From 8f7ab1bf46d5e8610b167180b7631ff62e718a08 Mon Sep 17 00:00:00 2001
From: Campbell Barton <campbell@blender.org>
Date: Mon, 31 Oct 2022 13:04:30 +1100
Subject: BLI_path: only operate on native path slashes for BLI_path_join

Previously both slashes were considered when joining paths, meaning
slashes that were part of the path name could be stripped before joining
the path.

Prefer using the native path separator for low level path functions,
callers can always convert slashes into the expected direction if they
need. This also matches BLI_path_append behavior.
---
 source/blender/blenlib/intern/path_util.c          | 11 ++---
 source/blender/blenlib/tests/BLI_path_util_test.cc | 47 +++++++++++++++++++---
 2 files changed, 47 insertions(+), 11 deletions(-)

diff --git a/source/blender/blenlib/intern/path_util.c b/source/blender/blenlib/intern/path_util.c
index bb87a26dada..4e3d9be6186 100644
--- a/source/blender/blenlib/intern/path_util.c
+++ b/source/blender/blenlib/intern/path_util.c
@@ -1487,9 +1487,10 @@ size_t BLI_path_join_array(char *__restrict dst,
   bool has_trailing_slash = false;
   if (ofs != 0) {
     size_t len = ofs;
-    while ((len != 0) && ELEM(path[len - 1], SEP, ALTSEP)) {
+    while ((len != 0) && (path[len - 1] == SEP)) {
       len -= 1;
     }
+
     if (len != 0) {
       ofs = len;
     }
@@ -1500,18 +1501,18 @@ size_t BLI_path_join_array(char *__restrict dst,
     path = path_array[path_index];
     has_trailing_slash = false;
     const char *path_init = path;
-    while (ELEM(path[0], SEP, ALTSEP)) {
+    while (path[0] == SEP) {
       path++;
     }
     size_t len = strlen(path);
     if (len != 0) {
-      while ((len != 0) && ELEM(path[len - 1], SEP, ALTSEP)) {
+      while ((len != 0) && (path[len - 1] == SEP)) {
         len -= 1;
       }
 
       if (len != 0) {
         /* the very first path may have a slash at the end */
-        if (ofs && !ELEM(dst[ofs - 1], SEP, ALTSEP)) {
+        if (ofs && (dst[ofs - 1] != SEP)) {
           dst[ofs++] = SEP;
           if (ofs == dst_last) {
             break;
@@ -1534,7 +1535,7 @@ size_t BLI_path_join_array(char *__restrict dst,
   }
 
   if (has_trailing_slash) {
-    if ((ofs != dst_last) && (ofs != 0) && (ELEM(dst[ofs - 1], SEP, ALTSEP) == 0)) {
+    if ((ofs != dst_last) && (ofs != 0) && (dst[ofs - 1] != SEP)) {
       dst[ofs++] = SEP;
     }
   }
diff --git a/source/blender/blenlib/tests/BLI_path_util_test.cc b/source/blender/blenlib/tests/BLI_path_util_test.cc
index 89e537235db..1120e85c959 100644
--- a/source/blender/blenlib/tests/BLI_path_util_test.cc
+++ b/source/blender/blenlib/tests/BLI_path_util_test.cc
@@ -201,20 +201,53 @@ TEST(path_util, NameAtIndex_NoneComplexNeg)
 
 #undef AT_INDEX
 
-#define JOIN(str_expect, out_size, ...) \
+/* For systems with `/` path separator (non WIN32). */
+#define JOIN_FORWARD_SLASH(str_expect, out_size, ...) \
   { \
     const char *expect = str_expect; \
     char result[(out_size) + 1024]; \
-    /* check we don't write past the last byte */ \
+    /* Check we don't write past the last byte. */ \
     result[out_size] = '\0'; \
     BLI_path_join(result, out_size, __VA_ARGS__); \
-    /* simplify expected string */ \
+    EXPECT_STREQ(result, expect); \
+    EXPECT_EQ(result[out_size], '\0'); \
+  } \
+  ((void)0)
+
+/* For systems with `\` path separator (WIN32).
+ * Perform additional manipulation to behave as if input arguments used `\` separators.
+ * Needed since #BLI_path_join uses native slashes. */
+#define JOIN_BACK_SLASH(str_expect, out_size, ...) \
+  { \
+    const char *expect = str_expect; \
+    char result[(out_size) + 1024]; \
+    const char *input_forward_slash[] = {__VA_ARGS__}; \
+    char *input_back_slash[ARRAY_SIZE(input_forward_slash)] = {nullptr}; \
+    for (int i = 0; i < ARRAY_SIZE(input_forward_slash); i++) { \
+      input_back_slash[i] = strdup(input_forward_slash[i]); \
+      BLI_str_replace_char(input_back_slash[i], '/', '\\'); \
+    } \
+    /* Check we don't write past the last byte. */ \
+    result[out_size] = '\0'; \
+    BLI_path_join_array(result, \
+                        out_size, \
+                        const_cast<const char **>(input_back_slash), \
+                        ARRAY_SIZE(input_back_slash)); \
     BLI_str_replace_char(result, '\\', '/'); \
     EXPECT_STREQ(result, expect); \
     EXPECT_EQ(result[out_size], '\0'); \
+    for (int i = 0; i < ARRAY_SIZE(input_forward_slash); i++) { \
+      free(input_back_slash[i]); \
+    } \
   } \
   ((void)0)
 
+#ifdef WIN32
+#  define JOIN JOIN_BACK_SLASH
+#else
+#  define JOIN JOIN_FORWARD_SLASH
+#endif
+
 /* BLI_path_join */
 TEST(path_util, JoinNop)
 {
@@ -293,9 +326,9 @@ TEST(path_util, JoinTruncateLong)
 
 TEST(path_util, JoinComplex)
 {
-  JOIN("/a/b/c/d/e/f/g/", 100, "/", "\\a/b", "//////c/d", "", "e\\\\", "f", "g//");
-  JOIN("/aa/bb/cc/dd/ee/ff/gg/", 100, "/", "\\aa/bb", "//////cc/dd", "", "ee\\\\", "ff", "gg//");
-  JOIN("1/2/3/", 100, "1", "////////", "", "2", "3\\");
+  JOIN("/a/b/c/d/e/f/g/", 100, "/", "a/b", "//////c/d", "", "e", "f", "g//");
+  JOIN("/aa/bb/cc/dd/ee/ff/gg/", 100, "/", "aa/bb", "//////cc/dd", "", "ee", "ff", "gg//");
+  JOIN("1/2/3/", 100, "1", "////////", "", "2", "3///");
 }
 
 TEST(path_util, JoinRelativePrefix)
@@ -306,6 +339,8 @@ TEST(path_util, JoinRelativePrefix)
 }
 
 #undef JOIN
+#undef JOIN_BACK_SLASH
+#undef JOIN_FORWARD_SLASH
 
 /* BLI_path_frame */
 TEST(path_util, Frame)
-- 
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