initial dup

2 files changed, 29 insertions, 13 deletions

diff --git a/internal/eventloop.go b/internal/eventloop.go
index 0be7b7e..7d13839 100644
--- a/internal/eventloop.go
+++ b/internal/eventloop.go
@@ -262,21 +262,26 @@ func (e *eventLoop) syscallExit(exitEv event.Event, ch chan<- *event.Pair) {
 			break
 		}
 
+		fdFile, ok := ev.File.(file.FdFile)
+		if !ok {
+			panic("expected a file.FdFile")
+		}
+
+		// See fcntl(2) for implementation details
 		switch v.Cmd {
 		case syscall.F_SETFL:
-			fdFile, ok := ev.File.(file.FdFile)
-			if !ok {
-				panic("expected a file.FdFile")
-			}
-			// fcntl(2)
 			canChange := syscall.O_APPEND | syscall.O_ASYNC | syscall.O_DIRECT | syscall.O_NOATIME | syscall.O_NONBLOCK
-			fdFile.Flags |= (int32(v.Arg) & int32(canChange))
+			*fdFile.Flags |= (int32(v.Arg) & int32(canChange))
 			ev.File = fdFile
 			e.files[fd] = fdFile
 		case syscall.F_DUPFD:
-			fmt.Println("TODO: F_DUPFD with fcntl not yet implememented")
+			// TODO: Re-read dup(2), maybe they don't share the same open flags?
+			newFd := int32(retEvent.Ret)
+			e.files[newFd] = fdFile.Dup(newFd)
 		case syscall.F_DUPFD_CLOEXEC:
-			fmt.Println("TODO: F_DUPFD_CLOEXEC with fcntl not yet implememented")
+			newFd := int32(retEvent.Ret)
+			e.files[newFd] = fdFile.Dup(newFd) // Also set O_CLOEXEC
+			fmt.Println("TODO: F_DUPFD_CLOEXEC with fcntl not yet fully implememented")
 		}
 
 	default:
diff --git a/internal/file/file.go b/internal/file/file.go
index 513212b..d43a79e 100644
--- a/internal/file/file.go
+++ b/internal/file/file.go
@@ -18,7 +18,7 @@ type File interface {
 type FdFile struct {
 	fd              int32
 	name            string
-	Flags           int32
+	Flags           *int32 // TODO: This must be a pointer as via dup(2) - means, we need to synchronise access as well .. use atomicint
 	flagsFromFdInfo bool
 }
 
@@ -26,7 +26,7 @@ func NewFd(fd int32, name []byte, flags int32) FdFile {
 	return FdFile{
 		fd:    fd,
 		name:  stringValue(name),
-		Flags: flags,
+		Flags: &flags,
 	}
 }
 
@@ -36,7 +36,7 @@ func NewFdWithPid(fd int32, pid uint32) FdFile {
 		return FdFile{
 			fd:              fd,
 			name:            "?",
-			Flags:           -1,
+			Flags:           nil, // Unknown flags at this point
 			flagsFromFdInfo: true,
 		}
 	}
@@ -45,11 +45,18 @@ func NewFdWithPid(fd int32, pid uint32) FdFile {
 	return FdFile{
 		fd:              fd,
 		name:            linkName,
-		Flags:           flags,
+		Flags:           &flags,
 		flagsFromFdInfo: true,
 	}
 }
 
+func (f FdFile) Dup(fd int32) FdFile {
+	duppedFd := f
+	duppedFd.fd = fd
+	duppedFd.flagsFromFdInfo = false
+	return duppedFd
+}
+
 func readFlagsFromFdInfo(fd int32, pid uint32) (int32, error) {
 	data, err := os.ReadFile(fmt.Sprintf("/proc/%d/fdinfo/%d", pid, fd))
 	if err != nil {
@@ -72,7 +79,11 @@ func (f FdFile) Name() string {
 }
 
 func (f FdFile) FlagsString() string {
-	return flagsToStr(f.Flags)
+	var flags int32 = -1
+	if f.Flags != nil {
+		flags = *f.Flags
+	}
+	return flagsToStr(flags)
 }
 
 func (f FdFile) String() string {