src/misc.c

   1 #ifdef HAVE_CONFIG_H
   2 #       include "config.h"
   3 #endif
   4
   5 #include <stdio.h>
   6 #include <errno.h>
   7
   8 #include "misc.h"
   9 #include "lbx.h"
  10
  11 int _lbx_fseek(FILE *f, long *current, size_t offset)
  12 {
  13         static unsigned char oblivion[1024];
  14         long dist;
  15
  16         if (*current < offset) {
  17                 dist = offset - *current;
  18         } else if (*current > offset) {
  19                 dist = -(long)(*current - offset);
  20         } else {
  21                 return 0;
  22         }
  23
  24         if (fseek(f, dist, SEEK_CUR) == 0) {
  25                 *current += dist;
  26         } else if (*current < offset) {
  27                 while (dist) {
  28                         size_t rc, amt = MIN(sizeof oblivion, dist);
  29                         rc = fread(oblivion, 1, amt, f);
  30                         *current += rc;
  31                         dist -= rc;
  32                         if (rc < amt) {
  33                                 if (feof(f))
  34                                         lbx_errno = LBX_EEOF;
  35                                 else
  36                                         lbx_errno = -errno;
  37                                 return -1;
  38                         }
  39                 }
  40         } else {
  41                 lbx_errno = -errno;
  42                 return -1;
  43         }
  44         return 0;
  45 }