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// Copyright 2016 The Bazel Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef BAZEL_SRC_TOOLS_SINGLEJAR_MAPPED_FILE_H_
#define BAZEL_SRC_TOOLS_SINGLEJAR_MAPPED_FILE_H_ 1
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>
#include <string>
#include "src/tools/singlejar/diag.h"
/*
* A mapped read-only file with auto closing.
*
* MappedFile::Open maps a file with specified name to memory as read-only.
* It is assumed that the address space is large enough for that.
* MappedFile::Close deletes the mapping. The destructor calls it, too.
* A predictable set of methods provide conversion between file offsets and
* mapped addresses, returns map size, etc.
*
* The implementation is 64-bit Linux or OSX specific.
*/
#if !((defined(__linux__) || defined(__APPLE__)) && __SIZEOF_POINTER__ == 8)
#error This code for 64 bit Unix.
#endif
class MappedFile {
public:
MappedFile() : mapped_start_(nullptr), mapped_end_(nullptr), fd_(-1) {}
~MappedFile() { Close(); }
bool Open(const std::string& path) {
if (is_open()) {
diag_errx(1, "%s:%d: This instance is already open", __FILE__, __LINE__);
}
if ((fd_ = open(path.c_str(), O_RDONLY)) < 0) {
diag_warn("%s:%d: open %s:", __FILE__, __LINE__, path.c_str());
return false;
}
// Map the file, even if it is empty (in which case allocate 1 byte to it).
struct stat st;
if (fstat(fd_, &st) ||
(mapped_start_ = static_cast<unsigned char *>(
mmap(nullptr, st.st_size ? st.st_size : 1, PROT_READ, MAP_PRIVATE,
fd_, 0))) == MAP_FAILED) {
if (S_ISDIR(st.st_mode)) {
diag_warn("%s:%d: %s is a directory", __FILE__, __LINE__, path.c_str());
} else {
diag_warn("%s:%d: mmap %s:", __FILE__, __LINE__, path.c_str());
}
close(fd_);
fd_ = -1;
return false;
}
mapped_end_ = mapped_start_ + st.st_size;
return true;
}
void Close() {
if (is_open()) {
munmap(mapped_start_, mapped_end_ - mapped_start_);
mapped_start_ = mapped_end_ = nullptr;
close(fd_);
fd_ = -1;
}
}
bool mapped(const void *addr) const {
return mapped_start_ <= addr && addr < mapped_end_;
}
const unsigned char *start() const { return mapped_start_; }
const unsigned char *end() const { return mapped_end_; }
const unsigned char *address(off_t offset) const {
return mapped_start_ + offset;
}
off_t offset(const void *address) const {
return reinterpret_cast<const unsigned char *>(address) - mapped_start_;
}
int fd() const { return fd_; }
size_t size() const { return mapped_end_ - mapped_start_; }
bool is_open() { return fd_ >= 0; }
private:
unsigned char *mapped_start_;
unsigned char *mapped_end_;
int fd_;
};
#endif // BAZEL_SRC_TOOLS_SINGLEJAR_MAPPED_FILE_H_
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