/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */

/* kludge a bit to remove _FILE_OFFSET_BITS definition from config.h.

   It's required to be able to include sys/sendfile.h with Linux. */

#include "config.h"

#undef HAVE_CONFIG_H

#ifdef HAVE_LINUX_SENDFILE

#  undef _FILE_OFFSET_BITS

#endif

#include "lib.h"

#include "sendfile-util.h"

#ifdef HAVE_LINUX_SENDFILE

#include <sys/sendfile.h>

ssize_t safe_sendfile(int out_fd, int in_fd, uoff_t *offset, size_t count)

{

  /* REMEMBER: uoff_t and off_t may not be of same size. */

  off_t safe_offset;

  ssize_t ret;

  i_assert(count > 0);

  /* make sure given offset fits into off_t */

  if (sizeof(off_t) * CHAR_BIT == 32) {

    /* 32bit off_t */

    if (*offset >= 2147483647L) {

      errno = EINVAL;

      return -1;

    }

    if (count > 2147483647L - *offset)

      count = 2147483647L - *offset;

  } else {

    /* they're most likely the same size. if not, fix this

       code later */

    i_assert(sizeof(off_t) == sizeof(uoff_t));

    if (*offset >= OFF_T_MAX) {

      errno = EINVAL;

      return -1;

    }

    if (count > OFF_T_MAX - *offset)

      count = OFF_T_MAX - *offset;

  }

  safe_offset = (off_t)*offset;

  ret = sendfile(out_fd, in_fd, &safe_offset, count);

  /* ret=0 : trying to read past EOF */

  *offset = (uoff_t)safe_offset;

  return ret;

}

#elif defined(HAVE_FREEBSD_SENDFILE)

#include <sys/socket.h>

#include <sys/uio.h>

ssize_t safe_sendfile(int out_fd, int in_fd, uoff_t *offset, size_t count)

{

  struct sf_hdtr hdtr;

  off_t sbytes;

  int ret;

  /* if count=0 is passed to sendfile(), it sends everything

     from in_fd until EOF. We don't want that. */

  i_assert(count > 0);

  i_assert(count <= SSIZE_T_MAX);

  i_zero(&hdtr);

  ret = sendfile(in_fd, out_fd, *offset, count, &hdtr, &sbytes, 0);

  *offset += sbytes;

  if (ret == 0 || (ret < 0 && errno == EAGAIN && sbytes > 0))

    return (ssize_t)sbytes;

  else {

    if (errno == ENOTSOCK) {

      /* out_fd wasn't a socket. behave as if sendfile()

         wasn't supported at all. */

      errno = EINVAL;

    }

    return -1;

  }

}

#elif defined (HAVE_SOLARIS_SENDFILE)

#include <sys/sendfile.h>

#include "net.h"

ssize_t safe_sendfile(int out_fd, int in_fd, uoff_t *offset, size_t count)

{

  ssize_t ret;

  off_t s_offset;

  i_assert(count > 0);

  i_assert(count <= SSIZE_T_MAX);

  /* NOTE: if outfd is not a socket, some Solaris versions will

     kernel panic */

  s_offset = (off_t)*offset;

  ret = sendfile(out_fd, in_fd, &s_offset, count);

  if (ret < 0) {

    /* if remote is gone, EPIPE is returned */

    if (errno == EINVAL) {

      /* most likely trying to read past EOF */

      ret = 0;

    } else if (errno == EAFNOSUPPORT || errno == EOPNOTSUPP) {

      /* not supported, return Linux-like EINVAL so caller

         sees only consistent errnos. */

      errno = EINVAL;

    } else if (s_offset != (off_t)*offset) {

      /* some data was sent, return it */

      i_assert(s_offset > (off_t)*offset);

      ret = s_offset - (off_t)*offset;

    }

  }

  *offset = (uoff_t)s_offset;

  i_assert(ret < 0 || (size_t)ret <= count);

  return ret;

}

#else

ssize_t safe_sendfile(int out_fd ATTR_UNUSED, int in_fd ATTR_UNUSED,

          uoff_t *offset ATTR_UNUSED,

          size_t count ATTR_UNUSED)

{

  errno = EINVAL;

  return -1;

}

#endif