mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-25 16:50:16 +01:00
Chandler Carruth
2ddf0936fd
This library manages buffers of source code, either in-memory or mapped from the filesystem. At the moment it is a bit simplistic and assumes `mmap` is available in its implementation details. We should make this more portable in the future, but this is currently just a direct copy from the toolchain repository.
89 lines
2.4 KiB
C++
89 lines
2.4 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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#include "source/source_buffer.h"
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#include "llvm/ADT/ScopeExit.h"
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#include <errno.h>
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#include <fcntl.h>
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#include <stdint.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <system_error>
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namespace Carbon {
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auto SourceBuffer::CreateFromText(llvm::Twine text, llvm::StringRef filename)
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-> SourceBuffer {
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return SourceBuffer(filename, text.str());
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}
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static auto ErrnoToError(int errno_value) -> llvm::Error {
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return llvm::errorCodeToError(
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std::error_code(errno_value, std::generic_category()));
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}
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auto SourceBuffer::CreateFromFile(llvm::StringRef filename)
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-> llvm::Expected<SourceBuffer> {
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SourceBuffer buffer(filename);
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errno = 0;
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int file_descriptor = open(buffer.filename_.c_str(), O_RDONLY);
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if (file_descriptor == -1)
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return ErrnoToError(errno);
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// Now that we have an open file, we need to close it on any error.
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auto closer = llvm::make_scope_exit([file_descriptor] { close(file_descriptor); });
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struct stat stat_buffer = {};
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errno = 0;
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if (fstat(file_descriptor, &stat_buffer) == -1)
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return ErrnoToError(errno);
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int64_t size = stat_buffer.st_size;
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if (size == 0) {
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// Nothing to do for an empty file.
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return {std::move(buffer)};
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}
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errno = 0;
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void* mapped_text = mmap(nullptr, size, PROT_READ, MAP_PRIVATE | MAP_POPULATE,
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file_descriptor, /*offset=*/0);
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if (mapped_text == MAP_FAILED)
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return ErrnoToError(errno);
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errno = 0;
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closer.release();
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if (close(file_descriptor) == -1) {
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// Try to unmap the text. No errer handling as this is just best-effort
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// cleanup.
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munmap(mapped_text, size);
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return ErrnoToError(errno);
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}
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buffer.text_ = llvm::StringRef(static_cast<const char*>(mapped_text), size);
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assert(!buffer.text_.empty() &&
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"Must not have an empty text when we have mapped data from a file!");
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return {std::move(buffer)};
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}
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SourceBuffer::~SourceBuffer() {
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if (is_string_rep_) {
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string_storage_.~decltype(string_storage_)();
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return;
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}
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if (!text_.empty()) {
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errno = 0;
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int result =
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munmap(const_cast<void*>((const void*)text_.data()), text_.size());
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(void)result;
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assert(result != -1 && "Unmapping text failed!");
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}
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}
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} // namespace Carbon
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