/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "memfd.h"
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#include <errno.h>
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#include <stdio.h>
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#if !defined(_WIN32)
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#include <sys/syscall.h>
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#include <sys/utsname.h>
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#include <unistd.h>
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#endif
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#include "macros.h"
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// When building for linux host, glibc in prebuilts does not include memfd_create system call
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// number. As a temporary testing measure, we add the definition here.
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#if defined(__linux__) && !defined(__NR_memfd_create)
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#if defined(__x86_64__)
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#define __NR_memfd_create 319
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#elif defined(__i386__)
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#define __NR_memfd_create 356
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#endif // defined(__i386__)
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#endif // defined(__linux__) && !defined(__NR_memfd_create)
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namespace art {
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#if defined(__NR_memfd_create)
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int memfd_create(const char* name, unsigned int flags) {
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// Check kernel version supports memfd_create(). Some older kernels segfault executing
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// memfd_create() rather than returning ENOSYS (b/116769556).
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static constexpr int kRequiredMajor = 3;
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static constexpr int kRequiredMinor = 17;
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struct utsname uts;
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int major, minor;
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if (uname(&uts) != 0 ||
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strcmp(uts.sysname, "Linux") != 0 ||
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sscanf(uts.release, "%d.%d", &major, &minor) != 2 ||
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(major < kRequiredMajor || (major == kRequiredMajor && minor < kRequiredMinor))) {
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errno = ENOSYS;
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return -1;
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}
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return syscall(__NR_memfd_create, name, flags);
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}
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#else // __NR_memfd_create
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int memfd_create(const char* name ATTRIBUTE_UNUSED, unsigned int flags ATTRIBUTE_UNUSED) {
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errno = ENOSYS;
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return -1;
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}
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#endif // __NR_memfd_create
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} // namespace art
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