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/* Copyright (c) 2003-2004, Roger Dingledine
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2019, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file fdio.c
*
* \brief Low-level compatibility wrappers for fd-based IO.
**/
#include "orconfig.h"
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef _WIN32
#include <windows.h>
#endif
#include "lib/fdio/fdio.h"
#include "lib/cc/torint.h"
#include "lib/err/torerr.h"
#include <stdlib.h>
/** @{ */
/** Some old versions of Unix didn't define constants for these values,
* and instead expect you to say 0, 1, or 2. */
#ifndef SEEK_SET
#define SEEK_SET 0
#endif
#ifndef SEEK_CUR
#define SEEK_CUR 1
#endif
#ifndef SEEK_END
#define SEEK_END 2
#endif
/** @} */
/** Return the position of <b>fd</b> with respect to the start of the file. */
off_t
tor_fd_getpos(int fd)
{
#ifdef _WIN32
return (off_t) _lseeki64(fd, 0, SEEK_CUR);
#else
return (off_t) lseek(fd, 0, SEEK_CUR);
#endif
}
/** Move <b>fd</b> to the end of the file. Return -1 on error, 0 on success.
* If the file is a pipe, do nothing and succeed.
**/
int
tor_fd_seekend(int fd)
{
#ifdef _WIN32
return _lseeki64(fd, 0, SEEK_END) < 0 ? -1 : 0;
#else
off_t rc = lseek(fd, 0, SEEK_END) < 0 ? -1 : 0;
#ifdef ESPIPE
/* If we get an error and ESPIPE, then it's a pipe or a socket of a fifo:
* no need to worry. */
if (rc < 0 && errno == ESPIPE)
rc = 0;
#endif /* defined(ESPIPE) */
return (rc < 0) ? -1 : 0;
#endif /* defined(_WIN32) */
}
/** Move <b>fd</b> to position <b>pos</b> in the file. Return -1 on error, 0
* on success. */
int
tor_fd_setpos(int fd, off_t pos)
{
#ifdef _WIN32
return _lseeki64(fd, pos, SEEK_SET) < 0 ? -1 : 0;
#else
return lseek(fd, pos, SEEK_SET) < 0 ? -1 : 0;
#endif
}
/** Replacement for ftruncate(fd, 0): move to the front of the file and remove
* all the rest of the file. Return -1 on error, 0 on success. */
int
tor_ftruncate(int fd)
{
/* Rumor has it that some versions of ftruncate do not move the file pointer.
*/
if (tor_fd_setpos(fd, 0) < 0)
return -1;
#ifdef _WIN32
return _chsize(fd, 0);
#else
return ftruncate(fd, 0);
#endif
}
/** Minimal version of write_all, for use by logging. */
int
write_all_to_fd_minimal(int fd, const char *buf, size_t count)
{
size_t written = 0;
raw_assert(count < SSIZE_MAX);
while (written < count) {
ssize_t result = write(fd, buf+written, count-written);
if (result<0)
return -1;
written += result;
}
return 0;
}
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