std::filesystem::space

Defined in header `<filesystem>`
std::filesystem::space_info space(const std::filesystem::path& p); std::filesystem::space_info space(const std::filesystem::path& p, std::error_code& ec) noexcept;		(since C++17)

Determines the information about the filesystem on which the pathname p is located, as if by POSIX statvfs

Populates and returns an object of type space_info, set from the members of the POSIX struct statvfs as follows

space_info.capacity is set as if by f_blocks*f_frsize
space_info.free is set to f_bfree*f_frsize
space_info.available is set to f_bavail*f_frsize
Any member that could not be determined is set to static_cast<uintmax_t>(-1)

The non-throwing overload sets all members to static_cast<uintmax_t>(-1) on error.

Parameters

p	-	path to examine
ec	-	out-parameter for error reporting in the non-throwing overload

Return value

The filesystem information (a space_info object)

Exceptions

The overload that does not take a std::error_code& parameter throws filesystem_error on underlying OS API errors, constructed with p as the first path argument and the OS error code as the error code argument. The overload taking a std::error_code& parameter sets it to the OS API error code if an OS API call fails, and executes ec.clear() if no errors occur. Any overload not marked noexcept may throw std::bad_alloc if memory allocation fails.

Notes

space_info.available may be less than space_info.free

Example

Run this code

#include <iostream>
#include <filesystem>
namespace fs = std::filesystem;
int main()
{
    fs::space_info devi = fs::space("/dev/null");
    fs::space_info tmpi = fs::space("/tmp");

    std::cout << ".        Capacity       Free      Available\n"
              << "/dev:   " << devi.capacity << "   "
              << devi.free << "   " << devi.available  << '\n'
              << "/tmp: " << tmpi.capacity << " "
              << tmpi.free << " " << tmpi.available  << '\n';
}

Possible output:

.         Capacity       Free      Available
/dev:   4175114240   4175110144   4175110144
/tmp: 420651237376 411962273792 390570749952