gnu: libevent@2.0: Add fix from upstream.

This fix was cherry-picked by Mozilla from upstream libevent-2.1 to its
bundled copy of libevent-2.0.21 in mozilla-esr45.

* gnu/packages/patches/libevent-2.0-evbuffer-add-use-last-with-datap.patch:
New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/libevent.scm (libevent-2.0)[source][patches]: Add it.

3 files changed, 54 insertions, 13 deletions

diff --git a/gnu/local.mk b/gnu/local.mk
index 48c134ba6e..885c1137a5 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -677,6 +677,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/libdrm-symbol-check.patch		\
   %D%/packages/patches/libepoxy-gl-null-checks.patch		\
   %D%/packages/patches/libevent-dns-tests.patch			\
+  %D%/packages/patches/libevent-2.0-evbuffer-add-use-last-with-datap.patch	\
   %D%/packages/patches/libevent-2.0-evdns-fix-remote-stack-overread.patch	\
   %D%/packages/patches/libevent-2.0-evdns-fix-searching-empty-hostnames.patch	\
   %D%/packages/patches/libevent-2.0-evutil-fix-buffer-overflow.patch	\
diff --git a/gnu/packages/libevent.scm b/gnu/packages/libevent.scm
index dd5f7c4067..6e2ce8f257 100644
--- a/gnu/packages/libevent.scm
+++ b/gnu/packages/libevent.scm
@@ -1,6 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2013, 2014, 2015, 2016 Ludovic Courtès <ludo@gnu.org>
-;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
+;;; Copyright © 2015, 2017 Mark H Weaver <mhw@netris.org>
 ;;; Copyright © 2015 Eric Dvorsak <eric@dvorsak.fr>
 ;;; Copyright © 2016 David Thompson <davet@gnu.org>
 ;;; Copyright © 2017 Marius Bakke <mbakke@fastmail.com>
@@ -74,18 +74,20 @@ loop.")
     (inherit libevent)
     (version "2.0.22")
     (source (origin
-          (method url-fetch)
-          (uri (string-append
-                "https://github.com/libevent/libevent/releases/download/release-"
-                version "-stable/libevent-" version "-stable.tar.gz"))
-          (sha256
-           (base32
-            "18qz9qfwrkakmazdlwxvjmw8p76g70n3faikwvdwznns1agw9hki"))
-          (patches (search-patches
-                    "libevent-dns-tests.patch"
-                    "libevent-2.0-evdns-fix-remote-stack-overread.patch"
-                    "libevent-2.0-evutil-fix-buffer-overflow.patch"
-                    "libevent-2.0-evdns-fix-searching-empty-hostnames.patch"))))))
+              (method url-fetch)
+              (uri (string-append
+                    "https://github.com/libevent/libevent/releases/download/release-"
+                    version "-stable/libevent-" version "-stable.tar.gz"))
+              (sha256
+               (base32
+                "18qz9qfwrkakmazdlwxvjmw8p76g70n3faikwvdwznns1agw9hki"))
+              (patches
+               (search-patches
+                "libevent-dns-tests.patch"
+                "libevent-2.0-evdns-fix-remote-stack-overread.patch"
+                "libevent-2.0-evutil-fix-buffer-overflow.patch"
+                "libevent-2.0-evdns-fix-searching-empty-hostnames.patch"
+                "libevent-2.0-evbuffer-add-use-last-with-datap.patch"))))))
 
 (define-public libev
   (package
diff --git a/gnu/packages/patches/libevent-2.0-evbuffer-add-use-last-with-datap.patch b/gnu/packages/patches/libevent-2.0-evbuffer-add-use-last-with-datap.patch
new file mode 100644
index 0000000000..0253700bf6
--- /dev/null
+++ b/gnu/packages/patches/libevent-2.0-evbuffer-add-use-last-with-datap.patch
@@ -0,0 +1,38 @@
+From a8769ef12d7e223e33fc47bed03fba2bfa2f3536 Mon Sep 17 00:00:00 2001
+From: Marcus Sundberg <marcus@marcussundberg.com>
+Date: Sat, 26 Mar 2016 20:11:43 +0100
+Subject: [PATCH] evbuffer_add: Use last_with_datap if set, not last.
+
+evbuffer_add() would always put data in the last chain, even if there
+was available space in a previous chain, and in doing so it also
+failed to update last_with_datap, causing subsequent calls to other
+functions that do look at last_with_datap to add data in the middle
+of the evbuffer instead of at the end.
+
+Fixes the evbuffer_add() part of issue #335, and the evbuffer/add2 and
+evbuffer/add3 tests, and also prevents wasting space available in the
+chain pointed to by last_with_datap.
+---
+ buffer.c | 6 +++++-
+ 1 file changed, 5 insertions(+), 1 deletion(-)
+
+diff --git a/buffer.c b/buffer.c
+index 7cca0e8a..f378b731 100644
+--- a/buffer.c
++++ b/buffer.c
+@@ -1732,7 +1732,11 @@ evbuffer_add(struct evbuffer *buf, const void *data_in, size_t datlen)
+ 		goto done;
+ 	}
+ 
+-	chain = buf->last;
++	if (*buf->last_with_datap == NULL) {
++		chain = buf->last;
++	} else {
++		chain = *buf->last_with_datap;
++	}
+ 
+ 	/* If there are no chains allocated for this buffer, allocate one
+ 	 * big enough to hold all the data. */
+-- 
+2.12.0
+