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/*************************************************
* FTW EntropySource Source File *
* (C) 1999-2008 Jack Lloyd *
*************************************************/
#include <botan/es_ftw.h>
#include <botan/secmem.h>
#include <botan/util.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 {
namespace {
class Directory_Walker : public FTW_EntropySource::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))
{
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;
}
u32bit FTW_EntropySource::slow_poll(byte buf[], u32bit length)
{
if(!dir)
dir = new Directory_Walker(path);
SecureVector<byte> read_buf(4096);
u32bit bytes_read = 0;
while(bytes_read < length * 32)
{
int fd = dir->next_fd();
if(fd == -1)
{
delete dir;
dir = new Directory_Walker(path);
fd = dir->next_fd();
if(fd == -1) // still fails (directory not mounted, etc) -> fail
return 0;
}
ssize_t got = ::read(fd, read_buf.begin(), read_buf.size());
if(got > 0 && got <= read_buf.size())
{
for(ssize_t i = 0; i != got; ++i)
buf[i % length] ^= read_buf[i];
// never count any one file for more than 128 bytes
bytes_read += std::min<u32bit>(got, 128);
}
::close(fd);
}
return length;
}
u32bit FTW_EntropySource::fast_poll(byte[], u32bit)
{
return 0; // no op
}
}
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