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 "busybox.h"
  11
  12 #define COMM_OPT_1 0x01
  13 #define COMM_OPT_2 0x02
  14 #define COMM_OPT_3 0x04
  15
  16 /* These three variables control behaviour if non-zero */
  17
  18 static int only_file_1;
  19 static int only_file_2;
  20 static int both;
  21
  22 /* writeline outputs the input given, appropriately aligned according to class */
  23 static void writeline(char *line, int class)
  24 {
  25         if (class == 0) {
  26                 if (!only_file_1)
  27                         return;
  28         } else if (class == 1) {
  29                 if (!only_file_2)
  30                         return;
  31                 if (only_file_1)
  32                         putchar('\t');
  33         }
  34         else /*if (class == 2)*/ {
  35                 if (!both)
  36                         return;
  37                 if (only_file_1)
  38                         putchar('\t');
  39                 if (only_file_2)
  40                         putchar('\t');
  41         }
  42         fputs(line, stdout);
  43 }
  44
  45 /* This is the real core of the program - lines are compared here */
  46 static void cmp_files(char **infiles)
  47 {
  48 #define LINE_LEN 100
  49 #define BB_EOF_0 0x1
  50 #define BB_EOF_1 0x2
  51         char thisline[2][LINE_LEN];
  52         FILE *streams[2];
  53         int i;
  54
  55         for (i = 0; i < 2; ++i) {
  56                 streams[i] = ((infiles[i][0] == '=' && infiles[i][1]) ? stdin : xfopen(infiles[i], "r"));
  57                 fgets(thisline[i], LINE_LEN, streams[i]);
  58         }
  59
  60         while (*thisline[0] || *thisline[1]) {
  61                 int order = 0;
  62
  63                 i = 0;
  64                 if (feof(streams[0])) i |= BB_EOF_0;
  65                 if (feof(streams[1])) i |= BB_EOF_1;
  66
  67                 if (!*thisline[0])
  68                         order = 1;
  69                 else if (!*thisline[1])
  70                         order = -1;
  71                 else {
  72                         int tl0_len, tl1_len;
  73                         tl0_len = strlen(thisline[0]);
  74                         tl1_len = strlen(thisline[1]);
  75                         order = memcmp(thisline[0], thisline[1], tl0_len < tl1_len ? tl0_len : tl1_len);
  76                         if (!order)
  77                                 order = tl0_len < tl1_len ? -1 : tl0_len != tl1_len;
  78                 }
  79
  80                 if (order == 0 && !i)
  81                         writeline(thisline[1], 2);
  82                 else if (order > 0 && !(i & BB_EOF_1))
  83                         writeline(thisline[1], 1);
  84                 else if (order < 0 && !(i & BB_EOF_0))
  85                         writeline(thisline[0], 0);
  86
  87                 if (i & BB_EOF_0 & BB_EOF_1) {
  88                         break;
  89
  90                 } else if (i) {
  91                         i = (i & BB_EOF_0 ? 1 : 0);
  92                         while (!feof(streams[i])) {
  93                                 if ((order < 0 && i) || (order > 0 && !i))
  94                                         writeline(thisline[i], i);
  95                                 fgets(thisline[i], LINE_LEN, streams[i]);
  96                         }
  97                         break;
  98
  99                 } else {
 100                         if (order >= 0)
 101                                 fgets(thisline[1], LINE_LEN, streams[1]);
 102                         if (order <= 0)
 103                                 fgets(thisline[0], LINE_LEN, streams[0]);
 104                 }
 105         }
 106
 107         fclose(streams[0]);
 108         fclose(streams[1]);
 109 }
 110
 111 int comm_main(int argc, char **argv)
 112 {
 113         unsigned long flags;
 114
 115         flags = getopt32(argc, argv, "123");
 116
 117         if (optind + 2 != argc)
 118                 bb_show_usage();
 119
 120         only_file_1 = !(flags & COMM_OPT_1);
 121         only_file_2 = !(flags & COMM_OPT_2);
 122         both = !(flags & COMM_OPT_3);
 123
 124         cmp_files(argv + optind);
 125         exit(EXIT_SUCCESS);
 126 }