Create Folder For File Path If Parent Directory Not Exist

We want to create a file which path looks like /Folder1/Folder2/Folder3/file.txt. The parent directory Folder3 of file.txt has to be there, or the creating action will fail. Similarly, Folder2 and Folder1 need to be on the disk firstly. If you are a Linux OS user, you can use the following command line to create folders.

mkdir -p /Folder1/Folder2/Folder3

Now the post introduces how to create these parent directories in CPlusPlus program.

#include <iostream> 
#include <sys/stat.h> 
#include <errno.h>

bool CreateDirForFilePath(const std::string& path)
{
    size_t pos = 0, found;
    found = path.find_last_of( '/', std::string::npos );
    if( found != std::string::npos )
    {
        std::string folder = path.substr( 0, found );
        if( folder.empty() == false )
        {
            LOG( INFO, "found folder: ", folder );
            return CreateDirectories( folder );
        }
    }
    return true;
}


bool CreateDirectories(const std::string& path) 
{
    size_t current = 0, found;
    while ((found = path.find_first_of('/', current)) != std::string::npos) {
        std::string sub_path = path.substr(0, found++);
        current = found;
        if (sub_path.empty()) continue;
        if (!CreateDirectory(sub_path)) {
            return false;
        }
    }
    return CreateDirectory(path);
}


bool CreateDirectory(const std::string& path) 
{
    int status = mkdir(path.c_str(), S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH);
    if (status == 0) {
        LOG( INFO, "created dir: ", path );
        return true;
    } else {
        if (errno == EEXIST) {
            return true;
        } else {
            LOG( ERR, "failed to create dir: ", path, ", ", strerror(errno) );
            return false;
        }
    }
}

The interface CreateDirForFilePath will find the directory prefix and create neccessary folders. These code can be compiled on Linux OS.