busybox/coreutils/comm.c

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/* vi: set sw=4 ts=4: */
/*
* Mini comm implementation for busybox
*
* Copyright (C) 2005 by Robert Sullivan <cogito.ergo.cogito@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
* 02111-1307 USA
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "busybox.h"
#define COMM_OPT_1 0x01
#define COMM_OPT_2 0x02
#define COMM_OPT_3 0x04
/* These three variables control behaviour if non-zero */
static int only_file_1;
static int only_file_2;
static int both;
/* writeline outputs the input given, appropriately aligned according to class */
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static void writeline (char *line, int class)
{
switch (class) {
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case 1:
if (!only_file_1)
return;
break;
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case 2:
if (!only_file_2)
return;
if (only_file_1)
putchar('\t');
break;
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case 3:
if (!both)
return;
if (only_file_1)
putchar('\t');
if (only_file_2)
putchar('\t');
break;
}
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fputs(line, stdout);
}
/* This is the real core of the program - lines are compared here */
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static int cmp_files(char **infiles)
{
char thisline[2][100];
FILE *streams[2];
int i = 0;
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for (i = 0; i < 2; i++) {
streams[i] = (strcmp(infiles[i], "=") == 0 ? stdin : fopen(infiles[i], "r"));
fgets(thisline[i], 100, streams[i]);
}
while (thisline[0] || thisline[1]) {
int order = 0;
int tl0_len = strlen(thisline[0]);
int tl1_len = strlen(thisline[1]);
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if (!thisline[0])
order = 1;
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else if (!thisline[1])
order = -1;
else {
order = memcmp(thisline[0], thisline[1], tl0_len < tl1_len ? tl0_len : tl1_len);
if (!order)
order = tl0_len < tl1_len ? -1 : tl0_len != tl1_len;
}
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if ((order == 0) && (!feof(streams[0])) && (!feof(streams[1])))
writeline(thisline[1], 3);
else if ((order > 0) && (!feof(streams[1])))
writeline(thisline[1], 2);
else if ((order < 0) && (!feof(streams[0])))
writeline(thisline[0], 1);
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if (feof(streams[0]) && feof(streams[1])) {
fclose(streams[0]);
fclose(streams[1]);
break;
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} else if (feof(streams[0])) {
while (!feof(streams[1])) {
if (order < 0)
writeline(thisline[1], 2);
fgets(thisline[1], 100, streams[1]);
}
fclose(streams[0]);
fclose(streams[1]);
break;
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} else if (feof(streams[1])) {
while (!feof(streams[0])) {
if (order > 0)
writeline(thisline[0], 1);
fgets(thisline[0], 100, streams[0]);
}
fclose(streams[0]);
fclose(streams[1]);
break;
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} else {
if (order >= 0)
fgets(thisline[1], 100, streams[1]);
if (order <= 0)
fgets(thisline[0], 100, streams[0]);
}
}
return 0;
}
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int comm_main (int argc, char **argv)
{
unsigned long opt;
only_file_1 = 1;
only_file_2 = 1;
both = 1;
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opt = bb_getopt_ulflags(argc, argv, "123");
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if ((opt & 0x80000000UL) || (optind == argc))
bb_show_usage();
if (opt & COMM_OPT_1)
only_file_1 = 0;
if (opt & COMM_OPT_2)
only_file_2 = 0;
if (opt & COMM_OPT_3)
both = 0;
exit(cmp_files(argv + optind) == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
}