podman

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//go:build !remote
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#define _GNU_SOURCE
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/mount.h>
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#include <sys/wait.h>
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#include <unistd.h>
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/* keep special_exit_code in sync with container_top_linux.go */
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int special_exit_code = 255;
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char **argv = NULL;
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void
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create_argv (int len)
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{
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  /* allocate one extra element because we need a final NULL in c */
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  argv = malloc (sizeof (char *) * (len + 1));
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  if (argv == NULL)
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    {
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      fprintf (stderr, "failed to allocate ps argv");
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      exit (special_exit_code);
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    }
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  /* add final NULL */
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  argv[len] = NULL;
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}
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void
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set_argv (int pos, char *arg)
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{
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  argv[pos] = arg;
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}
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/*
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  We use cgo code here so we can fork then exec separately,
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  this is done so we can mount proc after the fork because the pid namespace is
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  only active after spawning children.
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*/
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void
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fork_exec_ps ()
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{
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  int r, status = 0;
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  pid_t pid;
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  if (argv == NULL)
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    {
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      fprintf (stderr, "argv not initialized");
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      exit (special_exit_code);
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    }
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  pid = fork ();
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  if (pid < 0)
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    {
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      fprintf (stderr, "fork: %m");
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      exit (special_exit_code);
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    }
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  if (pid == 0)
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    {
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      r = mount ("proc", "/proc", "proc", 0, NULL);
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      if (r < 0)
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        {
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          fprintf (stderr, "mount proc: %m");
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          exit (special_exit_code);
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        }
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      /* use execve to unset all env vars, we do not want to leak anything into the container */
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      execve (argv[0], argv, NULL);
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      fprintf (stderr, "execve: %m");
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      exit (special_exit_code);
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    }
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  r = waitpid (pid, &status, 0);
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  if (r < 0)
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    {
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      fprintf (stderr, "waitpid: %m");
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      exit (special_exit_code);
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    }
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  if (WIFEXITED (status))
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    exit (WEXITSTATUS (status));
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  if (WIFSIGNALED (status))
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    exit (128 + WTERMSIG (status));
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  exit (special_exit_code);
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}
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