util: Add qsort_r/s args adapter for MSVC and BSD/macOS

MSVC's qsort_s behaves similarly to sort_r. Unfortunately, qsort_s's
compare function has the "context"/"args" as its first argument. BSD's
qsort_r has a different order than GNU's qsort_r. Finally, C11 added
qsort_s's which look like GNU's gsort_r.

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10989>

meson.build

@@ -1310,7 +1310,7 @@ foreach h : ['xlocale.h', 'linux/futex.h', 'endian.h', 'dlfcn.h', 'execinfo.h',
 endforeach
 
 foreach f : ['strtof', 'mkostemp', 'timespec_get', 'memfd_create', 'random_r',
-             'flock', 'strtok_r', 'getrandom', 'qsort_r']
+             'flock', 'strtok_r', 'getrandom', 'qsort_r', 'qsort_s']
   if cc.has_function(f)
     pre_args += '-DHAVE_@0@'.format(f.to_upper())
   endif

src/util/u_qsort.cpp

@@ -42,3 +42,11 @@ util_tls_qsort_r(void *base, size_t nmemb, size_t size,
    tl_qsort_r_arg = arg;
    return qsort(base, nmemb, size, qsort_r_compar);
 }
+
+int
+util_qsort_adapter(void *ctx, const void *elem1, const void *elem2)
+{
+   util_qsort_adapter_data *data = 
+      reinterpret_cast<util_qsort_adapter_data*>(ctx);
+   return data->compar(elem1, elem2, data->args);
+}

src/util/u_qsort.h

@@ -36,14 +36,56 @@ void util_tls_qsort_r(void *base, size_t nmemb, size_t size,
                       int (*compar)(const void *, const void *, void *),
                       void *arg);
 
+
+struct util_qsort_adapter_data {
+   int (*compar)(const void*, const void*, void*);
+   void *args;
+};
+
+/**
+ * Converts comparison function arguments
+ * from [MSVC, BSD, macOS]
+ * (void *ctx, const void *elem1, const void *elem2)
+ * to [GNU, C11]
+ * (const void *elem1, const void *elem2, void *ctx);
+ */
+int util_qsort_adapter(void *ctx, const void *elem1, const void *elem2);
+
 static inline void
 util_qsort_r(void *base, size_t nmemb, size_t size,
              int (*compar)(const void *, const void *, void *),
              void *arg)
 {
-#if HAVE_QSORT_R && !(DETECT_OS_APPLE || DETECT_OS_BSD)
+#if HAVE_QSORT_R
+#  if DETECT_OS_APPLE || DETECT_OS_BSD
+   /* BSD/macOS qsort_r takes "arg" before the comparison function and it
+    * pass the "arg" before the elements.
+    */
+   struct util_qsort_adapter_data data = {
+      compar,
+      arg
+   };
+   qsort_r(base, nmemb, size, &data, util_qsort_adapter);
+#  else
+   /* GNU extension added in glibc 2.8 */
    qsort_r(base, nmemb, size, compar, arg);
+#  endif
+#elif HAVE_QSORT_S
+#  ifdef _WIN32
+   /* MSVC/MinGW qsort_s takes "arg" after the comparison function and it
+    * pass the "arg" before the elements.
+    */
+   struct util_qsort_adapter_data data = {
+      compar,
+      arg
+   };
+   qsort_s(base, nmemb, size, util_qsort_adapter, &data);
+#  else
+   /* C11 added qsort_s */
+   qsort_s(base, nmemb, size, compar, arg);
+#  endif
 #else
+   /* Fall-back to using thread local storage */
    util_tls_qsort_r(base, nmemb, size, compar, arg);
 #endif
 }