>From 9b5ff988f8c49a179ee64dbb075cb289b0c1868c Mon Sep 17 00:00:00 2001
From: Kevin Hunter Kesling <address@hidden>
Date: Fri, 3 Nov 2017 11:36:03 -0400
Subject: [PATCH] diff: Add include command line option

Referencing a number of requests, both public[1] and internal, this
patch now enables --include, in a similar vein to grep's --include.
Heavy thanks to grep's sourcecode for having already solved this wheel.

[1] "Only include files that match a given pattern in a recursive diff"
https://stackoverflow.com/questions/10131908/
---
 NEWS                  |  3 +++
 doc/diffutils.texi    |  6 ++++++
 src/diff.c            | 14 +++++++++++---
 tests/Makefile.am     |  3 ++-
 tests/include-exclude | 23 +++++++++++++++++++++++
 5 files changed, 45 insertions(+), 4 deletions(-)
 create mode 100755 tests/include-exclude

diff --git a/NEWS b/NEWS
index 949136c..89afd91 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,9 @@ GNU diffutils NEWS                                    -*- outline -*-
 
 * Noteworthy changes in release ?.? (????-??-??) [?]
 
+** New features
+
+ With --include, diff now can include file patterns, like grep.
 
 * Noteworthy changes in release 3.6 (2017-05-21) [stable]
 
diff --git a/doc/diffutils.texi b/doc/diffutils.texi
index 8479b3f..5bca8ee 100644
--- a/doc/diffutils.texi
+++ b/doc/diffutils.texi
@@ -3842,6 +3842,12 @@ comparison of @file{d} to @file{e} might compare the contents of
 might compare the contents of @file{d/Init} and @file{inIt}.
 @xref{Comparing Directories}.
 
address@hidden address@hidden
address@hidden include files
address@hidden searching directory trees
+When comparing directories, only compare files whose name matches @var{glob}.
address@hidden Directories}.
+
 @item -l
 @itemx --paginate
 Pass the output through @command{pr} to paginate it.  @xref{Pagination}.
diff --git a/src/diff.c b/src/diff.c
index df3338c..8252264 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -144,6 +144,7 @@ enum
   COLOR_PALETTE_OPTION,
 
   PRESUME_OUTPUT_TTY_OPTION,
+  INCLUDE_OPTION,
 };
 
 static char const group_format_option[][sizeof "--unchanged-group-format"] =
@@ -185,6 +186,7 @@ static struct option const longopts[] =
   {"ignore-space-change", 0, 0, 'b'},
   {"ignore-tab-expansion", 0, 0, 'E'},
   {"ignore-trailing-space", 0, 0, 'Z'},
+  {"include", 1, 0, INCLUDE_OPTION},
   {"inhibit-hunk-merge", 0, 0, INHIBIT_HUNK_MERGE_OPTION},
   {"initial-tab", 0, 0, 'T'},
   {"label", 1, 0, 'L'},
@@ -648,9 +650,14 @@ main (int argc, char **argv)
 	  set_color_palette (optarg);
 	  break;
 
-        case PRESUME_OUTPUT_TTY_OPTION:
-          presume_output_tty = true;
-          break;
+	case PRESUME_OUTPUT_TTY_OPTION:
+	  presume_output_tty = true;
+	  break;
+
+	case INCLUDE_OPTION:
+	  add_exclude (excluded, optarg, 0);
+	  add_exclude (excluded, optarg, EXCLUDE_WILDCARDS | EXCLUDE_INCLUDE | EXCLUDE_ANCHORED);
+	  break;
 
 	default:
 	  try_help (NULL, NULL);
@@ -919,6 +926,7 @@ static char const * const option_help_msgid[] = {
   N_("    --no-ignore-file-name-case  consider case when comparing file names"),
   N_("-x, --exclude=PAT               exclude files that match PAT"),
   N_("-X, --exclude-from=FILE         exclude files that match any pattern in FILE"),
+  N_("    --include=PAT               include files that match PAT"),
   N_("-S, --starting-file=FILE        start with FILE when comparing directories"),
   N_("    --from-file=FILE1           compare FILE1 to all operands;\n"
      "                                  FILE1 can be a directory"),
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 6668863..ef236c7 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -13,7 +13,8 @@ TESTS = \
   invalid-re	\
   function-line-vs-leading-space \
   ignore-matching-lines \
-  label-vs-func	\
+  include-exclude       \
+  label-vs-func         \
   new-file \
   no-dereference \
   no-newline-at-eof \
diff --git a/tests/include-exclude b/tests/include-exclude
new file mode 100755
index 0000000..260d552
--- /dev/null
+++ b/tests/include-exclude
@@ -0,0 +1,23 @@
+#!/bin/sh
+# Use of any --include or --exclude* option would segfault in 2.6 and 2.6.1
+. "${srcdir=.}/init.sh"; path_prepend_ ../src
+
+mkdir -p x1/dir x2/dir || framework_failure_
+echo aaa > x1/a     || framework_failure_
+echo bbb > x1/b     || framework_failure_
+echo ddd > x1/dir/d || framework_failure_
+echo aaa > x2/a     || framework_failure_
+echo bbb > x2/c     || framework_failure_
+echo ddd > x2/dir/d || framework_failure_
+
+printf '%s\n' "Only in x1: b" "Only in x2: c" > only-in-b-c   || framework_failure_
+
+diff -r --exclude='a*' x1 x2 > out
+sort -o out out || framework_failure_
+compare only-in-b-c out > /tmp/t
+
+diff -r --include='a*' x1 x2 > out
+sort -o out out || framework_failure_
+compare only-in-b-c out || fail=1
+
+Exit $fail
-- 
2.7.4