From d2d8e8733c68c75097bac120162742ba4b15736b Mon Sep 17 00:00:00 2001
From: Aki <please@ignore.pl>
Date: Thu, 25 Feb 2021 21:08:34 +0100
Subject: Implemented basic until reading

---
 stream.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++++++++----------
 stream.h |  1 +
 2 files changed, 71 insertions(+), 13 deletions(-)

diff --git a/stream.c b/stream.c
index 781c821..cf92ad3 100644
--- a/stream.c
+++ b/stream.c
@@ -1,6 +1,7 @@
 #include "stream.h"
 
 #include <errno.h>
+#include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
@@ -101,9 +102,31 @@ int stream_read(lua_State * L)
 		}
 
 		s->in.data = buffer;
+		s->in.allocated = 1024;
+		s->in.length = 0;
+		s->in.offset = 0;
 	}
 
-	return stream_readk(L, LUA_OK, (lua_KContext) s); // Intentionally do not pop Stream that's on top of the stack.
+	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)
+{
+	int offset = b->offset;
+
+	while (offset + pattern_length < b->length)
+	{
+		if (0 == strncmp(&b->data[offset], pattern, pattern_length))
+		{
+			return offset;
+		}
+		else
+		{
+			offset++;
+		}
+	}
+
+	return -1;
 }
 
 /// Continuation function and core implementation of the reading operation from a stream.
@@ -115,27 +138,61 @@ int stream_readk(lua_State * L, int status, lua_KContext ctx)
 {
 	struct stream * s = (struct stream *) ctx;
 
-	int length = read(s->fd, s->in.data, 1023); // TODO: Allow user to control amount of bytes being read.
+	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;
+
+	// TODO: NULL check
 
-	if (-1 == length)
+	if (pattern_length <= remaining_bytes)
 	{
-		if (EWOULDBLOCK == errno || EAGAIN == errno)
+		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)
 		{
-			lua_yieldk(L, 0, ctx, stream_readk);
+			// TODO: Allow buffer to grow some before raising an error.
+			lua_pushliteral(L, "Read buffer growing not implemented");
+			return lua_error(L);
 		}
-		else
+
+		// 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)
 		{
-			lua_pop(L, 1);
-			lua_pushstring(L, strerror(errno));
+			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);
 		}
 	}
 
-	s->in.data[length] = 0;
-	s->in.length = length;
-	s->in.offset = 0;
-
-	lua_pushstring(L, s->in.data);
+	lua_pushlstring(L, &s->in.data[s->in.offset], offset - s->in.offset);
+	s->in.offset = offset + 1;
 
 	for (int n = -lua_gettop(L); n < -1; ++n)
 	{
diff --git a/stream.h b/stream.h
index c4bb3ef..a164981 100644
--- a/stream.h
+++ b/stream.h
@@ -7,6 +7,7 @@ struct buffer
 	char * data;
 	int length;
 	int offset;
+	int allocated;
 };
 
 struct stream
-- 
cgit v1.1