win32: workaround for lazy loading issue on Windows 7

Investigating why free(1) wasn't working on Windows 7 I found it's
possible for LoadLibraryEx to fail with exactly the flags we're
using.  Work around this.

This probably also explains GitHub issue #204.

1 files changed, 14 insertions, 0 deletions

diff --git a/win32/mingw.c b/win32/mingw.c
index b01198bd2..6e1dc6a9a 100644
--- a/win32/mingw.c
+++ b/win32/mingw.c
@@ -1878,6 +1878,20 @@ void *get_proc_addr(const char *dll, const char *function,
         /* only do this once */
         if (!proc->initialized) {
                 HANDLE hnd = LoadLibraryExA(dll, NULL, LOAD_LIBRARY_SEARCH_SYSTEM32);
+
+                /* The documentation for LoadLibraryEx says the above may fail
+                 * on Windows 7.  If it does, retry using LoadLibrary with an
+                 * explicit, backslash-separated path. */
+                if (!hnd) {
+                        char dir[PATH_MAX], *path;
+
+                        GetSystemDirectory(dir, PATH_MAX);
+                        path = concat_path_file(dir, dll);
+                        slash_to_bs(path);
+                        hnd = LoadLibrary(path);
+                        free(path);
+                }
+
                 if (hnd)
                         proc->pfunction = GetProcAddress(hnd, function);
                 proc->initialized = 1;