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/*
* FTW EntropySource
* (C) 1999-2008 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/internal/es_ftw.h>
#include <botan/secmem.h>
#include <cstring>
#include <deque>
#ifndef _POSIX_C_SOURCE
#define _POSIX_C_SOURCE 199309
#endif
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <dirent.h>
#include <fcntl.h>
namespace Botan {
/**
* Returns file descriptors. Until it doesn't
*/
class File_Descriptor_Source
{
public:
/**
* @return next file descriptor, or -1 if done
*/
virtual int next_fd() = 0;
virtual ~File_Descriptor_Source() {}
};
namespace {
class Directory_Walker : public File_Descriptor_Source
{
public:
Directory_Walker(const std::string& root) { add_directory(root); }
~Directory_Walker();
int next_fd();
private:
void add_directory(const std::string&);
std::deque<std::pair<DIR*, std::string> > dirs;
};
void Directory_Walker::add_directory(const std::string& dirname)
{
DIR* dir = ::opendir(dirname.c_str());
if(dir)
dirs.push_back(std::make_pair(dir, dirname));
}
Directory_Walker::~Directory_Walker()
{
while(dirs.size())
{
::closedir(dirs[0].first);
dirs.pop_front();
}
}
int Directory_Walker::next_fd()
{
while(dirs.size())
{
std::pair<DIR*, std::string> dirinfo = dirs[0];
struct dirent* entry = ::readdir(dirinfo.first);
if(!entry)
{
::closedir(dirinfo.first);
dirs.pop_front();
continue;
}
const std::string filename = entry->d_name;
if(filename == "." || filename == "..")
continue;
const std::string full_path = dirinfo.second + '/' + filename;
struct stat stat_buf;
if(::lstat(full_path.c_str(), &stat_buf) == -1)
continue;
if(S_ISDIR(stat_buf.st_mode))
add_directory(full_path);
else if(S_ISREG(stat_buf.st_mode) && (stat_buf.st_mode & S_IROTH))
{
int fd = ::open(full_path.c_str(), O_RDONLY | O_NOCTTY);
if(fd > 0)
return fd;
}
}
return -1;
}
}
/**
* FTW_EntropySource Constructor
*/
FTW_EntropySource::FTW_EntropySource(const std::string& p) : path(p)
{
dir = 0;
}
/**
* FTW_EntropySource Destructor
*/
FTW_EntropySource::~FTW_EntropySource()
{
delete dir;
}
void FTW_EntropySource::poll(Entropy_Accumulator& accum)
{
const size_t MAX_FILES_READ_PER_POLL = 2048;
if(!dir)
dir = new Directory_Walker(path);
MemoryRegion<byte>& io_buffer = accum.get_io_buffer(4096);
for(size_t i = 0; i != MAX_FILES_READ_PER_POLL; ++i)
{
int fd = dir->next_fd();
// If we've exhaused this walk of the directory, halt the poll
if(fd == -1)
{
delete dir;
dir = 0;
break;
}
ssize_t got = ::read(fd, &io_buffer[0], io_buffer.size());
::close(fd);
if(got > 0)
accum.add(&io_buffer[0], got, .001);
if(accum.polling_goal_achieved())
break;
}
}
}
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