NAME¶

std::filesystem::space_info - std::filesystem::space_info

Synopsis¶

Defined in header <filesystem>
struct space_info {

std::uintmax_t capacity;
std::uintmax_t free; (since C++17)
std::uintmax_t available;

};

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

Member objects¶

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

Non-member functions¶

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

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

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

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==.

Example¶

// Run this code

#include <cstdint>
#include <filesystem>
#include <iostream>

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

See also¶

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