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 nonzero, display usage information and exit.  */
  47 static int show_help;
  48
  49 /* If nonzero, 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 (int status)
  63 {
  64   if (status != 0)
  65     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  66              program_name);
  67   else
  68     {
  69       printf (_("\
  70 Usage: %s [OPTION]... LEFT_FILE RIGHT_FILE\n\
  71 "),
  72               program_name);
  73       printf (_("\
  74 Compare sorted files LEFT_FILE and RIGHT_FILE line by line.\n\
  75 \n\
  76   -1              suppress lines unique to left file\n\
  77   -2              suppress lines unique to right file\n\
  78   -3              suppress lines unique to both files\n\
  79       --help      display this help and exit\n\
  80       --version   output version information and exit\n\
  81 "));
  82     }
  83   exit (status);
  84 }
  85
  86 /* Output the line in linebuffer LINE to stream STREAM
  87    provided the switches say it should be output.
  88    CLASS is 1 for a line found only in file 1,
  89    2 for a line only in file 2, 3 for a line in both. */
  90
  91 static void
  92 writeline (struct linebuffer *line, FILE *stream, int class)
  93 {
  94   switch (class)
  95     {
  96     case 1:
  97       if (!only_file_1)
  98         return;
  99       break;
 100
 101     case 2:
 102       if (!only_file_2)
 103         return;
 104       /* Skip the tab stop for case 1, if we are printing case 1.  */
 105       if (only_file_1)
 106         putc ('\t', stream);
 107       break;
 108
 109     case 3:
 110       if (!both)
 111         return;
 112       /* Skip the tab stop for case 1, if we are printing case 1.  */
 113       if (only_file_1)
 114         putc ('\t', stream);
 115       /* Skip the tab stop for case 2, if we are printing case 2.  */
 116       if (only_file_2)
 117         putc ('\t', stream);
 118       break;
 119     }
 120
 121   fwrite (line->buffer, sizeof (char), line->length, stream);
 122   putc ('\n', stream);
 123 }
 124
 125 /* Compare INFILES[0] and INFILES[1].
 126    If either is "-", use the standard input for that file.
 127    Assume that each input file is sorted;
 128    merge them and output the result.
 129    Return 0 if successful, 1 if any errors occur. */
 130
 131 static int
 132 compare_files (char **infiles)
 133 {
 134   /* For each file, we have one linebuffer in lb1.  */
 135   struct linebuffer lb1[2];
 136
 137   /* thisline[i] points to the linebuffer holding the next available line
 138      in file i, or is NULL if there are no lines left in that file.  */
 139   struct linebuffer *thisline[2];
 140
 141   /* streams[i] holds the input stream for file i.  */
 142   FILE *streams[2];
 143
 144   int i, ret = 0;
 145
 146   /* Initialize the storage. */
 147   for (i = 0; i < 2; i++)
 148     {
 149       initbuffer (&lb1[i]);
 150       thisline[i] = &lb1[i];
 151       streams[i] = strcmp (infiles[i], "-")
 152         ? fopen (infiles[i], "r") : stdin;
 153       if (!streams[i])
 154         {
 155           error (0, errno, "%s", infiles[i]);
 156           return 1;
 157         }
 158
 159       thisline[i] = readline (thisline[i], streams[i]);
 160     }
 161
 162   while (thisline[0] || thisline[1])
 163     {
 164       int order;
 165
 166       /* Compare the next available lines of the two files.  */
 167
 168       if (!thisline[0])
 169         order = 1;
 170       else if (!thisline[1])
 171         order = -1;
 172       else
 173         {
 174           /* Cannot use bcmp -- it only returns a boolean value. */
 175           order = memcmp (thisline[0]->buffer, thisline[1]->buffer,
 176                           min (thisline[0]->length, thisline[1]->length));
 177           if (order == 0)
 178             order = thisline[0]->length - thisline[1]->length;
 179         }
 180
 181       /* Output the line that is lesser. */
 182       if (order == 0)
 183         writeline (thisline[1], stdout, 3);
 184       else if (order > 0)
 185         writeline (thisline[1], stdout, 2);
 186       else
 187         writeline (thisline[0], stdout, 1);
 188
 189       /* Step the file the line came from.
 190          If the files match, step both files.  */
 191       if (order >= 0)
 192         thisline[1] = readline (thisline[1], streams[1]);
 193       if (order <= 0)
 194         thisline[0] = readline (thisline[0], streams[0]);
 195     }
 196
 197   /* Free all storage and close all input streams. */
 198   for (i = 0; i < 2; i++)
 199     {
 200       free (lb1[i].buffer);
 201       if (ferror (streams[i]) || fclose (streams[i]) == EOF)
 202         {
 203           error (0, errno, "%s", infiles[i]);
 204           ret = 1;
 205         }
 206     }
 207   if (ferror (stdout) || fclose (stdout) == EOF)
 208     {
 209       error (0, errno, _("write error"));
 210       ret = 1;
 211     }
 212   return ret;
 213 }
 214
 215 void
 216 main (int argc, char **argv)
 217 {
 218   int c;
 219
 220   program_name = argv[0];
 221   setlocale (LC_ALL, "");
 222   bindtextdomain (PACKAGE, LOCALEDIR);
 223   textdomain (PACKAGE);
 224
 225   only_file_1 = 1;
 226   only_file_2 = 1;
 227   both = 1;
 228
 229   while ((c = getopt_long (argc, argv, "123", long_options, (int *) 0)) != EOF)
 230     switch (c)
 231       {
 232       case 0:
 233         break;
 234
 235       case '1':
 236         only_file_1 = 0;
 237         break;
 238
 239       case '2':
 240         only_file_2 = 0;
 241         break;
 242
 243       case '3':
 244         both = 0;
 245         break;
 246
 247       default:
 248         usage (1);
 249       }
 250
 251   if (show_version)
 252     {
 253       printf ("comm - %s\n", version_string);
 254       exit (0);
 255     }
 256
 257   if (show_help)
 258     usage (0);
 259
 260   if (optind + 2 != argc)
 261     usage (1);
 262
 263   exit (compare_files (argv + optind));
 264 }