From b1d77d2d891f04b710d610b47388e431fc519a07 Mon Sep 17 00:00:00 2001
From: Paul Buetow <paul@buetow.org>
Date: Mon, 24 Mar 2025 17:56:23 +0200
Subject: initial dup

---
 internal/file/file.go | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

(limited to 'internal/file')

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 {
-- 
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