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 static int compare_files ();
  60 static void writeline ();
  61 static void usage ();
  62 \f
  63 void
  64 main (argc, argv)
  65      int argc;
  66      char *argv[];
  67 {
  68   int c;
  69
  70   program_name = argv[0];
  71
  72   only_file_1 = 1;
  73   only_file_2 = 1;
  74   both = 1;
  75
  76   while ((c = getopt_long (argc, argv, "123", long_options, (int *) 0)) != EOF)
  77     switch (c)
  78       {
  79       case 0:
  80         break;
  81
  82       case '1':
  83         only_file_1 = 0;
  84         break;
  85
  86       case '2':
  87         only_file_2 = 0;
  88         break;
  89
  90       case '3':
  91         both = 0;
  92         break;
  93
  94       default:
  95         usage (1);
  96       }
  97
  98   if (show_version)
  99     {
 100       printf ("comm - %s\n", version_string);
 101       exit (0);
 102     }
 103
 104   if (show_help)
 105     usage (0);
 106
 107   if (optind + 2 != argc)
 108     usage (1);
 109
 110   exit (compare_files (argv + optind));
 111 }
 112 \f
 113 /* Compare INFILES[0] and INFILES[1].
 114    If either is "-", use the standard input for that file.
 115    Assume that each input file is sorted;
 116    merge them and output the result.
 117    Return 0 if successful, 1 if any errors occur. */
 118
 119 static int
 120 compare_files (infiles)
 121      char **infiles;
 122 {
 123   /* For each file, we have one linebuffer in lb1.  */
 124   struct linebuffer lb1[2];
 125
 126   /* thisline[i] points to the linebuffer holding the next available line
 127      in file i, or is NULL if there are no lines left in that file.  */
 128   struct linebuffer *thisline[2];
 129
 130   /* streams[i] holds the input stream for file i.  */
 131   FILE *streams[2];
 132
 133   int i, ret = 0;
 134
 135   /* Initialize the storage. */
 136   for (i = 0; i < 2; i++)
 137     {
 138       initbuffer (&lb1[i]);
 139       thisline[i] = &lb1[i];
 140       streams[i] = strcmp (infiles[i], "-")
 141         ? fopen (infiles[i], "r") : stdin;
 142       if (!streams[i])
 143         {
 144           error (0, errno, "%s", infiles[i]);
 145           return 1;
 146         }
 147
 148       thisline[i] = readline (thisline[i], streams[i]);
 149     }
 150
 151   while (thisline[0] || thisline[1])
 152     {
 153       int order;
 154
 155       /* Compare the next available lines of the two files.  */
 156
 157       if (!thisline[0])
 158         order = 1;
 159       else if (!thisline[1])
 160         order = -1;
 161       else
 162         {
 163           /* Cannot use bcmp -- it only returns a boolean value. */
 164           order = memcmp (thisline[0]->buffer, thisline[1]->buffer,
 165                           min (thisline[0]->length, thisline[1]->length));
 166           if (order == 0)
 167             order = thisline[0]->length - thisline[1]->length;
 168         }
 169
 170       /* Output the line that is lesser. */
 171       if (order == 0)
 172         writeline (thisline[1], stdout, 3);
 173       else if (order > 0)
 174         writeline (thisline[1], stdout, 2);
 175       else
 176         writeline (thisline[0], stdout, 1);
 177
 178       /* Step the file the line came from.
 179          If the files match, step both files.  */
 180       if (order >= 0)
 181         thisline[1] = readline (thisline[1], streams[1]);
 182       if (order <= 0)
 183         thisline[0] = readline (thisline[0], streams[0]);
 184     }
 185
 186   /* Free all storage and close all input streams. */
 187   for (i = 0; i < 2; i++)
 188     {
 189       free (lb1[i].buffer);
 190       if (ferror (streams[i]) || fclose (streams[i]) == EOF)
 191         {
 192           error (0, errno, "%s", infiles[i]);
 193           ret = 1;
 194         }
 195     }
 196   if (ferror (stdout) || fclose (stdout) == EOF)
 197     {
 198       error (0, errno, "write error");
 199       ret = 1;
 200     }
 201   return ret;
 202 }
 203
 204 /* Output the line in linebuffer LINE to stream STREAM
 205    provided the switches say it should be output.
 206    CLASS is 1 for a line found only in file 1,
 207    2 for a line only in file 2, 3 for a line in both. */
 208
 209 static void
 210 writeline (line, stream, class)
 211      struct linebuffer *line;
 212      FILE *stream;
 213      int class;
 214 {
 215   switch (class)
 216     {
 217     case 1:
 218       if (!only_file_1)
 219         return;
 220       break;
 221
 222     case 2:
 223       if (!only_file_2)
 224         return;
 225       /* Skip the tab stop for case 1, if we are printing case 1.  */
 226       if (only_file_1)
 227         putc ('\t', stream);
 228       break;
 229
 230     case 3:
 231       if (!both)
 232         return;
 233       /* Skip the tab stop for case 1, if we are printing case 1.  */
 234       if (only_file_1)
 235         putc ('\t', stream);
 236       /* Skip the tab stop for case 2, if we are printing case 2.  */
 237       if (only_file_2)
 238         putc ('\t', stream);
 239       break;
 240     }
 241
 242   fwrite (line->buffer, sizeof (char), line->length, stream);
 243   putc ('\n', stream);
 244 }
 245 \f
 246 static void
 247 usage (status)
 248      int status;
 249 {
 250   if (status != 0)
 251     fprintf (stderr, "Try `%s --help' for more information.\n",
 252              program_name);
 253   else
 254     {
 255       printf ("\
 256 Usage: %s [OPTION]... LEFT_FILE RIGHT_FILE\n\
 257 ",
 258               program_name);
 259       printf ("\
 260 Compare sorted files LEFT_FILE and RIGHT_FILE line by line.\n\
 261 \n\
 262   -1              suppress lines unique to left file\n\
 263   -2              suppress lines unique to right file\n\
 264   -3              suppress lines unique to both files\n\
 265       --help      display this help and exit\n\
 266       --version   output version information and exit\n\
 267 ");
 268     }
 269   exit (status);
 270 }