[Lldb-commits] [lldb] [lldb/Host] Enable inheriting "non-inheritable" FDs (PR #126935)

[David Spickett via lldb-commits]

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@@ -122,8 +123,14 @@ struct ForkLaunchInfo {
         ExitWithError(error_fd, "close");
       break;
     case FileAction::eFileActionDuplicate:
-      if (dup2(action.fd, action.arg) == -1)
-        ExitWithError(error_fd, "dup2");
+      if (action.fd != action.arg) {
+        if (dup2(action.fd, action.arg) == -1)
+          ExitWithError(error_fd, "dup2");
+      } else {
+        if (fcntl(action.fd, F_SETFD,
+                  fcntl(action.fd, F_GETFD) & ~FD_CLOEXEC) == -1)
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DavidSpickett wrote:

So if the file descriptors are not the same, we want to duplicate what action.fd refers to, into the file descriptor action.arg. Seems logical, we can then pass the new file descriptor to the debugee, I think?

(unless this is forking into another part of lldb)

If they are not the same, then we don't want to close action.fd when we next exec, which is when we fork to run the debugee process? Is this because action.fd is for example opened by the system, not by lldb or the debugee and we don't want to interfere with that?

https://github.com/llvm/llvm-project/pull/126935