diff: fix generation of the header of a removal patch

3 files changed, 18 insertions, 8 deletions

diff --git a/src/diff.c b/src/diff.c
index 7d2ad59aa..b239031a2 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -232,9 +232,6 @@ static int diff_delta__from_two(
 	return 0;
 }
 
-#define DIFF_SRC_PREFIX_DEFAULT "a/"
-#define DIFF_DST_PREFIX_DEFAULT "b/"
-
 static char *diff_strdup_prefix(git_pool *pool, const char *prefix)
 {
 	size_t len = strlen(prefix);
diff --git a/src/diff.h b/src/diff.h
index 4de18beea..6c432c894 100644
--- a/src/diff.h
+++ b/src/diff.h
@@ -14,6 +14,9 @@
 #include "repository.h"
 #include "pool.h"
 
+#define DIFF_SRC_PREFIX_DEFAULT "a/"
+#define DIFF_DST_PREFIX_DEFAULT "b/"
+
 enum {
 	GIT_DIFFCAPS_HAS_SYMLINKS     = (1 << 0), /* symlinks on platform? */
 	GIT_DIFFCAPS_ASSUME_UNCHANGED = (1 << 1), /* use stat? */
diff --git a/src/diff_output.c b/src/diff_output.c
index f4c214314..7c5b6f276 100644
--- a/src/diff_output.c
+++ b/src/diff_output.c
@@ -553,9 +553,16 @@ static int print_patch_file(void *data, git_diff_delta *delta, float progress)
 	const char *oldpath = delta->old.path;
 	const char *newpfx = pi->diff->opts.dst_prefix;
 	const char *newpath = delta->new.path;
+	int result;
 
 	GIT_UNUSED(progress);
 
+	if (!oldpfx)
+		oldpfx = DIFF_SRC_PREFIX_DEFAULT;
+
+	if (!newpfx)
+		newpfx = DIFF_DST_PREFIX_DEFAULT;
+
 	git_buf_clear(pi->buf);
 	git_buf_printf(pi->buf, "diff --git %s%s %s%s\n", oldpfx, delta->old.path, newpfx, delta->new.path);
 
@@ -567,8 +574,8 @@ static int print_patch_file(void *data, git_diff_delta *delta, float progress)
 		oldpath = "/dev/null";
 	}
 	if (git_oid_iszero(&delta->new.oid)) {
-		oldpfx = "";
-		oldpath = "/dev/null";
+		newpfx = "";
+		newpath = "/dev/null";
 	}
 
 	if (delta->binary != 1) {
@@ -579,9 +586,12 @@ static int print_patch_file(void *data, git_diff_delta *delta, float progress)
 	if (git_buf_oom(pi->buf))
 		return -1;
 
-	if (pi->print_cb(pi->cb_data, GIT_DIFF_LINE_FILE_HDR, pi->buf->ptr) < 0 ||
-		delta->binary != 1)
-		return -1;
+    result = pi->print_cb(pi->cb_data, GIT_DIFF_LINE_FILE_HDR, pi->buf->ptr);
+    if (result < 0)
+        return result;
+
+    if (delta->binary != 1)
+        return 0;
 
 	git_buf_clear(pi->buf);
 	git_buf_printf(