From efee4e0eae8cc15fdb8614c022e67b9568d8a0cb Mon Sep 17 00:00:00 2001
From: Simon Tatham <anakin@pobox.com>
Date: Fri, 19 Nov 2021 10:21:40 +0000
Subject: [PATCH] Add some more bufchain_try_* functions.

We already had bufchain_try_fetch_consume; now we also have
bufchain_try_fetch (for when you want to wait until that much data is
available but then not commit to removing it), and
bufchain_try_consume (so you can conveniently ignore a certain amount
of incoming data).
---
 misc.h           |  2 ++
 utils/bufchain.c | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/misc.h b/misc.h
index 5c8f982e..84643936 100644
--- a/misc.h
+++ b/misc.h
@@ -123,6 +123,8 @@ ptrlen bufchain_prefix(bufchain *ch);
 void bufchain_consume(bufchain *ch, size_t len);
 void bufchain_fetch(bufchain *ch, void *data, size_t len);
 void bufchain_fetch_consume(bufchain *ch, void *data, size_t len);
+bool bufchain_try_consume(bufchain *ch, size_t len);
+bool bufchain_try_fetch(bufchain *ch, void *data, size_t len);
 bool bufchain_try_fetch_consume(bufchain *ch, void *data, size_t len);
 size_t bufchain_fetch_consume_up_to(bufchain *ch, void *data, size_t len);
 void bufchain_set_callback_inner(
diff --git a/utils/bufchain.c b/utils/bufchain.c
index 60ebc2be..9b02c65f 100644
--- a/utils/bufchain.c
+++ b/utils/bufchain.c
@@ -153,6 +153,26 @@ void bufchain_fetch_consume(bufchain *ch, void *data, size_t len)
     bufchain_consume(ch, len);
 }
 
+bool bufchain_try_fetch(bufchain *ch, void *data, size_t len)
+{
+    if (ch->buffersize >= len) {
+        bufchain_fetch(ch, data, len);
+        return true;
+    } else {
+        return false;
+    }
+}
+
+bool bufchain_try_consume(bufchain *ch, size_t len)
+{
+    if (ch->buffersize >= len) {
+        bufchain_consume(ch, len);
+        return true;
+    } else {
+        return false;
+    }
+}
+
 bool bufchain_try_fetch_consume(bufchain *ch, void *data, size_t len)
 {
     if (ch->buffersize >= len) {