From: Felix Riemann <felix.riemann@sma.de>
Date: Wed, 29 May 2019 19:17:42 +0000 (+0200)
Subject: pager: Fix deadlock when using built-in pager
X-Git-Tag: v243-rc1~344
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=d8f8b18cdb099ac0604d26037e2f9f9f5bd135ce;p=thirdparty%2Fsystemd.git

pager: Fix deadlock when using built-in pager

The parent is waiting for an EOF on the pipe transmitting the pager name
before starting to send data. With external pagers this happens due to
execlp() CLOEXEC'ing the pipe, so the internal pager needs to close it
manually.
---

diff --git a/src/shared/pager.c b/src/shared/pager.c
index 2abb0f62d27..7c20b100b46 100644
--- a/src/shared/pager.c
+++ b/src/shared/pager.c
@@ -194,11 +194,13 @@ int pager_open(PagerFlags flags) {
                                        "Failed to execute '%s', using next fallback pager: %m", exe);
                 }
 
-                r = loop_write(exe_name_pipe[1], "(built-in)", strlen("(built-in") + 1, false);
+                r = loop_write(exe_name_pipe[1], "(built-in)", strlen("(built-in)") + 1, false);
                 if (r < 0) {
                         log_error_errno(r, "Failed to write pager name to socket: %m");
                         _exit(EXIT_FAILURE);
                 }
+                /* Close pipe to signal the parent to start sending data */
+                safe_close_pair(exe_name_pipe);
                 pager_fallback();
                 /* not reached */
         }