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// OpenVPN -- An application to securely tunnel IP networks
// over a single port, with support for SSL/TLS-based
// session authentication and key exchange,
// packet encryption, packet authentication, and
// packet compression.
//
// Copyright (C) 2012- OpenVPN Inc.
//
// SPDX-License-Identifier: MPL-2.0 OR AGPL-3.0-only WITH openvpn3-openssl-exception
//
// Unix file read/write
#pragma once
#include <openvpn/common/platform.hpp>
#if defined(OPENVPN_PLATFORM_WIN)
#error unix file methods not supported on Windows
#endif
#include <errno.h>
#include <unistd.h> // for lseek
#include <sys/types.h> // for lseek, open
#include <sys/stat.h> // for open
#include <fcntl.h> // for open
#include <cstdint>
#include <openvpn/common/exception.hpp>
#include <openvpn/common/size.hpp>
#include <openvpn/common/scoped_fd.hpp>
#include <openvpn/common/write.hpp>
#include <openvpn/common/strerror.hpp>
#include <openvpn/common/stat.hpp>
#include <openvpn/common/modstat.hpp>
#include <openvpn/common/stringtempl.hpp>
#include <openvpn/buffer/bufread.hpp>
namespace openvpn {
OPENVPN_EXCEPTION(file_unix_error);
// write binary buffer to file
static constexpr mode_t WRITE_BINARY_UNIX_EXISTING = 010000; // special mode that is useful for writing /proc files
inline void write_binary_unix(const std::string &fn,
const mode_t mode,
const std::uint64_t mtime_ns, // set explicit modification-time in nanoseconds since epoch, or 0 to defer to system
const void *buf,
const ssize_t size)
{
// open
int flags = O_WRONLY | O_CLOEXEC;
if (!(mode & WRITE_BINARY_UNIX_EXISTING))
flags |= O_CREAT | O_TRUNC;
ScopedFD fd(::open(fn.c_str(), flags, mode & (WRITE_BINARY_UNIX_EXISTING - 1)));
if (!fd.defined())
{
const int eno = errno;
throw file_unix_error(fn + " : open for write : " + strerror_str(eno));
}
// write
if (size)
{
const ssize_t len = write_retry(fd(), buf, size);
if (len != size)
{
if (len == -1)
{
const int eno = errno;
throw file_unix_error(fn + " : write error : " + strerror_str(eno));
}
else
throw file_unix_error(fn + " : incomplete write, request_size=" + std::to_string(size) + " actual_size=" + std::to_string(len));
}
}
// explicit modification time
if (mtime_ns)
update_file_mod_time_nanoseconds(fd(), mtime_ns);
// close
{
const int eno = fd.close_with_errno();
if (eno)
throw file_unix_error(fn + " : close for write : " + strerror_str(eno));
}
}
inline void write_binary_unix(const std::string &fn,
const mode_t mode,
const std::uint64_t mtime_ns,
const Buffer &buf)
{
write_binary_unix(fn, mode, mtime_ns, buf.c_data(), buf.size());
}
inline void write_binary_unix(const std::string &fn,
const mode_t mode,
const std::uint64_t mtime_ns,
const ConstBuffer &buf)
{
write_binary_unix(fn, mode, mtime_ns, buf.c_data(), buf.size());
}
inline void write_text_unix(const std::string &fn,
const mode_t mode,
const std::uint64_t mtime_ns,
const std::string &content)
{
write_binary_unix(fn, mode, mtime_ns, content.c_str(), content.length());
}
enum
{ // MUST be distinct from BufferAllocated flags
NULL_ON_ENOENT = (1 << 8),
};
inline BufferPtr read_binary_unix(const std::string &fn,
const std::uint64_t max_size = 0,
const unsigned int buffer_flags = 0,
std::uint64_t *mtime_ns = nullptr)
{
// open
ScopedFD fd(::open(fn.c_str(), O_RDONLY | O_CLOEXEC));
if (!fd.defined())
{
const int eno = errno;
if ((buffer_flags & NULL_ON_ENOENT) && eno == ENOENT)
return BufferPtr();
throw file_unix_error(fn + " : open for read : " + strerror_str(eno));
}
// get file timestamp
if (mtime_ns)
*mtime_ns = fd_mod_time_nanoseconds(fd());
// get file length
const off_t length = ::lseek(fd(), 0, SEEK_END);
if (length < 0)
{
const int eno = errno;
throw file_unix_error(fn + " : seek end error : " + strerror_str(eno));
}
if (::lseek(fd(), 0, SEEK_SET) != 0)
{
const int eno = errno;
throw file_unix_error(fn + " : seek begin error : " + strerror_str(eno));
}
// maximum size exceeded?
if (max_size && std::uint64_t(length) > max_size)
throw file_unix_error(fn + " : file too large [" + std::to_string(length) + '/' + std::to_string(max_size) + ']');
// allocate buffer
auto bp = BufferAllocatedRc::Create(size_t(length), buffer_flags);
// read file content into buffer
while (buf_read(fd(), *bp, fn))
;
// check for close error
{
const int eno = fd.close_with_errno();
if (eno)
throw file_unix_error(fn + " : close for read : " + strerror_str(eno));
}
return bp;
}
// read file into a fixed buffer, return zero or errno
template <typename STRING>
inline int read_binary_unix_fast(const STRING &fn,
Buffer &out,
std::uint64_t *mtime_ns = nullptr)
{
ScopedFD fd(::open(StringTempl::to_cstring(fn), O_RDONLY | O_CLOEXEC));
if (!fd.defined())
return errno;
if (mtime_ns)
*mtime_ns = fd_mod_time_nanoseconds(fd());
while (true)
{
const size_t remaining = out.remaining(0);
if (!remaining)
return EAGAIN; // note that we also return EAGAIN if buffer is exactly the same size as content
const ssize_t status = ::read(fd(), out.data_end(), remaining);
if (status == 0)
return 0;
else if (status < 0)
return errno;
out.inc_size(status);
}
}
inline std::string read_text_unix(const std::string &filename,
const std::uint64_t max_size = 0,
const unsigned int buffer_flags = 0,
std::uint64_t *mtime_ns = nullptr)
{
BufferPtr bp = read_binary_unix(filename, max_size, buffer_flags, mtime_ns);
if (bp)
return buf_to_string(*bp);
else
return std::string();
}
} // namespace openvpn
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