format: ~x/~X specifiers support buffers.

* buf.c (buf_hex): New function.

* buf.h (buf_hex): Declared.

* stream.c (formatv): Support printing of buffers in hex
via temporary buffer containing hex characters, similarly
to how bignums are handled.

* tests/018/format.tl: New file, providing some coverage over
new and affected code.

1 files changed, 14 insertions, 0 deletions

diff --git a/buf.c b/buf.c
index 5d0fb268..1804733a 100644
--- a/buf.c
+++ b/buf.c
@@ -834,6 +834,20 @@ val buf_pprint(val buf, val stream_in)
   return t;
 }
 
+void buf_hex(val buf, char *hex, size_t sz, int caps)
+{
+  val self = lit("buf-hex");
+  struct buf *b = buf_handle(buf, self);
+  size_t i;
+  unsigned char *data = b->data;
+  const char *fmt = caps ? "%02X" : "%02x";
+
+  *hex = 0;
+
+  for (i = 0; i < sz - 1; i += 2)
+    hex += sprintf(hex, fmt, *data++);
+}
+
 struct buf_strm {
   struct strm_base a;
   utf8_decoder_t ud;