Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

tools/sgen/sgen-entry-stream.c

@@ -0,0 +1,67 @@
+/*
+ * sgen-entry-stream.c: EntryStream implementation
+ *
+ * Copyright (C) 2016 Xamarin Inc
+ *
+ * Licensed under the MIT license. See LICENSE file in the project root for full license information.
+ */
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <glib.h>
+#include "sgen-entry-stream.h"
+
+#define BUFFER_SIZE (1 << 20)
+
+void
+init_stream (EntryStream *stream, int file)
+{
+	stream->file = file;
+	stream->buffer = g_malloc0 (BUFFER_SIZE);
+	stream->end = stream->buffer + BUFFER_SIZE;
+	stream->pos = stream->end;
+}
+
+void
+reset_stream (EntryStream *stream)
+{
+	stream->end = stream->buffer + BUFFER_SIZE;
+	stream->pos = stream->end;
+	lseek (stream->file, 0, SEEK_SET);
+}
+
+void
+close_stream (EntryStream *stream)
+{
+	g_free (stream->buffer);
+}
+
+gboolean
+refill_stream (EntryStream *in, size_t size)
+{
+	size_t remainder = in->end - in->pos;
+	ssize_t refilled;
+	g_assert (size > 0);
+	g_assert (in->pos >= in->buffer);
+	if (in->pos + size <= in->end)
+		return TRUE;
+	memmove (in->buffer, in->pos, remainder);
+	in->pos = in->buffer;
+	refilled = read (in->file, in->buffer + remainder, BUFFER_SIZE - remainder);
+	if (refilled < 0)
+		return FALSE;
+	g_assert (refilled + remainder <= BUFFER_SIZE);
+	in->end = in->buffer + refilled + remainder;
+	return in->end - in->buffer >= size;
+}
+
+ssize_t
+read_stream (EntryStream *stream, void *out, size_t size)
+{
+	if (refill_stream (stream, size)) {
+		memcpy (out, stream->pos, size);
+		stream->pos += size;
+		return size;
+	}
+	return 0;
+}