std::filesystem::space

 

C++

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Feature test macros (C++20)

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Filesystem library (C++17)

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Technical specifications

Symbols index

External libraries

 

Filesystem library

Classes
filesystem::path filesystem::filesystem_error filesystem::directory_entry filesystem::directory_iterator filesystem::recursive_directory_iterator      filesystem::file_status	filesystem::space_info filesystem::file_type filesystem::perms filesystem::perm_options filesystem::copy_options filesystem::directory_options filesystem::file_time_type
Functions
filesystem::absolute filesystem::canonicalfilesystem::weakly_canonical filesystem::relativefilesystem::proximate filesystem::copy filesystem::copy_file filesystem::copy_symlink filesystem::create_directory filesystem::create_directories filesystem::create_hard_link filesystem::create_symlink filesystem::create_directory_symlink filesystem::current_path	filesystem::exists filesystem::equivalent filesystem::file_size filesystem::hard_link_count filesystem::last_write_time filesystem::permissions filesystem::read_symlink filesystem::remove filesystem::remove_all filesystem::rename filesystem::resize_file filesystem::space filesystem::status filesystem::symlink_status filesystem::temp_directory_path
File types
filesystem::is_block_file filesystem::is_character_file filesystem::is_directory filesystem::is_empty filesystem::status_known	filesystem::is_fifo filesystem::is_other filesystem::is_regular_file filesystem::is_socket filesystem::is_symlink

 

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 filesystem::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<std::uintmax_t>(-1)

The non-throwing overload sets all members to static_cast<std::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 filesystem::space_info object).

Exceptions

The overload that does not take a std::error_code& parameter throws filesystem::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>
#include <cstdint>
 
void print_space_info(auto const& dirs, int width = 15)
{
    (std::cout << std::left).imbue(std::locale("en_US.UTF-8"));
    for (const auto s : {"Capacity", "Free", "Available", "Dir"})
        std::cout << "│ " << std::setw(width) << s << ' ';
    std::cout << '\n';
    std::error_code ec;
    for (auto const& dir : dirs) {
        const std::filesystem::space_info si = std::filesystem::space(dir, ec);
        std::cout
            << "│ " << std::setw(width) << static_cast<std::intmax_t>(si.capacity) << ' '
            << "│ " << std::setw(width) << static_cast<std::intmax_t>(si.free) << ' '
            << "│ " << std::setw(width) << static_cast<std::intmax_t>(si.available) << ' '
            << "│ " << dir << '\n';
    }
}
 
int main()
{
    const auto dirs = { "/dev/null", "/tmp", "/home", "/null" };
    print_space_info(dirs);
}

Possible output:

│ Capacity        │ Free            │ Available       │ Dir            
│ 84,417,331,200  │ 24,069,705,728  │ 21,492,748,288  │ /dev/null
│ 84,417,331,200  │ 24,069,705,728  │ 21,492,748,288  │ /tmp
│ 250,321,567,744 │ 37,623,181,312  │ 25,152,159,744  │ /home
│ -1              │ -1              │ -1              │ /null

See also

space_info (C++17)

information about free and available space on the filesystem (class)