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/* anonfile.c - open and close temporary files (anonymous and memory-backed if possible). */
/* Copyright (C) 2023-2024 Free Software Foundation, Inc.
This file is part of GNU Bash, the Bourne Again SHell.
Bash 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.
Bash 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 Bash. If not, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#if defined (HAVE_UNISTD_H)
# include <unistd.h>
#endif
#include <bashtypes.h>
#if defined (HAVE_MEMFD_CREATE) || defined (HAVE_SHM_OPEN) || defined (HAVE_SHM_MKSTEMP)
# include <sys/mman.h>
#endif
#include <filecntl.h>
#include <errno.h>
#include <shell.h>
#include <bashansi.h>
static int anonunlink (const char *);
#if defined (HAVE_MEMFD_CREATE) && !defined (MFD_NOEXEC_SEAL)
# define MFD_NOEXEC_SEAL 0
#endif
#if defined (HAVE_SHM_OPEN)
#ifndef O_NOFOLLOW
# define O_NOFOLLOW 0
#endif
static int
anonshmunlink (const char *fn)
{
return (shm_unlink (fn));
}
static int
anonshmopen (const char *name, int flags, char **fn)
{
int fd;
char *fname;
fd = -1;
if (fn)
*fn = 0;
#if defined (HAVE_SHM_MKSTEMP)
fname = savestring ("/shm-XXXXXXXXXX");
fd = shm_mkstemp (fname);
if (fd < 0)
free (fname);
#endif
if (fd < 0)
{
fname = sh_mktmpname (name, flags);
fd = shm_open (fname, O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW, 0600);
}
if (fd < 0)
{
free (fname);
return fd;
}
if (shm_unlink (fname) < 0)
{
int o;
o = errno;
free (fname);
close (fd);
errno = o;
return -1;
}
if (fn)
*fn = fname;
else
free (fname);
return fd;
}
#endif
int
anonopen (const char *name, int flags, char **fn)
{
int fd, flag;
char *fname;
#if defined (HAVE_MEMFD_CREATE)
/* "Names do not affect the behavior of the file descriptor." */
fd = memfd_create ("anonopen", MFD_NOEXEC_SEAL);
if (fd >= 0)
{
if (fn)
*fn = 0;
return fd;
}
/* If memfd_create fails, we fall through to the unlinked-shm-or-regular-file
implementation. */
#endif
/* Heuristic */
flag = (name && *name == '/') ? MT_TEMPLATE : MT_USETMPDIR;
#if defined (HAVE_SHM_OPEN)
fd = anonshmopen (name, flag, fn);
if (fd >= 0)
return fd; /* anonshmopen sets *FN appropriately */
#endif
fd = sh_mktmpfd (name, flag|MT_USERANDOM|MT_READWRITE|MT_UNLINK, fn);
return fd;
}
int
anonclose (int fd, const char *name)
{
int r;
r = close (fd);
return r;
}
static int
anonunlink (const char *fn)
{
int r;
r = unlink (fn);
return r;
}
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