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  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15  * General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  20  * 02111-1307 USA
  21  *
  22  */
  23
  24 #include <stdio.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <unistd.h>
  28 #include "busybox.h"
  29
  30 #define COMM_OPT_1 0x01
  31 #define COMM_OPT_2 0x02
  32 #define COMM_OPT_3 0x04
  33
  34 /* These three variables control behaviour if non-zero */
  35
  36 static int only_file_1;
  37 static int only_file_2;
  38 static int both;
  39
  40 /* writeline outputs the input given, appropriately aligned according to class */
  41 static void writeline (char *line, int class)
  42 {
  43         switch (class) {
  44                 case 1:
  45                         if (!only_file_1)
  46                                 return;
  47                         break;
  48                 case 2:
  49                         if (!only_file_2)
  50                                 return;
  51                         if (only_file_1)
  52                                 putchar('\t');
  53                         break;
  54                 case 3:
  55                         if (!both)
  56                                 return;
  57                         if (only_file_1)
  58                                 putchar('\t');
  59                         if (only_file_2)
  60                                 putchar('\t');
  61                         break;
  62         }
  63         fputs(line, stdout);
  64 }
  65
  66 /* This is the real core of the program - lines are compared here */
  67 static int cmp_files(char **infiles)
  68 {
  69         char thisline[2][100];
  70         FILE *streams[2];
  71         int i = 0;
  72
  73         for (i = 0; i < 2; i++) {
  74                 streams[i] = (strcmp(infiles[i], "=") == 0 ? stdin : fopen(infiles[i], "r"));
  75                 fgets(thisline[i], 100, streams[i]);
  76         }
  77
  78         while (thisline[0] || thisline[1]) {
  79                 int order = 0;
  80                 int tl0_len = strlen(thisline[0]);
  81                 int tl1_len = strlen(thisline[1]);
  82
  83                 if (!thisline[0])
  84                         order = 1;
  85                 else if (!thisline[1])
  86                         order = -1;
  87                 else {
  88                         order = memcmp(thisline[0], thisline[1], tl0_len < tl1_len ? tl0_len : tl1_len);
  89                         if (!order)
  90                                 order = tl0_len < tl1_len ? -1 : tl0_len != tl1_len;
  91                 }
  92
  93                 if ((order == 0) && (!feof(streams[0])) && (!feof(streams[1])))
  94                         writeline(thisline[1], 3);
  95                 else if ((order > 0) && (!feof(streams[1])))
  96                         writeline(thisline[1], 2);
  97                 else if ((order < 0) && (!feof(streams[0])))
  98                         writeline(thisline[0], 1);
  99
 100                 if (feof(streams[0]) && feof(streams[1])) {
 101                         fclose(streams[0]);
 102                         fclose(streams[1]);
 103                         break;
 104
 105                 } else if (feof(streams[0])) {
 106                         while (!feof(streams[1])) {
 107                                 if (order < 0)
 108                                         writeline(thisline[1], 2);
 109                                 fgets(thisline[1], 100, streams[1]);
 110                         }
 111                         fclose(streams[0]);
 112                         fclose(streams[1]);
 113                         break;
 114
 115                 } else if (feof(streams[1])) {
 116                         while (!feof(streams[0])) {
 117                                 if (order > 0)
 118                                         writeline(thisline[0], 1);
 119                                 fgets(thisline[0], 100, streams[0]);
 120                         }
 121                         fclose(streams[0]);
 122                         fclose(streams[1]);
 123                         break;
 124
 125                 } else {
 126                         if (order >= 0)
 127                                 fgets(thisline[1], 100, streams[1]);
 128                         if (order <= 0)
 129                                 fgets(thisline[0], 100, streams[0]);
 130                 }
 131         }
 132
 133         return 0;
 134 }
 135
 136 int comm_main (int argc, char **argv)
 137 {
 138         unsigned long opt;
 139         only_file_1 = 1;
 140         only_file_2 = 1;
 141         both = 1;
 142
 143         opt = bb_getopt_ulflags(argc, argv, "123");
 144
 145         if (optind != argc + 2)
 146                 bb_show_usage();
 147
 148         if (opt & COMM_OPT_1)
 149                 only_file_1 = 0;
 150         if (opt & COMM_OPT_2)
 151                 only_file_2 = 0;
 152         if (opt & COMM_OPT_3)
 153                 both = 0;
 154
 155         exit(cmp_files(argv + optind) == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
 156 }