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 answer to a nearly duplicate question — Basile Starynkevitch
– Basile Starynkevitch, Commented May 11, 2018 at 9:42

user3706415 · Accepted Answer · 2018-05-11 09:35:27Z

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, 2018 at 9:35

user3706415

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3 Comments

Basile Starynkevitch Over a year ago

I would recommend using stat(2) instead.

user3706415 Over a year ago

Yeah stat should work as well. But for this lseek also should work

Basile Starynkevitch Over a year ago

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.

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