Mirror of forum.nim-lang.org

10752 :: Nim raw syscalls

• Kind-Distribution376 (orginal) [2023-12-10T10:41:15+01:00] view original

  Hey! C programmer trying to use Nim a bit more.

  in C, when I want to perform a raw syscall I can just execute

  #include <unistd.h>
  #include <sys/syscall.h>
  int main(void) {
    syscall(SYS_write, 1, "hello, world!\n", 14);
    return 0;
  }
  Run

  I compiled it on my fedora, this is (clearly) the output

  
  [cat@Fedora~]$ gcc file.c -o file
  [cat@Fedora~]$ ./file
  hello, world!
  Run

  How can I perform raw syscalls in Nim? Is that a built in feature?

  Thanks in advance <3

---

• blackmius (orginal) [2023-12-10T10:46:43+01:00] view original

  its not builtin you need to do importc

  proc syscall(arg: cint): cint {.importc, header: "<unistd.h>", varargs.}
  var
    SYS_write {.importc, header: "<sys/syscall.h>".}: cint
  
  syscall(SYS_write, 1, "hello world\n".cstring, 12)
  Run

---

• mratsim (orginal) [2023-12-11T10:08:09+01:00] view original

  Additionally you can add the {.discardable.} pragma if you want using the return value or explicitly discarding it to not be mandatory.

---