From 9b2a36ee8da4e25d919a435f871cc1e0fee8eace Mon Sep 17 00:00:00 2001
From: Aki <please@ignore.pl>
Date: Wed, 3 Mar 2021 23:54:34 +0100
Subject: Added handling for 0 length reads

---
 stream.c | 33 +++++++++++++++++++++------------
 stream.h |  1 +
 2 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/stream.c b/stream.c
index 6e99cde..eac89a8 100644
--- a/stream.c
+++ b/stream.c
@@ -105,6 +105,7 @@ int stream_read(lua_State * L)
 		s->in.allocated = 1024;
 		s->in.length = 0;
 		s->in.offset = 0;
+		s->in.next = 0;
 	}
 
 	return stream_readk(L, LUA_OK, 2); // Intentionally do not remove arguments from the stack.
@@ -177,29 +178,27 @@ static int read_more(lua_State * L, struct stream * s, int minimum_length, lua_K
 
 static int prepare_at_least(lua_State * L, struct stream * s, int minimum_length, lua_KContext ctx)
 {
-	const int remaining_bytes = s->in.length - s->in.offset;
+	const int remaining_bytes = s->in.length - s->in.next;
 
 	if (remaining_bytes < minimum_length)
 	{
 		return read_more(L, s, minimum_length, ctx);
 	}
 
-	return 0;
+	return remaining_bytes;
 }
 
 static int until(struct buffer * b, const char * pattern, int pattern_length)
 {
-	int offset = b->offset;
-
-	while (offset + pattern_length <= b->length)
+	while (b->next + pattern_length <= b->length)
 	{
-		if (0 == strncmp(&b->data[offset], pattern, pattern_length))
+		if (0 == strncmp(&b->data[b->next], pattern, pattern_length))
 		{
-			return offset;
+			return b->next;
 		}
 		else
 		{
-			offset++;
+			b->next++;
 		}
 	}
 
@@ -222,15 +221,25 @@ int stream_readk(lua_State * L, int status, lua_KContext ctx)
 		const char * pattern = lua_tolstring(L, ctx, &pattern_length);
 
 		int offset;
+		int remaining_bytes;
 		do
 		{
-			prepare_at_least(L, s, (int) pattern_length, ctx);
+			remaining_bytes = prepare_at_least(L, s, (int) pattern_length, ctx);
 			offset = until(&s->in, pattern, (int) pattern_length);
 		}
-		while (-1 == offset);
+		while (-1 == offset && 0 < remaining_bytes);
+
+		if (-1 != offset)
+		{
+			lua_pushlstring(L, &s->in.data[s->in.offset], offset - s->in.offset);
+			s->in.offset = offset + 1;
+			s->in.next = offset + 1;
+		}
+		else
+		{
+			lua_pushnil(L);
+		}
 
-		lua_pushlstring(L, &s->in.data[s->in.offset], offset - s->in.offset);
-		s->in.offset = offset + 1;
 		lua_remove(L, ctx);
 		lua_insert(L, ctx);
 	}
diff --git a/stream.h b/stream.h
index a164981..f1bc32c 100644
--- a/stream.h
+++ b/stream.h
@@ -7,6 +7,7 @@ struct buffer
 	char * data;
 	int length;
 	int offset;
+	int next;
 	int allocated;
 };
 
-- 
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