#include <u.h>#include <libc.h>#include <ctype.h> #include "git.h" typedef struct Eval	Eval; enum {	Blank,	Keep,	Drop,	Skip,}; enum {	Lca,	Twixt,	Range,}; struct Eval {	char	*str;	char	*p;	Object	**stk;	int	nstk;	int	stksz;}; static char *colors[] = {[Keep] "keep",[Drop] "drop",[Blank] "blank",[Skip] "skip",}; static Object zcommit = {	.type=GCommit}; voideatspace(Eval *ev){	while(isspace(ev->p[0]))		ev->p++;} voidpush(Eval *ev, Object *o){	if(ev->nstk == ev->stksz){		ev->stksz = 2*ev->stksz + 1;		ev->stk = erealloc(ev->stk, ev->stksz*sizeof(Object*));	}	ev->stk[ev->nstk++] = o;} Object*pop(Eval *ev){	if(ev->nstk == 0)		sysfatal("stack underflow");	return ev->stk[--ev->nstk];} Object*peek(Eval *ev){	if(ev->nstk == 0)		sysfatal("stack underflow");	return ev->stk[ev->nstk - 1];} intisword(char e){	return isalnum(e) || e == '/' || e == '-' || e == '_' || e == '.';} intword(Eval *ev, char *b, int nb){	char *p, *e;	int n; 	p = ev->p;	for(e = p; isword(*e) && strncmp(e, "..", 2) != 0; e++)		/* nothing */;	/* 1 for nul terminator */	n = e - p + 1;	if(n >= nb)		n = nb;	snprint(b, n, "%s", p);	ev->p = e;	return n > 0;} inttake(Eval *ev, char *m){	int l; 	l = strlen(m);	if(strncmp(ev->p, m, l) != 0)		return 0;	ev->p += l;	return 1;} static intpaint(Hash *head, int nhead, Hash *tail, int ntail, Object ***res, int *nres, int mode){	Qelt e;	Objq objq;	Objset keep, drop, skip;	Object *o, *c, **range;	int i, nskip, nrange; 	osinit(&keep);	osinit(&drop);	osinit(&skip);	qinit(&objq);	range = nil;	nrange = 0;	nskip = 0; 	for(i = 0; i < nhead; i++){		if(hasheq(&head[i], &Zhash))			continue;		if((o = readobject(head[i])) == nil){			fprint(2, "warning: %H does not point at commit\n", head[i]);			werrstr("read head %H: %r", head[i]);			return -1;		}		if(o->type != GCommit){			fprint(2, "warning: %H does not point at commit\n", o->hash);			unref(o);			continue;		}		dprint(1, "init: keep %H\n", o->hash);		qput(&objq, o, Keep);		unref(o);	}			for(i = 0; i < ntail; i++){		if(hasheq(&tail[i], &Zhash))			continue;		if((o = readobject(tail[i])) == nil){			werrstr("read tail %H: %r", tail[i]);			return -1;		}		if(o->type != GCommit){			fprint(2, "warning: %H does not point at commit\n", o->hash);			unref(o);			continue;		}		dprint(1, "init: drop %H\n", o->hash);		qput(&objq, o, Drop);		unref(o);	} 	dprint(1, "finding twixt commits\n");	while(objq.nheap != 0 && qpop(&objq, &e)){		if(e.color == Skip)			nskip--;		if(oshas(&skip, e.o->hash))			continue;		switch(e.color){		case Keep:			if(oshas(&keep, e.o->hash))				continue;			if(oshas(&drop, e.o->hash))				e.color = Skip;			else if(mode == Range){				range = earealloc(range, nrange+1, sizeof(Object*));				range[nrange++] = e.o;			}			osadd(&keep, e.o);			break;		case Drop:			if(oshas(&drop, e.o->hash))				continue;			if(oshas(&keep, e.o->hash))				e.color = Skip;			osadd(&drop, e.o);			break;		case Skip:			osadd(&skip, e.o);			break;		}		o = readobject(e.o->hash);		if(o->type != GCommit){			werrstr("not a commit: %H", o->hash);			goto error;		}		for(i = 0; i < o->commit->nparent; i++){			if((c = readobject(e.o->commit->parent[i])) == nil)				goto error;			if(c->type != GCommit){				fprint(2, "warning: %H does not point at commit\n", c->hash);				unref(c);				continue;			}			dprint(2, "\tenqueue: %s %H\n", colors[e.color], c->hash);			qput(&objq, c, e.color);			unref(c);			if(e.color == Skip)				nskip++;		}		unref(o);	}	switch(mode){	case Lca:		dprint(1, "found ancestor\n");		o = nil;		for(i = 0; i < keep.sz; i++){			o = keep.obj[i];			if(o != nil && oshas(&drop, o->hash) && !oshas(&skip, o->hash))				break;		}		if(i == keep.sz){			*nres = 0;			*res = nil;		}else{			*nres = 1;			*res = eamalloc(1, sizeof(Object*));			(*res)[0] = o;		}		break;	case Twixt:		dprint(1, "found twixt\n");		*res = eamalloc(keep.nobj, sizeof(Object*));		*nres = 0;		for(i = 0; i < keep.sz; i++){			o = keep.obj[i];			if(o != nil && !oshas(&drop, o->hash) && !oshas(&skip, o->hash)){				(*res)[*nres] = o;				(*nres)++;			}		}		break;	case Range:		dprint(1, "found range\n");		*res = eamalloc(nrange, sizeof(Object*));		*nres = 0;		for(i = nrange - 1; i >= 0; i--){			o = range[i];			if(!oshas(&drop, o->hash) && !oshas(&skip, o->hash)){				(*res)[*nres] = o;				(*nres)++;			}		}		free(range);		break;	}	osclear(&keep);	osclear(&drop);	osclear(&skip);	return 0;error:	dprint(1, "paint error: %r\n");	free(objq.heap);	free(range);	return -1;} intfindtwixt(Hash *head, int nhead, Hash *tail, int ntail, Object ***res, int *nres){	return paint(head, nhead, tail, ntail, res, nres, Twixt);} Object*ancestor(Object *a, Object *b){	Object **o, *r;	int n; 	if(paint(&a->hash, 1, &b->hash, 1, &o, &n, Lca) == -1 || n == 0)		return nil;	r = ref(o[0]);	free(o);	return r;} intlca(Eval *ev){	Object *a, *b, **o;	int n; 	if(ev->nstk < 2){		werrstr("ancestor needs 2 objects");		return -1;	}	n = 0;	b = pop(ev);	a = pop(ev);	paint(&a->hash, 1, &b->hash, 1, &o, &n, Lca);	if(n == 0)		return -1;	push(ev, *o);	free(o);	return 0;} static intparent(Eval *ev){	Object *o, *p; 	o = pop(ev);	if(o->type != GCommit){		werrstr("not a commit: %H", o->hash);		return -1;	}	/* Special case: first commit has no parent. */	if(o->commit->nparent == 0)		p = emptydir();	else if ((p = readobject(o->commit->parent[0])) == nil){		werrstr("no parent for %H", o->hash);		return -1;	}			push(ev, p);	return 0;} static intrange(Eval *ev){	Object *a, *b, **o;	int i, n; 	b = pop(ev);	a = pop(ev);	if(hasheq(&b->hash, &Zhash))		b = &zcommit;	if(hasheq(&a->hash, &Zhash))		a = &zcommit;	if(a->type != GCommit || b->type != GCommit){		werrstr("non-commit object in range");		return -1;	} 	if(paint(&b->hash, 1, &a->hash, 1, &o, &n, Range) == -1)		return -1;	for(i = 0; i < n; i++)		push(ev, o[i]);	free(o);	return 0;} static intmatchpfx(Hash *h, char *ref){	int i, c;	Hash pfx;	char *p; 	memset(&pfx, 0, sizeof(Hash));	for(i = 0, p = ref; *p; p++, i++){		if((c = charval(*p)) == -1)			return -1;		pfx.h[i/2] |= c;		if((i & 1) == 0)			pfx.h[i/2] <<= 4;	}	return expandprefix(h, pfx, i*4);} intreadref(Hash *h, char *ref){	static char *try[] = {"", "refs/", "refs/heads/", "refs/remotes/", "refs/tags/", nil};	char buf[256], s[256], **pfx;	int r, f, n; 	if((r = hparse(h, ref)) != -1)		return r;	if(strcmp(ref, "HEAD") == 0){		snprint(buf, sizeof(buf), ".git/HEAD");		if((f = open(buf, OREAD)) == -1)			return -1;		if((n = readn(f, s, sizeof(s) - 1))== -1)			return -1;		s[n] = 0;		strip(s);		r = hparse(h, s);		goto found;	}	for(pfx = try; *pfx; pfx++){		snprint(buf, sizeof(buf), ".git/%s%s", *pfx, ref);		if((f = open(buf, OREAD)) == -1)			continue;		if((n = readn(f, s, sizeof(s) - 1)) == -1)			continue;		s[n] = 0;		strip(s);		r = hparse(h, s);		close(f);		goto found;	}	if((r = matchpfx(h, ref)) != -1)		return r;	return -1; found:	if(r == -1 && strncmp(s, "ref: ", 5) == 0)		r = readref(h, s + 5);	return r;} intevalpostfix(Eval *ev){	char name[256];	Object *o;	Hash h; 	eatspace(ev);	if(!word(ev, name, sizeof(name))){		werrstr("expected name in expression");		return -1;	}	if(readref(&h, name) == -1){		werrstr("invalid ref %s", name);		return -1;	}	if(hasheq(&h, &Zhash))		o = &zcommit;	else if((o = readobject(h)) == nil){		werrstr("invalid ref %s (hash %H)", name, h);		return -1;	}	push(ev, o); 	while(1){		eatspace(ev);		switch(ev->p[0]){		case '^':		case '~':			ev->p++;			if(parent(ev) == -1)				return -1;			break;		case '@':			ev->p++;			if(lca(ev) == -1)				return -1;			break;		default:			goto done;			break;		}		}done:	return 0;} intevalexpr(Eval *ev, char *ref){	memset(ev, 0, sizeof(*ev));	ev->str = ref;	ev->p = ref; 	while(1){		if(evalpostfix(ev) == -1)			return -1;		if(ev->p[0] == '\0')			return 0;		else if(take(ev, ":") || take(ev, "..")){			if(evalpostfix(ev) == -1)				return -1;			if(ev->p[0] != '\0'){				werrstr("junk at end of expression");				return -1;			}			return range(ev);		}	}} intresolverefs(Hash **r, char *ref){	Eval ev;	Hash *h;	int i; 	if(evalexpr(&ev, ref) == -1){		free(ev.stk);		return -1;	}	h = eamalloc(ev.nstk, sizeof(Hash));	for(i = 0; i < ev.nstk; i++)		h[i] = ev.stk[i]->hash;	*r = h;	free(ev.stk);	return ev.nstk;

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