How can I copy a directory using Boost Filesystem
Solution 1
bool copyDir(
boost::filesystem::path const & source,
boost::filesystem::path const & destination
)
{
namespace fs = boost::filesystem;
try
{
// Check whether the function call is valid
if(
!fs::exists(source) ||
!fs::is_directory(source)
)
{
std::cerr << "Source directory " << source.string()
<< " does not exist or is not a directory." << '\n'
;
return false;
}
if(fs::exists(destination))
{
std::cerr << "Destination directory " << destination.string()
<< " already exists." << '\n'
;
return false;
}
// Create the destination directory
if(!fs::create_directory(destination))
{
std::cerr << "Unable to create destination directory"
<< destination.string() << '\n'
;
return false;
}
}
catch(fs::filesystem_error const & e)
{
std::cerr << e.what() << '\n';
return false;
}
// Iterate through the source directory
for(
fs::directory_iterator file(source);
file != fs::directory_iterator(); ++file
)
{
try
{
fs::path current(file->path());
if(fs::is_directory(current))
{
// Found directory: Recursion
if(
!copyDir(
current,
destination / current.filename()
)
)
{
return false;
}
}
else
{
// Found file: Copy
fs::copy_file(
current,
destination / current.filename()
);
}
}
catch(fs::filesystem_error const & e)
{
std:: cerr << e.what() << '\n';
}
}
return true;
}
Usage:
copyDir(boost::filesystem::path("/home/nijansen/test"), boost::filesystem::path("/home/nijansen/test_copy"));
(Unix)
copyDir(boost::filesystem::path("C:\\Users\\nijansen\\test"), boost::filesystem::path("C:\\Users\\nijansen\\test2"));
(Windows)
As far as I see, the worst that can happen is that nothing happens, but I won't promise anything! Use at your own risk.
Please note that the directory you're copying to must not exist. If directories within the directory you are trying to copy can't be read (think rights management), they will be skipped, but the other ones should still be copied.
Update
Refactored the function respective to the comments. Furthermore the function now returns a success result. It will return false
if the requirements for the given directories or any directory within the source directory are not met, but not if a single file could not be copied.
Solution 2
Since C++17 you don't need boost for this operation anymore as filesystem has been added to the standard.
#include <exception>
#include <filesystem>
namespace fs = std::filesystem;
int main()
{
fs::path source = "path/to/source/folder";
fs::path target = "path/to/target/folder";
try {
fs::copy(source, target, fs::copy_options::recursive);
}
catch (std::exception& e) { // Not using fs::filesystem_error since std::bad_alloc can throw too.
// Handle exception or use error code overload of fs::copy.
}
}
See also std::filesystem::copy_options
.
Solution 3
I see this version as an improved upon version of @nijansen's answer. It also supports the source and/or destination directories to be relative.
namespace fs = boost::filesystem;
void copyDirectoryRecursively(const fs::path& sourceDir, const fs::path& destinationDir)
{
if (!fs::exists(sourceDir) || !fs::is_directory(sourceDir))
{
throw std::runtime_error("Source directory " + sourceDir.string() + " does not exist or is not a directory");
}
if (fs::exists(destinationDir))
{
throw std::runtime_error("Destination directory " + destinationDir.string() + " already exists");
}
if (!fs::create_directory(destinationDir))
{
throw std::runtime_error("Cannot create destination directory " + destinationDir.string());
}
for (const auto& dirEnt : fs::recursive_directory_iterator{sourceDir})
{
const auto& path = dirEnt.path();
auto relativePathStr = path.string();
boost::replace_first(relativePathStr, sourceDir.string(), "");
fs::copy(path, destinationDir / relativePathStr);
}
}
The main differences are exceptions instead of return values, the use of recursive_directory_iterator
and boost::replace_first
to strip the common part of the iterator path, and relying on boost::filesystem::copy()
to do the right thing with different file types (preserving symlinks, for instance).
Ant
Senior Software Engineer currently working in the audio industry.
Updated on November 28, 2020Comments
-
Ant over 3 years
How can I copy a directory using Boost Filesystem? I have tried boost::filesystem::copy_directory() but that only creates the target directory and does not copy the contents.