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         if (class == 1 && !only_file_1)
  44                 return;
  45         else if (class == 2) {
  46                 if (!only_file_2)
  47                         return;
  48                 if (only_file_1)
  49                         putchar('\t');
  50         }
  51         else if (class == 3) {
  52                 if (!both)
  53                         return;
  54                 if (only_file_1)
  55                         putchar('\t');
  56                 if (only_file_2)
  57                         putchar('\t');
  58         }
  59         fputs(line, stdout);
  60 }
  61
  62 /* This is the real core of the program - lines are compared here */
  63 static int cmp_files(char **infiles)
  64 {
  65         char thisline[2][100];
  66         FILE *streams[2];
  67         int i = 0;
  68
  69         for (i = 0; i < 2; i++) {
  70                 streams[i] = (strcmp(infiles[i], "=") == 0 ? stdin : bb_xfopen(infiles[i], "r"));
  71                 fgets(thisline[i], 100, streams[i]);
  72         }
  73
  74         while (thisline[0] || thisline[1]) {
  75                 int order = 0;
  76                 int tl0_len = strlen(thisline[0]);
  77                 int tl1_len = strlen(thisline[1]);
  78
  79                 if (!thisline[0])
  80                         order = 1;
  81                 else if (!thisline[1])
  82                         order = -1;
  83                 else {
  84                         order = memcmp(thisline[0], thisline[1], tl0_len < tl1_len ? tl0_len : tl1_len);
  85                         if (!order)
  86                                 order = tl0_len < tl1_len ? -1 : tl0_len != tl1_len;
  87                 }
  88
  89                 if ((order == 0) && (!feof(streams[0])) && (!feof(streams[1])))
  90                         writeline(thisline[1], 3);
  91                 else if ((order > 0) && (!feof(streams[1])))
  92                         writeline(thisline[1], 2);
  93                 else if ((order < 0) && (!feof(streams[0])))
  94                         writeline(thisline[0], 1);
  95
  96                 if (feof(streams[0]) && feof(streams[1])) {
  97                         fclose(streams[0]);
  98                         fclose(streams[1]);
  99                         break;
 100
 101                 } else if (feof(streams[0])) {
 102                         while (!feof(streams[1])) {
 103                                 if (order < 0)
 104                                         writeline(thisline[1], 2);
 105                                 fgets(thisline[1], 100, streams[1]);
 106                         }
 107                         fclose(streams[0]);
 108                         fclose(streams[1]);
 109                         break;
 110
 111                 } else if (feof(streams[1])) {
 112                         while (!feof(streams[0])) {
 113                                 if (order > 0)
 114                                         writeline(thisline[0], 1);
 115                                 fgets(thisline[0], 100, streams[0]);
 116                         }
 117                         fclose(streams[0]);
 118                         fclose(streams[1]);
 119                         break;
 120
 121                 } else {
 122                         if (order >= 0)
 123                                 fgets(thisline[1], 100, streams[1]);
 124                         if (order <= 0)
 125                                 fgets(thisline[0], 100, streams[0]);
 126                 }
 127         }
 128
 129         return 0;
 130 }
 131
 132 int comm_main(int argc, char **argv)
 133 {
 134         unsigned long flags;
 135
 136         flags = bb_getopt_ulflags(argc, argv, "123");
 137
 138         if (optind + 2 != argc)
 139                 bb_show_usage();
 140
 141         only_file_1 = !(flags & COMM_OPT_1);
 142         only_file_2 = !(flags & COMM_OPT_2);
 143         both = !(flags & COMM_OPT_3);
 144
 145         exit(cmp_files(argv + optind) == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
 146 }