uwac-os.c

/*
 * Copyright © 2012 Collabora, Ltd.
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting documentation, and
 * that the name of the copyright holders not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  The copyright holders make no representations
 * about the suitability of this software for any purpose.  It is provided "as
 * is" without express or implied warranty.
 *
 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
 * OF THIS SOFTWARE.
 */
 
/*
 * This file is an adaptation of src/wayland-os.h from the wayland project and
 * shared/os-compatiblity.h from the weston project.
 *
 * Functions have been renamed just to prevent name clashes.
 */
 
#if defined(__clang__)
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wreserved-id-macro"
#endif
 
#define _GNU_SOURCE // NOLINT(bugprone-reserved-identifier,cert-dcl37-c,cert-dcl51-cpp)
 
#if defined(__clang__)
#pragma clang diagnostic pop
#endif
 
#if defined(__FreeBSD__) || defined(__DragonFly__)
#define USE_SHM
#endif
 
/* uClibc and uClibc-ng don't provide O_TMPFILE */
#if !defined(O_TMPFILE) && !defined(__FreeBSD__)
#define O_TMPFILE (020000000 | O_DIRECTORY)
#endif
 
#include <sys/types.h>
#include <sys/socket.h>
#ifdef USE_SHM
#include <sys/mman.h>
#endif
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/epoll.h>
#include <sys/stat.h>
 
#include <uwac/config.h>
 
#include "uwac-os.h"
#include "uwac-utils.h"
 
static int set_cloexec_or_close(int fd)
{
  long flags = 0;
 
  if (fd == -1)
    return -1;
 
  flags = fcntl(fd, F_GETFD);
 
  if (flags == -1)
    goto err;
 
  if (fcntl(fd, F_SETFD, flags | FD_CLOEXEC) == -1)
    goto err;
 
  return fd;
err:
  close(fd);
  return -1;
}
 
int uwac_os_socket_cloexec(int domain, int type, int protocol)
{
  int fd = 0;
  fd = socket(domain, type | SOCK_CLOEXEC, protocol);
 
  if (fd >= 0)
    return fd;
 
  if (errno != EINVAL)
    return -1;
 
  fd = socket(domain, type, protocol);
  return set_cloexec_or_close(fd);
}
 
int uwac_os_dupfd_cloexec(int fd, long minfd)
{
  int newfd = 0;
  newfd = fcntl(fd, F_DUPFD_CLOEXEC, minfd);
 
  if (newfd >= 0)
    return newfd;
 
  if (errno != EINVAL)
    return -1;
 
  newfd = fcntl(fd, F_DUPFD, minfd);
  return set_cloexec_or_close(newfd);
}
 
static ssize_t recvmsg_cloexec_fallback(int sockfd, struct msghdr* msg, int flags)
{
  ssize_t len = 0;
  struct cmsghdr* cmsg = NULL;
  unsigned char* data = NULL;
  int* end = NULL;
  len = recvmsg(sockfd, msg, flags);
 
  if (len == -1)
    return -1;
 
  if (!msg->msg_control || msg->msg_controllen == 0)
    return len;
 
  cmsg = CMSG_FIRSTHDR(msg);
 
  for (; cmsg != NULL; cmsg = CMSG_NXTHDR(msg, cmsg))
  {
    if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS)
      continue;
 
    data = CMSG_DATA(cmsg);
    end = (int*)(data + cmsg->cmsg_len - CMSG_LEN(0));
 
    for (int* fd = (int*)data; fd < end; ++fd)
      *fd = set_cloexec_or_close(*fd);
  }
 
  return len;
}
 
ssize_t uwac_os_recvmsg_cloexec(int sockfd, struct msghdr* msg, int flags)
{
  ssize_t len = 0;
  len = recvmsg(sockfd, msg, flags | MSG_CMSG_CLOEXEC);
 
  if (len >= 0)
    return len;
 
  if (errno != EINVAL)
    return -1;
 
  return recvmsg_cloexec_fallback(sockfd, msg, flags);
}
 
int uwac_os_epoll_create_cloexec(void)
{
  int fd = 0;
#ifdef EPOLL_CLOEXEC
  fd = epoll_create1(EPOLL_CLOEXEC);
 
  if (fd >= 0)
    return fd;
 
  if (errno != EINVAL)
    return -1;
 
#endif
  fd = epoll_create(1);
  return set_cloexec_or_close(fd);
}
 
static int secure_mkstemp(char* tmpname)
{
  const mode_t mask = umask(S_IRWXU);
  int fd = mkstemp(tmpname);
  (void)umask(mask);
  return fd;
}
 
static int create_tmpfile_cloexec(char* tmpname)
{
  int fd = 0;
#ifdef USE_SHM
  fd = shm_open(SHM_ANON, O_CREAT | O_RDWR, 0600);
#elif defined(UWAC_HAVE_MKOSTEMP)
  fd = mkostemp(tmpname, O_CLOEXEC);
 
  if (fd >= 0)
    unlink(tmpname);
 
#else
  fd = secure_mkstemp(tmpname);
 
  if (fd >= 0)
  {
    fd = set_cloexec_or_close(fd);
    unlink(tmpname);
  }
 
#endif
  return fd;
}
 
/*
 * Create a new, unique, anonymous file of the given size, and
 * return the file descriptor for it. The file descriptor is set
 * CLOEXEC. The file is immediately suitable for mmap()'ing
 * the given size at offset zero.
 *
 * The file should not have a permanent backing store like a disk,
 * but may have if XDG_RUNTIME_DIR is not properly implemented in OS.
 *
 * The file name is deleted from the file system.
 *
 * The file is suitable for buffer sharing between processes by
 * transmitting the file descriptor over Unix sockets using the
 * SCM_RIGHTS methods.
 *
 * If the C library implements posix_fallocate(), it is used to
 * guarantee that disk space is available for the file at the
 * given size. If disk space is insufficient, errno is set to ENOSPC.
 * If posix_fallocate() is not supported, program may receive
 * SIGBUS on accessing mmap()'ed file contents instead.
 */
int uwac_create_anonymous_file(off_t size)
{
  static const char template[] = "/weston-shared-XXXXXX";
  size_t length = 0;
  char* name = NULL;
  int fd = 0;
  int ret = 0;
  // NOLINTNEXTLINE(concurrency-mt-unsafe)
  const char* path = getenv("XDG_RUNTIME_DIR");
 
  if (!path)
  {
    errno = ENOENT;
    return -1;
  }
 
#ifdef O_TMPFILE
  fd = open(path, O_TMPFILE | O_RDWR | O_EXCL, 0600);
#else
  /*
   * Some platforms (e.g. FreeBSD) won't support O_TMPFILE and can't
   * reasonably emulate it at first blush.  Opt to make them rely on
   * the create_tmpfile_cloexec() path instead.
   */
  fd = -1;
#endif
 
  if (fd < 0)
  {
    length = strlen(path) + sizeof(template);
    name = xmalloc(length);
 
    if (!name)
      return -1;
 
    (void)snprintf(name, length, "%s%s", path, template);
    fd = create_tmpfile_cloexec(name);
    free(name);
  }
 
  if (fd < 0)
    return -1;
 
#ifdef UWAC_HAVE_POSIX_FALLOCATE
  ret = posix_fallocate(fd, 0, size);
 
  if (ret != 0)
  {
    close(fd);
    errno = ret;
    return -1;
  }
 
#else
  ret = ftruncate(fd, size);
 
  if (ret < 0)
  {
    close(fd);
    return -1;
  }
 
#endif
  return fd;
}