+static char sccsid[] = "@(#)diffreg.c 4.1 %G%";
+
+#include "diff.h"
+/*
+ * diff - compare two files.
+ */
+
+/*
+ * 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''). In particular, this
+ * collects the equivalence classes in file1 together.
+ * Subroutine equiv 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 squeezes file1 into a single
+ * array member 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 are unsorted into
+ * array class according to the original order of file0.
+ *
+ * The cleverness lies in routine stone. This marches
+ * through the lines of file0, developing a vector klist
+ * 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 length 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) 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
+ *
+ * With J in hand, the matches there recorded are
+ * check'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.
+ */
+
+#define prints(s) fputs(s,stdout)
+
+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] */
+
+diffreg()
+{
+ register int k;
+
+ if (hflag) {
+ diffargv[0] = "diffh";
+ execv(diffh, diffargv);
+ fprintf(stderr, "diff: ");
+ perror(diffh);
+ done();
+ }
+ dummy = malloc(1);
+ if ((stb1.st_mode & S_IFMT) == S_IFDIR)
+ file1 = splice(file1, file2);
+ else if ((stb2.st_mode & S_IFMT) == S_IFDIR)
+ file2 = splice(file2, file1);
+ else if (!strcmp(file1, "-")) {
+ if (!strcmp(file2, "-")) {
+ fprintf(stderr, "diff: can't specify - -\n");
+ done();
+ }
+ file1 = copytemp();
+ } else if (!strcmp(file2, "-"))
+ file2 = copytemp();
+ prepare(0, file1);
+ prepare(1, file2);
+ 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();
+ output();
+ status = anychange;
+ if (opt == D_CONTEXT && anychange == 0)
+ printf("No differences encountered\n");
+ done();
+}
+
+char *
+copytemp()
+{
+ char buf[BUFSIZ];
+ register int i, f;
+
+ signal(SIGHUP,done);
+ signal(SIGINT,done);
+ signal(SIGPIPE,done);
+ signal(SIGTERM,done);
+ tempfile = mktemp("/tmp/dXXXXX");
+ f = creat(tempfile,0600);
+ if (f < 0) {
+ fprintf("diff: ");
+ perror(tempfile);
+ done();
+ }
+ while ((i = read(0,buf,BUFSIZ)) > 0)
+ if (write(f,buf,i) != i) {
+ fprintf(stderr, "diff: ");
+ perror(tempfile);
+ done();
+ }
+ close(f);
+ return (tempfile);
+}
+
+char *
+splice(dir, file)
+ char *dir, *file;
+{
+ char *tail;
+ char buf[BUFSIZ];
+
+ if (!strcmp(file, "-")) {
+ fprintf(stderr, "diff: can't specify - with other arg directory\n");
+ done();
+ }
+ tail = rindex(file, '/');
+ if (tail == 0)
+ tail = file;
+ else
+ tail++;
+ sprintf(buf, "%s/%s", dir, tail);
+ return (savestr(buf));
+}
+
+prepare(i, arg)
+char *arg;
+{
+ register struct line *p;
+ register j,h;
+ if((input[i] = fopen(arg,"r")) == NULL){
+ fprintf(stderr, "diff: ");
+ perror(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;
+}
+
+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()
+{
+ register int i, j;
+ int jackpot;
+ long ctold, ctnew;
+ char c,d;
+ input[0] = fopen(file1,"r");
+ input[1] = fopen(file2,"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)
+ fprintf(stderr, "jackpot\n");
+*/
+}
+
+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);
+}
+
+skipline(f)
+{
+ register i;
+ for(i=1;getc(input[f])!='\n';i++) ;
+ return(i);
+}
+
+output()
+{
+ int m;
+ register int i0, i1, j1;
+ int j0;
+ input[0] = fopen(file1,"r");
+ input[1] = fopen(file2,"r");
+ m = len[0];
+ J[0] = 0;
+ J[m+1] = len[1]+1;
+ if(opt!=D_EDIT) 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]);
+ if (opt==D_IFDEF) {
+ for (;;) {
+#define c i0
+ c = getc(input[0]);
+ if (c < 0)
+ return;
+ putchar(c);
+ }
+#undef c
+ }
+}
+
+/* indicate that there is a difference between lines a and b of the from file
+ to get to lines c to d of the to file.
+ If a is greater then b then there are no lines in the from file involved
+ and this means that there were lines appended (beginning at b).
+ If c is greater than d then there are lines missing from the to file.
+*/
+change(a,b,c,d)
+{
+ char ch;
+ int lowa,upb,lowc,upd;
+ struct stat stbuf;
+
+ if (opt != D_IFDEF && a>b && c>d)
+ return;
+ if (anychange == 0) {
+ anychange = 1;
+ if(opt == D_CONTEXT) {
+ printf("*** %s ", file1);
+ stat(file1, &stbuf);
+ printf("%s--- %s ",
+ ctime(&stbuf.st_mtime), file2);
+ stat(file2, &stbuf);
+ printf("%s", ctime(&stbuf.st_mtime));
+ }
+ }
+ if (a <= b && c <= d)
+ ch = 'c';
+ else
+ ch = (a <= b) ? 'd' : 'a';
+ if(opt == D_CONTEXT) {
+ lowa = max(1, a-context);
+ upb = min(len[0], b+context);
+ lowc = max(1, c-context);
+ upd = min(len[1], d+context);
+
+ /* print out from file */
+ printf("***************\n*** ");
+ range(lowa,upb,",");
+ printf("\n");
+ if (ch == 'a')
+ fetch(ixold,lowa,upb,input[0]," ");
+ else {
+ fetch(ixold,lowa,a-1,input[0]," ");
+ fetch(ixold,a,b,input[0],ch == 'c' ? "! " : "- ");
+ fetch(ixold,b+1,upb,input[0]," ");
+ }
+ putchar('\n');
+ printf("--- ");
+ range(lowc,upd,",");
+ printf(" -----\n");
+ if (ch == 'd')
+ fetch(ixnew,lowc,upd,input[1]," ");
+ else {
+ fetch(ixnew,lowc,c-1,input[1]," ");
+ fetch(ixnew,c,d,input[1],ch == 'c' ? "! " : "+ ");
+ fetch(ixnew,d+1,upd,input[1]," ");
+ }
+ return;
+ }
+ switch (opt) {
+
+ case D_NORMAL:
+ case D_EDIT:
+ range(a,b,",");
+ putchar(a>b?'a':c>d?'d':'c');
+ if(opt==D_NORMAL)
+ range(c,d,",");
+ putchar('\n');
+ break;
+ case D_REVERSE:
+ putchar(a>b?'a':c>d?'d':'c');
+ range(a,b," ");
+ putchar('\n');
+ break;
+ }
+ if(opt == D_NORMAL || opt == D_IFDEF) {
+ fetch(ixold,a,b,input[0],"< ", 1);
+ if(a<=b&&c<=d && opt == D_NORMAL)
+ prints("---\n");
+ }
+ fetch(ixnew,c,d,input[1],opt==D_NORMAL?"> ":"", 0);
+ if ((opt ==D_EDIT || opt == D_REVERSE) && c<=d)
+ prints(".\n");
+ if (inifdef) {
+ fprintf(stdout, "#endif %s\n", endifname);
+ inifdef = 0;
+ }
+}
+
+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,oldfile)
+long *f;
+FILE *lb;
+char *s;
+{
+ register int i, j;
+ register int nc;
+ int oneflag = (*ifdef1!='\0') != (*ifdef2!='\0');
+
+ /*
+ * When doing #ifdef's, copy down to current line
+ * if this is the first file, so that stuff makes it to output.
+ */
+ if (opt == D_IFDEF && oldfile){
+ long curpos = ftell(lb);
+ /* print through if append (a>b), else to (nb: 0 vs 1 orig) */
+ nc = f[a>b? b : a-1 ] - curpos;
+ for (i = 0; i < nc; i++)
+ putchar(getc(lb));
+ }
+ if (a > b)
+ return;
+ if (opt == D_IFDEF) {
+ if (inifdef)
+ fprintf(stdout, "#else %s%s\n", oneflag && oldfile==1 ? "!" : "", ifdef2);
+ else {
+ if (oneflag) {
+ /* There was only one ifdef given */
+ endifname = ifdef2;
+ if (oldfile)
+ fprintf(stdout, "#ifndef %s\n", endifname);
+ else
+ fprintf(stdout, "#ifdef %s\n", endifname);
+ }
+ else {
+ endifname = oldfile ? ifdef1 : ifdef2;
+ fprintf(stdout, "#ifdef %s\n", endifname);
+ }
+ }
+ inifdef = 1+oldfile;
+ }
+ for(i=a;i<=b;i++) {
+ fseek(lb,f[i-1],0);
+ nc = f[i]-f[i-1];
+ if (opt != D_IFDEF)
+ prints(s);
+ for(j=0;j<nc;j++)
+ putchar(getc(lb));
+ }
+ if (inifdef && !wantelses) {
+ fprintf(stdout, "#endif %s\n", endifname);
+ inifdef = 0;
+ }
+}
+
+#define HALFLONG 16
+#define low(x) (x&((1L<<HALFLONG)-1))
+#define high(x) (x>>HALFLONG)
+
+/*
+ * 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));
+}
projects / unix-history / commitdiff