[unix-history] / usr / src / cmd / diff3.c

#include <stdio.h>
#

/* diff3 - 3-way differential file comparison*/

/* diff3 [-e] d13 d23 f1 f2 f3 
 *
 * d13 = diff report on f1 vs f3
 * d23 = diff report on f2 vs f3
 * f1, f2, f3 the 3 files
*/

struct  range {int from,to; };
	/* from is first in range of changed lines
	 * to is last+1
	 * from=to=line after point of insertion
	* for added lines
	*/
struct diff {struct range old, new;};

#define NC 200
/* de is used to gather editing scripts,
 * that are later spewed out in reverse order.
 * its first element must be all zero
 * the "new" component of de contains line positions
 * or byte positions depending on when you look(!?)
*/
struct diff d13[NC];
struct diff d23[NC];
struct diff de[NC];
char line[256];
FILE *fp[3];
int linct[3] = {0,0,0};
/*	the number of the last-read line in each file
 *	is kept in cline[0-2]
*/
int cline[3];
/*	the latest known correspondence between line
 *	numbers of the 3 files is stored in last[1-3]
*/
int last[4];
int eflag;
int debug  = 0;

main(argc,argv)
char **argv;
{
	register i,m,n;
	if(*argv[1]=='-') {
		switch(argv[1][1]) {
		default:
			eflag = 3;
			break;
		case '3':
			eflag = 2;
			break;
		case 'x':
			eflag = 1;
		}
		argv++;
		argc--;
	}
	if(argc<6) {
		fprintf(stderr,"diff3: arg count\n");
		exit(1);
	}
	m = readin(argv[1],d13);
	n = readin(argv[2],d23);
	for(i=0;i<=2;i++)
		if((fp[i] = fopen(argv[i+3],"r")) == NULL) {
			printf("diff3: can't open %s\n",argv[i+3]);
			exit(1);
		}
	merge(m,n);
}

/*pick up the line numbers of allcahnges from
 * one change file
 * (this puts the numbers in a vector, which is not
 * strictly necessary, since the vector is processed
 * in one sequential pass. The vector could be optimized
 * out of existence)
*/

readin(name,dd)
char *name;
struct diff *dd;
{
	register i;
	int a,b,c,d;
	char kind;
	char *p;
	fp[0] = fopen(name,"r");
	for(i=0;getchange(fp[0]);i++) {
		if(i>=NC) {
			fprintf(stderr,"diff3: too many changes\n");
			exit(0);
		}
		p = line;
		a = b = number(&p);
		if(*p==',') {
			p++;
			b = number(&p);
		}
		kind = *p++;
		c = d = number(&p);
		if(*p==',') {
			p++;
			d = number(&p);
		}
		if(kind=='a')
			a++;
		if(kind=='d')
			c++;
		b++;
		d++;
		dd[i].old.from = a;
		dd[i].old.to = b;
		dd[i].new.from = c;
		dd[i].new.to = d;
	}
	dd[i].old.from = dd[i-1].old.to;
	dd[i].new.from = dd[i-1].new.to;
	fclose(fp[0]);
	return(i);
}

number(lc)
char **lc;
{
	register nn;
	nn = 0;
	while(digit(**lc))
		nn = nn*10 + *(*lc)++ - '0';
	return(nn);
}

digit(c)
{
	return(c>='0'&&c<='9');
}

getchange(b)
FILE *b;
{
	while(getline(b))
		if(digit(line[0]))
			return(1);
	return(0);
}

getline(b)
FILE *b;
{
	register i, c;
	for(i=0;i<sizeof(line)-1;i++) {
		c = getc(b);
		if(c==EOF)
			break;
		line[i] = c;
		if(c=='\n') {
			line[++i] = 0;
			return(i);
		}
	}
	return(0);
}

merge(m1,m2)
{
	register struct diff *d1, *d2, *d3;
	int dup;
	int j;
	int t1,t2;
	d1 = d13;
	d2 = d23;
	j = 0;
	for(;(t1 = d1<d13+m1) | (t2 = d2<d23+m2);) {
		if(debug) {
			printf("%d,%d=%d,%d %d,%d=%d,%d\n",
			d1->old.from,d1->old.to,
			d1->new.from,d1->new.to,
			d2->old.from,d2->old.to,
			d2->new.from,d2->new.to);
		}
/*			first file is different from others*/
		if(!t2||t1&&d1->new.to < d2->new.from) {
/*			stuff peculiar to 1st file */
			if(eflag==0) {
				separate("1");
				change(1,&d1->old,0);
				keep(2,&d1->old,&d1->new);
				change(3,&d1->new,0);
			}
			d1++;
			continue;
		}
/*			second file is different from others*/
		if(!t1||t2&&d2->new.to < d1->new.from) {
			if(eflag==0) {
				separate("2");
				keep(1,&d2->old,&d2->new);
				change(2,&d2->old,0);
				change(3,&d2->new,0);
			}
			d2++;
			continue;
		}
/*			merge overlapping changes in first file
 *			this happens after extension see below*/
		if(d1+1<d13+m1 &&
		   d1->new.to>=d1[1].new.from) {
			d1[1].old.from = d1->old.from;
			d1[1].new.from = d1->new.from;
			d1++;
			continue;
		}
/*			merge overlapping changes in second*/
		if(d2+1<d23+m2 &&
		   d2->new.to>=d2[1].new.from) {
			d2[1].old.from = d2->old.from;
			d2[1].new.from = d2->new.from;
			d2++;
			continue;
		}
/*			stuff peculiar to third file or different in all*/
		if(d1->new.from==d2->new.from&&
		   d1->new.to==d2->new.to) {
			dup = duplicate(&d1->old,&d2->old);
/*				dup=0 means all files differ
 *				dup =1 meands files 1&2 identical*/
			if(eflag==0) {
				separate(dup?"3":"");
				change(1,&d1->old,dup);
				change(2,&d2->old,0);
				d3 = d1->old.to>d1->old.from?d1:d2;
				change(3,&d3->new,0);
			} else
				j = edit(d1,dup,j);
			d1++;
			d2++;
			continue;
		}
/*			overlapping changes from file1 & 2
 *			extend changes appropriately to
 *			make them coincide*/
		 if(d1->new.from<d2->new.from) {
			d2->old.from -= d2->new.from-d1->new.from;
			d2->new.from = d1->new.from;
		}
		else if(d2->new.from<d1->new.from) {
			d1->old.from -= d1->new.from-d2->new.from;
			d1->new.from = d2->new.from;
		}
		if(d1->new.to >d2->new.to) {
			d2->old.to += d1->new.to - d2->new.to;
			d2->new.to = d1->new.to;
		}
		else if(d2->new.to >d1->new.to) {
			d1->old.to += d2->new.to - d1->new.to;
			d1->new.to = d2->new.to;
		}
	}
	if(eflag)
		edscript(j);
}

separate(s)
char *s;
{
	printf("====%s\n",s);
}

/*	the range of ines rold.from thru rold.to in file i
 *	is to be changed. it is to be printed only if
 *	it does not duplicate something to be printed later
*/
change(i,rold,dup)
struct range *rold;
{
	printf("%d:",i);
	last[i] = rold->to;
	prange(rold);
	if(dup)
		return;
	if(debug)
		return;
	i--;
	skip(i,rold->from,(char *)0);
	skip(i,rold->to,"  ");
}

/*	print the range of line numbers, rold.from  thru rold.to
 *	as n1,n2 or n1
*/
prange(rold)
struct range *rold;
{
	if(rold->to<=rold->from)
		printf("%da\n",rold->from-1);
	else {
		printf("%d",rold->from);
		if(rold->to > rold->from+1)
			printf(",%d",rold->to-1);
		printf("c\n");
	}
}

/*	no difference was reported by diff between file 1(or 2)
 *	and file 3, and an artificial dummy difference (trange)
 *	must be ginned up to correspond to the change reported
 *	in the other file
*/
keep(i,rold,rnew)
struct range *rold, *rnew;
{
	register delta;
	struct range trange;
	delta = last[3] - last[i];
	trange.from = rnew->from - delta;
	trange.to = rnew->to - delta;
	change(i,&trange,1);
}

/*	skip to just befor line number from in file i
 *	if "pr" is nonzero, print all skipped stuff
 * w	with string pr as a prefix
*/
skip(i,from,pr)
char *pr;
{
	register j,n;
	for(n=0;cline[i]<from-1;n+=j) {
		if((j=getline(fp[i]))==0)
			trouble();
		if(pr)
			printf("%s%s",pr,line);
		cline[i]++;
	}
	return(n);
}

/*	return 1 or 0 according as the old range
 *	(in file 1) contains exactly the same data
 *	as the new range (in file 2)
*/
duplicate(r1,r2)
struct range *r1, *r2;
{
	register c,d;
	register nchar;
	int nline;
	if(r1->to-r1->from != r2->to-r2->from)
		return(0);
	skip(0,r1->from,(char *)0);
	skip(1,r2->from,(char *)0);
	nchar = 0;
	for(nline=0;nline<r1->to-r1->from;nline++) {
		do {
			c = getc(fp[0]);
			d = getc(fp[1]);
			if(c== -1||d== -1)
				trouble();
			nchar++;
			if(c!=d) {
				repos(nchar);
				return;
			}
		} while(c!= '\n');
	}
	repos(nchar);
	return(1);
}

repos(nchar)
{
	register i;
	for(i=0;i<2;i++) 
		fseek(fp[i], (long)-nchar, 1);
}

trouble()
{
	fprintf(stderr,"diff3: logic error\n");
	abort();
}

/*	collect an editing script for later regurgitation
*/
edit(diff,dup,j)
struct diff *diff;
{
	if(((dup+1)&eflag)==0)
		return(j);
	j++;
	de[j].old.from = diff->old.from;
	de[j].old.to = diff->old.to;
	de[j].new.from = de[j-1].new.to
	    +skip(2,diff->new.from,(char *)0);
	de[j].new.to = de[j].new.from
	    +skip(2,diff->new.to,(char *)0);
	return(j);
}

/*		regurgitate */
edscript(n)
{
	register j,k;
	char block[512];
	for(n=n;n>0;n--) {
		prange(&de[n].old);
		fseek(fp[2], (long)de[n].new.from, 0);
		for(k=de[n].new.to-de[n].new.from;k>0;k-= j) {
			j = k>512?512:k;
			if(fread(block,1,j,fp[2])!=j)
				trouble();
			fwrite(block, 1, j, stdout);
		}
		printf(".\n");
	}
}
Commit	Line	Data
5d932d04 DM	1	#include <stdio.h>
	2	#
	3
	4	/* diff3 - 3-way differential file comparison*/
	5
	6	/* diff3 [-e] d13 d23 f1 f2 f3
	7	*
	8	* d13 = diff report on f1 vs f3
	9	* d23 = diff report on f2 vs f3
	10	* f1, f2, f3 the 3 files
	11	*/
	12
	13	struct range {int from,to; };
	14	/* from is first in range of changed lines
	15	* to is last+1
	16	* from=to=line after point of insertion
	17	* for added lines
	18	*/
	19	struct diff {struct range old, new;};
	20
	21	#define NC 200
	22	/* de is used to gather editing scripts,
	23	* that are later spewed out in reverse order.
	24	* its first element must be all zero
	25	* the "new" component of de contains line positions
	26	* or byte positions depending on when you look(!?)
	27	*/
	28	struct diff d13[NC];
	29	struct diff d23[NC];
	30	struct diff de[NC];
	31	char line[256];
	32	FILE *fp[3];
	33	int linct[3] = {0,0,0};
	34	/* the number of the last-read line in each file
	35	* is kept in cline[0-2]
	36	*/
	37	int cline[3];
	38	/* the latest known correspondence between line
	39	* numbers of the 3 files is stored in last[1-3]
	40	*/
	41	int last[4];
	42	int eflag;
	43	int debug = 0;
	44
	45	main(argc,argv)
	46	char **argv;
	47	{
	48	register i,m,n;
	49	if(*argv[1]=='-') {
	50	switch(argv[1][1]) {
	51	default:
	52	eflag = 3;
	53	break;
	54	case '3':
	55	eflag = 2;
	56	break;
	57	case 'x':
	58	eflag = 1;
	59	}
	60	argv++;
	61	argc--;
	62	}
	63	if(argc<6) {
	64	fprintf(stderr,"diff3: arg count\n");
65	exit(1);
66	}
67	m = readin(argv[1],d13);
68	n = readin(argv[2],d23);
69	for(i=0;i<=2;i++)
70	if((fp[i] = fopen(argv[i+3],"r")) == NULL) {
71	printf("diff3: can't open %s\n",argv[i+3]);
72	exit(1);
73	}
74	merge(m,n);
75	}
76
77	/*pick up the line numbers of allcahnges from
78	* one change file
79	* (this puts the numbers in a vector, which is not
80	* strictly necessary, since the vector is processed
81	* in one sequential pass. The vector could be optimized
82	* out of existence)
83	*/
84
85	readin(name,dd)
86	char *name;
87	struct diff *dd;
88	{
89	register i;
90	int a,b,c,d;
91	char kind;
92	char *p;
93	fp[0] = fopen(name,"r");
94	for(i=0;getchange(fp[0]);i++) {
95	if(i>=NC) {
96	fprintf(stderr,"diff3: too many changes\n");
97	exit(0);
98	}
99	p = line;
100	a = b = number(&p);
101	if(*p==',') {
102	p++;
103	b = number(&p);
104	}
105	kind = *p++;
106	c = d = number(&p);
107	if(*p==',') {
108	p++;
109	d = number(&p);
110	}
111	if(kind=='a')
112	a++;
113	if(kind=='d')
114	c++;
115	b++;
116	d++;
117	dd[i].old.from = a;
118	dd[i].old.to = b;
119	dd[i].new.from = c;
120	dd[i].new.to = d;
121	}
122	dd[i].old.from = dd[i-1].old.to;
123	dd[i].new.from = dd[i-1].new.to;
124	fclose(fp[0]);
125	return(i);
126	}
127
128	number(lc)
129	char **lc;
130	{
131	register nn;
132	nn = 0;
133	while(digit(**lc))
134	nn = nn10 + (*lc)++ - '0';
135	return(nn);
136	}
137
138	digit(c)
139	{
140	return(c>='0'&&c<='9');
141	}
142
143	getchange(b)
144	FILE *b;
145	{
146	while(getline(b))
147	if(digit(line[0]))
148	return(1);
149	return(0);
150	}
151
152	getline(b)
153	FILE *b;
154	{
155	register i, c;
156	for(i=0;i<sizeof(line)-1;i++) {
157	c = getc(b);
158	if(c==EOF)
159	break;
160	line[i] = c;
161	if(c=='\n') {
162	line[++i] = 0;
163	return(i);
164	}
165	}
166	return(0);
167	}
168
169	merge(m1,m2)
170	{
171	register struct diff d1, d2, *d3;
172	int dup;
173	int j;
174	int t1,t2;
175	d1 = d13;
176	d2 = d23;
177	j = 0;
178	for(;(t1 = d1<d13+m1) \| (t2 = d2<d23+m2);) {
179	if(debug) {
180	printf("%d,%d=%d,%d %d,%d=%d,%d\n",
181	d1->old.from,d1->old.to,
182	d1->new.from,d1->new.to,
183	d2->old.from,d2->old.to,
184	d2->new.from,d2->new.to);
185	}
186	/* first file is different from others*/
187	if(!t2\|\|t1&&d1->new.to < d2->new.from) {
188	/* stuff peculiar to 1st file */
189	if(eflag==0) {
190	separate("1");
191	change(1,&d1->old,0);
192	keep(2,&d1->old,&d1->new);
193	change(3,&d1->new,0);
194	}
195	d1++;
196	continue;
197	}
198	/* second file is different from others*/
199	if(!t1\|\|t2&&d2->new.to < d1->new.from) {
200	if(eflag==0) {
201	separate("2");
202	keep(1,&d2->old,&d2->new);
203	change(2,&d2->old,0);
204	change(3,&d2->new,0);
205	}
206	d2++;
207	continue;
208	}
209	/* merge overlapping changes in first file
210	* this happens after extension see below*/
211	if(d1+1<d13+m1 &&
212	d1->new.to>=d1[1].new.from) {
213	d1[1].old.from = d1->old.from;
214	d1[1].new.from = d1->new.from;
215	d1++;
216	continue;
217	}
218	/* merge overlapping changes in second*/
219	if(d2+1<d23+m2 &&
220	d2->new.to>=d2[1].new.from) {
221	d2[1].old.from = d2->old.from;
222	d2[1].new.from = d2->new.from;
223	d2++;
224	continue;
225	}
226	/* stuff peculiar to third file or different in all*/
227	if(d1->new.from==d2->new.from&&
228	d1->new.to==d2->new.to) {
229	dup = duplicate(&d1->old,&d2->old);
230	/* dup=0 means all files differ
231	* dup =1 meands files 1&2 identical*/
232	if(eflag==0) {
233	separate(dup?"3":"");
234	change(1,&d1->old,dup);
235	change(2,&d2->old,0);
236	d3 = d1->old.to>d1->old.from?d1:d2;
237	change(3,&d3->new,0);
238	} else
239	j = edit(d1,dup,j);
240	d1++;
241	d2++;
242	continue;
243	}
244	/* overlapping changes from file1 & 2
245	* extend changes appropriately to
246	* make them coincide*/
247	if(d1->new.from<d2->new.from) {
248	d2->old.from -= d2->new.from-d1->new.from;
249	d2->new.from = d1->new.from;
250	}
251	else if(d2->new.from<d1->new.from) {
252	d1->old.from -= d1->new.from-d2->new.from;
253	d1->new.from = d2->new.from;
254	}
255	if(d1->new.to >d2->new.to) {
256	d2->old.to += d1->new.to - d2->new.to;
257	d2->new.to = d1->new.to;
258	}
259	else if(d2->new.to >d1->new.to) {
260	d1->old.to += d2->new.to - d1->new.to;
261	d1->new.to = d2->new.to;
262	}
263	}
264	if(eflag)
265	edscript(j);
266	}
267
268	separate(s)
269	char *s;
270	{
271	printf("====%s\n",s);
272	}
273
274	/* the range of ines rold.from thru rold.to in file i
275	* is to be changed. it is to be printed only if
276	* it does not duplicate something to be printed later
277	*/
278	change(i,rold,dup)
279	struct range *rold;
280	{
281	printf("%d:",i);
282	last[i] = rold->to;
283	prange(rold);
284	if(dup)
285	return;
286	if(debug)
287	return;
288	i--;
289	skip(i,rold->from,(char *)0);
290	skip(i,rold->to," ");
291	}
292
293	/* print the range of line numbers, rold.from thru rold.to
294	* as n1,n2 or n1
295	*/
296	prange(rold)
297	struct range *rold;
298	{
299	if(rold->to<=rold->from)
300	printf("%da\n",rold->from-1);
301	else {
302	printf("%d",rold->from);
303	if(rold->to > rold->from+1)
304	printf(",%d",rold->to-1);
305	printf("c\n");
306	}
307	}
308
309	/* no difference was reported by diff between file 1(or 2)
310	* and file 3, and an artificial dummy difference (trange)
311	* must be ginned up to correspond to the change reported
312	* in the other file
313	*/
314	keep(i,rold,rnew)
315	struct range rold, rnew;
316	{
317	register delta;
318	struct range trange;
319	delta = last[3] - last[i];
320	trange.from = rnew->from - delta;
321	trange.to = rnew->to - delta;
322	change(i,&trange,1);
323	}
324
325	/* skip to just befor line number from in file i
326	* if "pr" is nonzero, print all skipped stuff
327	* w with string pr as a prefix
328	*/
329	skip(i,from,pr)
330	char *pr;
331	{
332	register j,n;
333	for(n=0;cline[i]<from-1;n+=j) {
334	if((j=getline(fp[i]))==0)
335	trouble();
336	if(pr)
337	printf("%s%s",pr,line);
338	cline[i]++;
339	}
340	return(n);
341	}
342
343	/* return 1 or 0 according as the old range
344	* (in file 1) contains exactly the same data
345	* as the new range (in file 2)
346	*/
347	duplicate(r1,r2)
348	struct range r1, r2;
349	{
350	register c,d;
351	register nchar;
352	int nline;
353	if(r1->to-r1->from != r2->to-r2->from)
354	return(0);
355	skip(0,r1->from,(char *)0);
356	skip(1,r2->from,(char *)0);
357	nchar = 0;
358	for(nline=0;nline<r1->to-r1->from;nline++) {
359	do {
360	c = getc(fp[0]);
361	d = getc(fp[1]);
362	if(c== -1\|\|d== -1)
363	trouble();
364	nchar++;
365	if(c!=d) {
366	repos(nchar);
367	return;
368	}
369	} while(c!= '\n');
370	}
371	repos(nchar);
372	return(1);
373	}
374
375	repos(nchar)
376	{
377	register i;
378	for(i=0;i<2;i++)
379	fseek(fp[i], (long)-nchar, 1);
380	}
381
382	trouble()
383	{
384	fprintf(stderr,"diff3: logic error\n");
385	abort();
386	}
387
388	/* collect an editing script for later regurgitation
389	*/
390	edit(diff,dup,j)
391	struct diff *diff;
392	{
393	if(((dup+1)&eflag)==0)
394	return(j);
395	j++;
396	de[j].old.from = diff->old.from;
397	de[j].old.to = diff->old.to;
398	de[j].new.from = de[j-1].new.to
399	+skip(2,diff->new.from,(char *)0);
400	de[j].new.to = de[j].new.from
401	+skip(2,diff->new.to,(char *)0);
402	return(j);
403	}
404
405	/* regurgitate */
406	edscript(n)
407	{
408	register j,k;
409	char block[512];
410	for(n=n;n>0;n--) {
411	prange(&de[n].old);
412	fseek(fp[2], (long)de[n].new.from, 0);
413	for(k=de[n].new.to-de[n].new.from;k>0;k-= j) {
414	j = k>512?512:k;
415	if(fread(block,1,j,fp[2])!=j)
416	trouble();
417	fwrite(block, 1, j, stdout);
418	}
419	printf(".\n");
420	}
421	}