url.c: add a compile-time check that CURL_MAX_WRITE_SIZE is large enough

Some code (e.g. Curl_fillreadbuffer) assumes that this buffer is not
exceedingly tiny and will break if it is. This same check is already
done at run time in the CURLOPT_BUFFERSIZE option.

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/url.c b/lib/url.c
index 073c4331b..8e470b0e1 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -144,6 +144,15 @@ static unsigned int get_protocol_family(unsigned int protocol);
 #define READBUFFER_MAX  CURL_MAX_READ_SIZE
 #define READBUFFER_MIN  1024
 
+/* Some parts of the code (e.g. chunked encoding) assume this buffer has at
+ * more than just a few bytes to play with. Don't let it become too small or
+ * bad things will happen.
+ */
+#if READBUFFER_SIZE < READBUFFER_MIN
+# error READBUFFER_SIZE is too small
+#endif
+
+
 /*
  * Protocol table.
  */