From 0afb2efada7e435ae18ef7d3db0758464189f44f Mon Sep 17 00:00:00 2001
From: Bernhard Voelker <mail@bernhard-voelker.de>
Date: Tue, 30 Jan 2018 23:30:09 +0100
Subject: [PATCH 159/224] find: make -delete honour the -ignore_readdir_race
 option

* find/pred.c (pred_delete): Return true when the -ignore_readdir_race
option is active and unlinkat() came back with ENOENT.
* doc/find.texi (Option -ignore_readdir_race): Document the change.
(Action -delete): Likewise.
* find/find.1: Likewise.
* NEWS (Bug Fixes): Mention the fix.

For now, it seems a bit hard to add a proper test for this,
so the following shell snippet demonstrates the race:

  $ seq 10 | xargs touch
  $ env time -f 'find exit status: %x\nfind time: %e' \
      find -ignore_readdir_race -type f \
        -delete \
        -exec sh -c 'sleep $(basename {})' \; \
        -printf 'find deleted: %p\n' \
        & \
    sleep 20; \
    seq 10 | xargs rm -fv; \
    wait $!

Reported by Alexander Golubev in
https://savannah.gnu.org/bugs/?52981
---
 NEWS          |  4 ++++
 doc/find.texi | 15 ++++++++++++++-
 find/find.1   | 22 ++++++++++++++++++++++
 find/pred.c   |  6 ++++++
 4 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/doc/find.texi b/doc/find.texi
index 3580be75..0089193e 100644
--- a/doc/find.texi
+++ b/doc/find.texi
@@ -1424,7 +1424,15 @@ gives a significant increase in search speed.
 If a file disappears after its name has been read from a directory but
 before @code{find} gets around to examining the file with @code{stat},
 don't issue an error message.  If you don't specify this option, an
-error message will be issued.  This option can be useful in system
+error message will be issued.
+
+Furthermore, @code{find} with the @samp{-ignore_readdir_race} option
+will ignore errors of the @samp{-delete} action in the case the file
+has disappeared since the parent directory was read: it will not output
+an error diagnostic, and the return code of the @samp{-delete} action
+will be true.
+
+This option can be useful in system
 scripts (cron scripts, for example) that examine areas of the
 filesystem that change frequently (mail queues, temporary directories,
 and so forth), because this scenario is common for those sorts of
@@ -2787,6 +2795,11 @@ explicitly.
 
 If @samp{-delete} fails, @code{find}'s exit status will be nonzero
 (when it eventually exits).
+
+Together with the @samp{-ignore_readdir_race} option, @code{find} will
+ignore errors of the @samp{-delete} action in the case the file has disappeared
+since the parent directory was read: it will not output an error diagnostic, and
+the return code of the @samp{-delete} action will be true.
 @end deffn
 
 @node Adding Tests
diff --git a/find/pred.c b/find/pred.c
index 7e2a7bde..af3bacbc 100644
--- a/find/pred.c
+++ b/find/pred.c
@@ -316,6 +316,12 @@ pred_delete (const char *pathname, struct stat *stat_buf, struct predicate *pred
 	}
       else
 	{
+	  if (ENOENT == errno && options.ignore_readdir_race)
+	    {
+	      /* Ignore unlink() error for vanished files.  */
+	      errno = 0;
+	      return true;
+	    }
 	  if (EISDIR == errno)
 	    {
 	      if ((flags & AT_REMOVEDIR) == 0)
-- 
2.19.1