Replacing C code written in win32 into linux based system

Question

I am trying to replicate WIN32 code for MacOSX, however I am unable to replicate a part of code

Here is the code.

main_int64 pos;
  OP_ASSERT(sizeof(pos)==sizeof(fpos_t));
  /*Translate the seek to an absolute one.*/
  if(_whence==SEEK_CUR)
  {
    int ret;
    ret=fgetpos((FILE *)_stream,(fpos_t *)&pos);
    if(ret)return ret;
  }
  else if(_whence==SEEK_END)pos=_filelengthi64(_fileno((FILE *)_stream));
  else if(_whence==SEEK_SET)pos=0;
  else return -1;
  /*Check for errors or overflow.*/
  if(pos<0||_offset<-pos||_offset>OP_INT64_MAX-pos)return -1;
  pos+=_offset;

  int seeko = fsetpos((FILE *)_stream,(fpos_t *)&pos);
  fprintf("BaseTool", "SEEKO VALUE %d \n", seeko);
  return seeko;

I am stuck at

else if(_whence==SEEK_END)pos=_filelengthi64(_fileno((FILE *)_stream));

I am not sure how can I replace these functions in mac based system as these are WIN based functions

MacOSX is not Linux, but both are (nearly) POSIX. See [this](https://stackoverflow.com/a/50119218/841108) answer to a nearly duplicate question — Basile Starynkevitch, May 11 '18 at 09:42

score 1 · Accepted Answer · answered May 11 '18 at 09:35

1

from the code I understand you are trying to get the length of the file, in linux you can do this way,

 int fp           = open("check5.c", O_RDONLY);
off_t lengthOfFile = lseek(fp, 0, SEEK_END);
close(fp);
printf("%d",lengthOfFile);

So replace it with "lseek(fileno,0, SEEK_END)" should give length of the file.

answered May 11 '18 at 09:35

user3706415

54
6

2

I would recommend using [stat(2)](http://man7.org/linux/man-pages/man2/stat.2.html) instead. – Basile Starynkevitch May 11 '18 at 09:44
Yeah stat should work as well. But for this lseek also should work – user3706415 May 11 '18 at 09:54
It won't work if `check5.c` was not a plain file, but e.g. a fifo... And your `lseek` trick would give strange results if `check5.c` is written at the same time by some other process. – Basile Starynkevitch May 11 '18 at 09:58

Replacing C code written in win32 into linux based system

1 Answers1