osdep/fseeko.c

   1 /*
   2  * fseeko.c
   3  *        64-bit versions of fseeko/ftello() for systems which do not have them
   4  */
   5
   6 #include "../config.h"
   7
   8 #if !defined(HAVE_FSEEKO) || !defined(HAVE_FTELLO)
   9 #include <stdio.h>
  10 #include <sys/types.h>
  11 #include <sys/stat.h>
  12 #include <errno.h>
  13 #endif
  14
  15 #ifdef WIN32
  16 #define flockfile
  17 #define funlockfile
  18 #endif
  19
  20 /*
  21  *      On BSD/OS and NetBSD (and perhaps others), off_t and fpos_t are the
  22  *      same.  Standards say off_t is an arithmetic type, but not necessarily
  23  *      integral, while fpos_t might be neither.
  24  *
  25  *      This is thread-safe on BSD/OS using flockfile/funlockfile.
  26  */
  27
  28 #ifndef HAVE_FSEEKO
  29 int
  30 fseeko(FILE *stream, off_t offset, int whence)
  31 {
  32         fpos_t floc;
  33         struct stat filestat;
  34
  35         switch (whence)
  36         {
  37                 case SEEK_CUR:
  38                         flockfile(stream);
  39                         if (fgetpos(stream, &floc) != 0)
  40                                 goto failure;
  41                         floc += offset;
  42                         if (fsetpos(stream, &floc) != 0)
  43                                 goto failure;
  44                         funlockfile(stream);
  45                         return 0;
  46                         break;
  47                 case SEEK_SET:
  48                         if (fsetpos(stream, &offset) != 0)
  49                                 return -1;
  50                         return 0;
  51                         break;
  52                 case SEEK_END:
  53                         flockfile(stream);
  54                         if (fstat(fileno(stream), &filestat) != 0)
  55                                 goto failure;
  56                         floc = filestat.st_size;
  57                         if (fsetpos(stream, &floc) != 0)
  58                                 goto failure;
  59                         funlockfile(stream);
  60                         return 0;
  61                         break;
  62                 default:
  63                         errno = EINVAL;
  64                         return -1;
  65         }
  66
  67 failure:
  68         funlockfile(stream);
  69         return -1;
  70 }
  71 #endif
  72
  73
  74 #ifndef HAVE_FTELLO
  75 off_t
  76 ftello(FILE *stream)
  77 {
  78         fpos_t floc;
  79
  80         if (fgetpos(stream, &floc) != 0)
  81                 return -1;
  82         return floc;
  83 }
  84 #endif