50 lines
1.7 KiB
C++
50 lines
1.7 KiB
C++
/*
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* Copyright (C) 2014 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 "berberis/kernel_api/unistd_emulation.h"
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#include <fcntl.h> // AT_FDCWD, AT_SYMLINK_NOFOLLOW
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#include <cerrno>
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#include <cstring> // memcpy
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#include "berberis/kernel_api/main_executable_real_path_emulation.h"
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namespace berberis {
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ssize_t ReadLinkAtForGuest(int dirfd, const char* path, char* buf, size_t buf_size) {
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const char* real_path = TryReadLinkToMainExecutableRealPath(path);
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if (!real_path) {
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return readlinkat(dirfd, path, buf, buf_size);
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}
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// readlink have quite unusual semantic WRT handling of buffer length. readlink should not add
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// terminating null byte if it doesn't fit in the buffer, so can't use strlcpy. readlink should
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// return the number of bytes placed in buffer thus strncpy doesn't help.
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size_t real_path_len = strlen(real_path);
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if (real_path_len + 1 > buf_size) {
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memcpy(buf, real_path, buf_size);
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return buf_size;
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}
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memcpy(buf, real_path, real_path_len + 1);
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return real_path_len;
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}
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ssize_t ReadLinkForGuest(const char* path, char* buf, size_t buf_size) {
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return ReadLinkAtForGuest(AT_FDCWD, path, buf, buf_size);
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}
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} // namespace berberis
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