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1//===---------- Shared implementations for shm_open/shm_unlink ------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "src/__support/CPP/array.h"
10#include "src/__support/CPP/optional.h"
11#include "src/__support/CPP/string_view.h"
12#include "src/__support/libc_errno.h"
13#include "src/__support/macros/config.h"
14#include "src/string/memory_utils/inline_memcpy.h"
15
16// TODO: Get PATH_MAX via https://github.com/llvm/llvm-project/issues/85121
17#include <linux/limits.h>
18
19namespace LIBC_NAMESPACE_DECL {
20
21namespace shm_common {
22
23LIBC_INLINE_VAR constexpr cpp::string_view SHM_PREFIX = "/dev/shm/";
24using SHMPath = cpp::array<char, NAME_MAX + SHM_PREFIX.size() + 1>;
25
26LIBC_INLINE cpp::optional<SHMPath> translate_name(cpp::string_view name) {
27 // trim leading slashes
28 size_t offset = name.find_first_not_of('/');
29 if (offset == cpp::string_view::npos) {
30 libc_errno = EINVAL;
31 return cpp::nullopt;
32 }
33 name = name.substr(offset);
34
35 // check the name
36 if (name.size() > NAME_MAX) {
37 libc_errno = ENAMETOOLONG;
38 return cpp::nullopt;
39 }
40 if (name == "." || name == ".." || name.contains('/')) {
41 libc_errno = EINVAL;
42 return cpp::nullopt;
43 }
44
45 // prepend the prefix
46 SHMPath buffer;
47 inline_memcpy(buffer.data(), SHM_PREFIX.data(), SHM_PREFIX.size());
48 inline_memcpy(buffer.data() + SHM_PREFIX.size(), name.data(), name.size());
49 buffer[SHM_PREFIX.size() + name.size()] = '\0';
50 return buffer;
51}
52} // namespace shm_common
53
54} // namespace LIBC_NAMESPACE_DECL
55

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source code of libc/src/sys/mman/linux/shm_common.h