lib/libc/sys-minix/pwrite.c

   1 #include <sys/cdefs.h>
   2 #include "namespace.h"
   3 #include <lib.h>
   4
   5 #include <unistd.h>
   6
   7 #ifdef __weak_alias
   8 __weak_alias(pwrite, _pwrite)
   9 #endif
  10
  11 #include <minix/u64.h>
  12
  13 ssize_t pwrite64(int fd, const void *buffer, size_t nbytes, u64_t where)
  14 {
  15         u64_t here;
  16         ssize_t w;
  17
  18         if (lseek64(fd, make64(0,0), SEEK_CUR, &here) < 0) return(-1);
  19         if (lseek64(fd, where, SEEK_SET, NULL) < 0) return(-1);
  20         if ((w = write(fd, buffer, nbytes)) < 0) {
  21                 int e = errno;
  22                 lseek64(fd, here, SEEK_SET, NULL);
  23                 errno = e;
  24                 return(-1);
  25         }
  26
  27         if (lseek64(fd, here, SEEK_SET, NULL) < 0) return(-1);
  28
  29         return(w);
  30 }
  31
  32 ssize_t pwrite(int fd, const void *buffer, size_t nbytes, off_t where)
  33 {
  34         off_t here;
  35         ssize_t w;
  36
  37         if((here = lseek(fd, 0, SEEK_CUR)) < 0)
  38                 return -1;
  39
  40         if(lseek(fd, where, SEEK_SET) < 0)
  41                 return -1;
  42
  43         if((w=write(fd, buffer, nbytes)) < 0) {
  44                 int e = errno;
  45                 lseek(fd, here, SEEK_SET);
  46                 errno = e;
  47                 return -1;
  48         }
  49
  50         if(lseek(fd, here, SEEK_SET) < 0)
  51                 return -1;
  52
  53         return w;
  54 }