[bug#50239] [PATCH core-updates-frozen v2] gnu: diffutils: Fix signal processing.

[Thiago Jung Bauermann via Guix-patches via <guix-patches@gnu.org>]

diffutils has a race condition in its signal processing code which is easy
to trigger on powerpc64le-linux. More often than not, it causes the
‘colors’ test to fail and therefore the build of the package fails as well.

Add the patch proposed in Debian bug 922552 which fixes the problem.

* gnu/packages/patches/diffutils-fix-signal-processing.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/base.scm (diffutils)[source]: Use it.
---

Hello,

Here is the same patch rebased on top of ‘core-updates-frozen’. I didn’t
yet do it in a way that preserves derivations on other platforms because
there will be a batch of world-rebuilding changes¹, so depending on how
soon the branch is going to be merged into master, it could be a good
opportunity to land this fix now.

So far, there hasn’t been news from upstream on a fix for the problem,
but it’s been only a bit over a week since they last proposed a patch
so it’s too early to be worried about anything.

I am perfectly fine with skipping this world-rebuilding window and sending
a v3 which preserves derivations on other platforms as you suggested. Or
even not fixing this bug on ’core-updates-frozen’ if the upstream fix
doesn’t arrive by then. As I mentioned earlier, we can just hit the “try
again” button until the CI produces a successful build. :-)

I’m just sending this version to have the option on the table.

Thanks!

¹ https://lists.nongnu.org/archive/html/guix-devel/2021-09/msg00097.html

 gnu/local.mk                                  |  1 +
 gnu/packages/base.scm                         |  3 +-
 .../diffutils-fix-signal-processing.patch     | 58 +++++++++++++++++++
 3 files changed, 61 insertions(+), 1 deletion(-)
 create mode 100644 gnu/packages/patches/diffutils-fix-signal-processing.patch

diff --git a/gnu/local.mk b/gnu/local.mk
index 07e6787642e9..d37b1b577a04 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -967,6 +967,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/desmume-gcc6-fixes.patch			\
   %D%/packages/patches/desmume-gcc7-fixes.patch			\
   %D%/packages/patches/dfu-programmer-fix-libusb.patch		\
+  %D%/packages/patches/diffutils-fix-signal-processing.patch	\
   %D%/packages/patches/diffutils-gets-undeclared.patch		\
   %D%/packages/patches/disarchive-cross-compilation.patch	\
   %D%/packages/patches/dkimproxy-add-ipv6-support.patch		\
diff --git a/gnu/packages/base.scm b/gnu/packages/base.scm
index 70eb135a1e41..bfe769fbc4ed 100644
--- a/gnu/packages/base.scm
+++ b/gnu/packages/base.scm
@@ -274,7 +274,8 @@ differences.")
             (sha256
              (base32
               "09isrg0isjinv8c535nxsi1s86wfdfzml80dbw41dj9x3hiad9xk"))
-            (patches (search-patches "coreutils-gnulib-tests.patch"))))
+            (patches (search-patches "coreutils-gnulib-tests.patch"
+                                     "diffutils-fix-signal-processing.patch"))))
    (build-system gnu-build-system)
    (native-inputs (list perl))
    (synopsis "Comparing and merging files")
diff --git a/gnu/packages/patches/diffutils-fix-signal-processing.patch b/gnu/packages/patches/diffutils-fix-signal-processing.patch
new file mode 100644
index 000000000000..134dd3f718bd
--- /dev/null
+++ b/gnu/packages/patches/diffutils-fix-signal-processing.patch
@@ -0,0 +1,58 @@
+Author: Frédéric Bonnard <frediz@debian.org>
+
+Obtained from:
+
+https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=922552#19
+
+Fixes bug reported upstream at:
+
+https://debbugs.gnu.org/cgi/bugreport.cgi?bug=34519
+
+diff --git a/src/diff.c b/src/diff.c
+index e2eb32437353..b574e8282dc9 100644
+--- a/src/diff.c
++++ b/src/diff.c
+@@ -1451,6 +1451,8 @@ compare_files (struct comparison const *parent,
+ 	}
+     }
+ 
++  final_process_signals ();
++
+   /* Now the comparison has been done, if no error prevented it,
+      and STATUS is the value this function will return.  */
+ 
+diff --git a/src/diff.h b/src/diff.h
+index 03daaa4a0530..e177fe600a25 100644
+--- a/src/diff.h
++++ b/src/diff.h
+@@ -390,6 +390,7 @@ extern enum changes analyze_hunk (struct change *, lin *, lin *, lin *, lin *);
+ extern void begin_output (void);
+ extern void debug_script (struct change *);
+ extern void fatal (char const *) __attribute__((noreturn));
++extern void final_process_signals (void);
+ extern void finish_output (void);
+ extern void message (char const *, char const *, char const *);
+ extern void message5 (char const *, char const *, char const *,
+diff --git a/src/util.c b/src/util.c
+index 4f4d9bb285eb..56d292de2927 100644
+--- a/src/util.c
++++ b/src/util.c
+@@ -237,6 +237,18 @@ process_signals (void)
+     }
+ }
+ 
++/* Process remaining signals once before exit  */
++void
++final_process_signals (void)
++{
++  static int last = 1;
++
++  if (last) {
++    process_signals ();
++    last = 0;
++  }
++}
++
+ static void
+ install_signal_handlers (void)
+ {