text: // SPDX-License-Identifier: GPL-2.0
  /* Copyright (c) 2020 Facebook */
  /* "undefine" structs in vmlinux.h, because we "override" them below */
  #define bpf_iter_meta bpf_iter_meta___not_used
  #define bpf_iter__task_file bpf_iter__task_file___not_used
  #include "vmlinux.h"
  #undef bpf_iter_meta
  #undef bpf_iter__task_file
  #include <bpf/bpf_helpers.h>
  #include <bpf/bpf_tracing.h>
  
  char _license[] SEC("license") = "GPL";
  
  struct bpf_iter_meta {
  	struct seq_file *seq;
  	__u64 session_id;
  	__u64 seq_num;
  } __attribute__((preserve_access_index));
  
  struct bpf_iter__task_file {
  	struct bpf_iter_meta *meta;
  	struct task_struct *task;
  	__u32 fd;
  	struct file *file;
  } __attribute__((preserve_access_index));
  
  SEC("iter/task_file")
  int dump_task_file(struct bpf_iter__task_file *ctx)
  {
  	struct seq_file *seq = ctx->meta->seq;
  	struct task_struct *task = ctx->task;
  	__u32 fd = ctx->fd;
  	struct file *file = ctx->file;
  
  	if (task == (void *)0 || file == (void *)0)
  		return 0;
  
  	if (ctx->meta->seq_num == 0)
  		BPF_SEQ_PRINTF(seq, "    tgid      gid       fd      file\n");
  
  	BPF_SEQ_PRINTF(seq, "%8d %8d %8d %lx\n", task->tgid, task->pid, fd,
  		       (long)file->f_op);
  	return 0;
  }
  