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/errno/libc_errno.h" 13 #include "src/string/memory_utils/inline_memcpy.h" 14 15 // TODO: Get PATH_MAX via https://github.com/llvm/llvm-project/issues/85121 16 #include <linux/limits.h> 17 18 namespace LIBC_NAMESPACE { 19 20 namespace shm_common { 21 22 LIBC_INLINE_VAR constexpr cpp::string_view SHM_PREFIX = "/dev/shm/"; 23 using SHMPath = cpp::array<char, NAME_MAX + SHM_PREFIX.size() + 1>; 24 translate_name(cpp::string_view name)25LIBC_INLINE cpp::optional<SHMPath> translate_name(cpp::string_view name) { 26 // trim leading slashes 27 size_t offset = name.find_first_not_of('/'); 28 if (offset == cpp::string_view::npos) { 29 libc_errno = EINVAL; 30 return cpp::nullopt; 31 } 32 name = name.substr(offset); 33 34 // check the name 35 if (name.size() > NAME_MAX) { 36 libc_errno = ENAMETOOLONG; 37 return cpp::nullopt; 38 } 39 if (name == "." || name == ".." || name.contains('/')) { 40 libc_errno = EINVAL; 41 return cpp::nullopt; 42 } 43 44 // prepend the prefix 45 SHMPath buffer; 46 inline_memcpy(buffer.data(), SHM_PREFIX.data(), SHM_PREFIX.size()); 47 inline_memcpy(buffer.data() + SHM_PREFIX.size(), name.data(), name.size()); 48 buffer[SHM_PREFIX.size() + name.size()] = '\0'; 49 return buffer; 50 } 51 } // namespace shm_common 52 53 } // namespace LIBC_NAMESPACE 54