Is there a POSIX function to copy a file? [closed]

Answer 1

I tried running strace on the cp command on Linux and it actually open both files and it reads from one file and write to the other one in blocks of 32768 bytes:

...
stat64("log", {st_mode=S_IFREG|0644, st_size=352, ...}) = 0
stat64("copied", 0xbf99e1c0)              = -1 ENOENT (No such file or directory)
open("log", O_RDONLY|O_LARGEFILE) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=352, ...}) = 0
open("copied", O_WRONLY|O_CREAT|O_EXCL|O_LARGEFILE, 0644) = 4
fstat64(4, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
read(3, "2012-04-27 22:26:55-0400 [-] Log"..., 32768) = 352
write(4, "2012-04-27 22:26:55-0400 [-] Log"..., 352) = 352
read(3, "", 32768)                      = 0
close(4)                                = 0
close(3)                                = 0
...

So yes, there is no cp syscall out there. Hope it helps you.