lejp: unified strings

Adds helpers that transform lejp-processed chunked strings into
reallocated single linear strings with a terminating NUL, in the
same ac.

Author: lws-team

include/libwebsockets/lws-lejp.h

@@ -217,6 +217,20 @@ struct _lejp_parsing_stack {
 	uint8_t			path_match;
 };
 
+typedef struct lejp_string_piece {
+	struct lejp_string_piece	*next;
+	const char			*piece;
+	size_t				len;
+} lejp_string_piece_t;
+
+typedef struct {
+	lejp_string_piece_t	*sph;
+	lejp_string_piece_t	**sp_next;
+	int			pieces;
+	size_t			asl;
+	char			*fp;
+} lejp_string_unifier_t;
+
 struct lejp_ctx {
 
 	/* sorted by type for most compact alignment
@@ -234,6 +248,8 @@ struct lejp_ctx {
 	char path[LEJP_MAX_PATH];
 	char buf[LEJP_STRING_CHUNK + 1];
 
+	lejp_string_unifier_t	su;
+
 	/* size_t */
 
 	size_t path_stride; /* 0 means default ptr size, else stride */
@@ -306,4 +322,10 @@ lejp_get_wildcard(struct lejp_ctx *ctx, int wildcard, char *dest, int len);
 
 LWS_VISIBLE LWS_EXTERN const char *
 lejp_error_to_string(int e);
+
+LWS_VISIBLE LWS_EXTERN int
+lejp_string_unify(struct lejp_ctx *ctx, struct lwsac **ac);
+
+LWS_VISIBLE LWS_EXTERN int
+lejp_string_unify_part(struct lejp_ctx *ctx, struct lwsac **ac, char reason);
 //@}

lib/misc/lejp.c

@@ -952,3 +952,61 @@ lejp_error_to_string(int e)
 	return parser_errs[e];
 }
 
+int
+lejp_string_unify(struct lejp_ctx *ctx, struct lwsac **ac)
+{
+	char *p;
+
+	if (ctx->su.pieces == 1)
+		return 0;
+
+	ctx->su.fp = lwsac_use(ac, ctx->su.asl + 1u, 512);
+	if (!ctx->su.fp)
+		return 1;
+
+	p = ctx->su.fp;
+	while (ctx->su.sph) {
+		memcpy(p, ctx->su.sph->piece, ctx->su.sph->len);
+		p += ctx->su.sph->len;
+		ctx->su.sph = ctx->su.sph->next;
+	}
+	*p = '\0';
+
+	return 0;
+}
+
+int
+lejp_string_unify_part(struct lejp_ctx *ctx, struct lwsac **ac, char reason)
+{
+	if (reason == LEJPCB_VAL_STR_START) {
+		memset(&ctx->su, 0, sizeof(ctx->su));
+		ctx->su.sp_next = &ctx->su.sph;
+	}
+
+	if (
+	    (reason == LEJPCB_VAL_STR_START && ctx->npos) ||
+	    (reason == LEJPCB_VAL_STR_CHUNK && ctx->npos) ||
+	    (reason == LEJPCB_VAL_STR_END)) {
+		lejp_string_piece_t *s;
+
+		ctx->su.fp = lwsac_use(ac, ctx->npos + 1u, 512);
+		if (!ctx->su.fp)
+			return 1;
+		memcpy(ctx->su.fp, ctx->buf, ctx->npos);
+		ctx->su.fp[ctx->npos] = '\0';
+		s = lwsac_use_zero(ac, sizeof(*s), 512);
+		if (!s)
+			return 1;
+		*ctx->su.sp_next = s;
+		s->piece = ctx->su.fp;
+		s->len = ctx->npos;
+		ctx->su.asl += ctx->npos;
+		ctx->su.sp_next = &s->next;
+
+		if (reason == LEJPCB_VAL_STR_END)
+			ctx->su.sp_next = &ctx->su.sph;
+	}
+
+	return 0;
+}
+