Fix segfault in output_file_later()

Bug reported by Dmitry V. Levin <ldv@altlinux.org>.
* src/patch.c (output_file_later): Fix case where the output file is identical
with the input file (and to == NULL).

2 files changed, 22 insertions, 1 deletions

diff --git a/src/patch.c b/src/patch.c
index 40987c1..e0e4f38 100644
--- a/src/patch.c
+++ b/src/patch.c
@@ -1730,7 +1730,7 @@ output_file_later (char const *from, int *from_needs_removal, const struct stat
   file_to_output = xmalloc (sizeof *file_to_output);
   file_to_output->from = xstrdup (from);
   file_to_output->from_st = *from_st;
-  file_to_output->to = xstrdup (to);
+  file_to_output->to = to ? xstrdup (to) : NULL;
   file_to_output->mode = mode;
   file_to_output->backup = backup;
   gl_list_add_last (files_to_output, file_to_output);
diff --git a/tests/create-delete b/tests/create-delete
index c9d9ff9..9a6e1bb 100644
--- a/tests/create-delete
+++ b/tests/create-delete
@@ -168,3 +168,24 @@ EOF
 check 'cat f' <<EOF
 f
 EOF
+#
+# ----------------------------------------------------------------
+
+# This test deletes the target file.
+
+echo data > target
+cat > p.diff <<EOF
+diff --git a/target b/target
+index 1..0
+EOF
+
+check 'patch -p1 -b < p.diff || echo status: $?' <<EOF
+patching file target
+File target is not empty after patch, as expected
+EOF
+
+ncheck 'test ! -e target'
+
+check 'cat target.orig' <<EOF
+data
+EOF