1 files changed, 18 insertions, 0 deletions
diff --git a/src/base/bufio/unget.c b/src/base/bufio/unget.c
new file mode 100644
index 0000000..3fd16de
--- /dev/null
+++ b/src/base/bufio/unget.c
@@ -0,0 +1,18 @@
+#include "internal.h"
+
+error
+bufio·ungetbyte(io·Buffer *buf, byte c)
+{
+    if(!(buf->state & bufio·rdr)) {
+        errorf("attempted to unget on non-active reader");
+        return bufio·err;
+    }
+
+    if(buf->pos == buf->buf) {
+        errorf("attempted to unget past end of buffer");
+        return bufio·err;
+    }
+
+    buf->pos--;
+    return 0;
+}