patch(1): add some basic tests

Summary:
- basic: test application of patches created by diff -u at the
  beginning/middle/end of file, which have differing amounts of context
  before and after chunks being added
- limited_ctx: stems from PR 74127 in which a rogue line was getting added
  when the patch should have been rejected. Similar behavior was
  reproducible with larger contexts near the beginning/end of a file. See
  r326084 for details
- file_creation: patch sourced from /dev/null should create the file
- file_nodupe: said patch sourced from /dev/null shouldn't dupe the contents
  when re-applied (personal vendetta, WIP, see comment)
- file_removal: this follows from nodupe; the reverse of a patch sourced
  from /dev/null is most naturally deleting the file, as is expected based
  on GNU patch behavior (WIP)

etc/mtree/BSD.tests.dist

@@ -1018,6 +1018,8 @@
         ..
         opensm
         ..
+        patch
+        ..
         pr
         ..
         printf

usr.bin/patch/Makefile

@@ -1,8 +1,13 @@
 #	$OpenBSD: Makefile,v 1.4 2005/05/16 15:22:46 espie Exp $
 # $FreeBSD$
 
+.include <src.opts.mk>
+
 PROG=	patch
 
 SRCS=	backupfile.c inp.c mkpath.c patch.c pch.c util.c
 
+HAS_TESTS=
+SUBDIR.${MK_TESTS}+= tests
+
 .include <bsd.prog.mk>

usr.bin/patch/tests/Makefile

@@ -0,0 +1,12 @@
+# $FreeBSD$
+
+PACKAGE=	tests
+
+ATF_TESTS_SH+=	unified_patch_test
+
+${PACKAGE}FILES+=		PR74127-cline.diff
+${PACKAGE}FILES+=		PR74127-good.diff
+${PACKAGE}FILES+=		PR74127-repro.diff
+${PACKAGE}FILES+=		PR74127.in
+
+.include <bsd.test.mk>

usr.bin/patch/tests/PR74127-cline.diff

@@ -0,0 +1,4 @@
+file.c
+@@ -3,1 +3,1 @@
+-       set Log(compressProg) /usr/local/bin/gzip
++       set Log(compressProg) /usr/bin/gzip

usr.bin/patch/tests/PR74127-good.diff

@@ -0,0 +1,4 @@
+file.c
+@@ -3,1 +3,1 @@
+-        set Log(compressProg) gzip
++        set Log(compressProg) /usr/local/bin/gzip

usr.bin/patch/tests/PR74127-repro.diff

@@ -0,0 +1,4 @@
+file.c
+@@ -5,1 +5,1 @@
+-       set Log(compressProg) /usr/local/bin/gzip
++       set Log(compressProg) /usr/bin/gzip

usr.bin/patch/tests/PR74127.in

@@ -0,0 +1,14 @@
+# This program is used to compress log files
+if {![info exists Log(compressProg)]} {
+        set Log(compressProg) gzip
+}
+
+# Flush interval
+if {![info exists Log(flushInterval)]} {
+        set Log(flushInterval) [expr {60 * 1000}]
+}
+
+# This is used to turn on an alternate debug log file
+if {![info exist Log(debug_log)]} {
+        set Log(debug_log) 0
+}

usr.bin/patch/tests/unified_patch_test.sh

@@ -0,0 +1,140 @@
+#
+# SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+#
+# Copyright (c) 2019 Kyle Evans <kevans@FreeBSD.org>
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+#
+# $FreeBSD$
+
+atf_test_case basic
+basic_body()
+{
+	printf "a\nb\nc\nd\ne\nf\ng\nh\ni\n" > foo_full
+	printf "a\nb\nc\n" > foo_start
+	printf "g\nh\ni\n" > foo_end
+	printf "d\ne\nf\n" > foo_middle
+
+	diff -u foo_start foo_full > foo_start2full.diff
+	diff -u foo_end foo_full > foo_end2full.diff
+	diff -u foo_middle foo_full > foo_mid2full.diff
+
+	# Check lengths... each should have all 9 lines + 3 line header
+	atf_check -o inline:"12" -x \
+	    "cat foo_start2full.diff | wc -l | tr -d '[:space:]'"
+	atf_check -o inline:"12" -x \
+	    "cat foo_end2full.diff | wc -l | tr -d '[:space:]'"
+	atf_check -o inline:"12" -x \
+	    "cat foo_mid2full.diff | wc -l | tr -d '[:space:]'"
+
+	# Apply the patch! Should succeed
+	atf_check -o ignore patch foo_start foo_start2full.diff \
+	    -o foo_start2full
+	atf_check -o ignore patch foo_end foo_end2full.diff \
+	    -o foo_end2full
+	atf_check -o ignore patch foo_middle foo_mid2full.diff \
+	    -o foo_mid2full
+
+	# And these should all produce equivalent to the original full
+	atf_check -o ignore diff foo_start2full foo_full
+	atf_check -o ignore diff foo_end2full foo_full
+	atf_check -o ignore diff foo_mid2full foo_full
+}
+
+atf_test_case limited_ctx
+limited_ctx_head()
+{
+	atf_set "descr" "Verify correct behavior with limited context (PR 74127)"
+}
+limited_ctx_body()
+{
+
+	# First; PR74127-repro.diff should not have applied, but it instead
+	# assumed a match and added the modified line at the offset specified...
+	atf_check -s not-exit:0 -o ignore -e ignore patch -o _.out \
+	    "$(atf_get_srcdir)/PR74127.in" \
+	    "$(atf_get_srcdir)/PR74127-repro.diff"
+
+	# Let's extend that and make sure a similarly ill-contexted diff does
+	# not apply even with the correct line number
+	atf_check -s not-exit:0 -o ignore -e ignore patch -o _.out \
+	    "$(atf_get_srcdir)/PR74127.in" \
+	    "$(atf_get_srcdir)/PR74127-line.diff"
+
+	# Correct line number and correct old line should always work
+	atf_check -o ignore -e ignore patch -o _.out \
+	    "$(atf_get_srcdir)/PR74127.in" \
+	    "$(atf_get_srcdir)/PR74127-good.diff"
+}
+
+atf_test_case file_creation
+file_creation_body()
+{
+
+	echo "x" > foo
+	diff -u /dev/null foo > foo.diff
+	rm foo
+
+	atf_check -x "patch -s < foo.diff"
+	atf_check -o ignore stat foo
+}
+
+# This test is motivated by long-standing bugs that occasionally slip by in
+# commits.  If a file is created by a diff, patch(1) will happily duplicate the
+# contents as many times as you apply the diff.  It should instead detect that
+# a source of /dev/null creates the file, so it shouldn't exist.  Furthermore,
+# the reverse of creation is deletion -- hence the next test.
+atf_test_case file_nodupe
+file_nodupe_body()
+{
+
+	# WIP
+	atf_expect_fail "patch(1) erroneously duplicates created files"
+	echo "x" > foo
+	diff -u /dev/null foo > foo.diff
+
+	atf_check -x "patch -s < foo.diff"
+	atf_check -s not-exit:0 -x "patch -fs < foo.diff"
+}
+
+atf_test_case file_removal
+file_removal_body()
+{
+
+	# WIP
+	atf_expect_fail "patch(1) does not yet recognize /dev/null as creation"
+
+	echo "x" > foo
+	diff -u /dev/null foo > foo.diff
+
+	atf_check -x "patch -Rs < foo.diff"
+	atf_check -s not-exit:0 -o ignore stat foo
+}
+
+atf_init_test_cases()
+{
+	atf_add_test_case basic
+	atf_add_test_case limited_ctx
+	atf_add_test_case file_creation
+	atf_add_test_case file_nodupe
+	atf_add_test_case file_removal
+}