Refactor body match iterator from double pointer to extent (ptr+len)

This is in preparation of an upcoming refactor to heap space.

src/vmod_re.c

@@ -459,7 +459,8 @@ struct re_iter_priv {
 	struct vmod_priv	*task;
 	const struct vre_limits	*vre_limits;
 
-	char			*b, *e;
+	char			*buf;
+	size_t			len;
 };
 
 static int v_matchproto_(objiterate_f)
@@ -485,25 +486,23 @@ match_iter_f(void *priv, unsigned flush, const void *ptr, ssize_t len)
 
 	if (reip->s == PCRE2_ERROR_NOMATCH) {
 		AZ(reip->startoffset);
-		AZ(reip->b);
-		AZ(reip->e);
+		AZ(reip->buf);
+		AZ(reip->len);
 
 		subject = ptr;
 	}
 	else if (reip->s == PCRE2_ERROR_PARTIAL) {
-		AN(reip->e);
-		assert(reip->e >= reip->b);
-		if ((reip->e - reip->b) + len >
-		    WS_ReservationSize(reip->ctx->ws)) {
+		AN(reip->buf);
+		if (reip->len + len > WS_ReservationSize(reip->ctx->ws)) {
 			errmsg(reip->ctx, "vmod re: insufficient workspace "
 			    "while iterating (append)");
 			return (-1);
 		}
-		memcpy(reip->e, ptr, len);
-		reip->e += len;
+		memcpy(reip->buf + reip->len, ptr, len);
+		reip->len += len;
 
-		len = (reip->e - reip->b);
-		subject = reip->b;
+		len = reip->len;
+		subject = reip->buf;
 	}
 	else {
 		WRONG("match error should have been latched "
@@ -524,7 +523,7 @@ match_iter_f(void *priv, unsigned flush, const void *ptr, ssize_t len)
 
 	CAST_OBJ_NOTNULL(ov, reip->task->priv, OV_MAGIC);
 
-	if (reip->s == PCRE2_ERROR_PARTIAL && reip->b != NULL)
+	if (reip->s == PCRE2_ERROR_PARTIAL && reip->buf != NULL)
 		return (0);
 
 	if (reip->s == PCRE2_ERROR_PARTIAL) {
@@ -533,9 +532,9 @@ match_iter_f(void *priv, unsigned flush, const void *ptr, ssize_t len)
 			       "for partial copy");
 			return (-1);
 		}
-		reip->b = WS_Reservation(reip->ctx->ws);
-		memcpy(reip->b, ptr, len);
-		reip->e = reip->b + len;
+		reip->buf = WS_Reservation(reip->ctx->ws);
+		memcpy(reip->buf, ptr, len);
+		reip->len = len;
 
 		reip->startoffset = ov->ovector[0];
 
@@ -549,15 +548,15 @@ match_iter_f(void *priv, unsigned flush, const void *ptr, ssize_t len)
 
 	if (reip->s == PCRE2_ERROR_NOMATCH) {
 		reip->startoffset = 0;
-		reip->b = 0;
-		reip->e = 0;
+		reip->buf = NULL;
+		reip->len = 0;
 
 		return (0);
 	}
 
 	assert(reip->s > PCRE2_ERROR_NOMATCH);
 
-	if (reip->b == NULL && (flush & OBJ_ITER_FLUSH) == 0) {
+	if (reip->buf == NULL && (flush & OBJ_ITER_FLUSH) == 0) {
 		/* no need to copy */
 		WS_Release(reip->ctx->ws, 0);
 		return (0);
@@ -566,7 +565,7 @@ match_iter_f(void *priv, unsigned flush, const void *ptr, ssize_t len)
 	len = (ssize_t)ov->ovector[1] - (ssize_t)ov->ovector[0];
 	assert(len >= 0);
 
-	if (reip->b == NULL && len > WS_ReservationSize(reip->ctx->ws)) {
+	if (reip->buf == NULL && len > WS_ReservationSize(reip->ctx->ws)) {
 		errmsg(reip->ctx, "vmod re: insufficient workspace "
 		       "for match copy");
 		WS_Release(reip->ctx->ws, 0);
@@ -574,7 +573,7 @@ match_iter_f(void *priv, unsigned flush, const void *ptr, ssize_t len)
 	}
 
 	ov->subject = p = WS_Reservation(reip->ctx->ws);
-	if (reip->b == NULL)
+	if (reip->buf == NULL)
 		memcpy(p, subject + ov->ovector[0], len);
 	else
 		memmove(p, subject + ov->ovector[0], len);