The branch main has been updated by kevans:
URL:
https://cgit.FreeBSD.org/src/commit/?id=f97b6a8f84b3ed209c2aea0958a7b889d0bf27ed
commit f97b6a8f84b3ed209c2aea0958a7b889d0bf27ed
Author: Kyle Evans <kev...@freebsd.org>
AuthorDate: 2025-08-29 19:24:35 +0000
Commit: Kyle Evans <kev...@freebsd.org>
CommitDate: 2025-08-29 19:24:35 +0000
patch: fix pch_context() for unified diffs with no leading context
When the first line of a file is a removal, we may not have any leading
context. Only adjusting p_context if context > 0 means that we
incorrectly believe that we have 100 lines of context when the reality
is that we have none.
This fixes a bug with fuzz-checking, which ends up fuzzing away the line
we're trying to replace if it's the first line in the file. We use
pch_context() to determine a reasonable max-fuzz.
PR: 250511
Reviewed by: pfg
Differential Revision: https://reviews.freebsd.org/D51837
---
usr.bin/patch/pch.c | 2 +-
usr.bin/patch/tests/unified_patch_test.sh | 21 +++++++++++++++++++++
2 files changed, 22 insertions(+), 1 deletion(-)
diff --git a/usr.bin/patch/pch.c b/usr.bin/patch/pch.c
index 71f73125a8cb..9bc4599026ae 100644
--- a/usr.bin/patch/pch.c
+++ b/usr.bin/patch/pch.c
@@ -1054,7 +1054,7 @@ hunk_done:
p_end = fillnew;
malformed();
}
- if (ch != ' ' && context > 0) {
+ if (ch != ' ' && context >= 0) {
if (context < p_context)
p_context = context;
context = -1000;
diff --git a/usr.bin/patch/tests/unified_patch_test.sh
b/usr.bin/patch/tests/unified_patch_test.sh
index 7d4b74182c41..47c4dc5faf73 100755
--- a/usr.bin/patch/tests/unified_patch_test.sh
+++ b/usr.bin/patch/tests/unified_patch_test.sh
@@ -25,6 +25,26 @@
# SUCH DAMAGE.
#
+atf_test_case badfuzz
+badfuzz_head()
+{
+ atf_set "descr" "Test for patch(1) erroneously fuzzing away action
lines"
+}
+badfuzz_body()
+{
+ # PR 250511 demonstrates a scenario where patch(1) will happily apply a
+ # patch into the wrong location if we have some lines that are still
+ # similar in the trailing context. In the following example, it would
+ # actually replace the underscore before the second series of B\nC\nO
+ # with "Z", when the patch should have been rejected instead.
+ printf "A\nB\nC\nO\n_\nB\nC\nO\n" > file.orig
+ printf "Z\nB\nC\nO\n_\nB\nC\nO\n" > file
+ printf "OK\nDIFF1\nDIFF2\n\n_\nB\nC\nO\n" > file.newer
+
+ atf_check -s not-exit:0 -o save:file.patch diff -u3 file.orig file
+ atf_check -s not-exit:0 -o not-empty patch file.newer file.patch
+}
+
atf_test_case basic
basic_body()
{
@@ -161,6 +181,7 @@ EOF
atf_init_test_cases()
{
+ atf_add_test_case badfuzz
atf_add_test_case basic
atf_add_test_case limited_ctx
atf_add_test_case file_creation
