src/comm.c

   1 /* comm -- compare two sorted files line by line.
   2    Copyright (C) 1986, 1990, 1991, 1995 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software
  16    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* Written by Richard Stallman and David MacKenzie. */
  19 \f
  20 #include <config.h>
  21
  22 #include <stdio.h>
  23 #include <getopt.h>
  24 #include <sys/types.h>
  25 #include "system.h"
  26 #include "linebuffer.h"
  27 #include "version.h"
  28 #include "error.h"
  29
  30 /* Undefine, to avoid warning about redefinition on some systems.  */
  31 #undef min
  32 #define min(x, y) ((x) < (y) ? (x) : (y))
  33
  34 /* The name this program was run with. */
  35 char *program_name;
  36
  37 /* If nonzero, print lines that are found only in file 1. */
  38 static int only_file_1;
  39
  40 /* If nonzero, print lines that are found only in file 2. */
  41 static int only_file_2;
  42
  43 /* If nonzero, print lines that are found in both files. */
  44 static int both;
  45
  46 /* If non-zero, display usage information and exit.  */
  47 static int show_help;
  48
  49 /* If non-zero, print the version on standard output then exit.  */
  50 static int show_version;
  51
  52 static struct option const long_options[] =
  53 {
  54   {"help", no_argument, &show_help, 1},
  55   {"version", no_argument, &show_version, 1},
  56   {0, 0, 0, 0}
  57 };
  58
  59 \f
  60
  61 static void
  62 usage (status)
  63      int status;
  64 {
  65   if (status != 0)
  66     fprintf (stderr, "Try `%s --help' for more information.\n",
  67              program_name);
  68   else
  69     {
  70       printf ("\
  71 Usage: %s [OPTION]... LEFT_FILE RIGHT_FILE\n\
  72 ",
  73               program_name);
  74       printf ("\
  75 Compare sorted files LEFT_FILE and RIGHT_FILE line by line.\n\
  76 \n\
  77   -1              suppress lines unique to left file\n\
  78   -2              suppress lines unique to right file\n\
  79   -3              suppress lines unique to both files\n\
  80       --help      display this help and exit\n\
  81       --version   output version information and exit\n\
  82 ");
  83     }
  84   exit (status);
  85 }
  86
  87 /* Output the line in linebuffer LINE to stream STREAM
  88    provided the switches say it should be output.
  89    CLASS is 1 for a line found only in file 1,
  90    2 for a line only in file 2, 3 for a line in both. */
  91
  92 static void
  93 writeline (line, stream, class)
  94      struct linebuffer *line;
  95      FILE *stream;
  96      int class;
  97 {
  98   switch (class)
  99     {
 100     case 1:
 101       if (!only_file_1)
 102         return;
 103       break;
 104
 105     case 2:
 106       if (!only_file_2)
 107         return;
 108       /* Skip the tab stop for case 1, if we are printing case 1.  */
 109       if (only_file_1)
 110         putc ('\t', stream);
 111       break;
 112
 113     case 3:
 114       if (!both)
 115         return;
 116       /* Skip the tab stop for case 1, if we are printing case 1.  */
 117       if (only_file_1)
 118         putc ('\t', stream);
 119       /* Skip the tab stop for case 2, if we are printing case 2.  */
 120       if (only_file_2)
 121         putc ('\t', stream);
 122       break;
 123     }
 124
 125   fwrite (line->buffer, sizeof (char), line->length, stream);
 126   putc ('\n', stream);
 127 }
 128
 129 /* Compare INFILES[0] and INFILES[1].
 130    If either is "-", use the standard input for that file.
 131    Assume that each input file is sorted;
 132    merge them and output the result.
 133    Return 0 if successful, 1 if any errors occur. */
 134
 135 static int
 136 compare_files (infiles)
 137      char **infiles;
 138 {
 139   /* For each file, we have one linebuffer in lb1.  */
 140   struct linebuffer lb1[2];
 141
 142   /* thisline[i] points to the linebuffer holding the next available line
 143      in file i, or is NULL if there are no lines left in that file.  */
 144   struct linebuffer *thisline[2];
 145
 146   /* streams[i] holds the input stream for file i.  */
 147   FILE *streams[2];
 148
 149   int i, ret = 0;
 150
 151   /* Initialize the storage. */
 152   for (i = 0; i < 2; i++)
 153     {
 154       initbuffer (&lb1[i]);
 155       thisline[i] = &lb1[i];
 156       streams[i] = strcmp (infiles[i], "-")
 157         ? fopen (infiles[i], "r") : stdin;
 158       if (!streams[i])
 159         {
 160           error (0, errno, "%s", infiles[i]);
 161           return 1;
 162         }
 163
 164       thisline[i] = readline (thisline[i], streams[i]);
 165     }
 166
 167   while (thisline[0] || thisline[1])
 168     {
 169       int order;
 170
 171       /* Compare the next available lines of the two files.  */
 172
 173       if (!thisline[0])
 174         order = 1;
 175       else if (!thisline[1])
 176         order = -1;
 177       else
 178         {
 179           /* Cannot use bcmp -- it only returns a boolean value. */
 180           order = memcmp (thisline[0]->buffer, thisline[1]->buffer,
 181                           min (thisline[0]->length, thisline[1]->length));
 182           if (order == 0)
 183             order = thisline[0]->length - thisline[1]->length;
 184         }
 185
 186       /* Output the line that is lesser. */
 187       if (order == 0)
 188         writeline (thisline[1], stdout, 3);
 189       else if (order > 0)
 190         writeline (thisline[1], stdout, 2);
 191       else
 192         writeline (thisline[0], stdout, 1);
 193
 194       /* Step the file the line came from.
 195          If the files match, step both files.  */
 196       if (order >= 0)
 197         thisline[1] = readline (thisline[1], streams[1]);
 198       if (order <= 0)
 199         thisline[0] = readline (thisline[0], streams[0]);
 200     }
 201
 202   /* Free all storage and close all input streams. */
 203   for (i = 0; i < 2; i++)
 204     {
 205       free (lb1[i].buffer);
 206       if (ferror (streams[i]) || fclose (streams[i]) == EOF)
 207         {
 208           error (0, errno, "%s", infiles[i]);
 209           ret = 1;
 210         }
 211     }
 212   if (ferror (stdout) || fclose (stdout) == EOF)
 213     {
 214       error (0, errno, "write error");
 215       ret = 1;
 216     }
 217   return ret;
 218 }
 219
 220 void
 221 main (argc, argv)
 222      int argc;
 223      char *argv[];
 224 {
 225   int c;
 226
 227   program_name = argv[0];
 228
 229   only_file_1 = 1;
 230   only_file_2 = 1;
 231   both = 1;
 232
 233   while ((c = getopt_long (argc, argv, "123", long_options, (int *) 0)) != EOF)
 234     switch (c)
 235       {
 236       case 0:
 237         break;
 238
 239       case '1':
 240         only_file_1 = 0;
 241         break;
 242
 243       case '2':
 244         only_file_2 = 0;
 245         break;
 246
 247       case '3':
 248         both = 0;
 249         break;
 250
 251       default:
 252         usage (1);
 253       }
 254
 255   if (show_version)
 256     {
 257       printf ("comm - %s\n", version_string);
 258       exit (0);
 259     }
 260
 261   if (show_help)
 262     usage (0);
 263
 264   if (optind + 2 != argc)
 265     usage (1);
 266
 267   exit (compare_files (argv + optind));
 268 }