patch_parse: fix segfault when header path contains whitespace only

When parsing header paths from a patch, we reject any patches with empty
paths as malformed patches. We perform the check whether a path is empty
before sanitizing it, though, which may lead to a path becoming empty
after the check, e.g. if we have trimmed whitespace. This may lead to a
segfault later when any part of our patching logic actually references
such a path, which may then be a `NULL` pointer.

Fix the issue by performing the check after sanitizing. Add tests to
catch the issue as they would have produced a segfault previosuly.

1 files changed, 12 insertions, 0 deletions

diff --git a/tests/patch/patch_common.h b/tests/patch/patch_common.h
index 153bab57f..4f2141dbe 100644
--- a/tests/patch/patch_common.h
+++ b/tests/patch/patch_common.h
@@ -912,6 +912,18 @@
 	"+++ \n" \
 	"Binary files "
 
+#define PATCH_BINARY_FILE_WITH_WHITESPACE_PATHS \
+	"diff --git a/file b/file\n" \
+	"---  \n" \
+	"+++  \n" \
+	"Binary files "
+
+#define PATCH_BINARY_FILE_WITH_QUOTED_EMPTY_PATHS \
+	"diff --git a/file b/file\n" \
+	"--- \"\"\n" \
+	"+++ \"\"\n" \
+	"Binary files "
+
 #define PATCH_MULTIPLE_OLD_PATHS \
 	"diff --git  \n" \
 	"---  \n" \