Remove configure probe for dlopen, and refactor.

dlopen() is in SUSv2 and all targeted Unix systems have it.  We still
need replacement functions for Windows, but we don't need a configure
probe for that.

Since it's no longer needed by other operating systems, rename dlopen.c
to win32dlopen.c and move the declarations into win32_port.h.

Likewise, the macros RTLD_NOW and RTLD_GLOBAL now only need to be
defined on Windows, since all targeted Unix systems have 'em.

Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/CA+hUKGJ3LHeP9w5Fgzdr4G8AnEtJ=z=p6hGDEm4qYGEUX5B6fQ@mail.gmail.com

1 files changed, 93 insertions, 0 deletions

diff --git a/src/port/win32dlopen.c b/src/port/win32dlopen.c
new file mode 100644
index 00000000000..2657537c294
--- /dev/null
+++ b/src/port/win32dlopen.c
@@ -0,0 +1,93 @@
+/*-------------------------------------------------------------------------
+ *
+ * win32dlopen.c
+ *	  dynamic loader for Windows
+ *
+ * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/port/win32dlopen.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "c.h"
+
+static char last_dyn_error[512];
+
+static void
+set_dl_error(void)
+{
+	DWORD		err = GetLastError();
+
+	if (FormatMessage(FORMAT_MESSAGE_IGNORE_INSERTS |
+					  FORMAT_MESSAGE_FROM_SYSTEM,
+					  NULL,
+					  err,
+					  MAKELANGID(LANG_ENGLISH, SUBLANG_DEFAULT),
+					  last_dyn_error,
+					  sizeof(last_dyn_error) - 1,
+					  NULL) == 0)
+	{
+		snprintf(last_dyn_error, sizeof(last_dyn_error) - 1,
+				 "unknown error %lu", err);
+	}
+}
+
+char *
+dlerror(void)
+{
+	if (last_dyn_error[0])
+		return last_dyn_error;
+	else
+		return NULL;
+}
+
+int
+dlclose(void *handle)
+{
+	if (!FreeLibrary((HMODULE) handle))
+	{
+		set_dl_error();
+		return 1;
+	}
+	last_dyn_error[0] = 0;
+	return 0;
+}
+
+void *
+dlsym(void *handle, const char *symbol)
+{
+	void	   *ptr;
+
+	ptr = GetProcAddress((HMODULE) handle, symbol);
+	if (!ptr)
+	{
+		set_dl_error();
+		return NULL;
+	}
+	last_dyn_error[0] = 0;
+	return ptr;
+}
+
+void *
+dlopen(const char *file, int mode)
+{
+	HMODULE		h;
+	int			prevmode;
+
+	/* Disable popup error messages when loading DLLs */
+	prevmode = SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOOPENFILEERRORBOX);
+	h = LoadLibrary(file);
+	SetErrorMode(prevmode);
+
+	if (!h)
+	{
+		set_dl_error();
+		return NULL;
+	}
+	last_dyn_error[0] = 0;
+	return (void *) h;
+}