C++文件路径处理4 - 根据软连接的路径获取真实路径&根据相对路径获取绝对路径
- 1. 关键词
- 2. filesystem.h
- 3. filesystem_unix.cpp
- 4. filesystem_win.cpp
- 5. filepath.h
- 6. filepath.cpp
- 7. 测试代码
- 8. 运行结果
- 9. 源码地址
1. 关键词
C++ 文件路径处理 软连接 真实路径 相对路径 绝对路径 跨平台
2. filesystem.h
#pragma once
#include <string>
#include <iostream>
#include <cstdio>
#include "filetype.h"
namespace cutl
{
// 根据软连接的路径获取真实路径
std::string file_readlink(const std::string &filepath);
// 相对路径转绝对路径
std::string absolute_path(const std::string &releative_path);
} // namespace cutl
3. filesystem_unix.cpp
#if defined(_WIN32) || defined(__WIN32__)
// do nothing
#else
#include <unistd.h>
#include <sys/stat.h>
#include <dirent.h>
#include <stack>
#include <cstring>
#include <utime.h>
#include <stdlib.h>
#include <sys/time.h>
#include "filesystem.h"
#include "inner/logger.h"
namespace cutl
{
std::string file_readlink(const std::string &filepath)
{
char buffer[MAX_PATH_LEN] = {0};
ssize_t len = ::readlink(filepath.c_str(), buffer, MAX_PATH_LEN);
if (len < 0)
{
CUTL_ERROR("readlink error. filepath:" + filepath + ", error:" + strerror(errno));
return "";
}
return std::string(buffer, len);
}
std::string absolute_path(const std::string &releative_path)
{
char absPath[PATH_MAX] = {0};
auto pAbsolutePath = realpath(releative_path.c_str(), absPath);
if (pAbsolutePath == nullptr)
{
CUTL_WARN("realpath failure for " + releative_path + ", pAbsolutePath is nullptr, absPath:" + absPath);
return std::string(absPath);
}
return std::string(absPath);
}
} // namespace cutl
#endif // defined(_WIN32) || defined(__WIN32__)
4. filesystem_win.cpp
#if defined(_WIN32) || defined(__WIN32__)
#include <io.h>
#include <direct.h>
#include <Windows.h>
#include <stdlib.h>
#include "strutil.h"
#include "filesystem.h"
#include "logger.h"
namespace cutl
{
std::string file_readlink(const std::string &filepath)
{
CUTL_ERROR("file_readlink() is not supported on Windows");
return "";
}
std::string absolute_path(const std::string &releative_path)
{
char absPath[MAX_PATH_LEN] = {0};
auto pAbsolutePath = _fullpath(absPath, releative_path.c_str(), MAX_PATH_LEN);
if (pAbsolutePath == nullptr)
{
CUTL_WARN("_fullpath failure, pAbsolutePath is nullptr");
return std::string(absPath);
}
return std::string(absPath);
}
} // namespace cutl
#endif // defined(_WIN32) || defined(__WIN32__)
5. filepath.h
#pragma once
#include <string>
#include <iostream>
#include <cstdio>
#include "filetype.h"
namespace cutl
{
/**
* @brief The class for file path operations.
*
*/
class filepath
{
public:
/**
* @brief Construct a new filepath object
*
* @param path file path string
*/
filepath(const std::string &path);
/**
* @brief Construct a new filepath object by copy
*
* @param other other filepath object
*/
filepath(const filepath &other);
/**
* @brief Assign operator, assign a new filepath object by copy
*
* @param other other filepath object
* @return filepath& the reference of the current filepath object
*/
filepath &operator=(const filepath &other);
/**
* @brief Destroy the filepath object
*
*/
~filepath() = default;
public:
/**
* @brief Get the real path referenced by symbolic link
*
* @note This function only works on Unix-like systems, not support on Windows.
*
* @return real path referenced by symbolic link or shortcuts
*/
std::string realpath() const;
/**
* @brief Get the absolute path of the filepath.
*
* @return std::string the absolute path of the filepath.
*/
std::string abspath() const;
private:
std::string filepath_;
};
/**
* @brief Define the output stream operator for filepath object.
*
* @param os the std::ostream object
* @param fp the filepath object to be output
* @return std::ostream& the reference of the std::ostream object after outputing the filepath object.
*/
std::ostream &operator<<(std::ostream &os, const filepath &fp);
/**
* @brief Create a filepath object from a string.
*
* @param path file path string
* @return filepath object
*/
filepath path(const std::string &path);
} // namespace cutl
6. filepath.cpp
#include "filepath.h"
#include "inner/logger.h"
#include "inner/filesystem.h"
#include "strutil.h"
#include "sysutil.h"
namespace cutl
{
static constexpr char win_separator = '\\';
static constexpr char unix_separator = '/';
void fixpath(std::string &path)
{
if (win_separator == filepath::separator())
{
for (size_t i = 0; i < path.size(); i++)
{
if (path[i] == unix_separator)
{
path[i] = win_separator;
}
}
}
else if (unix_separator == filepath::separator())
{
for (size_t i = 0; i < path.size(); i++)
{
if (path[i] == win_separator)
{
path[i] = unix_separator;
}
}
}
else
{
// do nothing
}
while (path.empty() || path.back() == filepath::separator())
{
path.pop_back();
}
}
filepath::filepath(const std::string &path)
{
filepath_ = path;
fixpath(filepath_);
}
filepath::filepath(const filepath &other)
{
filepath_ = other.filepath_;
}
filepath &filepath::operator=(const filepath &other)
{
this->filepath_ = other.filepath_;
return *this;
}
char filepath::separator()
{
#if defined(_WIN32) || defined(__WIN32__)
return win_separator;
#else
return unix_separator;
#endif
}
std::string filepath::str() const
{
return filepath_;
}
filepath filepath::join(const std::string &filename) const
{
std::string path = filepath_ + separator() + filename;
return filepath(path);
}
std::string filepath::realpath() const
{
if (issymlink())
{
return file_readlink(filepath_);
}
CUTL_ERROR("not a symlink, cannot get realpath");
return "";
}
std::string filepath::abspath() const
{
auto filepath = filepath_;
if (starts_with(filepath_, "~"))
{
// 把 ~ 替换成用户目录
filepath = homedir() + filepath_.substr(1);
}
return absolute_path(filepath);
}
std::ostream &operator<<(std::ostream &os, const filepath &fp)
{
os << fp.str();
return os;
}
filepath path(const std::string &path)
{
return filepath(path);
}
} // namespace cutl
7. 测试代码
#include "common.hpp"
#include "fileutil.h"
void TestRealpathAndAbspath()
{
PrintSubTitle("TestRealpathAndAbspath");
auto symlink_path = cutl::path("./fileutil_test/link4");
std::cout << "symlink_path: " << symlink_path << std::endl;
std::cout << "realpath: " << symlink_path.realpath() << std::endl;
std::cout << "abspath: " << symlink_path.abspath() << std::endl;
auto path1 = cutl::path("../common_util/fileutil_test/file4.data");
std::cout << "path1 abspath: " << path1.abspath()
<< ", exists: " << path1.exists() << std::endl;
auto path2 = cutl::path("./fileutil_test/file4.data");
std::cout << "path2 abspath: " << path2.abspath()
<< ", exists: " << path2.exists() << std::endl;
auto path3 = cutl::path("./fileutil_test/../../common_util/fileutil_test/file4.data");
std::cout << "path3 abspath: " << path3.abspath()
<< ", exists: " << path3.exists() << std::endl;
auto path4 = cutl::path("./fileutil_test/../../common_util/fileutil_test/file_xx.data");
std::cout << "path4 abspath: " << path4.abspath()
<< ", exists: " << path4.exists() << std::endl;
auto path5 = cutl::path("~/workspace/common_util/fileutil_test/file4.data");
std::cout << "path5 abspath: " << path5.abspath()
<< ", exists: " << path5.exists() << std::endl;
}
8. 运行结果
---------------------------------------TestRealpathAndAbspath---------------------------------------
symlink_path: ./fileutil_test/link4
realpath: /Users/spencer/workspace/common_util/fileutil_test/file4.data
abspath: /Users/spencer/workspace/common_util/fileutil_test/file4.data
path1 abspath: /Users/spencer/workspace/common_util/fileutil_test/file4.data, exists: 1
path2 abspath: /Users/spencer/workspace/common_util/fileutil_test/file4.data, exists: 1
path3 abspath: /Users/spencer/workspace/common_util/fileutil_test/file4.data, exists: 1
path4 abspath: [2024-06-26 12:25:45.877][W]]0x7ff85b8d5fc0](cutl) [filesystem_unix.cpp:46:absolute_path] realpath failure for ./fileutil_test/../../common_util/fileutil_test/file_xx.data, pAbsolutePath is nullptr, absPath:/Users/spencer/workspace/common_util/fileutil_test/file_xx.data
/Users/spencer/workspace/common_util/fileutil_test/file_xx.data, exists: 0
9. 源码地址
更多详细代码，请查看本人写的C++ 通用工具库: common_util, 本项目已开源，代码简洁，且有详细的文档和Demo。
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