You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: cmp.rs
    path of file: ./repos/rustybox/editors
    
    the code of the file until where you have to start completion: use crate::libbb::default_error_retval::xfunc_error_retval;
use crate::librb::smallint;
use libc;
use libc::fprintf;
use libc::off_t;
use libc::FILE;
extern "C" {
  #[no_mangle]
  static mut optind: libc::c_int;
  #[no_mangle]
  static mut stdout: *mut FILE;
  #[no_mangle]
  static mut stderr: *mut FILE;
  #[no_mangle]
  fn getc_unlocked(__stream: *mut FILE) -> libc::c_int;
  #[no_mangle]
  static mut logmode: smallint;
}

pub type C2RustUnnamed = libc::c_uint;
pub const LOGMODE_BOTH: C2RustUnnamed = 3;
pub const LOGMODE_SYSLOG: C2RustUnnamed = 2;
pub const LOGMODE_STDIO: C2RustUnnamed = 1;
pub const LOGMODE_NONE: C2RustUnnamed = 0;

#[inline(always)]
unsafe fn xatoul_range(
  mut str: *const libc::c_char,
  mut l: libc::c_ulong,
  mut u: libc::c_ulong,
) -> libc::c_ulong {
  return crate::libbb::xatonum::xatoull_range(str, l as libc::c_ulonglong, u as libc::c_ulonglong)
    as libc::c_ulong;
}

/*
 * Mini cmp implementation for busybox
 *
 * Copyright (C) 2000,2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
//config:config CMP
//config:	bool "cmp (4.9 kb)"
//config:	default y
//config:	help
//config:	cmp is used to compare two files and returns the result
//config:	to standard output.
//applet:IF_CMP(APPLET(cmp, BB_DIR_USR_BIN, SUID_DROP))
//kbuild:lib-$(CONFIG_CMP) += cmp.o
//usage:#define cmp_trivial_usage
//usage:       "[-l] [-s] FILE1 [FILE2" IF_DESKTOP(" [SKIP1 [SKIP2]]") "]"
//usage:#define cmp_full_usage "\n\n"
//usage:       "Compare FILE1 with FILE2 (or stdin)\n"
//usage:     "\n	-l	Write the byte numbers (decimal) and values (octal)"
//usage:     "\n		for all differing bytes"
//usage:     "\n	-s	Quiet"
/* BB_AUDIT SUSv3 (virtually) compliant -- uses nicer GN
    
pub unsafe fn cmp_main(mut _argc: libc::c_int, mut argv: *mut *mut libc::c_char) -> libc::c_int {
  let mut fp1: *mut FILE = std::ptr::null_mut(); /* Hopefully won't overflow... */
  let mut fp2: *mut FILE = std::ptr::null_mut(); /* missing file results in exitcode 2 */
  let mut outfile: *mut FILE = stdout; /* -s suppresses open error messages */
  let mut filename1: *const libc::c_char = std::ptr::null();
  let mut filename2: *const libc::c_char = b"-\x00" as *const u8 as *const libc::c_char;
  let mut skip1: off_t = 0 as off_t;
  let mut skip2: off_t = 0 as off_t;
  let mut char_pos: off_t = 0 as off_t;
  let mut line_pos: libc::c_int = 1i32;
  let mut fmt: *const libc::c_char = std::ptr::null();
  let mut c1: libc::c_int = 0;
  let mut c2: libc::c_int = 0;
  let mut opt: libc::c_uint = 0;
  let mut retval: libc::c_int = 0;
  opt = crate::libbb::getopt32::getopt32(
    argv,
    b"^sl\x00-1:?4:l--s:s--l\x00" as *const u8 as *const libc::c_char,
  );
  argv = argv.offset(optind as isize);
  filename1 = *argv;
  argv = argv.offset(1);
  if !(*argv).is_null() {
    filename2 = *argv;
    if 1i32 != 0 && {
      argv = argv.offset(1);
      !(*argv).is_null()
    } {
      skip1 = xatoul_range(
        *argv,
        0 as libc::c_ulong,
        9223372036854775807i64 as libc::c_ulong,
      ) as off_t;
      argv = argv.offset(1);
      if !(*argv).is_null() {
        skip2 = xatoul_range(
          *argv,
          0 as libc::c_ulong,
          9223372036854775807i64 as libc::c_ulong,
        ) as off_t
      }
    }
  }
  xfunc_error_retval = 2i32 as u8;
  if opt & (1i32 << 0) as libc::c_uint != 0 {
    logmode = 0 as smallint
  }
  fp1 = crate::libbb::wfopen_input::xfopen_stdin(filename1);
  fp2 = crate::libbb::wfopen_input::xfopen_stdin(filename2);
  if fp1 == fp2 {
    /* Paranoia check... stdin == stdin? */
    /* Note that we don't bother reading stdin.  Neither does gnu wc.
     * But perhaps we should, so that other apps down the chain don't
     * get the input.  Consider 'echo hello | (cmp - - && cat -)'.
     */
    return 0;
  }
  logmode = LOGMODE_STDIO as libc::c_int as smallint;
  if opt & (1i32 << 1i32) as libc::c_uint != 0 {
    fmt = fmt_l_opt.as_ptr()
  } else {
    fmt = fmt_differ.as_ptr()
  }
  while skip1 != 0 {
    getc_unlocked(fp1);
    skip1 -= 1
  }
  while skip2 != 0 {
    getc_unlocked(fp2);
    skip2 -= 1
  }
  loop {
    c1 = getc_unlocked(fp1);
    c2 = getc_unlocked(fp2);
    char_pos += 1;
    if c1 != c2 {
      /* Remember: a read error may have occurred. */
      retval = 1i32; /* But assume the files are different for now. */
      if c2 == -1i32 {
        /* We know that fp1 isn't at EOF or in an error state.  But to
         * save space below, things are setup to expect an EOF in fp1
         * if an EOF occurred.  So, swap things around.
         */
        fp1 = fp2; /* Well, no error, so it must really be EOF. */
        filename1 = filename2;
        c1 = c2
      }
      if c1 == -1i32 {
        crate::libbb::xfuncs_printf::die_if_ferror(fp1, filename1);
        fmt = fmt_eof.as_ptr();
        outfile = stderr;
        /* There may have been output to stdout (option -l), so
         * make sure we fflush before writing to stderr. */
        crate::libbb::xfuncs_printf::fflush_all();
      }
      if !(opt & (1i32 << 0) as libc::c_uint == 0) {
        break;
      }
      if opt & (1i32 << 1i32) as libc::c_uint != 0 {
        line_pos = c1
        /* line_pos is unused in the -l case. */
      }
      fprintf(outfile, fmt, filename1, filename2, char_pos, line_pos, c2);
      if !(opt != 0) {
        break;
      }
    } else if c1 == '\n' as i32 {
      line_pos += 1
    }
    /* This must be -l since not -s. */
    /* If we encountered an EOF,
     * the while check will catch it. */
    if !(c1 != -1i32) {
      break;
    }
  }
  crate::libbb::xfuncs_printf::die_if_ferror(fp1, filename1);
  crate::libbb::xfuncs_printf::die_if_ferror(fp2, filename2);
  crate::libbb::fflush_stdout_and_exit::fflush_stdout_and_exit(retval);
}