Fix: BLI_getenv returns ascii not UTF8 on windows

BLI_getenv has always incorrectly returned ascii rather
than UTF-8. This change corrects this behaviour.

This resolves issues when the `BLENDER_USER_CONFIG`
environment variable contains a path with Unicode characters
on windows as reported in T74510 (but unlikely the root
cause for the issue at hand there)

Differential Revision: https://developer.blender.org/D9831

Reviewed by: brecht

1 files changed, 20 insertions, 7 deletions

diff --git a/source/blender/blenlib/intern/path_util.c b/source/blender/blenlib/intern/path_util.c
index 74bbe59bc04..461f8a53beb 100644
--- a/source/blender/blenlib/intern/path_util.c
+++ b/source/blender/blenlib/intern/path_util.c
@@ -32,6 +32,7 @@
 #include "BLI_fnmatch.h"
 #include "BLI_path_util.h"
 #include "BLI_string.h"
+#include "BLI_string_utf8.h"
 #include "BLI_utildefines.h"
 
 #ifdef WIN32
@@ -1307,18 +1308,30 @@ void BLI_setenv_if_new(const char *env, const char *val)
  * On windows getenv gets its variables from a static copy of the environment variables taken at
  * process start-up, causing it to not pick up on environment variables created during runtime.
  * This function uses an alternative method to get environment variables that does pick up on
- * runtime environment variables.
+ * runtime environment variables. The result will be UTF-8 encoded.
  */
+
 const char *BLI_getenv(const char *env)
 {
 #ifdef _MSC_VER
-  static char buffer[32767]; /* 32767 is the total size of the environment block on windows*/
-  if (GetEnvironmentVariableA(env, buffer, sizeof(buffer))) {
-    return buffer;
-  }
-  else {
-    return NULL;
+  const char *result = NULL;
+  static wchar_t buffer[32768]; /* 32767 is the maximum size of the environment variable on
+                                   windows, reserve one more character for the zero terminator. */
+  wchar_t *env_16 = alloc_utf16_from_8(env, 0);
+  if (env_16) {
+    if (GetEnvironmentVariableW(env_16, buffer, ARRAY_SIZE(buffer))) {
+      char *res_utf8 = alloc_utf_8_from_16(buffer, 0);
+      // make sure the result is valid, and will fit into our temporary storage buffer
+      if (res_utf8 && (strlen(res_utf8) + 1) < sizeof(buffer)) {
+        // We are re-using the utf16 buffer here, since allocating a second static buffer to
+        // contain the UTF-8 version to return would be wasteful.
+        memcpy(buffer, res_utf8, strlen(res_utf8) + 1);
+        free(res_utf8);
+        result = (const char *)buffer;
+      }
+    }
   }
+  return result;
 #else
   return getenv(env);
 #endif