>From 32e06128dbc97ceb0d060c88ec8db204fa51be5c Mon Sep 17 00:00:00 2001
From: Stefan Zager <sza...@google.com>
Date: Thu, 18 Oct 2012 16:23:53 -0700
Subject: [PATCH] Fix potential hang in https handshake.

It has been observed that curl_multi_timeout may return a very long
timeout value (e.g., 294 seconds and some usec) just before
curl_multi_fdset returns no file descriptors for reading.  The
upshot is that select() will hang for a long time -- long enough for
an https handshake to be dropped.  The observed behavior is that
the git command will hang at the terminal and never transfer any

This patch is a workaround for a probable bug in libcurl.  The bug
only seems to manifest around a very specific set of circumstances:

- curl version (from curl/curlver.h):

 #define LIBCURL_VERSION_NUM 0x071307

- git-remote-https running on an ubuntu-lucid VM.
- Connecting through squid proxy running on another VM.

Interestingly, the problem doesn't manifest if a host connects
through squid proxy running on localhost; only if the proxy is on
a separate VM (not sure if the squid host needs to be on a separate
physical machine).  That would seem to suggest that this issue
is timing-sensitive.

This patch is more or less in line with a recommendation in the
curl docs about how to behave when curl_multi_fdset doesn't return
and file descriptors:


Signed-off-by: Stefan Zager <sza...@google.com>
 http.c |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/http.c b/http.c
index df9bb71..51eef02 100644
--- a/http.c
+++ b/http.c
@@ -631,6 +631,17 @@ void run_active_slot(struct active_request_slot *slot)
                        curl_multi_fdset(curlm, &readfds, &writefds, &excfds, 
+                       /* It can happen that curl_multi_timeout returns a 
+                        * long timeout when curl_multi_fdset returns no file 
+                        * to read.  See commit message for more details.
+                        */
+                       if (max_fd < 0 &&
+                           select_timeout.tv_sec > 0 ||
+                           select_timeout.tv_usec > 50000) {
+                               select_timeout.tv_sec  = 0;
+                               select_timeout.tv_usec = 50000;
+                       }
                        select(max_fd+1, &readfds, &writefds, &excfds, 

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