newlib/libc/reent/lseekr.c

   1 /* Reentrant versions of lseek system call. */
   2
   3 #include <reent.h>
   4 #include <unistd.h>
   5 #include <_syslist.h>
   6
   7 /* Some targets provides their own versions of this functions.  Those
   8    targets should define REENTRANT_SYSCALLS_PROVIDED in TARGET_CFLAGS.  */
   9
  10 #ifdef _REENT_ONLY
  11 #ifndef REENTRANT_SYSCALLS_PROVIDED
  12 #define REENTRANT_SYSCALLS_PROVIDED
  13 #endif
  14 #endif
  15
  16 #ifndef REENTRANT_SYSCALLS_PROVIDED
  17
  18 /* We use the errno variable used by the system dependent layer.  */
  19 #undef errno
  20 extern int errno;
  21
  22 /*
  23 FUNCTION
  24         <<_lseek_r>>---Reentrant version of lseek
  25
  26 INDEX
  27         _lseek_r
  28
  29 SYNOPSIS
  30         #include <reent.h>
  31         off_t _lseek_r(struct _reent *<[ptr]>,
  32                        int <[fd]>, off_t <[pos]>, int <[whence]>);
  33
  34 DESCRIPTION
  35         This is a reentrant version of <<lseek>>.  It
  36         takes a pointer to the global data block, which holds
  37         <<errno>>.
  38 */
  39
  40 _off_t
  41 _lseek_r (struct _reent *ptr,
  42      int fd,
  43      _off_t pos,
  44      int whence)
  45 {
  46   _off_t ret;
  47
  48   errno = 0;
  49   if ((ret = _lseek (fd, pos, whence)) == (_off_t) -1 && errno != 0)
  50     _REENT_ERRNO(ptr) = errno;
  51   return ret;
  52 }
  53
  54 #endif /* ! defined (REENTRANT_SYSCALLS_PROVIDED) */