BLI_path: remove trailing NULL argument to BLI_path_join

Using varargs had the disadvantages, replace with a macro which has
some advantages.

- Arguments are type checked.
- Less verbose.
- Unintended NULL arguments would silently terminate joining paths.
- Passing in a NULL argument warns with GCC.

3 files changed, 108 insertions, 8 deletions

diff --git a/source/blender/blenlib/BLI_path_util.h b/source/blender/blenlib/BLI_path_util.h
index 1e45e76afe1..739b894eafe 100644
--- a/source/blender/blenlib/BLI_path_util.h
+++ b/source/blender/blenlib/BLI_path_util.h
@@ -7,7 +7,9 @@
  */
 
 #include "BLI_compiler_attrs.h"
+#include "BLI_compiler_compat.h"
 #include "BLI_utildefines.h"
+#include "BLI_utildefines_variadic.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -81,6 +83,14 @@ void BLI_join_dirfile(char *__restrict dst,
                       const char *__restrict dir,
                       const char *__restrict file) ATTR_NONNULL();
 /**
+ * See #BLI_path_join doc-string.
+ */
+size_t BLI_path_join_array(char *__restrict dst,
+                           const size_t dst_len,
+                           const char *path_array[],
+                           const int path_array_num);
+
+/**
  * Join multiple strings into a path, ensuring only a single path separator between each,
  * and trailing slash is kept.
  *
@@ -95,8 +105,94 @@ void BLI_join_dirfile(char *__restrict dst,
  * \note If you want a trailing slash, add `SEP_STR` as the last path argument,
  * duplicate slashes will be cleaned up.
  */
-size_t BLI_path_join(char *__restrict dst, size_t dst_len, const char *path, ...)
-    ATTR_NONNULL(1, 3) ATTR_SENTINEL(0);
+#define BLI_path_join(...) VA_NARGS_CALL_OVERLOAD(_BLI_path_join_, __VA_ARGS__)
+
+#define _BLI_PATH_JOIN_ARGS_1 char *__restrict dst, size_t dst_len, const char *a
+#define _BLI_PATH_JOIN_ARGS_2 _BLI_PATH_JOIN_ARGS_1, const char *b
+#define _BLI_PATH_JOIN_ARGS_3 _BLI_PATH_JOIN_ARGS_2, const char *c
+#define _BLI_PATH_JOIN_ARGS_4 _BLI_PATH_JOIN_ARGS_3, const char *d
+#define _BLI_PATH_JOIN_ARGS_5 _BLI_PATH_JOIN_ARGS_4, const char *e
+#define _BLI_PATH_JOIN_ARGS_6 _BLI_PATH_JOIN_ARGS_5, const char *f
+#define _BLI_PATH_JOIN_ARGS_7 _BLI_PATH_JOIN_ARGS_6, const char *g
+#define _BLI_PATH_JOIN_ARGS_8 _BLI_PATH_JOIN_ARGS_7, const char *h
+#define _BLI_PATH_JOIN_ARGS_9 _BLI_PATH_JOIN_ARGS_8, const char *i
+#define _BLI_PATH_JOIN_ARGS_10 _BLI_PATH_JOIN_ARGS_9, const char *j
+#define _BLI_PATH_JOIN_ARGS_11 _BLI_PATH_JOIN_ARGS_10, const char *k
+
+BLI_INLINE size_t _BLI_path_join_3(_BLI_PATH_JOIN_ARGS_1) ATTR_NONNULL();
+BLI_INLINE size_t _BLI_path_join_4(_BLI_PATH_JOIN_ARGS_2) ATTR_NONNULL();
+BLI_INLINE size_t _BLI_path_join_5(_BLI_PATH_JOIN_ARGS_3) ATTR_NONNULL();
+BLI_INLINE size_t _BLI_path_join_6(_BLI_PATH_JOIN_ARGS_4) ATTR_NONNULL();
+BLI_INLINE size_t _BLI_path_join_7(_BLI_PATH_JOIN_ARGS_5) ATTR_NONNULL();
+BLI_INLINE size_t _BLI_path_join_8(_BLI_PATH_JOIN_ARGS_6) ATTR_NONNULL();
+BLI_INLINE size_t _BLI_path_join_9(_BLI_PATH_JOIN_ARGS_7) ATTR_NONNULL();
+BLI_INLINE size_t _BLI_path_join_10(_BLI_PATH_JOIN_ARGS_8) ATTR_NONNULL();
+BLI_INLINE size_t _BLI_path_join_11(_BLI_PATH_JOIN_ARGS_9) ATTR_NONNULL();
+BLI_INLINE size_t _BLI_path_join_12(_BLI_PATH_JOIN_ARGS_10) ATTR_NONNULL();
+
+BLI_INLINE size_t _BLI_path_join_3(_BLI_PATH_JOIN_ARGS_1)
+{
+  const char *path_array[] = {a};
+  return BLI_path_join_array(dst, dst_len, path_array, ARRAY_SIZE(path_array));
+}
+BLI_INLINE size_t _BLI_path_join_4(_BLI_PATH_JOIN_ARGS_2)
+{
+  const char *path_array[] = {a, b};
+  return BLI_path_join_array(dst, dst_len, path_array, ARRAY_SIZE(path_array));
+}
+BLI_INLINE size_t _BLI_path_join_5(_BLI_PATH_JOIN_ARGS_3)
+{
+  const char *path_array[] = {a, b, c};
+  return BLI_path_join_array(dst, dst_len, path_array, ARRAY_SIZE(path_array));
+}
+BLI_INLINE size_t _BLI_path_join_6(_BLI_PATH_JOIN_ARGS_4)
+{
+  const char *path_array[] = {a, b, c, d};
+  return BLI_path_join_array(dst, dst_len, path_array, ARRAY_SIZE(path_array));
+}
+BLI_INLINE size_t _BLI_path_join_7(_BLI_PATH_JOIN_ARGS_5)
+{
+  const char *path_array[] = {a, b, c, d, e};
+  return BLI_path_join_array(dst, dst_len, path_array, ARRAY_SIZE(path_array));
+}
+BLI_INLINE size_t _BLI_path_join_8(_BLI_PATH_JOIN_ARGS_6)
+{
+  const char *path_array[] = {a, b, c, d, e, f};
+  return BLI_path_join_array(dst, dst_len, path_array, ARRAY_SIZE(path_array));
+}
+BLI_INLINE size_t _BLI_path_join_9(_BLI_PATH_JOIN_ARGS_7)
+{
+  const char *path_array[] = {a, b, c, d, e, f, g};
+  return BLI_path_join_array(dst, dst_len, path_array, ARRAY_SIZE(path_array));
+}
+BLI_INLINE size_t _BLI_path_join_10(_BLI_PATH_JOIN_ARGS_8)
+{
+  const char *path_array[] = {a, b, c, d, e, f, g, h};
+  return BLI_path_join_array(dst, dst_len, path_array, ARRAY_SIZE(path_array));
+}
+BLI_INLINE size_t _BLI_path_join_11(_BLI_PATH_JOIN_ARGS_9)
+{
+  const char *path_array[] = {a, b, c, d, e, f, g, h, i};
+  return BLI_path_join_array(dst, dst_len, path_array, ARRAY_SIZE(path_array));
+}
+BLI_INLINE size_t _BLI_path_join_12(_BLI_PATH_JOIN_ARGS_10)
+{
+  const char *path_array[] = {a, b, c, d, e, f, g, h, i, j};
+  return BLI_path_join_array(dst, dst_len, path_array, ARRAY_SIZE(path_array));
+}
+
+#undef _BLI_PATH_JOIN_ARGS_1
+#undef _BLI_PATH_JOIN_ARGS_2
+#undef _BLI_PATH_JOIN_ARGS_3
+#undef _BLI_PATH_JOIN_ARGS_4
+#undef _BLI_PATH_JOIN_ARGS_5
+#undef _BLI_PATH_JOIN_ARGS_6
+#undef _BLI_PATH_JOIN_ARGS_7
+#undef _BLI_PATH_JOIN_ARGS_8
+#undef _BLI_PATH_JOIN_ARGS_9
+#undef _BLI_PATH_JOIN_ARGS_10
+#undef _BLI_PATH_JOIN_ARGS_11
+
 /**
  * Like Python's `os.path.basename()`
  *
diff --git a/source/blender/blenlib/intern/path_util.c b/source/blender/blenlib/intern/path_util.c
index 6ff4d57aecb..0a6e39504df 100644
--- a/source/blender/blenlib/intern/path_util.c
+++ b/source/blender/blenlib/intern/path_util.c
@@ -1490,14 +1490,20 @@ void BLI_join_dirfile(char *__restrict dst,
   BLI_strncpy(dst + dirlen, file, maxlen - dirlen);
 }
 
-size_t BLI_path_join(char *__restrict dst, const size_t dst_len, const char *path, ...)
+size_t BLI_path_join_array(char *__restrict dst,
+                           const size_t dst_len,
+                           const char *path_array[],
+                           const int path_array_num)
 {
+  BLI_assert(path_array_num > 0);
 #ifdef DEBUG_STRSIZE
   memset(dst, 0xff, sizeof(*dst) * dst_len);
 #endif
   if (UNLIKELY(dst_len == 0)) {
     return 0;
   }
+  const char *path = path_array[0];
+
   const size_t dst_last = dst_len - 1;
   size_t ofs = BLI_strncpy_rlen(dst, path, dst_len);
 
@@ -1519,9 +1525,8 @@ size_t BLI_path_join(char *__restrict dst, const size_t dst_len, const char *pat
     has_trailing_slash = (path[len] != '\0');
   }
 
-  va_list args;
-  va_start(args, path);
-  while ((path = (const char *)va_arg(args, const char *))) {
+  for (int path_index = 1; path_index < path_array_num; path_index++) {
+    path = path_array[path_index];
     has_trailing_slash = false;
     const char *path_init = path;
     while (ELEM(path[0], SEP, ALTSEP)) {
@@ -1556,7 +1561,6 @@ size_t BLI_path_join(char *__restrict dst, const size_t dst_len, const char *pat
       has_trailing_slash = (path_init != path);
     }
   }
-  va_end(args);
 
   if (has_trailing_slash) {
     if ((ofs != dst_last) && (ofs != 0) && (ELEM(dst[ofs - 1], SEP, ALTSEP) == 0)) {
diff --git a/source/blender/blenlib/tests/BLI_path_util_test.cc b/source/blender/blenlib/tests/BLI_path_util_test.cc
index 2d415534693..89e537235db 100644
--- a/source/blender/blenlib/tests/BLI_path_util_test.cc
+++ b/source/blender/blenlib/tests/BLI_path_util_test.cc
@@ -207,7 +207,7 @@ TEST(path_util, NameAtIndex_NoneComplexNeg)
     char result[(out_size) + 1024]; \
     /* check we don't write past the last byte */ \
     result[out_size] = '\0'; \
-    BLI_path_join(result, out_size, __VA_ARGS__, NULL); \
+    BLI_path_join(result, out_size, __VA_ARGS__); \
     /* simplify expected string */ \
     BLI_str_replace_char(result, '\\', '/'); \
     EXPECT_STREQ(result, expect); \