From 23b5331ef181f0ab81c5fd30ec3aae3d2f86c69d Mon Sep 17 00:00:00 2001
From: Matej Habrnal <mhabrnal@redhat.com>
Date: Fri, 21 Sep 2018 15:39:21 +0200
Subject: [PATCH] dd: extend the scope of DD_DONT_WAIT_FOR_LOCK

The current implementation uses the flag only to ignore *unlocked or
broken* problems that misses some of the required files. If the dump
directory is locked by an existing process, dd_lock() waits until
the
process unlocks it and that causes problems in UI.

Example:
1. abrt-hook-ccpp creates a new dump directory and goes to generate
core_backtrace, which blocks it for several seconds.
2. An user wants to get list of all problems from abrt-dbus.
3. abrt-dbus got stucked on the new problem locked by
abrt-hook-ccpp.
4. D-Bus connection time-outs, abrt-dbus becomes unreachable.

This patch adds a new condition which breaks the loop wait for lock
if
the problem directory is locked by existing process. All other cases
are already handled and dd_lock() either returns an error or steals
the
lock file if the locking process seems to not exist. Transitional
states
like when the locking process just unlocked the directory are
handled too.

errno is set to EAGAIN that is used by standard functions when an
operation failed but it is possible that a next call can be
successful.
It should inform the calling function that the failure is not fatal
and
the function can silently continue.

Related: rhbz#1588272

Signed-off-by: Matej Habrnal <mhabrnal@redhat.com>
---
 src/lib/dump_dir.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/lib/dump_dir.c b/src/lib/dump_dir.c
index d7ddec7a..acc5e561 100644
--- a/src/lib/dump_dir.c
+++ b/src/lib/dump_dir.c
@@ -341,6 +341,11 @@ static int dd_lock(struct dump_dir *dd, unsigned sleep_usec, int flags)
             return r; /* error */
         if (r > 0)
             break; /* locked successfully */
+        if (flags & DD_DONT_WAIT_FOR_LOCK)
+        {
+            errno = EAGAIN;
+            return -1;
+        }
         /* Other process has the lock, wait for it to go away */
         usleep(sleep_usec);
     }
@@ -473,6 +478,10 @@ static struct dump_dir *dd_do_open(struct dump_dir *dd, int flags)
              */
             error_msg("'%s' is not a problem directory", dd->dd_dirname);
         }
+        else if (errno == EAGAIN && (flags & DD_DONT_WAIT_FOR_LOCK))
+        {
+            log_debug("Can't access locked directory '%s'", dd->dd_dirname);
+        }
         else
         {
  cant_access:
-- 
2.17.2