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std::filesystem::space_info

From cppreference.com
 
C++
 
Filesystem library
Classes
Functions
File types
 
Defined in header <filesystem>
struct space_info {

    std::uintmax_t capacity;
    std::uintmax_t free;
    std::uintmax_t available;

};
 (since C++17)

Represents the filesystem information as determined by filesystem::space.

Contents

[edit] Member objects

capacity
 total size of the filesystem, in bytes
(public member object)
free
 free space on the filesystem, in bytes
(public member object)
available
 free space available to a non-privileged process (may be equal or less than free)
(public member object)

[edit] Non-member functions

operator==
(C++20)
 compares two space_infos
(function)

operator==(std::filesystem::space_info)

friend bool operator==( const space_info&, const space_info& ) = default;
 (since C++20)

Checks if capacity, free and available of both arguments are equal respectively.

This function is not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when std::filesystem::space_info is an associated class of the arguments.

The != operator is synthesized from operator==.

[edit] Example

Run this code
#include <cstdint>
#include <filesystem>
#include <iostream>
#include <locale>
 
std::uintmax_t disk_usage_percent(const std::filesystem::space_info& si,
                                  bool is_privileged = false) noexcept
{
    if (constexpr std::uintmax_t X(-1);
        si.capacity == 0 || si.free == 0 || si.available == 0 ||
        si.capacity == X || si.free == X || si.available == X
    )
        return 100;
 
    std::uintmax_t unused_space = si.free, capacity = si.capacity;
    if (!is_privileged)
    {
        const std::uintmax_t privileged_only_space = si.free - si.available;
        unused_space -= privileged_only_space;
        capacity -= privileged_only_space;
    }
    const std::uintmax_t used_space{capacity - unused_space};
    return 100 * used_space / capacity;
}
 
void print_disk_space_info(auto const& dirs, int width = 14)
{
    (std::cout << std::left).imbue(std::locale("en_US.UTF-8"));
 
    for (const auto s : {"Capacity", "Free", "Available", "Use%", "Dir"})
        std::cout << "│ " << std::setw(width) << s << ' ';
 
    for (std::cout << '\n'; auto const& dir : dirs)
    {
        std::error_code ec;
        const std::filesystem::space_info si = std::filesystem::space(dir, ec);
        for (auto x : {si.capacity, si.free, si.available, disk_usage_percent(si)})
            std::cout << "│ " << std::setw(width) << static_cast<std::intmax_t>(x) << ' ';
        std::cout << "│ " << dir << '\n';
    }
}
 
int main()
{
    const auto dirs = {"/dev/null", "/tmp", "/home", "/proc", "/null"};
    print_disk_space_info(dirs);
}

Possible output: 

│ Capacity       │ Free           │ Available      │ Use%           │ Dir            
│ 84,417,331,200 │ 42,732,986,368 │ 40,156,028,928 │ 50             │ /dev/null
│ 84,417,331,200 │ 42,732,986,368 │ 40,156,028,928 │ 50             │ /tmp
│ -1             │ -1             │ -1             │ 100            │ /home
│ 0              │ 0              │ 0              │ 100            │ /proc
│ -1             │ -1             │ -1             │ 100            │ /null

[edit] See also

(C++17)
 determines available free space on the file system
(function) [edit]
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