1 files changed, 125 insertions, 0 deletions
diff --git a/src/port/win32env.c b/src/port/win32env.c
new file mode 100644
index 0000000..2021f3d
--- /dev/null
+++ b/src/port/win32env.c
@@ -0,0 +1,125 @@
+/*-------------------------------------------------------------------------
+ *
+ * win32env.c
+ *	  putenv() and unsetenv() for win32, which update both process environment
+ *	  and caches in (potentially multiple) C run-time library (CRT) versions.
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/port/win32env.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "c.h"
+
+int
+pgwin32_putenv(const char *envval)
+{
+	char	   *envcpy;
+	char	   *cp;
+	typedef int (_cdecl * PUTENVPROC) (const char *);
+	static const char *const modulenames[] = {
+		"msvcrt",				/* Visual Studio 6.0 / MinGW */
+		"msvcrtd",
+		"msvcr70",				/* Visual Studio 2002 */
+		"msvcr70d",
+		"msvcr71",				/* Visual Studio 2003 */
+		"msvcr71d",
+		"msvcr80",				/* Visual Studio 2005 */
+		"msvcr80d",
+		"msvcr90",				/* Visual Studio 2008 */
+		"msvcr90d",
+		"msvcr100",				/* Visual Studio 2010 */
+		"msvcr100d",
+		"msvcr110",				/* Visual Studio 2012 */
+		"msvcr110d",
+		"msvcr120",				/* Visual Studio 2013 */
+		"msvcr120d",
+		"ucrtbase",				/* Visual Studio 2015 and later */
+		"ucrtbased",
+		NULL
+	};
+	int			i;
+
+	/*
+	 * Update process environment, making this change visible to child
+	 * processes and to CRTs initializing in the future.  Do this before the
+	 * _putenv() loop, for the benefit of any CRT that initializes during this
+	 * pgwin32_putenv() execution, after the loop checks that CRT.
+	 *
+	 * Need a copy of the string so we can modify it.
+	 */
+	envcpy = strdup(envval);
+	if (!envcpy)
+		return -1;
+	cp = strchr(envcpy, '=');
+	if (cp == NULL)
+	{
+		free(envcpy);
+		return -1;
+	}
+	*cp = '\0';
+	cp++;
+	if (strlen(cp))
+	{
+		/*
+		 * Only call SetEnvironmentVariable() when we are adding a variable,
+		 * not when removing it. Calling it on both crashes on at least
+		 * certain versions of MinGW.
+		 */
+		if (!SetEnvironmentVariable(envcpy, cp))
+		{
+			free(envcpy);
+			return -1;
+		}
+	}
+	free(envcpy);
+
+	/*
+	 * Each CRT has its own _putenv() symbol and copy of the environment.
+	 * Update the environment in each CRT module currently loaded, so every
+	 * third-party library sees this change regardless of the CRT it links
+	 * against.  Addresses within these modules may become invalid the moment
+	 * we call FreeLibrary(), so don't cache them.
+	 */
+	for (i = 0; modulenames[i]; i++)
+	{
+		HMODULE		hmodule = NULL;
+		BOOL		res = GetModuleHandleEx(0, modulenames[i], &hmodule);
+
+		if (res != 0 && hmodule != NULL)
+		{
+			PUTENVPROC	putenvFunc;
+
+			putenvFunc = (PUTENVPROC) GetProcAddress(hmodule, "_putenv");
+			if (putenvFunc)
+				putenvFunc(envval);
+			FreeLibrary(hmodule);
+		}
+	}
+
+	/*
+	 * Finally, update our "own" cache.  This is redundant with the loop
+	 * above, except when PostgreSQL itself links to a CRT not listed above.
+	 * Ideally, the loop does visit all possible CRTs, making this redundant.
+	 */
+	return _putenv(envval);
+}
+
+void
+pgwin32_unsetenv(const char *name)
+{
+	char	   *envbuf;
+
+	envbuf = (char *) malloc(strlen(name) + 2);
+	if (!envbuf)
+		return;
+
+	sprintf(envbuf, "%s=", name);
+	pgwin32_putenv(envbuf);
+	free(envbuf);
+}