grub/grub-core/osdep/unix/hostdisk.c
Michael Chang 42acdd3b40 hostdisk: Set linux file descriptor to O_CLOEXEC as default
We are often bothered by this sort of lvm warning while running grub-install
every now and then:

  File descriptor 4 (/dev/vda1) leaked on vgs invocation. Parent PID 1991: /usr/sbin/grub2-install

The requirement related to the warning is dictated in the lvm man page:

  "On invocation, lvm requires that only the standard file descriptors stdin,
  stdout and stderr are available.  If others are found, they get closed and
  messages are issued warning about the leak.  This warning can be suppressed by
  setting the environment variable LVM_SUPPRESS_FD_WARNINGS."

While it could be disabled through settings, most Linux distributions seem to
enable it by default and the justification provided by the developer looks to
be valid to me: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=466138#15

Rather than trying to close and reopen the file descriptor to the same file
multiple times, which is rather cumbersome, for the sake of no vgs invocation
could happen in between. This patch enables the close-on-exec flag (O_CLOEXEC)
for new file descriptor returned by the open() system call, making it closed
thus not inherited by the child process forked and executed by the exec()
family of functions.

Fixes Debian bug #466138.

Signed-off-by: Michael Chang <mchang@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2019-11-18 13:42:55 +01:00

319 lines
6.1 KiB
C

/* hostdisk.c - emulate biosdisk */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 1999,2000,2001,2002,2003,2004,2006,2007,2008,2009,2010,2011,2012,2013 Free Software Foundation, Inc.
*
* GRUB is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GRUB is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
#include <config-util.h>
#include <grub/disk.h>
#include <grub/partition.h>
#include <grub/msdos_partition.h>
#include <grub/types.h>
#include <grub/err.h>
#include <grub/emu/misc.h>
#include <grub/emu/hostdisk.h>
#include <grub/emu/getroot.h>
#include <grub/misc.h>
#include <grub/i18n.h>
#include <grub/list.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <limits.h>
#if !defined (__CYGWIN__) && !defined (__MINGW32__) && !defined (__AROS__)
#ifdef __linux__
# include <sys/ioctl.h> /* ioctl */
# include <sys/mount.h>
#endif /* __linux__ */
grub_uint64_t
grub_util_get_fd_size (grub_util_fd_t fd, const char *name, unsigned *log_secsize)
{
struct stat st;
grub_int64_t ret = -1;
if (fstat (fd, &st) < 0)
/* TRANSLATORS: "stat" comes from the name of POSIX function. */
grub_util_error (_("cannot stat `%s': %s"), name, strerror (errno));
#if GRUB_DISK_DEVS_ARE_CHAR
if (S_ISCHR (st.st_mode))
#else
if (S_ISBLK (st.st_mode))
#endif
ret = grub_util_get_fd_size_os (fd, name, log_secsize);
if (ret != -1LL)
return ret;
if (log_secsize)
*log_secsize = 9;
return st.st_size;
}
int
grub_util_fd_seek (grub_util_fd_t fd, grub_uint64_t off)
{
#if SIZEOF_OFF_T == 8
off_t offset = (off_t) off;
if (lseek (fd, offset, SEEK_SET) != offset)
return -1;
#elif SIZEOF_OFF64_T == 8
off64_t offset = (off64_t) off;
if (lseek64 (fd, offset, SEEK_SET) != offset)
return -1;
#else
#error "No large file support"
#endif
return 0;
}
/* Read LEN bytes from FD in BUF. Return less than or equal to zero if an
error occurs, otherwise return LEN. */
ssize_t
grub_util_fd_read (grub_util_fd_t fd, char *buf, size_t len)
{
ssize_t size = 0;
while (len)
{
ssize_t ret = read (fd, buf, len);
if (ret == 0)
break;
if (ret < 0)
{
if (errno == EINTR)
continue;
else
return ret;
}
len -= ret;
buf += ret;
size += ret;
}
return size;
}
/* Write LEN bytes from BUF to FD. Return less than or equal to zero if an
error occurs, otherwise return LEN. */
ssize_t
grub_util_fd_write (grub_util_fd_t fd, const char *buf, size_t len)
{
ssize_t size = 0;
while (len)
{
ssize_t ret = write (fd, buf, len);
if (ret == 0)
break;
if (ret < 0)
{
if (errno == EINTR)
continue;
else
return ret;
}
len -= ret;
buf += ret;
size += ret;
}
return size;
}
#if !defined (__NetBSD__) && !defined (__APPLE__) && !defined (__FreeBSD__) && !defined(__FreeBSD_kernel__)
grub_util_fd_t
grub_util_fd_open (const char *os_dev, int flags)
{
#ifdef O_LARGEFILE
flags |= O_LARGEFILE;
#endif
#ifdef O_BINARY
flags |= O_BINARY;
#endif
#ifdef O_CLOEXEC
flags |= O_CLOEXEC;
#endif
return open (os_dev, flags, S_IROTH | S_IRGRP | S_IRUSR | S_IWUSR);
}
#endif
const char *
grub_util_fd_strerror (void)
{
return strerror (errno);
}
static int allow_fd_syncs = 1;
int
grub_util_fd_sync (grub_util_fd_t fd)
{
if (allow_fd_syncs)
return fsync (fd);
return 0;
}
int
grub_util_file_sync (FILE *f)
{
if (fflush (f) != 0)
return -1;
if (!allow_fd_syncs)
return 0;
return fsync (fileno (f));
}
void
grub_util_disable_fd_syncs (void)
{
allow_fd_syncs = 0;
}
int
grub_util_fd_close (grub_util_fd_t fd)
{
return close (fd);
}
char *
grub_canonicalize_file_name (const char *path)
{
#if defined (PATH_MAX)
char *ret;
ret = xmalloc (PATH_MAX);
if (!realpath (path, ret))
return NULL;
return ret;
#else
return realpath (path, NULL);
#endif
}
FILE *
grub_util_fopen (const char *path, const char *mode)
{
return fopen (path, mode);
}
int
grub_util_is_directory (const char *path)
{
struct stat st;
if (stat (path, &st) == -1)
return 0;
return S_ISDIR (st.st_mode);
}
int
grub_util_is_regular (const char *path)
{
struct stat st;
if (stat (path, &st) == -1)
return 0;
return S_ISREG (st.st_mode);
}
grub_uint32_t
grub_util_get_mtime (const char *path)
{
struct stat st;
if (stat (path, &st) == -1)
return 0;
return st.st_mtime;
}
#endif
#if defined (__CYGWIN__) || (!defined (__MINGW32__) && !defined (__AROS__))
int
grub_util_is_special_file (const char *path)
{
struct stat st;
if (lstat (path, &st) == -1)
return 1;
return (!S_ISREG (st.st_mode) && !S_ISDIR (st.st_mode));
}
char *
grub_util_make_temporary_file (void)
{
const char *t = getenv ("TMPDIR");
size_t tl;
char *tmp;
if (!t)
t = "/tmp";
tl = strlen (t);
tmp = xmalloc (tl + sizeof ("/grub.XXXXXX"));
memcpy (tmp, t, tl);
memcpy (tmp + tl, "/grub.XXXXXX",
sizeof ("/grub.XXXXXX"));
if (mkstemp (tmp) == -1)
grub_util_error (_("cannot make temporary file: %s"), strerror (errno));
return tmp;
}
char *
grub_util_make_temporary_dir (void)
{
const char *t = getenv ("TMPDIR");
size_t tl;
char *tmp;
if (!t)
t = "/tmp";
tl = strlen (t);
tmp = xmalloc (tl + sizeof ("/grub.XXXXXX"));
memcpy (tmp, t, tl);
memcpy (tmp + tl, "/grub.XXXXXX",
sizeof ("/grub.XXXXXX"));
if (!mkdtemp (tmp))
grub_util_error (_("cannot make temporary directory: %s"),
strerror (errno));
return tmp;
}
#endif