Fix TestFdLeak on Linux.

[chaoren]

Summary

LLGS leaks pipes (when launched by lldb), sockets (when launched by platform),
and/or log file to the inferior. This should prevent all possible leaks.

[clayborg]

My main concern is that we allow the ProcessLaunchInfo to specify rules for things other than file STDIN, STDOUT and STDERR. This fix would close anything but STDIN/OUT/ERR. Maybe this functionality just wasn't implemented on Linux in which case this won't hurt anything, but we should look into that. I am not sure how ProcessLaunchInfo makes its way down into the NativeProcessLinux::Launch() function, but you should check it out.

source/Plugins/Process/Linux/NativeProcessLinux.cpp

1799–1801 ↗

(On Diff #24263)

Don't we allow file rules for other files that should be opened/duped/closed/etc via the posix_spawn style file rules? If so, this would close all of those... Not sure if this just isn't implemented for linux?

[chaoren]

Don't close fds with file actions.

[clayborg]

Much better.

lldb/trunk/source/Plugins/Process/Linux/NativeProcessLinux.cpp

if (pid == 0)
         if (!args->m_stdout_path.empty ())
             if (!DupDescriptor(args->m_stdout_path.c_str (), STDOUT_FILENO, O_WRONLY | O_CREAT | O_TRUNC))
                 exit(eDupStdoutFailed);
 
         if (!args->m_stderr_path.empty ())
             if (!DupDescriptor(args->m_stderr_path.c_str (), STDERR_FILENO, O_WRONLY | O_CREAT | O_TRUNC))
                 exit(eDupStderrFailed);
 
+        // Close everything besides stdin, stdout, and stderr that has no file
+        // action to avoid leaking
+        for (int fd = 3; fd < sysconf(_SC_OPEN_MAX); ++fd)
+            if (!args->m_launch_info.GetFileActionForFD(fd))
+                close(fd);
+
         // Change working directory
         if (working_dir != NULL && working_dir[0])
           if (0 != ::chdir(working_dir))
               exit(eChdirFailed);
 
         // Disable ASLR if requested.
         if (args->m_launch_info.GetFlags ().Test (lldb::eLaunchFlagDisableASLR))
         {