coreutils/comm.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini comm implementation for busybox
   4  *
   5  * Copyright (C) 2005 by Robert Sullivan <cogito.ergo.cogito@gmail.com>
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   8  */
   9
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <string.h>
  13 #include <unistd.h>
  14 #include "busybox.h"
  15
  16 #define COMM_OPT_1 0x01
  17 #define COMM_OPT_2 0x02
  18 #define COMM_OPT_3 0x04
  19
  20 /* These three variables control behaviour if non-zero */
  21
  22 static int only_file_1;
  23 static int only_file_2;
  24 static int both;
  25
  26 /* writeline outputs the input given, appropriately aligned according to class */
  27 static void writeline(char *line, int class)
  28 {
  29         if (class == 0) {
  30                 if (!only_file_1)
  31                         return;
  32         } else if (class == 1) {
  33                 if (!only_file_2)
  34                         return;
  35                 if (only_file_1)
  36                         putchar('\t');
  37         }
  38         else /*if (class == 2)*/ {
  39                 if (!both)
  40                         return;
  41                 if (only_file_1)
  42                         putchar('\t');
  43                 if (only_file_2)
  44                         putchar('\t');
  45         }
  46         fputs(line, stdout);
  47 }
  48
  49 /* This is the real core of the program - lines are compared here */
  50 static void cmp_files(char **infiles)
  51 {
  52 #define LINE_LEN 100
  53 #define BB_EOF_0 0x1
  54 #define BB_EOF_1 0x2
  55         char thisline[2][LINE_LEN];
  56         FILE *streams[2];
  57         int i;
  58
  59         for (i = 0; i < 2; ++i) {
  60                 streams[i] = ((infiles[i][0] == '=' && infiles[i][1]) ? stdin : bb_xfopen(infiles[i], "r"));
  61                 fgets(thisline[i], LINE_LEN, streams[i]);
  62         }
  63
  64         while (*thisline[0] || *thisline[1]) {
  65                 int order = 0;
  66
  67                 i = 0;
  68                 if (feof(streams[0])) i |= BB_EOF_0;
  69                 if (feof(streams[1])) i |= BB_EOF_1;
  70
  71                 if (!*thisline[0])
  72                         order = 1;
  73                 else if (!*thisline[1])
  74                         order = -1;
  75                 else {
  76                         int tl0_len, tl1_len;
  77                         tl0_len = strlen(thisline[0]);
  78                         tl1_len = strlen(thisline[1]);
  79                         order = memcmp(thisline[0], thisline[1], tl0_len < tl1_len ? tl0_len : tl1_len);
  80                         if (!order)
  81                                 order = tl0_len < tl1_len ? -1 : tl0_len != tl1_len;
  82                 }
  83
  84                 if (order == 0 && !i)
  85                         writeline(thisline[1], 2);
  86                 else if (order > 0 && !(i & BB_EOF_1))
  87                         writeline(thisline[1], 1);
  88                 else if (order < 0 && !(i & BB_EOF_0))
  89                         writeline(thisline[0], 0);
  90
  91                 if (i & BB_EOF_0 & BB_EOF_1) {
  92                         break;
  93
  94                 } else if (i) {
  95                         i = (i & BB_EOF_0 ? 1 : 0);
  96                         while (!feof(streams[i])) {
  97                                 if ((order < 0 && i) || (order > 0 && !i))
  98                                         writeline(thisline[i], i);
  99                                 fgets(thisline[i], LINE_LEN, streams[i]);
 100                         }
 101                         break;
 102
 103                 } else {
 104                         if (order >= 0)
 105                                 fgets(thisline[1], LINE_LEN, streams[1]);
 106                         if (order <= 0)
 107                                 fgets(thisline[0], LINE_LEN, streams[0]);
 108                 }
 109         }
 110
 111         fclose(streams[0]);
 112         fclose(streams[1]);
 113 }
 114
 115 int comm_main(int argc, char **argv)
 116 {
 117         unsigned long flags;
 118
 119         flags = bb_getopt_ulflags(argc, argv, "123");
 120
 121         if (optind + 2 != argc)
 122                 bb_show_usage();
 123
 124         only_file_1 = !(flags & COMM_OPT_1);
 125         only_file_2 = !(flags & COMM_OPT_2);
 126         both = !(flags & COMM_OPT_3);
 127
 128         cmp_files(argv + optind);
 129         exit(EXIT_SUCCESS);
 130 }