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         switch (class) {
  43                 case 1: if (!only_file_1)
  44                                 return;
  45                         break;
  46                 case 2: if (!only_file_2)
  47                                 return;
  48                         if (only_file_1)
  49                                 putchar('\t');
  50                         break;
  51                 case 3: if (!both)
  52                                 return;
  53                         if (only_file_1)
  54                                 putchar('\t');
  55                         if (only_file_2)
  56                                 putchar('\t');
  57                         break;
  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 : fopen(infiles[i], "r"));
  71                 fgets(thisline[i], 100, streams[i]);
  72         }
  73
  74         while (thisline[0] || thisline[1]) {
  75
  76                 int order = 0;
  77                 int tl0_len = strlen(thisline[0]);
  78                 int tl1_len = strlen(thisline[1]);
  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
 103                         while (!feof(streams[1])) {
 104                                 if (order < 0)
 105                                         writeline(thisline[1], 2);
 106                                 fgets(thisline[1], 100, streams[1]);
 107                         }
 108                         fclose(streams[0]);
 109                         fclose(streams[1]);
 110                         break;
 111                 }
 112                 else if (feof(streams[1])) {
 113
 114                         while (!feof(streams[0])) {
 115                                 if (order > 0)
 116                                         writeline(thisline[0], 1);
 117                                 fgets(thisline[0], 100, streams[0]);
 118                         }
 119                         fclose(streams[0]);
 120                         fclose(streams[1]);
 121                         break;
 122                 }
 123                 else {
 124                         if (order >= 0)
 125                                 fgets(thisline[1], 100, streams[1]);
 126                         if (order <= 0)
 127                                 fgets(thisline[0], 100, streams[0]);
 128                 }
 129         }
 130
 131         return 0;
 132 }
 133
 134 int comm_main (int argc, char **argv) {
 135
 136         unsigned long opt;
 137         only_file_1 = 1;
 138         only_file_2 = 1;
 139         both = 1;
 140
 141         opt = bb_getopt_ulflags(argc, argv, "123");
 142
 143         if ((opt & 0x80000000UL) || (optind == argc)) {
 144                 bb_show_usage();
 145         }
 146
 147         if (opt & COMM_OPT_1)
 148                 only_file_1 = 0;
 149         if (opt & COMM_OPT_2)
 150                 only_file_2 = 0;
 151         if (opt & COMM_OPT_3)
 152                 both = 0;
 153
 154         exit(cmp_files(argv + optind) == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
 155 }