ioworkload/scenario_unlink.go | 185 ++ integrationtests/cmd/ioworkload/scenarios.go | 2386 -------------------- 14 files changed, 2492 insertions(+), 2386 deletions(-) create mode 100644 integrationtests/cmd/ioworkload/scenario_close.go create mode 100644 integrationtests/cmd/ioworkload/scenario_dir.go create mode 100644 integrationtests/cmd/ioworkload/scenario_dup.go create mode 100644 integrationtests/cmd/ioworkload/scenario_fcntl.go create mode 100644 integrationtests/cmd/ioworkload/scenario_iouring.go create mode 100644 integrationtests/cmd/ioworkload/scenario_link.go create mode 100644 integrationtests/cmd/ioworkload/scenario_open.go create mode 100644 integrationtests/cmd/ioworkload/scenario_readwrite.go create mode 100644 integrationtests/cmd/ioworkload/scenario_rename.go create mode 100644 integrationtests/cmd/ioworkload/scenario_stat.go create mode 100644 integrationtests/cmd/ioworkload/scenario_sync.go create mode 100644 integrationtests/cmd/ioworkload/scenario_truncate.go create mode 100644 integrationtests/cmd/ioworkload/scenario_unlink.go diff --git a/integrationtests/cmd/ioworkload/scenario_close.go b/integrationtests/cmd/ioworkload/scenario_close.go new file mode 100644 index 0000000..a36160a --- /dev/null +++ b/integrationtests/cmd/ioworkload/scenario_close.go @@ -0,0 +1,114 @@ +package main + +import ( + "fmt" + "path/filepath" + "syscall" +) + +const sysCloseRange = 436 + +// closeBasic opens multiple files and closes them. +func closeBasic() error { + dir, cleanup, err := makeTempDir("close-basic") + if err != nil { + return err + } + defer cleanup() + + var fds []int + for i := range 3 { + path := filepath.Join(dir, fmt.Sprintf("closefile-%d.txt", i)) + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open %d: %w", i, err) + } + fds = append(fds, fd) + } + for _, fd := range fds { + if err := syscall.Close(fd); err != nil { + return fmt.Errorf("close fd %d: %w", fd, err) + } + } + return nil +} + +// closeRange opens multiple files and closes a range of them via close_range(2). +func closeRange() error { + dir, cleanup, err := makeTempDir("close-range") + if err != nil { + return err + } + defer cleanup() + + var fds []int + for i := range 3 { + path := filepath.Join(dir, fmt.Sprintf("closerangefile-%d.txt", i)) + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open %d: %w", i, err) + } + fds = append(fds, fd) + } + + if fds[2]-fds[0] != 2 { + return fmt.Errorf("fds not contiguous: %v", fds) + } + + first := uintptr(fds[0]) + last := uintptr(fds[len(fds)-1]) + _, _, errno := syscall.Syscall(sysCloseRange, first, last, 0) + if errno != 0 { + return fmt.Errorf("close_range: %w", errno) + } + return nil +} + +// closeInvalidFd attempts to close a very high fd number that is not open. +// The close fails with EBADF, but ior should capture the enter_close tracepoint +// because arguments are read on syscall entry before the kernel returns an error. +func closeInvalidFd() error { + err := syscall.Close(99999) + if err == nil { + return fmt.Errorf("expected close of invalid fd to fail") + } + return nil +} + +// closeDoubleClose opens a file, closes it normally, then closes the same fd again. +// The second close fails with EBADF, but ior should capture both enter_close +// tracepoints because arguments are read on syscall entry. +func closeDoubleClose() error { + dir, cleanup, err := makeTempDir("close-double-close") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "doubleclosefile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + + if err := syscall.Close(fd); err != nil { + return fmt.Errorf("first close: %w", err) + } + + err = syscall.Close(fd) + if err == nil { + return fmt.Errorf("expected second close of same fd to fail") + } + return nil +} + +// closeRangeEmpty calls close_range(2) with a range of very high fd numbers +// (9000–9999) where no fds are open. The syscall succeeds (empty range is valid), +// and ior should capture the enter_close_range tracepoint. +func closeRangeEmpty() error { + _, _, errno := syscall.Syscall(sysCloseRange, 9000, 9999, 0) + if errno != 0 { + return fmt.Errorf("close_range: %w", errno) + } + return nil +} diff --git a/integrationtests/cmd/ioworkload/scenario_dir.go b/integrationtests/cmd/ioworkload/scenario_dir.go new file mode 100644 index 0000000..0c48d54 --- /dev/null +++ b/integrationtests/cmd/ioworkload/scenario_dir.go @@ -0,0 +1,186 @@ +package main + +import ( + "fmt" + "os" + "path/filepath" + "runtime" + "syscall" + "unsafe" +) + +// dirBasic creates a directory via raw SYS_MKDIR, checks access, then removes it +// via raw SYS_RMDIR. We use raw syscalls because Go's syscall.Mkdir wraps mkdirat +// and syscall.Rmdir wraps unlinkat on amd64. +func dirBasic() error { + dir, cleanup, err := makeTempDir("dir-basic") + if err != nil { + return err + } + defer cleanup() + + subDir := filepath.Join(dir, "subdir") + pathBytes, err := syscall.BytePtrFromString(subDir) + if err != nil { + return fmt.Errorf("path bytes: %w", err) + } + _, _, errno := syscall.Syscall(syscall.SYS_MKDIR, uintptr(unsafe.Pointer(pathBytes)), 0o755, 0) + runtime.KeepAlive(pathBytes) + if errno != 0 { + return fmt.Errorf("mkdir: %w", errno) + } + + if err := syscall.Access(subDir, syscall.F_OK); err != nil { + return fmt.Errorf("access: %w", err) + } + + pathBytes2, err := syscall.BytePtrFromString(subDir) + if err != nil { + return fmt.Errorf("path bytes: %w", err) + } + _, _, errno = syscall.Syscall(syscall.SYS_RMDIR, uintptr(unsafe.Pointer(pathBytes2)), 0, 0) + runtime.KeepAlive(pathBytes2) + if errno != 0 { + return fmt.Errorf("rmdir: %w", errno) + } + return nil +} + +// dirMkdirat creates a directory via mkdirat(2) using Go's syscall.Mkdir +// which wraps mkdirat with AT_FDCWD on amd64. +func dirMkdirat() error { + dir, cleanup, err := makeTempDir("dir-mkdirat") + if err != nil { + return err + } + defer cleanup() + + subDir := filepath.Join(dir, "mkdirat-subdir") + if err := syscall.Mkdir(subDir, 0o755); err != nil { + return fmt.Errorf("mkdirat: %w", err) + } + return nil +} + +// dirChdir creates a temp directory, then changes to it via chdir(2). +// Restores the original working directory afterward. +func dirChdir() error { + origDir, err := os.Getwd() + if err != nil { + return fmt.Errorf("getwd: %w", err) + } + + dir, cleanup, err := makeTempDir("dir-chdir") + if err != nil { + return err + } + defer cleanup() + defer syscall.Chdir(origDir) + + if err := syscall.Chdir(dir); err != nil { + return fmt.Errorf("chdir: %w", err) + } + return nil +} + +// dirGetdents opens a directory and reads its entries via getdents64(2). +func dirGetdents() error { + dir, cleanup, err := makeTempDir("dir-getdents") + if err != nil { + return err + } + defer cleanup() + + // Create a file so getdents has something to return. + filePath := filepath.Join(dir, "getdents-file.txt") + fd, err := syscall.Open(filePath, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open file: %w", err) + } + syscall.Close(fd) + + dirFD, err := syscall.Open(dir, syscall.O_RDONLY|syscall.O_DIRECTORY, 0) + if err != nil { + return fmt.Errorf("open dir: %w", err) + } + defer syscall.Close(dirFD) + + buf := make([]byte, 4096) + _, _, errno := syscall.Syscall(syscall.SYS_GETDENTS64, uintptr(dirFD), uintptr(unsafe.Pointer(&buf[0])), uintptr(len(buf))) + runtime.KeepAlive(buf) + if errno != 0 { + return fmt.Errorf("getdents64: %w", errno) + } + return nil +} + +// dirMkdirEexist attempts to create a directory that already exists via raw +// SYS_MKDIR. The syscall fails with EEXIST, but ior captures the tracepoint +// on entry. +func dirMkdirEexist() error { + dir, cleanup, err := makeTempDir("dir-mkdir-eexist") + if err != nil { + return err + } + defer cleanup() + + subDir := filepath.Join(dir, "mkdir-eexist-subdir") + pathBytes, err := syscall.BytePtrFromString(subDir) + if err != nil { + return fmt.Errorf("path bytes: %w", err) + } + + // Create the directory first so the second attempt fails. + _, _, errno := syscall.Syscall(syscall.SYS_MKDIR, uintptr(unsafe.Pointer(pathBytes)), 0o755, 0) + runtime.KeepAlive(pathBytes) + if errno != 0 { + return fmt.Errorf("first mkdir: %w", errno) + } + + // Second mkdir on the same path should fail with EEXIST. + pathBytes2, err := syscall.BytePtrFromString(subDir) + if err != nil { + return fmt.Errorf("path bytes: %w", err) + } + _, _, errno = syscall.Syscall(syscall.SYS_MKDIR, uintptr(unsafe.Pointer(pathBytes2)), 0o755, 0) + runtime.KeepAlive(pathBytes2) + if errno == 0 { + return fmt.Errorf("expected EEXIST, but mkdir succeeded") + } + return nil +} + +// dirChdirEnoent attempts to change to a nonexistent directory via raw +// SYS_CHDIR. The syscall fails with ENOENT, but ior captures the tracepoint +// on entry. +func dirChdirEnoent() error { + dir, cleanup, err := makeTempDir("dir-chdir-enoent") + if err != nil { + return err + } + defer cleanup() + + badPath := filepath.Join(dir, "chdir-enoent-missing") + pathBytes, err := syscall.BytePtrFromString(badPath) + if err != nil { + return fmt.Errorf("path bytes: %w", err) + } + _, _, errno := syscall.Syscall(syscall.SYS_CHDIR, uintptr(unsafe.Pointer(pathBytes)), 0, 0) + runtime.KeepAlive(pathBytes) + if errno == 0 { + return fmt.Errorf("expected ENOENT, but chdir succeeded") + } + return nil +} + +// dirGetdentsEbadf calls getdents64(2) with an invalid file descriptor. +// The syscall fails with EBADF, but ior captures the tracepoint on entry. +func dirGetdentsEbadf() error { + buf := make([]byte, 4096) + _, _, errno := syscall.Syscall(syscall.SYS_GETDENTS64, uintptr(9999), uintptr(unsafe.Pointer(&buf[0])), uintptr(len(buf))) + runtime.KeepAlive(buf) + if errno == 0 { + return fmt.Errorf("expected EBADF, but getdents64 succeeded") + } + return nil +} diff --git a/integrationtests/cmd/ioworkload/scenario_dup.go b/integrationtests/cmd/ioworkload/scenario_dup.go new file mode 100644 index 0000000..6a89970 --- /dev/null +++ b/integrationtests/cmd/ioworkload/scenario_dup.go @@ -0,0 +1,151 @@ +package main + +import ( + "fmt" + "path/filepath" + "syscall" +) + +// dupBasic opens a file, dups the fd, writes via the dup, closes both. +func dupBasic() error { + dir, cleanup, err := makeTempDir("dup-basic") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "dupfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + newFd, err := syscall.Dup(fd) + if err != nil { + return fmt.Errorf("dup: %w", err) + } + defer syscall.Close(newFd) + + if _, err := syscall.Write(newFd, []byte("via dup")); err != nil { + return fmt.Errorf("write via dup: %w", err) + } + return nil +} + +// dupDup2 opens a file and duplicates the fd onto a specific target fd via dup2. +func dupDup2() error { + dir, cleanup, err := makeTempDir("dup-dup2") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "dup2file.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + // Use a high fd number to avoid collisions. + targetFd := 500 + if err := syscall.Dup2(fd, targetFd); err != nil { + return fmt.Errorf("dup2: %w", err) + } + defer syscall.Close(targetFd) + + if _, err := syscall.Write(targetFd, []byte("via dup2")); err != nil { + return fmt.Errorf("write via dup2: %w", err) + } + return nil +} + +// dupDup3 opens a file and duplicates the fd onto a specific target fd via dup3 +// with O_CLOEXEC flag. +func dupDup3() error { + dir, cleanup, err := makeTempDir("dup-dup3") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "dup3file.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + // Use a high fd number to avoid collisions. + targetFd := 501 + if err := syscall.Dup3(fd, targetFd, syscall.O_CLOEXEC); err != nil { + return fmt.Errorf("dup3: %w", err) + } + defer syscall.Close(targetFd) + + if _, err := syscall.Write(targetFd, []byte("via dup3")); err != nil { + return fmt.Errorf("write via dup3: %w", err) + } + return nil +} + +// dupInvalidFd attempts to dup a very high invalid fd number. +// The syscall fails with EBADF, but ior should capture the enter_dup +// tracepoint because arguments are read on syscall entry. +func dupInvalidFd() error { + _, err := syscall.Dup(99999) + if err == nil { + return fmt.Errorf("expected dup of invalid fd to fail") + } + return nil +} + +// dup2SameFd calls dup2 with the same fd for both oldfd and newfd. +// Per POSIX, dup2(fd, fd) is a no-op that returns fd without closing +// and reopening. ior should capture the enter_dup2 tracepoint. +func dup2SameFd() error { + dir, cleanup, err := makeTempDir("dup2-same-fd") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "dup2samefile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + if err := syscall.Dup2(fd, fd); err != nil { + return fmt.Errorf("dup2 same fd: %w", err) + } + return nil +} + +// dup3InvalidFlags calls dup3 with an invalid flags value. +// dup3 only accepts O_CLOEXEC; any other flag causes EINVAL. +// ior should capture the enter_dup3 tracepoint. +func dup3InvalidFlags() error { + dir, cleanup, err := makeTempDir("dup3-invalid-flags") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "dup3flagsfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + targetFd := 502 + _, _, errno := syscall.Syscall(syscall.SYS_DUP3, uintptr(fd), uintptr(targetFd), 0xBAD) + if errno == 0 { + syscall.Close(targetFd) + return fmt.Errorf("expected dup3 with invalid flags to fail") + } + return nil +} diff --git a/integrationtests/cmd/ioworkload/scenario_fcntl.go b/integrationtests/cmd/ioworkload/scenario_fcntl.go new file mode 100644 index 0000000..0d8e642 --- /dev/null +++ b/integrationtests/cmd/ioworkload/scenario_fcntl.go @@ -0,0 +1,129 @@ +package main + +import ( + "fmt" + "path/filepath" + "syscall" +) + +// fcntlDupfd uses fcntl F_DUPFD to duplicate a file descriptor. +func fcntlDupfd() error { + dir, cleanup, err := makeTempDir("fcntl-dupfd") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "fcntlfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + newFd, _, errno := syscall.Syscall(syscall.SYS_FCNTL, uintptr(fd), syscall.F_DUPFD, 0) + if errno != 0 { + return fmt.Errorf("fcntl F_DUPFD: %w", errno) + } + defer syscall.Close(int(newFd)) + + if _, err := syscall.Write(int(newFd), []byte("via fcntl")); err != nil { + return fmt.Errorf("write via fcntl dup: %w", err) + } + return nil +} + +// fcntlSetfl uses fcntl F_GETFL/F_SETFL to read and modify file status flags. +func fcntlSetfl() error { + dir, cleanup, err := makeTempDir("fcntl-setfl") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "fcntlsetflfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + flags, _, errno := syscall.Syscall(syscall.SYS_FCNTL, uintptr(fd), syscall.F_GETFL, 0) + if errno != 0 { + return fmt.Errorf("fcntl F_GETFL: %w", errno) + } + + _, _, errno = syscall.Syscall(syscall.SYS_FCNTL, uintptr(fd), syscall.F_SETFL, flags|syscall.O_APPEND) + if errno != 0 { + return fmt.Errorf("fcntl F_SETFL: %w", errno) + } + + if _, err := syscall.Write(fd, []byte("appended via fcntl setfl")); err != nil { + return fmt.Errorf("write: %w", err) + } + return nil +} + +// fcntlDupfdCloexec uses fcntl F_DUPFD_CLOEXEC to duplicate a file descriptor +// with the close-on-exec flag set. +func fcntlDupfdCloexec() error { + dir, cleanup, err := makeTempDir("fcntl-dupfd-cloexec") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "fcntlcloexecfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + newFd, _, errno := syscall.Syscall(syscall.SYS_FCNTL, uintptr(fd), syscall.F_DUPFD_CLOEXEC, 0) + if errno != 0 { + return fmt.Errorf("fcntl F_DUPFD_CLOEXEC: %w", errno) + } + defer syscall.Close(int(newFd)) + + if _, err := syscall.Write(int(newFd), []byte("via fcntl dupfd cloexec")); err != nil { + return fmt.Errorf("write via fcntl dup cloexec: %w", err) + } + return nil +} + +// fcntlInvalidFd calls fcntl F_GETFL on an invalid fd (99999). +// The syscall fails with EBADF, but ior should capture the enter_fcntl +// tracepoint because it is recorded on syscall entry. +func fcntlInvalidFd() error { + _, _, errno := syscall.Syscall(syscall.SYS_FCNTL, 99999, syscall.F_GETFL, 0) + if errno == 0 { + return fmt.Errorf("expected fcntl on invalid fd to fail") + } + return nil +} + +// fcntlDupfdMax opens a file and calls fcntl F_DUPFD with a minfd value +// that exceeds the process RLIMIT_NOFILE. The kernel rejects this with +// EINVAL, but ior should capture the enter_fcntl tracepoint. +func fcntlDupfdMax() error { + dir, cleanup, err := makeTempDir("fcntl-dupfd-max") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "fcntldupfdmaxfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + // Use a minfd far beyond any realistic RLIMIT_NOFILE. + _, _, errno := syscall.Syscall(syscall.SYS_FCNTL, uintptr(fd), syscall.F_DUPFD, 1<<30) + if errno == 0 { + return fmt.Errorf("expected fcntl F_DUPFD with extreme minfd to fail") + } + return nil +} diff --git a/integrationtests/cmd/ioworkload/scenario_iouring.go b/integrationtests/cmd/ioworkload/scenario_iouring.go new file mode 100644 index 0000000..b1aac4e --- /dev/null +++ b/integrationtests/cmd/ioworkload/scenario_iouring.go @@ -0,0 +1,129 @@ +package main + +import ( + "fmt" + "runtime" + "syscall" + "unsafe" +) + +const ( + sysIoUringSetup = 425 + sysIoUringEnter = 426 + sysIoUringRegister = 427 + + // io_uring_params struct size: 10 x uint32 + io_sqring_offsets(40) + io_cqring_offsets(40) = 120 bytes. + ioUringParamsSize = 120 + + ioringRegisterProbe = 8 // IORING_REGISTER_PROBE +) + +// iouringSetup creates an io_uring instance via io_uring_setup(2) and closes the fd. +func iouringSetup() error { + fd, err := ioUringSetupRing(1) + if err != nil { + return err + } + return syscall.Close(fd) +} + +// iouringEnter creates an io_uring instance, then calls io_uring_enter(2) +// with zero submissions/completions to exercise the enter tracepoint. +func iouringEnter() error { + fd, err := ioUringSetupRing(1) + if err != nil { + return err + } + defer syscall.Close(fd) + + _, _, errno := syscall.Syscall6( + sysIoUringEnter, + uintptr(fd), + 0, // to_submit + 0, // min_complete + 0, // flags + 0, // sig + 0, // sz + ) + if errno != 0 { + return fmt.Errorf("io_uring_enter: %w", errno) + } + return nil +} + +// iouringRegister creates an io_uring instance, then calls io_uring_register(2) +// with IORING_REGISTER_PROBE to exercise the register tracepoint. +func iouringRegister() error { + fd, err := ioUringSetupRing(1) + if err != nil { + return err + } + defer syscall.Close(fd) + + // io_uring_probe header is 16 bytes; we don't need probe_op entries. + var probeBuf [16]byte + _, _, errno := syscall.Syscall6( + sysIoUringRegister, + uintptr(fd), + ioringRegisterProbe, + uintptr(unsafe.Pointer(&probeBuf[0])), + 0, // nr_args (0 ops requested) + 0, 0, + ) + runtime.KeepAlive(probeBuf) + if errno != 0 { + return fmt.Errorf("io_uring_register: %w", errno) + } + return nil +} + +// iouringEnterEbadf calls io_uring_enter on an invalid fd. +// The syscall fails with EBADF, but ior captures the enter_io_uring_enter tracepoint. +func iouringEnterEbadf() error { + _, _, errno := syscall.Syscall6( + sysIoUringEnter, + 99999, // invalid fd + 0, // to_submit + 0, // min_complete + 0, // flags + 0, // sig + 0, // sz + ) + if errno == 0 { + return fmt.Errorf("expected EBADF, but io_uring_enter succeeded") + } + return nil +} + +// iouringRegisterEbadf calls io_uring_register on an invalid fd. +// The syscall fails with EBADF, but ior captures the enter_io_uring_register tracepoint. +func iouringRegisterEbadf() error { + _, _, errno := syscall.Syscall6( + sysIoUringRegister, + 99999, // invalid fd + ioringRegisterProbe, + 0, // arg (NULL) + 0, // nr_args + 0, 0, + ) + if errno == 0 { + return fmt.Errorf("expected EBADF, but io_uring_register succeeded") + } + return nil +} + +// ioUringSetupRing calls io_uring_setup(2) and returns the ring fd. +func ioUringSetupRing(entries uint32) (int, error) { + var params [ioUringParamsSize]byte + fd, _, errno := syscall.Syscall( + sysIoUringSetup, + uintptr(entries), + uintptr(unsafe.Pointer(¶ms[0])), + 0, + ) + runtime.KeepAlive(params) + if errno != 0 { + return 0, fmt.Errorf("io_uring_setup: %w", errno) + } + return int(fd), nil +} diff --git a/integrationtests/cmd/ioworkload/scenario_link.go b/integrationtests/cmd/ioworkload/scenario_link.go new file mode 100644 index 0000000..bb16984 --- /dev/null +++ b/integrationtests/cmd/ioworkload/scenario_link.go @@ -0,0 +1,385 @@ +package main + +import ( + "fmt" + "path/filepath" + "runtime" + "syscall" + "unsafe" +) + +// linkBasic creates a file, hard links it via link(2), symlinks it via +// symlink(2), and reads the symlink via readlink(2). +// Uses raw SYS_LINK, SYS_SYMLINK, SYS_READLINK because Go's syscall wrappers +// delegate to linkat/symlinkat/readlinkat on amd64. +func linkBasic() error { + dir, cleanup, err := makeTempDir("link-basic") + if err != nil { + return err + } + defer cleanup() + + origPath := filepath.Join(dir, "original.txt") + fd, err := syscall.Open(origPath, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + if err := syscall.Close(fd); err != nil { + return fmt.Errorf("close: %w", err) + } + + if err := rawLink(origPath, filepath.Join(dir, "hardlink.txt")); err != nil { + return err + } + + symPath := filepath.Join(dir, "symlink.txt") + if err := rawSymlink(origPath, symPath); err != nil { + return err + } + + return rawReadlink(symPath) +} + +// linkLinkat creates a file and hard links it via linkat(2). +func linkLinkat() error { + dir, cleanup, err := makeTempDir("link-linkat") + if err != nil { + return err + } + defer cleanup() + + origName := "linkat-original.txt" + origPath := filepath.Join(dir, origName) + fd, err := syscall.Open(origPath, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + if err := syscall.Close(fd); err != nil { + return fmt.Errorf("close: %w", err) + } + + dirFD, err := syscall.Open(dir, syscall.O_RDONLY|syscall.O_DIRECTORY, 0) + if err != nil { + return fmt.Errorf("open dir: %w", err) + } + defer syscall.Close(dirFD) + + hardName := "linkat-hard.txt" + oldBytes, err := syscall.BytePtrFromString(origName) + if err != nil { + return fmt.Errorf("old name bytes: %w", err) + } + newBytes, err := syscall.BytePtrFromString(hardName) + if err != nil { + return fmt.Errorf("new name bytes: %w", err) + } + + _, _, errno := syscall.Syscall6( + syscall.SYS_LINKAT, + uintptr(dirFD), + uintptr(unsafe.Pointer(oldBytes)), + uintptr(dirFD), + uintptr(unsafe.Pointer(newBytes)), + 0, // flags + 0, + ) + runtime.KeepAlive(oldBytes) + runtime.KeepAlive(newBytes) + if errno != 0 { + return fmt.Errorf("linkat: %w", errno) + } + return nil +} + +// linkSymlinkat creates a symlink via symlinkat(2). +func linkSymlinkat() error { + dir, cleanup, err := makeTempDir("link-symlinkat") + if err != nil { + return err + } + defer cleanup() + + origPath := filepath.Join(dir, "symlinkat-original.txt") + fd, err := syscall.Open(origPath, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + if err := syscall.Close(fd); err != nil { + return fmt.Errorf("close: %w", err) + } + + dirFD, err := syscall.Open(dir, syscall.O_RDONLY|syscall.O_DIRECTORY, 0) + if err != nil { + return fmt.Errorf("open dir: %w", err) + } + defer syscall.Close(dirFD) + + targetBytes, err := syscall.BytePtrFromString(origPath) + if err != nil { + return fmt.Errorf("target bytes: %w", err) + } + linkName := "symlinkat-link.txt" + linkBytes, err := syscall.BytePtrFromString(linkName) + if err != nil { + return fmt.Errorf("link name bytes: %w", err) + } + + _, _, errno := syscall.Syscall( + syscall.SYS_SYMLINKAT, + uintptr(unsafe.Pointer(targetBytes)), + uintptr(dirFD), + uintptr(unsafe.Pointer(linkBytes)), + ) + runtime.KeepAlive(targetBytes) + runtime.KeepAlive(linkBytes) + if errno != 0 { + return fmt.Errorf("symlinkat: %w", errno) + } + return nil +} + +// linkReadlinkat creates a symlink, then reads it via readlinkat(2). +func linkReadlinkat() error { + dir, cleanup, err := makeTempDir("link-readlinkat") + if err != nil { + return err + } + defer cleanup() + + origPath := filepath.Join(dir, "readlinkat-original.txt") + fd, err := syscall.Open(origPath, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + if err := syscall.Close(fd); err != nil { + return fmt.Errorf("close: %w", err) + } + + // Create symlink using raw SYS_SYMLINK so we don't mix tracepoints. + linkPath := filepath.Join(dir, "readlinkat-link.txt") + if err := rawSymlink(origPath, linkPath); err != nil { + return err + } + + // Read via readlinkat(2). + dirFD, err := syscall.Open(dir, syscall.O_RDONLY|syscall.O_DIRECTORY, 0) + if err != nil { + return fmt.Errorf("open dir: %w", err) + } + defer syscall.Close(dirFD) + + linkName := "readlinkat-link.txt" + nameBytes, err := syscall.BytePtrFromString(linkName) + if err != nil { + return fmt.Errorf("link name bytes: %w", err) + } + buf := make([]byte, 256) + _, _, errno := syscall.Syscall6( + syscall.SYS_READLINKAT, + uintptr(dirFD), + uintptr(unsafe.Pointer(nameBytes)), + uintptr(unsafe.Pointer(&buf[0])), + uintptr(len(buf)), + 0, 0, + ) + runtime.KeepAlive(nameBytes) + runtime.KeepAlive(buf) + if errno != 0 { + return fmt.Errorf("readlinkat: %w", errno) + } + return nil +} + +// linkEnoent attempts to hard link a nonexistent source via raw SYS_LINK. +// The syscall fails with ENOENT, but ior captures the enter_link tracepoint +// because arguments are read on syscall entry. +func linkEnoent() error { + dir, cleanup, err := makeTempDir("link-enoent") + if err != nil { + return err + } + defer cleanup() + + srcPath := filepath.Join(dir, "link-enoent-missing.txt") + dstPath := filepath.Join(dir, "link-enoent-dst.txt") + + srcBytes, err := syscall.BytePtrFromString(srcPath) + if err != nil { + return fmt.Errorf("src path bytes: %w", err) + } + dstBytes, err := syscall.BytePtrFromString(dstPath) + if err != nil { + return fmt.Errorf("dst path bytes: %w", err) + } + + _, _, errno := syscall.Syscall( + syscall.SYS_LINK, + uintptr(unsafe.Pointer(srcBytes)), + uintptr(unsafe.Pointer(dstBytes)), + 0, + ) + runtime.KeepAlive(srcBytes) + runtime.KeepAlive(dstBytes) + if errno == 0 { + return fmt.Errorf("expected ENOENT, but link succeeded") + } + return nil +} + +// linkSymlinkEexist creates a regular file, then attempts to create a symlink +// at the same path via raw SYS_SYMLINK. The syscall fails with EEXIST because +// the link path already exists, but ior captures the enter_symlink tracepoint. +func linkSymlinkEexist() error { + dir, cleanup, err := makeTempDir("link-symlink-eexist") + if err != nil { + return err + } + defer cleanup() + + existingPath := filepath.Join(dir, "symlink-eexist.txt") + fd, err := syscall.Open(existingPath, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + if err := syscall.Close(fd); err != nil { + return fmt.Errorf("close: %w", err) + } + + targetBytes, err := syscall.BytePtrFromString("/tmp/dummy-target") + if err != nil { + return fmt.Errorf("target bytes: %w", err) + } + linkBytes, err := syscall.BytePtrFromString(existingPath) + if err != nil { + return fmt.Errorf("link path bytes: %w", err) + } + + _, _, errno := syscall.Syscall( + syscall.SYS_SYMLINK, + uintptr(unsafe.Pointer(targetBytes)), + uintptr(unsafe.Pointer(linkBytes)), + 0, + ) + runtime.KeepAlive(targetBytes) + runtime.KeepAlive(linkBytes) + if errno == 0 { + return fmt.Errorf("expected EEXIST, but symlink succeeded") + } + return nil +} + +// linkReadlinkatEinval creates a regular file and calls readlinkat(2) on it. +// The syscall fails with EINVAL because the path is not a symlink, but ior +// captures the enter_readlinkat tracepoint on syscall entry. +func linkReadlinkatEinval() error { + dir, cleanup, err := makeTempDir("link-readlinkat-einval") + if err != nil { + return err + } + defer cleanup() + + regularFile := "readlinkat-einval.txt" + regularPath := filepath.Join(dir, regularFile) + fd, err := syscall.Open(regularPath, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + if err := syscall.Close(fd); err != nil { + return fmt.Errorf("close: %w", err) + } + + dirFD, err := syscall.Open(dir, syscall.O_RDONLY|syscall.O_DIRECTORY, 0) + if err != nil { + return fmt.Errorf("open dir: %w", err) + } + defer syscall.Close(dirFD) + + nameBytes, err := syscall.BytePtrFromString(regularFile) + if err != nil { + return fmt.Errorf("name bytes: %w", err) + } + buf := make([]byte, 256) + _, _, errno := syscall.Syscall6( + syscall.SYS_READLINKAT, + uintptr(dirFD), + uintptr(unsafe.Pointer(nameBytes)), + uintptr(unsafe.Pointer(&buf[0])), + uintptr(len(buf)), + 0, 0, + ) + runtime.KeepAlive(nameBytes) + runtime.KeepAlive(buf) + if errno == 0 { + return fmt.Errorf("expected EINVAL, but readlinkat succeeded") + } + return nil +} + +// rawLink calls link(2) via raw SYS_LINK. +func rawLink(oldPath, newPath string) error { + oldBytes, err := syscall.BytePtrFromString(oldPath) + if err != nil { + return fmt.Errorf("old path bytes: %w", err) + } + newBytes, err := syscall.BytePtrFromString(newPath) + if err != nil { + return fmt.Errorf("new path bytes: %w", err) + } + _, _, errno := syscall.Syscall( + syscall.SYS_LINK, + uintptr(unsafe.Pointer(oldBytes)), + uintptr(unsafe.Pointer(newBytes)), + 0, + ) + runtime.KeepAlive(oldBytes) + runtime.KeepAlive(newBytes) + if errno != 0 { + return fmt.Errorf("link: %w", errno) + } + return nil +} + +// rawSymlink calls symlink(2) via raw SYS_SYMLINK. +func rawSymlink(target, linkPath string) error { + targetBytes, err := syscall.BytePtrFromString(target) + if err != nil { + return fmt.Errorf("target path bytes: %w", err) + } + linkBytes, err := syscall.BytePtrFromString(linkPath) + if err != nil { + return fmt.Errorf("link path bytes: %w", err) + } + _, _, errno := syscall.Syscall( + syscall.SYS_SYMLINK, + uintptr(unsafe.Pointer(targetBytes)), + uintptr(unsafe.Pointer(linkBytes)), + 0, + ) + runtime.KeepAlive(targetBytes) + runtime.KeepAlive(linkBytes) + if errno != 0 { + return fmt.Errorf("symlink: %w", errno) + } + return nil +} + +// rawReadlink calls readlink(2) via raw SYS_READLINK. +func rawReadlink(path string) error { + pathBytes, err := syscall.BytePtrFromString(path) + if err != nil { + return fmt.Errorf("path bytes: %w", err) + } + buf := make([]byte, 256) + _, _, errno := syscall.Syscall( + syscall.SYS_READLINK, + uintptr(unsafe.Pointer(pathBytes)), + uintptr(unsafe.Pointer(&buf[0])), + uintptr(len(buf)), + ) + runtime.KeepAlive(pathBytes) + runtime.KeepAlive(buf) + if errno != 0 { + return fmt.Errorf("readlink: %w", errno) + } + return nil +} diff --git a/integrationtests/cmd/ioworkload/scenario_open.go b/integrationtests/cmd/ioworkload/scenario_open.go new file mode 100644 index 0000000..449549c --- /dev/null +++ b/integrationtests/cmd/ioworkload/scenario_open.go @@ -0,0 +1,228 @@ +package main + +import ( + "fmt" + "os/exec" + "path/filepath" + "runtime" + "syscall" + "unsafe" +) + +// openBasic opens a file with O_RDWR|O_CREAT, then closes it. +func openBasic() error { + dir, cleanup, err := makeTempDir("open-basic") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "testfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + return syscall.Close(fd) +} + +// openCreat creates a file via raw SYS_CREAT. +// Go's syscall.Creat wraps Open which delegates to openat on amd64, +// so we use the raw syscall to actually exercise the creat tracepoint. +func openCreat() error { + dir, cleanup, err := makeTempDir("open-creat") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "creatfile.txt") + pathBytes, err := syscall.BytePtrFromString(path) + if err != nil { + return fmt.Errorf("path bytes: %w", err) + } + fd, _, errno := syscall.Syscall(syscall.SYS_CREAT, uintptr(unsafe.Pointer(pathBytes)), 0o644, 0) + runtime.KeepAlive(pathBytes) + if errno != 0 { + return fmt.Errorf("creat: %w", errno) + } + return syscall.Close(int(fd)) +} + +// openEnoent attempts to open a nonexistent file path. The openat syscall +// returns ENOENT, but ior should still capture the enter_openat tracepoint +// because the filename is read on entry before the syscall executes. +func openEnoent() error { + dir, cleanup, err := makeTempDir("open-enoent") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "nonexistent", "enoentfile.txt") + _, err = syscall.Open(path, syscall.O_RDONLY, 0) + if err == nil { + return fmt.Errorf("expected ENOENT, but open succeeded") + } + return nil +} + +// openRdonlyWrite opens a file O_RDONLY, then attempts to write to it. +// The write fails with EBADF, but ior should capture both the openat +// tracepoint and the write tracepoint. +func openRdonlyWrite() error { + dir, cleanup, err := makeTempDir("open-rdonly-write") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "rdonlyfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("create file: %w", err) + } + syscall.Close(fd) + + fd, err = syscall.Open(path, syscall.O_RDONLY, 0) + if err != nil { + return fmt.Errorf("open rdonly: %w", err) + } + defer syscall.Close(fd) + + _, err = syscall.Write(fd, []byte("should fail")) + if err == nil { + return fmt.Errorf("expected write to rdonly fd to fail") + } + return nil +} + +// openPidFilter spawns a child process that performs file I/O. Since ior +// filters by the workload PID, the child's I/O should NOT appear in results. +// The parent also performs its own open so the test can verify positive and +// negative expectations simultaneously. +func openPidFilter() error { + dir, cleanup, err := makeTempDir("open-pid-filter") + if err != nil { + return err + } + defer cleanup() + + // Parent opens a file (should be captured by ior). + parentPath := filepath.Join(dir, "parentfile.txt") + fd, err := syscall.Open(parentPath, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("parent open: %w", err) + } + syscall.Close(fd) + + // Spawn a child process that creates a file with a distinctive name. + childPath := filepath.Join(dir, "childfile.txt") + cmd := exec.Command("touch", childPath) + if err := cmd.Run(); err != nil { + return fmt.Errorf("child touch: %w", err) + } + return nil +} + +// openByHandleAt creates a file, resolves its handle via name_to_handle_at, +// then opens it via open_by_handle_at. Requires root (CAP_DAC_READ_SEARCH). +// LockOSThread prevents goroutine migration between the two syscalls so that +// ior sees the same TID for both and can correlate the path. +func openByHandleAt() error { + runtime.LockOSThread() + defer runtime.UnlockOSThread() + + dir, cleanup, err := makeTempDir("open-by-handle-at") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "handlefile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + if err := syscall.Close(fd); err != nil { + return fmt.Errorf("close: %w", err) + } + + handle, mountFD, err := nameToHandleAt(dir, "handlefile.txt") + if err != nil { + return fmt.Errorf("name_to_handle_at: %w", err) + } + defer syscall.Close(mountFD) + + fd2, err := openByHandleAtSyscall(mountFD, handle, syscall.O_RDONLY) + if err != nil { + return fmt.Errorf("open_by_handle_at: %w", err) + } + return syscall.Close(fd2) +} + +// fileHandle matches the kernel's struct file_handle layout. +type fileHandle struct { + Size uint32 + Type int32 + // Handle bytes follow immediately after. +} + +const ( + sysNameToHandleAt = 303 + sysOpenByHandleAt = 304 +) + +// nameToHandleAt calls name_to_handle_at(2) and returns the file handle +// and the directory fd. The caller can pass this dirFD as the mount_fd +// argument to open_by_handle_at since any fd on the same filesystem works. +func nameToHandleAt(dirPath, name string) ([]byte, int, error) { + dirFD, err := syscall.Open(dirPath, syscall.O_RDONLY|syscall.O_DIRECTORY, 0) + if err != nil { + return nil, 0, fmt.Errorf("open dir: %w", err) + } + + nameBytes, err := syscall.BytePtrFromString(name) + if err != nil { + syscall.Close(dirFD) + return nil, 0, fmt.Errorf("name bytes: %w", err) + } + + // Start with a buffer large enough for most handles. + buf := make([]byte, unsafe.Sizeof(fileHandle{})+128) + fh := (*fileHandle)(unsafe.Pointer(&buf[0])) + fh.Size = uint32(len(buf) - int(unsafe.Sizeof(fileHandle{}))) + + var mountID int32 + _, _, errno := syscall.Syscall6( + sysNameToHandleAt, + uintptr(dirFD), + uintptr(unsafe.Pointer(nameBytes)), + uintptr(unsafe.Pointer(fh)), + uintptr(unsafe.Pointer(&mountID)), + 0, 0, + ) + if errno != 0 { + syscall.Close(dirFD) + return nil, 0, fmt.Errorf("syscall: %w", errno) + } + + handleLen := int(unsafe.Sizeof(fileHandle{})) + int(fh.Size) + handle := make([]byte, handleLen) + copy(handle, buf[:handleLen]) + + return handle, dirFD, nil +} + +// openByHandleAtSyscall calls open_by_handle_at(2). +func openByHandleAtSyscall(mountFD int, handle []byte, flags int) (int, error) { + fd, _, errno := syscall.Syscall( + sysOpenByHandleAt, + uintptr(mountFD), + uintptr(unsafe.Pointer(&handle[0])), + uintptr(flags), + ) + if errno != 0 { + return 0, fmt.Errorf("syscall: %w", errno) + } + return int(fd), nil +} diff --git a/integrationtests/cmd/ioworkload/scenario_readwrite.go b/integrationtests/cmd/ioworkload/scenario_readwrite.go new file mode 100644 index 0000000..c676b90 --- /dev/null +++ b/integrationtests/cmd/ioworkload/scenario_readwrite.go @@ -0,0 +1,263 @@ +package main + +import ( + "fmt" + "path/filepath" + "runtime" + "syscall" + "unsafe" +) + +// readwriteBasic opens a file, writes data, seeks to start, reads it back. +func readwriteBasic() error { + dir, cleanup, err := makeTempDir("readwrite-basic") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "rwfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + data := []byte("hello from ioworkload") + if _, err := syscall.Write(fd, data); err != nil { + return fmt.Errorf("write: %w", err) + } + if _, err := syscall.Seek(fd, 0, 0); err != nil { + return fmt.Errorf("seek: %w", err) + } + + buf := make([]byte, len(data)) + if _, err := syscall.Read(fd, buf); err != nil { + return fmt.Errorf("read: %w", err) + } + return nil +} + +// readwritePread opens a file, writes data, then reads it back via pread64. +func readwritePread() error { + dir, cleanup, err := makeTempDir("readwrite-pread") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "preadfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + data := []byte("pread test data") + if _, err := syscall.Write(fd, data); err != nil { + return fmt.Errorf("write: %w", err) + } + + buf := make([]byte, len(data)) + if _, err := syscall.Pread(fd, buf, 0); err != nil { + return fmt.Errorf("pread: %w", err) + } + return nil +} + +// readwritePwrite opens a file and writes data via pwrite64. +func readwritePwrite() error { + dir, cleanup, err := makeTempDir("readwrite-pwrite") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "pwritefile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + if _, err := syscall.Pwrite(fd, []byte("pwrite test data"), 0); err != nil { + return fmt.Errorf("pwrite: %w", err) + } + return nil +} + +// readwriteReadv opens a file, writes data, then reads it back via readv. +func readwriteReadv() error { + dir, cleanup, err := makeTempDir("readwrite-readv") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "readvfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + data := []byte("readv test data here") + if _, err := syscall.Write(fd, data); err != nil { + return fmt.Errorf("write: %w", err) + } + if _, err := syscall.Seek(fd, 0, 0); err != nil { + return fmt.Errorf("seek: %w", err) + } + + buf1 := make([]byte, 5) + buf2 := make([]byte, 15) + iovs := []syscall.Iovec{ + {Base: &buf1[0], Len: uint64(len(buf1))}, + {Base: &buf2[0], Len: uint64(len(buf2))}, + } + _, _, errno := syscall.Syscall(syscall.SYS_READV, uintptr(fd), uintptr(unsafe.Pointer(&iovs[0])), uintptr(len(iovs))) + runtime.KeepAlive(buf1) + runtime.KeepAlive(buf2) + if errno != 0 { + return fmt.Errorf("readv: %w", errno) + } + return nil +} + +// readwriteWritev opens a file and writes data via writev. +func readwriteWritev() error { + dir, cleanup, err := makeTempDir("readwrite-writev") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "writevfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + buf1 := []byte("writev ") + buf2 := []byte("test data") + iovs := []syscall.Iovec{ + {Base: &buf1[0], Len: uint64(len(buf1))}, + {Base: &buf2[0], Len: uint64(len(buf2))}, + } + _, _, errno := syscall.Syscall(syscall.SYS_WRITEV, uintptr(fd), uintptr(unsafe.Pointer(&iovs[0])), uintptr(len(iovs))) + runtime.KeepAlive(buf1) + runtime.KeepAlive(buf2) + if errno != 0 { + return fmt.Errorf("writev: %w", errno) + } + return nil +} + +// readwriteWronlyRead opens a file O_WRONLY, then attempts to read from it. +// The read fails with EBADF, but ior should capture the enter_read tracepoint +// because arguments are read on syscall entry before the kernel returns an error. +func readwriteWronlyRead() error { + dir, cleanup, err := makeTempDir("readwrite-wronly-read") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "wronlyfile.txt") + fd, err := syscall.Open(path, syscall.O_WRONLY|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + buf := make([]byte, 16) + _, err = syscall.Read(fd, buf) + if err == nil { + return fmt.Errorf("expected read from wronly fd to fail") + } + return nil +} + +// readwriteRdonlyWrite opens a file O_RDONLY, then attempts to write to it. +// The write fails with EBADF, but ior should capture the enter_write tracepoint +// because arguments are read on syscall entry before the kernel returns an error. +func readwriteRdonlyWrite() error { + dir, cleanup, err := makeTempDir("readwrite-rdonly-write") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "rdonlywritefile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("create file: %w", err) + } + syscall.Close(fd) + + fd, err = syscall.Open(path, syscall.O_RDONLY, 0) + if err != nil { + return fmt.Errorf("open rdonly: %w", err) + } + defer syscall.Close(fd) + + _, err = syscall.Write(fd, []byte("should fail")) + if err == nil { + return fmt.Errorf("expected write to rdonly fd to fail") + } + return nil +} + +// readwritePreadInvalid calls pread64 with a negative offset (-1). +// The syscall fails with EINVAL, but ior should capture the enter_pread64 +// tracepoint because arguments are read on syscall entry. +func readwritePreadInvalid() error { + dir, cleanup, err := makeTempDir("readwrite-pread-invalid") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "preadinvalid.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + if _, err := syscall.Write(fd, []byte("some data")); err != nil { + return fmt.Errorf("write: %w", err) + } + + buf := make([]byte, 16) + _, err = syscall.Pread(fd, buf, -1) + if err == nil { + return fmt.Errorf("expected pread with negative offset to fail") + } + return nil +} + +// readwritePwriteInvalid calls pwrite64 with a negative offset (-1). +// The syscall fails with EINVAL, but ior should capture the enter_pwrite64 +// tracepoint because arguments are read on syscall entry. +func readwritePwriteInvalid() error { + dir, cleanup, err := makeTempDir("readwrite-pwrite-invalid") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "pwriteinvalid.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + _, err = syscall.Pwrite(fd, []byte("should fail"), -1) + if err == nil { + return fmt.Errorf("expected pwrite with negative offset to fail") + } + return nil +} diff --git a/integrationtests/cmd/ioworkload/scenario_rename.go b/integrationtests/cmd/ioworkload/scenario_rename.go new file mode 100644 index 0000000..95b93e1 --- /dev/null +++ b/integrationtests/cmd/ioworkload/scenario_rename.go @@ -0,0 +1,251 @@ +package main + +import ( + "fmt" + "path/filepath" + "runtime" + "syscall" + "unsafe" +) + +const ( + sysRenameat2 = 316 // SYS_RENAMEAT2 on amd64 + renameNoreplaceFlag = 1 // RENAME_NOREPLACE +) + +// renameBasic creates a file and renames it via rename(2). +// Uses raw SYS_RENAME because Go's syscall.Rename wraps renameat on amd64. +func renameBasic() error { + dir, cleanup, err := makeTempDir("rename-basic") + if err != nil { + return err + } + defer cleanup() + + oldPath := filepath.Join(dir, "oldname.txt") + newPath := filepath.Join(dir, "newname.txt") + + fd, err := syscall.Open(oldPath, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + if err := syscall.Close(fd); err != nil { + return fmt.Errorf("close: %w", err) + } + + oldBytes, err := syscall.BytePtrFromString(oldPath) + if err != nil { + return fmt.Errorf("old path bytes: %w", err) + } + newBytes, err := syscall.BytePtrFromString(newPath) + if err != nil { + return fmt.Errorf("new path bytes: %w", err) + } + + _, _, errno := syscall.Syscall( + syscall.SYS_RENAME, + uintptr(unsafe.Pointer(oldBytes)), + uintptr(unsafe.Pointer(newBytes)), + 0, + ) + runtime.KeepAlive(oldBytes) + runtime.KeepAlive(newBytes) + if errno != 0 { + return fmt.Errorf("rename: %w", errno) + } + return nil +} + +// renameRenameat creates a file and renames it via renameat(2). +func renameRenameat() error { + dir, cleanup, err := makeTempDir("rename-renameat") + if err != nil { + return err + } + defer cleanup() + + oldName := "renameat-old.txt" + newName := "renameat-new.txt" + path := filepath.Join(dir, oldName) + + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + if err := syscall.Close(fd); err != nil { + return fmt.Errorf("close: %w", err) + } + + dirFD, err := syscall.Open(dir, syscall.O_RDONLY|syscall.O_DIRECTORY, 0) + if err != nil { + return fmt.Errorf("open dir: %w", err) + } + defer syscall.Close(dirFD) + + oldBytes, err := syscall.BytePtrFromString(oldName) + if err != nil { + return fmt.Errorf("old name bytes: %w", err) + } + newBytes, err := syscall.BytePtrFromString(newName) + if err != nil { + return fmt.Errorf("new name bytes: %w", err) + } + + _, _, errno := syscall.Syscall6( + syscall.SYS_RENAMEAT, + uintptr(dirFD), + uintptr(unsafe.Pointer(oldBytes)), + uintptr(dirFD), + uintptr(unsafe.Pointer(newBytes)), + 0, 0, + ) + runtime.KeepAlive(oldBytes) + runtime.KeepAlive(newBytes) + if errno != 0 { + return fmt.Errorf("renameat: %w", errno) + } + return nil +} + +// renameRenameat2 creates a file and renames it via renameat2(2) with no flags. +func renameRenameat2() error { + dir, cleanup, err := makeTempDir("rename-renameat2") + if err != nil { + return err + } + defer cleanup() + + oldName := "renameat2-old.txt" + newName := "renameat2-new.txt" + path := filepath.Join(dir, oldName) + + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + if err := syscall.Close(fd); err != nil { + return fmt.Errorf("close: %w", err) + } + + dirFD, err := syscall.Open(dir, syscall.O_RDONLY|syscall.O_DIRECTORY, 0) + if err != nil { + return fmt.Errorf("open dir: %w", err) + } + defer syscall.Close(dirFD) + + oldBytes, err := syscall.BytePtrFromString(oldName) + if err != nil { + return fmt.Errorf("old name bytes: %w", err) + } + newBytes, err := syscall.BytePtrFromString(newName) + if err != nil { + return fmt.Errorf("new name bytes: %w", err) + } + + _, _, errno := syscall.Syscall6( + sysRenameat2, + uintptr(dirFD), + uintptr(unsafe.Pointer(oldBytes)), + uintptr(dirFD), + uintptr(unsafe.Pointer(newBytes)), + 0, // flags=0: plain rename + 0, + ) + runtime.KeepAlive(oldBytes) + runtime.KeepAlive(newBytes) + if errno != 0 { + return fmt.Errorf("renameat2: %w", errno) + } + return nil +} + +// renameEnoent attempts to rename a nonexistent file via raw SYS_RENAME. +// The syscall fails with ENOENT, but ior captures the tracepoint on entry. +func renameEnoent() error { + dir, cleanup, err := makeTempDir("rename-enoent") + if err != nil { + return err + } + defer cleanup() + + oldPath := filepath.Join(dir, "rename-enoent-missing.txt") + newPath := filepath.Join(dir, "rename-enoent-new.txt") + + oldBytes, err := syscall.BytePtrFromString(oldPath) + if err != nil { + return fmt.Errorf("old path bytes: %w", err) + } + newBytes, err := syscall.BytePtrFromString(newPath) + if err != nil { + return fmt.Errorf("new path bytes: %w", err) + } + + _, _, errno := syscall.Syscall( + syscall.SYS_RENAME, + uintptr(unsafe.Pointer(oldBytes)), + uintptr(unsafe.Pointer(newBytes)), + 0, + ) + runtime.KeepAlive(oldBytes) + runtime.KeepAlive(newBytes) + if errno == 0 { + return fmt.Errorf("expected ENOENT, but rename succeeded") + } + return nil +} + +// renameNoreplace creates two files, then attempts renameat2 with +// RENAME_NOREPLACE. Because the target already exists, the syscall fails +// with EEXIST, but ior captures the tracepoint on entry. +func renameNoreplace() error { + dir, cleanup, err := makeTempDir("rename-noreplace") + if err != nil { + return err + } + defer cleanup() + + srcName := "noreplace-src.txt" + dstName := "noreplace-dst.txt" + + for _, name := range []string{srcName, dstName} { + path := filepath.Join(dir, name) + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("create %s: %w", name, err) + } + if err := syscall.Close(fd); err != nil { + return fmt.Errorf("close %s: %w", name, err) + } + } + + dirFD, err := syscall.Open(dir, syscall.O_RDONLY|syscall.O_DIRECTORY, 0) + if err != nil { + return fmt.Errorf("open dir: %w", err) + } + defer syscall.Close(dirFD) + + srcBytes, err := syscall.BytePtrFromString(srcName) + if err != nil { + return fmt.Errorf("src name bytes: %w", err) + } + dstBytes, err := syscall.BytePtrFromString(dstName) + if err != nil { + return fmt.Errorf("dst name bytes: %w", err) + } + + _, _, errno := syscall.Syscall6( + sysRenameat2, + uintptr(dirFD), + uintptr(unsafe.Pointer(srcBytes)), + uintptr(dirFD), + uintptr(unsafe.Pointer(dstBytes)), + renameNoreplaceFlag, + 0, + ) + runtime.KeepAlive(srcBytes) + runtime.KeepAlive(dstBytes) + if errno == 0 { + return fmt.Errorf("expected EEXIST, but renameat2 NOREPLACE succeeded") + } + return nil +} diff --git a/integrationtests/cmd/ioworkload/scenario_stat.go b/integrationtests/cmd/ioworkload/scenario_stat.go new file mode 100644 index 0000000..ce9807d --- /dev/null +++ b/integrationtests/cmd/ioworkload/scenario_stat.go @@ -0,0 +1,274 @@ +package main + +import ( + "fmt" + "path/filepath" + "runtime" + "syscall" + "unsafe" +) + +const ( + sysStatx = 332 + rOK = 0x4 // R_OK + statxBasicMask = 0x07ff // STATX_BASIC_STATS + atFDCwd = -100 // AT_FDCWD +) + +// statBasic creates a file and stats it via raw SYS_STAT (newstat). +// We use the raw syscall because Go's syscall.Stat wraps newfstatat on amd64. +func statBasic() error { + dir, cleanup, err := makeTempDir("stat-basic") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "statfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + syscall.Close(fd) + + var stat syscall.Stat_t + pathBytes, err := syscall.BytePtrFromString(path) + if err != nil { + return fmt.Errorf("path bytes: %w", err) + } + _, _, errno := syscall.Syscall(syscall.SYS_STAT, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(&stat)), 0) + runtime.KeepAlive(pathBytes) + runtime.KeepAlive(&stat) + if errno != 0 { + return fmt.Errorf("stat: %w", errno) + } + return nil +} + +// statFstat creates a file and stats it via raw SYS_FSTAT (newfstat). +// This is an fd_event, so ior resolves the path via its fd lookup table. +func statFstat() error { + dir, cleanup, err := makeTempDir("stat-fstat") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "fstatfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + var stat syscall.Stat_t + _, _, errno := syscall.Syscall(syscall.SYS_FSTAT, uintptr(fd), uintptr(unsafe.Pointer(&stat)), 0) + runtime.KeepAlive(&stat) + if errno != 0 { + return fmt.Errorf("fstat: %w", errno) + } + return nil +} + +// statLstat creates a file and stats it via raw SYS_LSTAT (newlstat). +// We use the raw syscall because Go's syscall.Lstat wraps newfstatat on amd64. +func statLstat() error { + dir, cleanup, err := makeTempDir("stat-lstat") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "lstatfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + syscall.Close(fd) + + var stat syscall.Stat_t + pathBytes, err := syscall.BytePtrFromString(path) + if err != nil { + return fmt.Errorf("path bytes: %w", err) + } + _, _, errno := syscall.Syscall(syscall.SYS_LSTAT, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(&stat)), 0) + runtime.KeepAlive(pathBytes) + runtime.KeepAlive(&stat) + if errno != 0 { + return fmt.Errorf("lstat: %w", errno) + } + return nil +} + +// statNewfstatat creates a file and stats it via Go's syscall.Stat, which +// wraps SYS_NEWFSTATAT (fstatat with AT_FDCWD) on amd64. +func statNewfstatat() error { + dir, cleanup, err := makeTempDir("stat-newfstatat") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "fstatatfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + syscall.Close(fd) + + var stat syscall.Stat_t + if err := syscall.Stat(path, &stat); err != nil { + return fmt.Errorf("newfstatat: %w", err) + } + return nil +} + +// statStatx creates a file and stats it via raw statx(2) syscall. +func statStatx() error { + dir, cleanup, err := makeTempDir("stat-statx") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "statxfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + syscall.Close(fd) + + pathBytes, err := syscall.BytePtrFromString(path) + if err != nil { + return fmt.Errorf("path bytes: %w", err) + } + var buf [256]byte // statx struct is ~256 bytes + _, _, errno := syscall.Syscall6( + sysStatx, + ^uintptr(99), // AT_FDCWD (-100) + uintptr(unsafe.Pointer(pathBytes)), + 0, + statxBasicMask, + uintptr(unsafe.Pointer(&buf[0])), + 0, + ) + runtime.KeepAlive(pathBytes) + runtime.KeepAlive(buf) + if errno != 0 { + return fmt.Errorf("statx: %w", errno) + } + return nil +} + +// statAccess creates a file and checks access via raw SYS_ACCESS. +// We use the raw syscall because Go's syscall.Access wraps faccessat on amd64. +func statAccess() error { + dir, cleanup, err := makeTempDir("stat-access") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "accessfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + syscall.Close(fd) + + pathBytes, err := syscall.BytePtrFromString(path) + if err != nil { + return fmt.Errorf("path bytes: %w", err) + } + _, _, errno := syscall.Syscall(syscall.SYS_ACCESS, uintptr(unsafe.Pointer(pathBytes)), rOK, 0) + runtime.KeepAlive(pathBytes) + if errno != 0 { + return fmt.Errorf("access: %w", errno) + } + return nil +} + +// statFaccessat creates a file and checks access via faccessat(2). +// Go's syscall.Faccessat wraps SYS_FACCESSAT. +func statFaccessat() error { + dir, cleanup, err := makeTempDir("stat-faccessat") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "faccessatfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + syscall.Close(fd) + + if err := syscall.Faccessat(atFDCwd, path, uint32(rOK), 0); err != nil { + return fmt.Errorf("faccessat: %w", err) + } + return nil +} + +// statEnoent attempts to stat a nonexistent file via raw SYS_STAT. +// The syscall fails with ENOENT, but ior captures the enter_newstat +// tracepoint because the filename is read on entry. +func statEnoent() error { + dir, cleanup, err := makeTempDir("stat-enoent") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "stat-enoent-missing.txt") + pathBytes, err := syscall.BytePtrFromString(path) + if err != nil { + return fmt.Errorf("path bytes: %w", err) + } + var stat syscall.Stat_t + _, _, errno := syscall.Syscall(syscall.SYS_STAT, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(&stat)), 0) + runtime.KeepAlive(pathBytes) + runtime.KeepAlive(&stat) + if errno == 0 { + return fmt.Errorf("expected ENOENT, but stat succeeded") + } + return nil +} + +// statAccessEnoent attempts to check access on a nonexistent file via raw +// SYS_ACCESS. The syscall fails with ENOENT, but ior captures the +// enter_access tracepoint because the path is read on entry. +// We use ENOENT instead of EACCES because integration tests run as root, +// which bypasses DAC permission checks. +func statAccessEnoent() error { + dir, cleanup, err := makeTempDir("stat-access-enoent") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "access-enoent-missing.txt") + pathBytes, err := syscall.BytePtrFromString(path) + if err != nil { + return fmt.Errorf("path bytes: %w", err) + } + _, _, errno := syscall.Syscall(syscall.SYS_ACCESS, uintptr(unsafe.Pointer(pathBytes)), rOK, 0) + runtime.KeepAlive(pathBytes) + if errno == 0 { + return fmt.Errorf("expected ENOENT, but access succeeded") + } + return nil +} + +// statFstatEbadf calls raw SYS_FSTAT on an invalid fd (99999). +// The syscall fails with EBADF, but ior captures the enter_newfstat +// tracepoint because it is recorded on syscall entry. +func statFstatEbadf() error { + var stat syscall.Stat_t + _, _, errno := syscall.Syscall(syscall.SYS_FSTAT, 99999, uintptr(unsafe.Pointer(&stat)), 0) + runtime.KeepAlive(&stat) + if errno == 0 { + return fmt.Errorf("expected EBADF, but fstat succeeded") + } + return nil +} diff --git a/integrationtests/cmd/ioworkload/scenario_sync.go b/integrationtests/cmd/ioworkload/scenario_sync.go new file mode 100644 index 0000000..214c783 --- /dev/null +++ b/integrationtests/cmd/ioworkload/scenario_sync.go @@ -0,0 +1,108 @@ +package main + +import ( + "fmt" + "path/filepath" + "syscall" +) + +// syncBasic opens a file, writes data, and fsyncs it. +func syncBasic() error { + dir, cleanup, err := makeTempDir("sync-basic") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "syncfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + if _, err := syscall.Write(fd, []byte("sync me")); err != nil { + return fmt.Errorf("write: %w", err) + } + return syscall.Fsync(fd) +} + +// syncFdatasync opens a file, writes data, and fdatasyncs it. +func syncFdatasync() error { + dir, cleanup, err := makeTempDir("sync-fdatasync") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "fdatasyncfile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer syscall.Close(fd) + + if _, err := syscall.Write(fd, []byte("fdatasync me")); err != nil { + return fmt.Errorf("write: %w", err) + } + return syscall.Fdatasync(fd) +} + +// syncSync calls sync(2) to flush all filesystem caches. +// sync is a null_event with no file arguments. +func syncSync() error { + syscall.Sync() + return nil +} + +// syncSyncFileRange opens a file, writes data, then calls sync_file_range(2). +func syncSyncFileRange() error { + dir, cleanup, err := makeTempDir("sync-sync-file-range") + if err != nil { + return err + } + defer cleanup() + + path := filepath.Join(dir, "syncrangefile.txt") + fd, err := syscall.Open(path, syscall.O_RDWR|syscall.O_CREAT, 0o644) + if err != nil { + return fmt.Errorf("open: %w", err) + } + defer sysc