File size: 3,855 Bytes
055eba4 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 | // Copyright 2024 Google LLC
// SPDX-License-Identifier: Apache-2.0
//
// 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
//
// https://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.
// Safe to be first, does not include POSIX headers.
#include "hwy/detect_compiler_arch.h"
// Only compile this file on non-Windows; it replaces io_win.cc. It is easier to
// check this in source code because we support multiple build systems.
#if !HWY_OS_WIN
// Request POSIX 2008, including `pread()` and `posix_fadvise()`.
#if !defined(_XOPEN_SOURCE) || _XOPEN_SOURCE < 700
#undef _XOPEN_SOURCE
#define _XOPEN_SOURCE 700
#endif
#if !defined(_POSIX_C_SOURCE) || _POSIX_C_SOURCE < 200809
#define _POSIX_C_SOURCE 200809
#endif
// Make `off_t` 64-bit even on 32-bit systems. Works for Android >= r15c.
#undef _FILE_OFFSET_BITS
#define _FILE_OFFSET_BITS 64
#include <fcntl.h> // open
#include <stddef.h>
#include <stdint.h>
#include <stdio.h> // SEEK_END - unistd isn't enough for IDE.
#include <sys/stat.h> // O_RDONLY
#include <unistd.h> // read, write, close
#include <memory>
#include "compression/io.h"
#include "hwy/base.h" // HWY_ASSERT
namespace gcpp {
class FilePosix : public File {
int fd_ = 0;
public:
explicit FilePosix(int fd) : fd_(fd) { HWY_ASSERT(fd > 0); }
~FilePosix() override {
if (fd_ != 0) {
HWY_ASSERT(close(fd_) != -1);
}
}
uint64_t FileSize() const override {
static_assert(sizeof(off_t) == 8, "64-bit off_t required");
const off_t size = lseek(fd_, 0, SEEK_END);
if (size < 0) {
return 0;
}
return static_cast<uint64_t>(size);
}
bool Read(uint64_t offset, uint64_t size, void* to) const override {
uint8_t* bytes = reinterpret_cast<uint8_t*>(to);
uint64_t pos = 0;
for (;;) {
// pread seems to be faster than lseek + read when parallelized.
const auto bytes_read = pread(fd_, bytes + pos, size - pos, offset + pos);
if (bytes_read <= 0) break;
pos += bytes_read;
HWY_ASSERT(pos <= size);
if (pos == size) break;
}
return pos == size; // success if managed to read desired size
}
bool Write(const void* from, uint64_t size, uint64_t offset) override {
const uint8_t* bytes = reinterpret_cast<const uint8_t*>(from);
uint64_t pos = 0;
for (;;) {
const auto bytes_written =
pwrite(fd_, bytes + pos, size - pos, offset + pos);
if (bytes_written <= 0) break;
pos += bytes_written;
HWY_ASSERT(pos <= size);
if (pos == size) break;
}
return pos == size; // success if managed to write desired size
}
}; // FilePosix
HWY_MAYBE_UNUSED extern std::unique_ptr<File> OpenFileGoogle(
const Path& filename, const char* mode);
std::unique_ptr<File> OpenFileOrNull(const Path& filename, const char* mode) {
std::unique_ptr<File> file; // OpenFileGoogle omitted
if (file) return file;
const bool is_read = mode[0] != 'w';
const int flags = is_read ? O_RDONLY : O_CREAT | O_RDWR | O_TRUNC;
const int fd = open(filename.path.c_str(), flags, 0644);
if (fd < 0) return file;
#if HWY_OS_LINUX && (!defined(__ANDROID_API__) || __ANDROID_API__ >= 21)
if (is_read) {
// Doubles the readahead window, which seems slightly faster when cached.
(void)posix_fadvise(fd, 0, 0, POSIX_FADV_SEQUENTIAL);
}
#endif
return std::make_unique<FilePosix>(fd);
}
} // namespace gcpp
#endif // !HWY_OS_WIN
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