[SVN-4879] Broken pipe on the diff command with --diff-cmd

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.14.1
• Component/s: cmdline client

Environment

Debian GNU/Linux.

• Assignee: Unassigned
• Reporter: Vincent Lefevre
• Created: 26/Aug/21 17:00
• Updated: 28/Dec/21 10:47

Description

When I pipe the output of "svn diff --diff-cmd diff" and a broken pipe occurs on the diff command, I get a "Broken pipe" error:

diff: standard output: Broken pipe
svn: E200012: 'diff' returned 2

The cause is that svn runs the diff command with SIGPIPE ignored, so that diff gets an EPIPE write error instead of being killed by the signal. I think that a fix should be to reset SIGPIPE to the default action just before executing the external diff command.

To reproduce the bug:

#!/bin/sh

set -e

export LC_ALL=C

mkdir my-test-svn
cd my-test-svn

svnadmin create svn
svn co file://`pwd`/svn wc
cd wc

seq 10000 > file
svn add file
svn diff | head
svn diff --diff-cmd diff | head

cd ../..
rm -rf my-test-svn

 

This gives:

Checked out revision 0.
A file
Index: file
===================================================================
--- file (nonexistent)
+++ file (working copy)
@@ -0,0 +1,10000 @@
+1
+2
+3
+4
+5
Index: file
===================================================================
--- file (nonexistent)
+++ file (working copy)
@@ -0,0 +1,10000 @@
+1
+2
+3
+4
+5
diff: standard output: Broken pipe
svn: E200012: 'diff' returned 2

A possible fix (to be tested): instead of ignoring SIGPIPE (using SIG_IGN), use a handler that does nothing. That way, when a command is executed, SIGPIPE will be reset to the default action in the command (i.e. killing the command, unless the command itself changes how it handles SIGPIPE).