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// filesystem unique_path.cpp --------------------------------------------------------//
// Copyright Beman Dawes 2010
// Distributed under the Boost Software License, Version 1.0.
// See http://www.boost.org/LICENSE_1_0.txt
// Library home page: http://www.boost.org/libs/filesystem
//--------------------------------------------------------------------------------------//
// define BOOST_FILESYSTEM_SOURCE so that <boost/filesystem/config.hpp> knows
// the library is being built (possibly exporting rather than importing code)
#define BOOST_FILESYSTEM_SOURCE
#ifndef BOOST_SYSTEM_NO_DEPRECATED
# define BOOST_SYSTEM_NO_DEPRECATED
#endif
#include <boost/filesystem/operations.hpp>
#include <cassert>
# ifdef BOOST_POSIX_API
# include <fcntl.h>
# ifdef BOOST_HAS_UNISTD_H
# include <unistd.h>
# endif
# else // BOOST_WINDOWS_API
# include <windows.h>
# include <wincrypt.h>
# ifdef _MSC_VER
# pragma comment(lib, "Advapi32.lib")
# endif
# endif
namespace {
void fail(int err, boost::system::error_code* ec)
{
if (ec == 0)
BOOST_FILESYSTEM_THROW( boost::system::system_error(err,
boost::system::system_category(),
"boost::filesystem::unique_path"));
ec->assign(err, boost::system::system_category());
return;
}
#ifdef BOOST_WINDOWS_API
int acquire_crypt_handle(HCRYPTPROV& handle)
{
if (::CryptAcquireContextW(&handle, 0, 0, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT | CRYPT_SILENT))
return 0;
int errval = ::GetLastError();
if (errval != NTE_BAD_KEYSET)
return errval;
if (::CryptAcquireContextW(&handle, 0, 0, PROV_RSA_FULL, CRYPT_NEWKEYSET | CRYPT_VERIFYCONTEXT | CRYPT_SILENT))
return 0;
errval = ::GetLastError();
// Another thread could have attempted to create the keyset at the same time.
if (errval != NTE_EXISTS)
return errval;
if (::CryptAcquireContextW(&handle, 0, 0, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT | CRYPT_SILENT))
return 0;
return ::GetLastError();
}
#endif
void system_crypt_random(void* buf, std::size_t len, boost::system::error_code* ec)
{
# ifdef BOOST_POSIX_API
int file = open("/dev/urandom", O_RDONLY);
if (file == -1)
{
file = open("/dev/random", O_RDONLY);
if (file == -1)
{
fail(errno, ec);
return;
}
}
size_t bytes_read = 0;
while (bytes_read < len)
{
ssize_t n = read(file, buf, len - bytes_read);
if (n == -1)
{
close(file);
fail(errno, ec);
return;
}
bytes_read += n;
buf = static_cast<char*>(buf) + n;
}
close(file);
# else // BOOST_WINDOWS_API
HCRYPTPROV handle;
int errval = acquire_crypt_handle(handle);
if (!errval)
{
BOOL gen_ok = ::CryptGenRandom(handle, static_cast<DWORD>(len), static_cast<unsigned char*>(buf));
if (!gen_ok)
errval = ::GetLastError();
::CryptReleaseContext(handle, 0);
}
if (!errval) return;
fail(errval, ec);
# endif
}
} // unnamed namespace
namespace boost { namespace filesystem { namespace detail {
BOOST_FILESYSTEM_DECL
path unique_path(const path& model, system::error_code* ec)
{
// This function used wstring for fear of misidentifying
// a part of a multibyte character as a percent sign.
// However, double byte encodings only have 80-FF as lead
// bytes and 40-7F as trailing bytes, whereas % is 25.
// So, use string on POSIX and avoid conversions.
path::string_type s( model.native() );
#ifdef BOOST_WINDOWS_API
const wchar_t hex[] = L"0123456789abcdef";
const wchar_t percent = L'%';
#else
const char hex[] = "0123456789abcdef";
const char percent = '%';
#endif
char ran[] = "123456789abcdef"; // init to avoid clang static analyzer message
// see ticket #8954
assert(sizeof(ran) == 16);
const int max_nibbles = 2 * sizeof(ran); // 4-bits per nibble
int nibbles_used = max_nibbles;
for(path::string_type::size_type i=0; i < s.size(); ++i)
{
if (s[i] == percent) // digit request
{
if (nibbles_used == max_nibbles)
{
system_crypt_random(ran, sizeof(ran), ec);
if (ec != 0 && *ec)
return "";
nibbles_used = 0;
}
int c = ran[nibbles_used/2];
c >>= 4 * (nibbles_used++ & 1); // if odd, shift right 1 nibble
s[i] = hex[c & 0xf]; // convert to hex digit and replace
}
}
if (ec != 0) ec->clear();
return s;
}
}}}
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