/* sysprof-platform.c
 *
 * Copyright 2016-2019 Christian Hergert <chergert@redhat.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * Subject to the terms and conditions of this license, each copyright holder
 * and contributor hereby grants to those receiving rights under this license
 * a perpetual, worldwide, non-exclusive, no-charge, royalty-free,
 * irrevocable (except for failure to satisfy the conditions of this license)
 * patent license to make, have made, use, offer to sell, sell, import, and
 * otherwise transfer this software, where such license applies only to those
 * patent claims, already acquired or hereafter acquired, licensable by such
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 *     Contribution.
 *
 * Except as expressly stated above, no rights or licenses from any copyright
 * holder or contributor is granted under this license, whether expressly, by
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 * DISCLAIMER
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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 */

#define G_LOG_DOMAIN "sysprof-platform"

#include "config.h"

#include <glib.h>
#include <glib/gstdio.h>
#include <sys/syscall.h>
#include <unistd.h>

#include "sysprof-platform.h"

/**
 * sysprof_memfd_create:
 * @name: (nullable): A descriptive name for the memfd or %NULL
 *
 * Creates a new memfd using the memfd_create syscall if available.
 * Otherwise, a tmpfile is used. Currently, no attempt is made to
 * ensure the tmpfile is on a tmpfs backed mount.
 *
 * Returns: An fd if successful; otherwise -1 and errno is set.
 */
int
sysprof_memfd_create (const gchar *name)
{
#ifdef __NR_memfd_create
  if (name == NULL)
    name = "[sysprof]";
  return syscall (__NR_memfd_create, name, 0);
#else
  gchar *name_used = NULL;
  int fd;

  /*
   * TODO: It would be nice to ensure tmpfs
   *
   * It is not strictly required that the preferred temporary directory
   * will be mounted as tmpfs. We should look through the mounts and ensure
   * that the tmpfile we open is on tmpfs so that we get anonymous backed
   * pages after unlinking.
   */
  fd = g_file_open_tmp (NULL, &name_used, NULL);

  if (name_used != NULL)
    {
      g_unlink (name_used);
      g_free (name_used);
    }

  return fd;
#endif
}