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>
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
#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 */
static void writeline(char *line, int class)
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{
if (class == 0) {
if (!only_file_1)
return;
} else if (class == 1) {
if (!only_file_2)
return;
if (only_file_1)
putchar('\t');
}
else /*if (class == 2)*/ {
if (!both)
return;
if (only_file_1)
putchar('\t');
if (only_file_2)
putchar('\t');
}
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fputs(line, stdout);
}
/* This is the real core of the program - lines are compared here */
static void cmp_files(char **infiles)
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{
#define LINE_LEN 100
#define BB_EOF_0 0x1
#define BB_EOF_1 0x2
char thisline[2][LINE_LEN];
FILE *streams[2];
int i;
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for (i = 0; i < 2; ++i) {
streams[i] = ((infiles[i][0] == '=' && infiles[i][1]) ? stdin : xfopen(infiles[i], "r"));
fgets(thisline[i], LINE_LEN, streams[i]);
}
while (*thisline[0] || *thisline[1]) {
int order = 0;
i = 0;
if (feof(streams[0])) i |= BB_EOF_0;
if (feof(streams[1])) i |= BB_EOF_1;
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if (!*thisline[0])
order = 1;
else if (!*thisline[1])
order = -1;
else {
int tl0_len, tl1_len;
tl0_len = strlen(thisline[0]);
tl1_len = strlen(thisline[1]);
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 && !i)
writeline(thisline[1], 2);
else if (order > 0 && !(i & BB_EOF_1))
writeline(thisline[1], 1);
else if (order < 0 && !(i & BB_EOF_0))
writeline(thisline[0], 0);
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if (i & BB_EOF_0 & BB_EOF_1) {
break;
} else if (i) {
i = (i & BB_EOF_0 ? 1 : 0);
while (!feof(streams[i])) {
if ((order < 0 && i) || (order > 0 && !i))
writeline(thisline[i], i);
fgets(thisline[i], LINE_LEN, streams[i]);
}
break;
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} else {
if (order >= 0)
fgets(thisline[1], LINE_LEN, streams[1]);
if (order <= 0)
fgets(thisline[0], LINE_LEN, streams[0]);
}
}
fclose(streams[0]);
fclose(streams[1]);
}
int comm_main(int argc, char **argv)
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{
unsigned long flags;
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flags = bb_getopt_ulflags(argc, argv, "123");
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if (optind + 2 != argc)
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bb_show_usage();
only_file_1 = !(flags & COMM_OPT_1);
only_file_2 = !(flags & COMM_OPT_2);
both = !(flags & COMM_OPT_3);
cmp_files(argv + optind);
exit(EXIT_SUCCESS);
}