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/* fcomp.c:
This code has been adapted from:
Software Practice and Experience
Vol 15, pp. 1025-1040, November 1985.
"A File Comparison Program"
by Miller and Myers
http://tx0.org/7eq
The modifications basically allow calling the diff routine
from a separate program, upping the max lines, and modernizing
some portions of the code. Please don't ask me about the
theory involved, I do not understand it.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "prism.h"
#define MAXLINES 15000
#define ORIGIN MAXLINES
#define INSERT 1
#define DELETE 2
struct edit {
struct edit *link;
int op;
int line1;
int line2;
};
static char **A, **B;
static void fatal(const char *msg)
{
printf(" ERR: %s\n",msg);
}
static void exceed(int d)
{
printf(" ERR: the files differ in at least %d lines\n",d);
}
static int in_file(const char *filename, char **P)
{
char *buf, *save;
FILE *fp, *fopen();
int lines = 0;
if ((fp = fopen(filename,"r")) == NULL)
{
fatal("cannot open file");
return PRET_READERROR;
}
buf = (char *)malloc(256*sizeof(char));
if(buf == NULL)
return PRET_ERROR;
while(fgets(buf,100,fp) != NULL)
{
if (lines >= MAXLINES) {
fatal("file is to large for diff");
return PRET_ERROR;
}
save = (char *)malloc((strlen(buf)+1)*sizeof(char));
if (save == NULL) {
fatal("not enough room to save the files");
return PRET_ERROR;
}
P[lines++] = save;
strcpy(save, buf);
}
fclose(fp);
free(buf);
return(lines);
}
static void put_scr(struct edit *start, const char *fname1, const char *fname2)
{
struct edit *ep, *behind, *ahead, *a, *b;
int change;
ahead = start;
ep = NULL;
while (ahead != NULL)
{
behind = ep;
ep = ahead;
ahead = ahead->link;
ep->link = behind;
}
while( ep != NULL && 0 == 0)
{
b = ep;
if (ep->op == INSERT)
//printf("Inserted after line %d:\n",ep->line1);
printf("line %s:%d || %s:%d\n", fname1, ep->line1, fname2, ep->line2);
else
{
do
{
a = b;
b = b->link;
} while (b!=NULL && b->op == DELETE && b->line1 == a->line1+1);
change = (b!=NULL && b->op == INSERT && b->line1 == a->line1);
if (a == ep)
printf("line %s:%d || %s:%d\n", fname1, ep->line1, fname2, ep->line2);
//printf("line %d:\n",ep->line1);
else
printf("line %s:%d-%d || %s:%d-%d\n", fname1, ep->line1, a->line1, fname2, ep->line2, a->line2);
//printf("lines %d-%d:\n",ep->line1,a->line1);
do
{
printf("-%s",A[ep->line1-1]);
ep = ep->link;
} while (ep != b);
if (!change) {
printf("\n");
continue;
}
}
do
{
printf("+%s",B[ep->line2-1]);
ep = ep->link;
} while (ep != NULL && ep->op == INSERT && ep->line1 == b->line1);
printf("\n");
}
}
int compare_files(const char *fname1, const char *fname2)
{
int max_d,
m,
n,
lower,
upper,
d,
k,
row,
col;
int *last_d;
struct edit **script;
struct edit *new;
last_d = (int *)malloc((2*MAXLINES+1)*sizeof(int));
script = (struct edit **)malloc((2*MAXLINES+1)*sizeof(struct edit *));
A = (char **)malloc(MAXLINES*sizeof(char *));
B = (char **)malloc(MAXLINES*sizeof(char *));
if(A == NULL || B == NULL) return PRET_ERROR;
memset(A, 0, MAXLINES);
memset(B, 0, MAXLINES);
max_d = 2*MAXLINES;
m = in_file(fname1,A);
n = in_file(fname2,B);
for (row=0 ; row<m && row < n && strcmp(A[row],B[row]) == 0 ; ++row)
;
last_d[ORIGIN] = row;
script[ORIGIN] = NULL;
lower = (row == m) ? ORIGIN + 1 : ORIGIN - 1;
upper = (row == n) ? ORIGIN - 1 : ORIGIN + 1;
if (lower > upper)
{
printf(" the files are identical\n");
return PRET_OK;
}
for (d = 1 ; d <= max_d ; ++d)
{
for ( k = lower ; k <= upper ; k +=2)
{
new = (struct edit *) malloc(sizeof(struct edit));
if (new == NULL) {
exceed(d);
return PRET_ERROR;
}
if (k == ORIGIN-d || k != ORIGIN+d && last_d[k+1] >= last_d[k-1])
{
row = last_d[k+1]+1;
new->link = script[k+1];
new->op = DELETE;
}
else
{
row = last_d[k-1];
new->link = script[k-1];
new->op = INSERT;
}
new->line1 = row;
new->line2 = col = row + k - ORIGIN;
script[k] = new;
while(row < m && col < n && strcmp(A[row],B[col]) == 0)
{
++row;
++col;
}
last_d[k] = row;
if (row == m && col == n)
{
put_scr(script[k], fname1, fname2);
return PRET_OK;
}
if (row == m)
lower = k+2;
if (col == n)
upper = k-2;
}
--lower;
++upper;
}
exceed(d);
return PRET_ERROR;
}
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