Remove dependency on user32

1 files changed, 38 insertions, 1 deletions

diff --git a/libarchive/filter_fork_windows.c b/libarchive/filter_fork_windows.c
index 8d11179f..0b963975 100644
--- a/libarchive/filter_fork_windows.c
+++ b/libarchive/filter_fork_windows.c
@@ -31,6 +31,43 @@
 
 #include "filter_fork.h"
 
+/* There are some editions of Windows ("nano server," for example) that
+ * do not host user32.dll. If we want to keep running on those editions,
+ * we need to delay-load WaitForInputIdle. */
+static void *
+la_GetFunctionUser32(const char *name)
+{
+	static HINSTANCE lib;
+	static int set;
+	if (!set) {
+		set = 1;
+		lib = LoadLibrary(TEXT("user32.dll"));
+	}
+	if (lib == NULL) {
+		return NULL;
+	}
+	return (void *)GetProcAddress(lib, name);
+}
+
+static int
+la_WaitForInputIdle(HANDLE hProcess, DWORD dwMilliseconds)
+{
+	static DWORD (WINAPI *f)(HANDLE, DWORD);
+	static int set;
+
+	if (!set) {
+		set = 1;
+		f = la_GetFunctionUser32("WaitForInputIdle");
+	}
+
+	if (!f) {
+		/* An inability to wait for input idle is
+		 * not _good_, but it is not catastrophic. */
+		return WAIT_FAILED;
+	}
+	return (*f)(hProcess, dwMilliseconds);
+}
+
 int
 __archive_create_child(const char *cmd, int *child_stdin, int *child_stdout,
 		HANDLE *out_child)
@@ -149,7 +186,7 @@ __archive_create_child(const char *cmd, int *child_stdin, int *child_stdout,
 	if (CreateProcessA(fullpath.s, cmdline.s, NULL, NULL, TRUE, 0,
 	      NULL, NULL, &staInfo, &childInfo) == 0)
 		goto fail;
-	WaitForInputIdle(childInfo.hProcess, INFINITE);
+	la_WaitForInputIdle(childInfo.hProcess, INFINITE);
 	CloseHandle(childInfo.hProcess);
 	CloseHandle(childInfo.hThread);