From 3b106f9bf513df365fe437905c710bdc3d79de25 Mon Sep 17 00:00:00 2001
From: Aki <please@ignore.pl>
Date: Thu, 25 Feb 2021 23:40:29 +0100
Subject: Split and extended read and grow implementation

---
 stream.c | 133 ++++++++++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 85 insertions(+), 48 deletions(-)

diff --git a/stream.c b/stream.c
index a4fb8c8..c633862 100644
--- a/stream.c
+++ b/stream.c
@@ -110,7 +110,84 @@ int stream_read(lua_State * L)
 	return stream_readk(L, LUA_OK, (lua_KContext) s); // Intentionally do not remove arguments from the stack.
 }
 
-static int until(struct buffer * b, const char * pattern, const int pattern_length)
+static int grow(lua_State *, struct buffer *);
+static int prepare_at_least(lua_State *, struct stream *, const int);
+static int read_more(lua_State *, struct stream *, const int);
+static int until(struct buffer *, const char *, const int);
+
+static int grow(lua_State * L, struct buffer * b)
+{
+	int allocated = b->allocated + 1024;
+
+	if (8192 < allocated)
+	{
+		lua_pushliteral(L, "Too large buffer");
+		return lua_error(L);
+	}
+
+	void * buffer = realloc(b->data, allocated);
+
+	if (NULL == buffer)
+	{
+		lua_pushliteral(L, "Could not grow buffer");
+		return lua_error(L);
+	}
+
+	b->data = buffer;
+	b->allocated = allocated;
+
+	return 0;
+}
+
+static int read_more(lua_State * L, struct stream * s, int minimum_length)
+{
+	const int free_space = s->in.allocated + s->in.offset - s->in.length - 1;
+
+	while (free_space < minimum_length)
+	{
+		grow(L, &s->in);
+	}
+
+	if (0 < s->in.offset)
+	{
+		memmove(s->in.data, s->in.data + s->in.offset, s->in.length - s->in.offset);
+		s->in.offset = 0;
+		s->in.length -= s->in.offset;
+	}
+
+	int length = read(s->fd, s->in.data + s->in.length, free_space);
+
+	if (-1 == length)
+	{
+		if (EWOULDBLOCK == errno || EAGAIN == errno)
+		{
+			return lua_yieldk(L, 0, (lua_KContext) s, stream_readk);
+		}
+		else
+		{
+			lua_pushstring(L, strerror(errno));
+			return lua_error(L);
+		}
+	}
+
+	s->in.length += length;
+
+	return length;
+}
+
+static int prepare_at_least(lua_State * L, struct stream * s, int minimum_length)
+{
+	const int remaining_bytes = s->in.length - s->in.offset;
+
+	if (remaining_bytes < minimum_length)
+	{
+		return read_more(L, s, minimum_length);
+	}
+
+	return 0;
+}
+
+static int until(struct buffer * b, const char * pattern, int pattern_length)
 {
 	int offset = b->offset;
 
@@ -138,58 +215,18 @@ int stream_readk(lua_State * L, int status, lua_KContext ctx)
 {
 	struct stream * s = (struct stream *) ctx;
 
-	int remaining_bytes = s->in.length - s->in.offset;
-	int offset = -1;
-
-	size_t len;
-	const char * pattern = lua_tolstring(L, 2, &len);
-	const int pattern_length = (int) len;
+	size_t pattern_length;
+	const char * pattern = lua_tolstring(L, 2, &pattern_length);
 
 	// TODO: NULL check
 
-	if (pattern_length <= remaining_bytes)
+	int offset;
+	do
 	{
-		offset = until(&s->in, pattern, pattern_length);
-	}
-
-	if (-1 == offset || 0 == remaining_bytes)
-	{
-		if (0 < s->in.length && 0 <= s->in.allocated - s->in.offset - 1)
-		{
-			// TODO: Allow buffer to grow some before raising an error.
-			lua_pushliteral(L, "Read buffer growing not implemented");
-			return lua_error(L);
-		}
-
-		// TODO: Allow user to control amount of bytes being read.
-		int length = read(s->fd, s->in.data + s->in.offset, s->in.allocated - s->in.offset - 1);
-
-		if (-1 == length)
-		{
-			if (EWOULDBLOCK == errno || EAGAIN == errno)
-			{
-				return lua_yieldk(L, 0, ctx, stream_readk);
-			}
-			else
-			{
-				lua_pop(L, 1);
-				lua_pushstring(L, strerror(errno));
-				return lua_error(L);
-			}
-		}
-
-		s->in.data[length] = 0;
-		s->in.length = s->in.offset + length;
-
-		offset = until(&s->in, pattern, pattern_length);
-
-		if (-1 == offset)
-		{
-			// TODO: Reiterate at this point, grow buffer until some error is reached or pattern is found.
-			lua_pushliteral(L, "Could not find pattern");
-			return lua_error(L);
-		}
+		prepare_at_least(L, s, (int) pattern_length);
+		offset = until(&s->in, pattern, (int) pattern_length);
 	}
+	while (-1 == offset);
 
 	lua_pushlstring(L, &s->in.data[s->in.offset], offset - s->in.offset);
 	s->in.offset = offset + 1;
-- 
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