/* cmp.c - Compare two files.
 *
 * Copyright 2012 Timothy Elliott <tle@holymonkey.com>
 *
 * See http://opengroup.org/onlinepubs/9699919799/utilities/cmp.html

USE_CMP(NEWTOY(cmp, "<2>2ls[!ls]", TOYFLAG_USR|TOYFLAG_BIN))

config CMP
  bool "cmp"
  default y
  help
    usage: cmp [-l] [-s] FILE1 FILE2

    Compare the contents of two files.

    -l	show all differing bytes
    -s	silent
*/

#define FOR_cmp
#include "toys.h"

GLOBALS(
  int fd;
  char *name;
)

// This handles opening the file and

static void do_cmp(int fd, char *name)
{
  int i, len1, len2, min_len, size = sizeof(toybuf)/2;
  long byte_no = 1, line_no = 1;
  char *buf2 = toybuf+size;

  // First time through, cache the data and return.
  if (!TT.fd) {
    TT.name = name;
    // On return the old filehandle is closed, and this assures that even
    // if we were called with stdin closed, the new filehandle != 0.
    TT.fd = dup(fd);
    return;
  }

  toys.exitval = 0;

  for (;;) {
    len1 = readall(TT.fd, toybuf, size);
    len2 = readall(fd, buf2, size);

    min_len = len1 < len2 ? len1 : len2;
    for (i=0; i<min_len; i++) {
      if (toybuf[i] != buf2[i]) {
        toys.exitval = 1;
        if (toys.optflags & FLAG_l)
          printf("%ld %o %o\n", byte_no, toybuf[i], buf2[i]);
        else {
          if (!(toys.optflags & FLAG_s)) 
            printf("%s %s differ: char %ld, line %ld\n",
              TT.name, name, byte_no, line_no);
          goto out;
        }
      }
      byte_no++;
      if (toybuf[i] == '\n') line_no++;
    }
    if (len1 != len2) {
      if (!(toys.optflags & FLAG_s))
        fprintf(stderr, "cmp: EOF on %s\n", len1 < len2 ? TT.name : name);
      toys.exitval = 1;
      break;
    }
    if (len1 < 1) break;
  }
out:
  if (CFG_TOYBOX_FREE) close(TT.fd);
}

void cmp_main(void)
{
  toys.exitval = 2;
  loopfiles_rw(toys.optargs, O_CLOEXEC|(WARN_ONLY*!(toys.optflags&FLAG_s)), 0,
    do_cmp);
}