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/*
* Copyright © 2013 Keith Packard
*
* 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.
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include "xshmfenceint.h"
#include <fcntl.h>
#if !HAVE_MEMFD_CREATE
#if HAVE_DECL___NR_MEMFD_CREATE
#include <asm/unistd.h>
static int memfd_create(const char *name,
unsigned int flags)
{
return syscall(__NR_memfd_create, name, flags);
}
#define HAVE_MEMFD_CREATE 1
#endif
#endif
#if HAVE_MEMFD_CREATE
/* Get defines for the memfd_create syscall, using the
* header if available, or just defining the constants otherwise
*/
#if HAVE_MEMFD_H
#include <sys/memfd.h>
#else
/* flags for memfd_create(2) (unsigned int) */
#define MFD_CLOEXEC 0x0001U
#define MFD_ALLOW_SEALING 0x0002U
#endif
#endif
/**
* xshmfence_alloc_shm:
*
* Allocates a shared memory object large enough to hold a single
* fence.
*
* Return value: the file descriptor of the object, or -1 on failure
* (in which case, errno will be set as appropriate).
**/
int
xshmfence_alloc_shm(void)
{
char template[] = SHMDIR "/shmfd-XXXXXX";
int fd;
#ifndef HAVE_MKOSTEMP
int flags;
#endif
#if HAVE_MEMFD_CREATE
fd = memfd_create("xshmfence", MFD_CLOEXEC|MFD_ALLOW_SEALING);
if (fd < 0)
#endif
#ifdef SHM_ANON
fd = shm_open(SHM_ANON, O_RDWR|O_CLOEXEC, 0600);
if (fd < 0)
#endif
{
#ifdef O_TMPFILE
fd = open(SHMDIR, O_TMPFILE|O_RDWR|O_CLOEXEC|O_EXCL, 0666);
if (fd < 0)
#endif
{
#ifdef HAVE_MKOSTEMP
fd = mkostemp(template, O_CLOEXEC);
#else
fd = mkstemp(template);
#endif
if (fd < 0)
return fd;
unlink(template);
#ifndef HAVE_MKOSTEMP
flags = fcntl(fd, F_GETFD);
if (flags != -1) {
flags |= FD_CLOEXEC;
fcntl(fd, F_SETFD, &flags);
}
#endif
}
}
if (ftruncate(fd, sizeof (struct xshmfence)) < 0) {
close(fd);
return -1;
}
xshmfence_init(fd);
return fd;
}
/**
* xshmfence_map_shm:
*
* Map a shared memory fence referenced by @fd.
*
* Return value: the fence or NULL (in which case, errno will be set
* as appropriate).
**/
struct xshmfence *
xshmfence_map_shm(int fd)
{
struct xshmfence *addr;
addr = mmap (NULL, sizeof (struct xshmfence) , PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
if (addr == MAP_FAILED) {
close (fd);
return 0;
}
return addr;
}
/**
* xshmfence_unmap_shm:
*
* Unap a shared memory fence @f.
**/
void
xshmfence_unmap_shm(struct xshmfence *f)
{
munmap(f, sizeof (struct xshmfence));
}
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