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increase robustness by always recalculating size

starting over using defensive programming
also fixes a bounding bug

--- a/cmd.c

+++ b/cmd.c

@@ -7,7 +7,7 @@

 /* stupidest implementation with the least amount of state to keep track of */

 Dot dot;

-usize totalsz_, totalsz;

+usize totalsz;

 static Chunk norris = {.left = &norris, .right = &norris};

 static Chunk *held;

 static uchar plentyofroom[Iochunksz];

@@ -30,6 +30,33 @@

 	fprint(2, "\n");

 }

+static void

+recalcsize(void)

+{

+	int n;

+	Chunk *c;

+

+	for(c=norris.right, n=0; c!=&norris; c=c->right)

+		n += c->bufsz;

+	if(dot.to.pos == totalsz || n < totalsz && dot.to.pos > n)

+		dot.to.pos = n;

+	totalsz = n;

+}

+

+#define ASSERT(x) {if(!(x)) printchunks(&norris); assert((x)); }

+static void

+paranoia(void)

+{

+	Chunk *c;

+

+	ASSERT(dot.pos >= dot.from.pos && dot.pos < dot.to.pos);

+	ASSERT(dot.to.pos <= totalsz);

+	for(c=norris.right; c!=&norris; c=c->right){

+		ASSERT(c->buf != nil);

+		ASSERT((c->bufsz & 3) == 0 && c->bufsz >= Sampsz);

+	}

+}

+

 static Chunk *

 newchunk(usize n)

 {

@@ -65,18 +92,6 @@

 }

 static void

-assertsize(void)

-{

-	Chunk *c;

-

-	totalsz_ = 0;

-	for(c=norris.right; c!=&norris; c=c->right)

-		totalsz_ += c->bufsz;

-	assert(totalsz_ == totalsz);

-	assert(dot.to.pos <= totalsz);

-}

-

-static void

 linkchunk(Chunk *left, Chunk *c)

 {

 	c->left->right = left->right;

@@ -83,7 +98,6 @@

 	left->right->left = c->left;

 	c->left = left;

 	left->right = c;

-	totalsz += c->bufsz;

 }

 static void

@@ -92,7 +106,6 @@

 	c->left->right = c->right;

 	c->right->left = c->left;

 	c->left = c->right = nil;

-	totalsz -= c->bufsz;

 }

 static void

@@ -105,7 +118,6 @@

 	c->bufsz = newsz;

 	if(c->right == &norris && Δ < 0)

 		dot.to.pos += Δ;

-	totalsz += Δ;

 }

 /* stupidest possible approach for now: minimal bookkeeping */

@@ -262,6 +274,7 @@

 	Chunk *c;

 	if(d->pos >= totalsz){

+		werrstr("out of bounds");

 		*sz = 0;

 		return nil;

 	}

@@ -506,12 +519,8 @@

 			werrstr("readintochunks: nothing read");

 			return nil;

 		}

-	}else if(n > 0 && n < Iochunksz){

+	}else if(n > 0 && n < Iochunksz)

 		resizechunk(c, n);

-		/* kludge! first chunk still unlinked */

-		if(m < Iochunksz)

-			totalsz += Iochunksz - c->bufsz;

-	}

 	return rc;

 }

@@ -593,7 +602,7 @@

 		threadexits("failed reading from pipe: %r");

 	close(fd);

 	paste(nil, c);

-	assertsize();

+	recalcsize();

 	redraw(0);

 	threadexits(nil);

 }

@@ -601,7 +610,6 @@

 static int

 pipeline(char *arg, int rr, int wr)

 {

-	assertsize();

 	if(pipe(epfd) < 0)

 		sysfatal("pipe: %r");

 	if(procrfork(rc, arg, mainstacksize, RFFDG|RFNOTEG|RFNAMEG) < 0)

@@ -661,7 +669,7 @@

 int

 cmd(char *s)

 {

-	int n;

+	int n, x;

 	Rune r, r´;

 	/* FIXME: avoid potential conflicts with keys in main() */

@@ -677,22 +685,24 @@

 			break;

 		s += n;

 	}

-	assertsize();

 	switch(r){

-	case '<': return pipefrom(s);

-	case '^': return pipethrough(s);

-	case '|': return pipeto(s);

-	case 'c': return copy(s);

-	case 'd': return cut(s);

-	case 'm': return forcemerge(s);

-	case 'p': return paste(s, nil);

+	case '<': x = pipefrom(s); break;

+	case '^': x = pipethrough(s); break;

+	case '|': x = pipeto(s); break;

+	case 'c': x = copy(s); break;

+	case 'd': x = cut(s); break;

+	case 'm': x = forcemerge(s); break;

+	case 'p': x = paste(s, nil); break;

 	case 'q': threadexitsall(nil);

-	case 'r': return readfrom(s);

-	case 'w': return writeto(s);

-	case 'x': return crop(s);

-	default: werrstr("unknown command %C", r); break;

+	case 'r': x = readfrom(s); break;

+	case 'w': x = writeto(s); break;

+	case 'x': x = crop(s); break;

+	default: werrstr("unknown command %C", r); x = -1; break;

 	}

-	return -1;

+	if(debug)

+		paranoia();

+	recalcsize();

+	return x;

 }

 int

@@ -703,6 +713,7 @@

 	if((c = readintochunks(fd)) == nil)

 		sysfatal("loadin: %r");

 	linkchunk(&norris, c);

+	recalcsize();

 	setrange(0, totalsz);

 	return 0;

 }