std::filesystem::space (3) - Linux Manuals

std::filesystem::space: std::filesystem::space

NAME

std::filesystem::space - std::filesystem::space

Synopsis

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

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