util: add fallback for qemu_memfd_alloc()

Add an open/unlink/mmap fallback for system that do not support
memfd (only available since 3.17, ~1y ago).

This patch may require additional SELinux policies to work for enforced
systems, but should fail gracefully in this case.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Thibaut Collet <thibaut.collet@6wind.com>
This commit is contained in:
Marc-André Lureau 2015-10-09 17:17:21 +02:00 committed by Michael S. Tsirkin
parent d3592199ba
commit 35f9b6ef3a
1 changed files with 18 additions and 2 deletions

View File

@ -97,8 +97,24 @@ void *qemu_memfd_alloc(const char *name, size_t size, unsigned int seals,
return NULL;
}
} else {
perror("memfd");
return NULL;
const char *tmpdir = g_get_tmp_dir();
gchar *fname;
fname = g_strdup_printf("%s/memfd-XXXXXX", tmpdir);
mfd = mkstemp(fname);
unlink(fname);
g_free(fname);
if (mfd == -1) {
perror("mkstemp");
return NULL;
}
if (ftruncate(mfd, size) == -1) {
perror("ftruncate");
close(mfd);
return NULL;
}
}
ptr = mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, mfd, 0);