+#
+/* diff - differential file comparison
+*
+* Uses an algorithm due to Harold Stone, which finds
+* a pair of longest identical subsequences in the two
+* files.
+*
+* The major goal is to generate the match vector J.
+* J[i] is the index of the line in file1 corresponding
+* to line i file0. J[i] = 0 if there is no
+* such line in file1.
+*
+* Lines are hashed so as to work in core. All potential
+* matches are located by sorting the lines of each file
+* on the hash (called value\b\b\b\b\b_____). In particular, this
+* collects the equivalence classes in file1 together.
+* Subroutine equiv\b\b\b\b____ replaces the value of each line in
+* file0 by the index of the first element of its
+* matching equivalence in (the reordered) file1.
+* To save space equiv\b\b\b\b\b_____ squeezes file1 into a single
+* array member\b\b\b\b\b\b______ in which the equivalence classes
+* are simply concatenated, except that their first
+* members are flagged by changing sign.
+*
+* Next the indices that point into member\b\b\b\b\b\b______ are unsorted\b\b\b\b\b\b\b\b_______ into
+* array class\b\b\b\b\b_____ according to the original order of file0.
+*
+* The cleverness lies in routine stone\b\b\b\b\b______. This marches
+* through the lines of file0, developing a vector klist\b\b\b\b\b_____
+* of "k-candidates". At step i a k-candidate is a matched
+* pair of lines x,y (x in file0 y in file1) such that
+* there is a common subsequence of lenght k
+* between the first i lines of file0 and the first y
+* lines of file1, but there is no such subsequence for
+* any smaller y. x is the earliest possible mate to y
+* that occurs in such a subsequence.
+*
+* Whenever any of the members of the equivalence class of
+* lines in file1 matable to a line in file0 has serial number
+* less than the y of some k-candidate, that k-candidate
+* with the smallest such y is replaced. The new
+* k-candidate is chained (via pred\b\b\b\b____) to the current
+* k-1 candidate so that the actual subsequence can
+* be recovered. When a member has serial number greater
+* that the y of all k-candidates, the klist is extended.
+* At the end, the longest subsequence is pulled out
+* and placed in the array J by unravel\b\b\b\b\b\b\b_______.
+*
+* With J in hand, the matches there recorded are
+* check\b\b\b\b\b_____ed against reality to assure that no spurious
+* matches have crept in due to hashing. If they have,
+* they are broken, and "jackpot " is recorded--a harmless
+* matter except that a true match for a spuriously
+* mated line may now be unnecessarily reported as a change.
+*
+* Much of the complexity of the program comes simply
+* from trying to minimize core utilization and
+* maximize the range of doable problems by dynamically
+* allocating what is needed and reusing what is not.
+* The core requirements for problems larger than somewhat
+* are (in words) 2*length(file0) + length(file1) +
+* 3*(number of k-candidates installed), typically about
+* 6n words for files of length n.
+*/
+#include <stdio.h>
+#include <ctype.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <signal.h>
+#define prints(s) fputs(s,stdout)
+
+#define HALFLONG 16
+#define low(x) (x&((1L<<HALFLONG)-1))
+#define high(x) (x>>HALFLONG)
+FILE *input[2];
+FILE *fopen();
+
+struct cand {
+ int x;
+ int y;
+ int pred;
+} cand;
+struct line {
+ int serial;
+ int value;
+} *file[2], line;
+int len[2];
+struct line *sfile[2]; /*shortened by pruning common prefix and suffix*/
+int slen[2];
+int pref, suff; /*length of prefix and suffix*/
+int *class; /*will be overlaid on file[0]*/
+int *member; /*will be overlaid on file[1]*/
+int *klist; /*will be overlaid on file[0] after class*/
+struct cand *clist; /* merely a free storage pot for candidates */
+int clen = 0;
+int *J; /*will be overlaid on class*/
+long *ixold; /*will be overlaid on klist*/
+long *ixnew; /*will be overlaid on file[1]*/
+int opt; /* -1,0,1 = -e,normal,-f */
+int status = 2;
+int anychange = 0;
+char *empty = "";
+int bflag;
+
+char *tempfile; /*used when comparing against std input*/
+char *mktemp();
+char *dummy; /*used in resetting storage search ptr*/
+
+done()
+{
+ unlink(tempfile);
+ exit(status);
+}
+
+char *talloc(n)
+{
+ extern char *malloc();
+ register char *p;
+ p = malloc((unsigned)n);
+ if(p!=NULL)
+ return(p);
+ noroom();
+}
+
+char *ralloc(p,n) /*compacting reallocation */
+char *p;
+{
+ register char *q;
+ char *realloc();
+ free(p);
+ free(dummy);
+ dummy = malloc(1);
+ q = realloc(p, (unsigned)n);
+ if(q==NULL)
+ noroom();
+ return(q);
+}
+
+noroom()
+{
+ mesg("files too big, try -h\n",empty);
+ done();
+}
+
+sort(a,n) /*shellsort CACM #201*/
+struct line *a;
+{
+ struct line w;
+ register int j,m;
+ struct line *ai;
+ register struct line *aim;
+ int k;
+ for(j=1;j<=n;j*= 2)
+ m = 2*j - 1;
+ for(m/=2;m!=0;m/=2) {
+ k = n-m;
+ for(j=1;j<=k;j++) {
+ for(ai = &a[j]; ai > a; ai -= m) {
+ aim = &ai[m];
+ if(aim < ai)
+ break; /*wraparound*/
+ if(aim->value > ai[0].value ||
+ aim->value == ai[0].value &&
+ aim->serial > ai[0].serial)
+ break;
+ w.value = ai[0].value;
+ ai[0].value = aim->value;
+ aim->value = w.value;
+ w.serial = ai[0].serial;
+ ai[0].serial = aim->serial;
+ aim->serial = w.serial;
+ }
+ }
+ }
+}
+
+unsort(f, l, b)
+struct line *f;
+int *b;
+{
+ register int *a;
+ register int i;
+ a = (int *)talloc((l+1)*sizeof(int));
+ for(i=1;i<=l;i++)
+ a[f[i].serial] = f[i].value;
+ for(i=1;i<=l;i++)
+ b[i] = a[i];
+ free((char *)a);
+}
+
+filename(pa1, pa2)
+char **pa1, **pa2;
+{
+ register char *a1, *b1, *a2;
+ char buf[512];
+ struct stat stbuf;
+ int i, f;
+ a1 = *pa1;
+ a2 = *pa2;
+ if(stat(a1,&stbuf)!=-1 && ((stbuf.st_mode&S_IFMT)==S_IFDIR)) {
+ b1 = *pa1 = malloc(100);
+ while(*b1++ = *a1++) ;
+ b1[-1] = '/';
+ a1 = b1;
+ while(*a1++ = *a2++)
+ if(*a2 && *a2!='/' && a2[-1]=='/')
+ a1 = b1;
+ }
+ else if(a1[0]=='-'&&a1[1]==0&&tempfile==0) {
+ signal(SIGHUP,done);
+ signal(SIGINT,done);
+ signal(SIGPIPE,done);
+ signal(SIGTERM,done);
+ *pa1 = tempfile = mktemp("/tmp/dXXXXX");
+ if((f=creat(tempfile,0600)) < 0) {
+ mesg("cannot create ",tempfile);
+ done();
+ }
+ while((i=read(0,buf,512))>0)
+ write(f,buf,i);
+ close(f);
+ }
+}
+
+prepare(i, arg)
+char *arg;
+{
+ register struct line *p;
+ register j,h;
+ if((input[i] = fopen(arg,"r")) == NULL){
+ mesg("cannot open ", arg);
+ done();
+ }
+ p = (struct line *)talloc(3*sizeof(line));
+ for(j=0; h=readhash(input[i]);) {
+ p = (struct line *)ralloc((char *)p,(++j+3)*sizeof(line));
+ p[j].value = h;
+ }
+ len[i] = j;
+ file[i] = p;
+ fclose(input[i]);
+}
+
+prune()
+{
+ register i,j;
+ for(pref=0;pref<len[0]&&pref<len[1]&&
+ file[0][pref+1].value==file[1][pref+1].value;
+ pref++ ) ;
+ for(suff=0;suff<len[0]-pref&&suff<len[1]-pref&&
+ file[0][len[0]-suff].value==file[1][len[1]-suff].value;
+ suff++) ;
+ for(j=0;j<2;j++) {
+ sfile[j] = file[j]+pref;
+ slen[j] = len[j]-pref-suff;
+ for(i=0;i<=slen[j];i++)
+ sfile[j][i].serial = i;
+ }
+}
+
+equiv(a,n,b,m,c)
+struct line *a, *b;
+int *c;
+{
+ register int i, j;
+ i = j = 1;
+ while(i<=n && j<=m) {
+ if(a[i].value <b[j].value)
+ a[i++].value = 0;
+ else if(a[i].value == b[j].value)
+ a[i++].value = j;
+ else
+ j++;
+ }
+ while(i <= n)
+ a[i++].value = 0;
+ b[m+1].value = 0;
+ j = 0;
+ while(++j <= m) {
+ c[j] = -b[j].serial;
+ while(b[j+1].value == b[j].value) {
+ j++;
+ c[j] = b[j].serial;
+ }
+ }
+ c[j] = -1;
+}
+
+main(argc, argv)
+char **argv;
+{
+ register int k;
+ char **args;
+
+ args = argv;
+ if(argc>3 && *argv[1]=='-') {
+ argc--;
+ argv++;
+ for(k=1;argv[0][k];k++) {
+ switch(argv[0][k]) {
+ case 'e':
+ opt = -1;
+ break;
+ case 'f':
+ opt = 1;
+ break;
+ case 'b':
+ bflag = 1;
+ break;
+ case 'h':
+ execv("/usr/lib/diffh",args);
+ mesg("cannot find diffh",empty);
+ done();
+ }
+ }
+ }
+ if(argc!=3) {
+ mesg("arg count",empty);
+ done();
+ }
+ dummy = malloc(1);
+
+ filename(&argv[1], &argv[2]);
+ filename(&argv[2], &argv[1]);
+ prepare(0, argv[1]);
+ prepare(1, argv[2]);
+ prune();
+ sort(sfile[0],slen[0]);
+ sort(sfile[1],slen[1]);
+
+ member = (int *)file[1];
+ equiv(sfile[0], slen[0], sfile[1], slen[1], member);
+ member = (int *)ralloc((char *)member,(slen[1]+2)*sizeof(int));
+
+ class = (int *)file[0];
+ unsort(sfile[0], slen[0], class);
+ class = (int *)ralloc((char *)class,(slen[0]+2)*sizeof(int));
+
+ klist = (int *)talloc((slen[0]+2)*sizeof(int));
+ clist = (struct cand *)talloc(sizeof(cand));
+ k = stone(class, slen[0], member, klist);
+ free((char *)member);
+ free((char *)class);
+
+ J = (int *)talloc((len[0]+2)*sizeof(int));
+ unravel(klist[k]);
+ free((char *)clist);
+ free((char *)klist);
+
+ ixold = (long *)talloc((len[0]+2)*sizeof(long));
+ ixnew = (long *)talloc((len[1]+2)*sizeof(long));
+ check(argv);
+ output(argv);
+ status = anychange;
+ done();
+}
+
+stone(a,n,b,c)
+int *a;
+int *b;
+int *c;
+{
+ register int i, k,y;
+ int j, l;
+ int oldc, tc;
+ int oldl;
+ k = 0;
+ c[0] = newcand(0,0,0);
+ for(i=1; i<=n; i++) {
+ j = a[i];
+ if(j==0)
+ continue;
+ y = -b[j];
+ oldl = 0;
+ oldc = c[0];
+ do {
+ if(y <= clist[oldc].y)
+ continue;
+ l = search(c, k, y);
+ if(l!=oldl+1)
+ oldc = c[l-1];
+ if(l<=k) {
+ if(clist[c[l]].y <= y)
+ continue;
+ tc = c[l];
+ c[l] = newcand(i,y,oldc);
+ oldc = tc;
+ oldl = l;
+ } else {
+ c[l] = newcand(i,y,oldc);
+ k++;
+ break;
+ }
+ } while((y=b[++j]) > 0);
+ }
+ return(k);
+}
+
+newcand(x,y,pred)
+{
+ register struct cand *q;
+ clist = (struct cand *)ralloc((char *)clist,++clen*sizeof(cand));
+ q = clist + clen -1;
+ q->x = x;
+ q->y = y;
+ q->pred = pred;
+ return(clen-1);
+}
+
+search(c, k, y)
+int *c;
+{
+ register int i, j, l;
+ int t;
+ if(clist[c[k]].y<y) /*quick look for typical case*/
+ return(k+1);
+ i = 0;
+ j = k+1;
+ while((l=(i+j)/2) > i) {
+ t = clist[c[l]].y;
+ if(t > y)
+ j = l;
+ else if(t < y)
+ i = l;
+ else
+ return(l);
+ }
+ return(l+1);
+}
+
+unravel(p)
+{
+ register int i;
+ register struct cand *q;
+ for(i=0; i<=len[0]; i++)
+ J[i] = i<=pref ? i:
+ i>len[0]-suff ? i+len[1]-len[0]:
+ 0;
+ for(q=clist+p;q->y!=0;q=clist+q->pred)
+ J[q->x+pref] = q->y+pref;
+}
+
+/* check does double duty:
+1. ferret out any fortuitous correspondences due
+to confounding by hashing (which result in "jackpot")
+2. collect random access indexes to the two files */
+
+check(argv)
+char **argv;
+{
+ register int i, j;
+ int jackpot;
+ long ctold, ctnew;
+ char c,d;
+ input[0] = fopen(argv[1],"r");
+ input[1] = fopen(argv[2],"r");
+ j = 1;
+ ixold[0] = ixnew[0] = 0;
+ jackpot = 0;
+ ctold = ctnew = 0;
+ for(i=1;i<=len[0];i++) {
+ if(J[i]==0) {
+ ixold[i] = ctold += skipline(0);
+ continue;
+ }
+ while(j<J[i]) {
+ ixnew[j] = ctnew += skipline(1);
+ j++;
+ }
+ for(;;) {
+ c = getc(input[0]);
+ d = getc(input[1]);
+ ctold++;
+ ctnew++;
+ if(bflag && isspace(c) && isspace(d)) {
+ do {
+ if(c=='\n') break;
+ ctold++;
+ } while(isspace(c=getc(input[0])));
+ do {
+ if(d=='\n') break;
+ ctnew++;
+ } while(isspace(d=getc(input[1])));
+ }
+ if(c!=d) {
+ jackpot++;
+ J[i] = 0;
+ if(c!='\n')
+ ctold += skipline(0);
+ if(d!='\n')
+ ctnew += skipline(1);
+ break;
+ }
+ if(c=='\n')
+ break;
+ }
+ ixold[i] = ctold;
+ ixnew[j] = ctnew;
+ j++;
+ }
+ for(;j<=len[1];j++) {
+ ixnew[j] = ctnew += skipline(1);
+ }
+ fclose(input[0]);
+ fclose(input[1]);
+/*
+ if(jackpot)
+ mesg("jackpot",empty);
+*/
+}
+
+skipline(f)
+{
+ register i;
+ for(i=1;getc(input[f])!='\n';i++) ;
+ return(i);
+}
+
+output(argv)
+char **argv;
+{
+ int m;
+ register int i0, i1, j1;
+ int j0;
+ input[0] = fopen(argv[1],"r");
+ input[1] = fopen(argv[2],"r");
+ m = len[0];
+ J[0] = 0;
+ J[m+1] = len[1]+1;
+ if(opt!=-1) for(i0=1;i0<=m;i0=i1+1) {
+ while(i0<=m&&J[i0]==J[i0-1]+1) i0++;
+ j0 = J[i0-1]+1;
+ i1 = i0-1;
+ while(i1<m&&J[i1+1]==0) i1++;
+ j1 = J[i1+1]-1;
+ J[i1] = j1;
+ change(i0,i1,j0,j1);
+ } else for(i0=m;i0>=1;i0=i1-1) {
+ while(i0>=1&&J[i0]==J[i0+1]-1&&J[i0]!=0) i0--;
+ j0 = J[i0+1]-1;
+ i1 = i0+1;
+ while(i1>1&&J[i1-1]==0) i1--;
+ j1 = J[i1-1]+1;
+ J[i1] = j1;
+ change(i1,i0,j1,j0);
+ }
+ if(m==0)
+ change(1,0,1,len[1]);
+}
+
+change(a,b,c,d)
+{
+ if(a>b&&c>d) return;
+ anychange = 1;
+ if(opt!=1) {
+ range(a,b,",");
+ putchar(a>b?'a':c>d?'d':'c');
+ if(opt!=-1) range(c,d,",");
+ } else {
+ putchar(a>b?'a':c>d?'d':'c');
+ range(a,b," ");
+ }
+ putchar('\n');
+ if(opt==0) {
+ fetch(ixold,a,b,input[0],"< ");
+ if(a<=b&&c<=d) prints("---\n");
+ }
+ fetch(ixnew,c,d,input[1],opt==0?"> ":empty);
+ if(opt!=0&&c<=d) prints(".\n");
+}
+
+range(a,b,separator)
+char *separator;
+{
+ printf("%d", a>b?b:a);
+ if(a<b) {
+ printf("%s%d", separator, b);
+ }
+}
+
+fetch(f,a,b,lb,s)
+long *f;
+FILE *lb;
+char *s;
+{
+ register int i, j;
+ register int nc;
+ for(i=a;i<=b;i++) {
+ fseek(lb,f[i-1],0);
+ nc = f[i]-f[i-1];
+ prints(s);
+ for(j=0;j<nc;j++)
+ putchar(getc(lb));
+ }
+}
+
+/* hashing has the effect of
+ * arranging line in 7-bit bytes and then
+ * summing 1-s complement in 16-bit hunks
+*/
+
+readhash(f)
+FILE *f;
+{
+ long sum;
+ register unsigned shift;
+ register space;
+ register t;
+ sum = 1;
+ space = 0;
+ if(!bflag) for(shift=0;(t=getc(f))!='\n';shift+=7) {
+ if(t==-1)
+ return(0);
+ sum += (long)t << (shift%=HALFLONG);
+ }
+ else for(shift=0;;) {
+ switch(t=getc(f)) {
+ case -1:
+ return(0);
+ case '\t':
+ case ' ':
+ space++;
+ continue;
+ default:
+ if(space) {
+ shift += 7;
+ space = 0;
+ }
+ sum += (long)t << (shift%=HALFLONG);
+ shift += 7;
+ continue;
+ case '\n':
+ break;
+ }
+ break;
+ }
+ sum = low(sum) + high(sum);
+ return((short)low(sum) + (short)high(sum));
+}
+
+mesg(s,t)
+char *s, *t;
+{
+ fprintf(stderr,"diff: %s%s\n",s,t);
+}
projects / unix-history / commitdiff