Use setenv() in preference to putenv().

Since at least 2001 we've used putenv() and avoided setenv(), on the
grounds that the latter was unportable and not in POSIX.  However,
POSIX added it that same year, and by now the situation has reversed:
setenv() is probably more portable than putenv(), since POSIX now
treats the latter as not being a core function.  And setenv() has
cleaner semantics too.  So, let's reverse that old policy.

This commit adds a simple src/port/ implementation of setenv() for
any stragglers (we have one in the buildfarm, but I'd not be surprised
if that code is never used in the field).  More importantly, extend
win32env.c to also support setenv().  Then, replace usages of putenv()
with setenv(), and get rid of some ad-hoc implementations of setenv()
wannabees.

Also, adjust our src/port/ implementation of unsetenv() to follow the
POSIX spec that it returns an error indicator, rather than returning
void as per the ancient BSD convention.  I don't feel a need to make
all the call sites check for errors, but the portability stub ought
to match real-world practice.

Discussion: https://postgr.es/m/2065122.1609212051@sss.pgh.pa.us

configure

@@ -15959,11 +15959,28 @@ case $host_os in
         # Windows uses a specialised env handler
         mingw*)
 
+$as_echo "#define HAVE_SETENV 1" >>confdefs.h
+
+
 $as_echo "#define HAVE_UNSETENV 1" >>confdefs.h
 
+                ac_cv_func_setenv=yes
                 ac_cv_func_unsetenv=yes
                 ;;
         *)
+                ac_fn_c_check_func "$LINENO" "setenv" "ac_cv_func_setenv"
+if test "x$ac_cv_func_setenv" = xyes; then :
+  $as_echo "#define HAVE_SETENV 1" >>confdefs.h
+
+else
+  case " $LIBOBJS " in
+  *" setenv.$ac_objext "* ) ;;
+  *) LIBOBJS="$LIBOBJS setenv.$ac_objext"
+ ;;
+esac
+
+fi
+
 ac_fn_c_check_func "$LINENO" "unsetenv" "ac_cv_func_unsetenv"
 if test "x$ac_cv_func_unsetenv" = xyes; then :
   $as_echo "#define HAVE_UNSETENV 1" >>confdefs.h

configure.ac

@@ -1757,11 +1757,13 @@ fi
 case $host_os in
         # Windows uses a specialised env handler
         mingw*)
+                AC_DEFINE(HAVE_SETENV, 1, [Define to 1 because replacement version used.])
                 AC_DEFINE(HAVE_UNSETENV, 1, [Define to 1 because replacement version used.])
+                ac_cv_func_setenv=yes
                 ac_cv_func_unsetenv=yes
                 ;;
         *)
-                AC_REPLACE_FUNCS([unsetenv])
+                AC_REPLACE_FUNCS([setenv unsetenv])
                 ;;
 esac
 

contrib/dblink/input/paths.source

@@ -1,8 +1,8 @@
 -- Initialization that requires path substitution.
 
-CREATE FUNCTION putenv(text)
+CREATE FUNCTION setenv(text, text)
    RETURNS void
-   AS '@libdir@/regress@DLSUFFIX@', 'regress_putenv'
+   AS '@libdir@/regress@DLSUFFIX@', 'regress_setenv'
    LANGUAGE C STRICT;
 
 CREATE FUNCTION wait_pid(int)
@@ -11,4 +11,4 @@ CREATE FUNCTION wait_pid(int)
    LANGUAGE C STRICT;
 
 CREATE FUNCTION set_pgservicefile(text) RETURNS void LANGUAGE SQL
-    AS $$SELECT putenv('PGSERVICEFILE=@abs_srcdir@/' || $1)$$;
+    AS $$SELECT setenv('PGSERVICEFILE', '@abs_srcdir@/' || $1)$$;

contrib/dblink/output/paths.source

@@ -1,11 +1,11 @@
 -- Initialization that requires path substitution.
-CREATE FUNCTION putenv(text)
+CREATE FUNCTION setenv(text, text)
    RETURNS void
-   AS '@libdir@/regress@DLSUFFIX@', 'regress_putenv'
+   AS '@libdir@/regress@DLSUFFIX@', 'regress_setenv'
    LANGUAGE C STRICT;
 CREATE FUNCTION wait_pid(int)
    RETURNS void
    AS '@libdir@/regress@DLSUFFIX@'
    LANGUAGE C STRICT;
 CREATE FUNCTION set_pgservicefile(text) RETURNS void LANGUAGE SQL
-    AS $$SELECT putenv('PGSERVICEFILE=@abs_srcdir@/' || $1)$$;
+    AS $$SELECT setenv('PGSERVICEFILE', '@abs_srcdir@/' || $1)$$;

src/backend/utils/adt/pg_locale.c

@@ -105,20 +105,6 @@ char	   *localized_full_months[12 + 1];
 static bool CurrentLocaleConvValid = false;
 static bool CurrentLCTimeValid = false;
 
-/* Environment variable storage area */
-
-#define LC_ENV_BUFSIZE (NAMEDATALEN + 20)
-
-static char lc_collate_envbuf[LC_ENV_BUFSIZE];
-static char lc_ctype_envbuf[LC_ENV_BUFSIZE];
-
-#ifdef LC_MESSAGES
-static char lc_messages_envbuf[LC_ENV_BUFSIZE];
-#endif
-static char lc_monetary_envbuf[LC_ENV_BUFSIZE];
-static char lc_numeric_envbuf[LC_ENV_BUFSIZE];
-static char lc_time_envbuf[LC_ENV_BUFSIZE];
-
 /* Cache for collation-related knowledge */
 
 typedef struct
@@ -163,7 +149,6 @@ pg_perm_setlocale(int category, const char *locale)
 {
 	char	   *result;
 	const char *envvar;
-	char	   *envbuf;
 
 #ifndef WIN32
 	result = setlocale(category, locale);
@@ -199,7 +184,7 @@ pg_perm_setlocale(int category, const char *locale)
 	 */
 	if (category == LC_CTYPE)
 	{
-		static char save_lc_ctype[LC_ENV_BUFSIZE];
+		static char save_lc_ctype[NAMEDATALEN + 20];
 
 		/* copy setlocale() return value before callee invokes it again */
 		strlcpy(save_lc_ctype, result, sizeof(save_lc_ctype));
@@ -216,16 +201,13 @@ pg_perm_setlocale(int category, const char *locale)
 	{
 		case LC_COLLATE:
 			envvar = "LC_COLLATE";
-			envbuf = lc_collate_envbuf;
 			break;
 		case LC_CTYPE:
 			envvar = "LC_CTYPE";
-			envbuf = lc_ctype_envbuf;
 			break;
 #ifdef LC_MESSAGES
 		case LC_MESSAGES:
 			envvar = "LC_MESSAGES";
-			envbuf = lc_messages_envbuf;
 #ifdef WIN32
 			result = IsoLocaleName(locale);
 			if (result == NULL)
@@ -236,26 +218,19 @@ pg_perm_setlocale(int category, const char *locale)
 #endif							/* LC_MESSAGES */
 		case LC_MONETARY:
 			envvar = "LC_MONETARY";
-			envbuf = lc_monetary_envbuf;
 			break;
 		case LC_NUMERIC:
 			envvar = "LC_NUMERIC";
-			envbuf = lc_numeric_envbuf;
 			break;
 		case LC_TIME:
 			envvar = "LC_TIME";
-			envbuf = lc_time_envbuf;
 			break;
 		default:
 			elog(FATAL, "unrecognized LC category: %d", category);
-			envvar = NULL;		/* keep compiler quiet */
+			return NULL;		/* keep compiler quiet */
-			envbuf = NULL;
-			return NULL;
 	}
 
-	snprintf(envbuf, LC_ENV_BUFSIZE - 1, "%s=%s", envvar, result);
+	if (setenv(envvar, result, 1) != 0)
-
-	if (putenv(envbuf))
 		return NULL;
 
 	return result;

src/bin/initdb/initdb.c

@@ -2355,8 +2355,7 @@ check_need_password(const char *authmethodlocal, const char *authmethodhost)
 void
 setup_pgdata(void)
 {
-	char	   *pgdata_get_env,
+	char	   *pgdata_get_env;
-			   *pgdata_set_env;
 
 	if (!pg_data)
 	{
@@ -2386,8 +2385,11 @@ setup_pgdata(void)
 	 * need quotes otherwise on Windows because paths there are most likely to
 	 * have embedded spaces.
 	 */
-	pgdata_set_env = psprintf("PGDATA=%s", pg_data);
+	if (setenv("PGDATA", pg_data, 1) != 0)
-	putenv(pgdata_set_env);
+	{
+		pg_log_error("could not set environment");
+		exit(1);
+	}
 }
 
 

src/bin/pg_ctl/pg_ctl.c

@@ -889,11 +889,10 @@ do_start(void)
 	 */
 #ifndef WIN32
 	{
-		static char env_var[32];
+		char		env_var[32];
 
-		snprintf(env_var, sizeof(env_var), "PG_GRANDPARENT_PID=%d",
+		snprintf(env_var, sizeof(env_var), "%d", (int) getppid());
-				 (int) getppid());
+		setenv("PG_GRANDPARENT_PID", env_var, 1);
-		putenv(env_var);
 	}
 #endif
 
@@ -2340,12 +2339,10 @@ main(int argc, char **argv)
 				case 'D':
 					{
 						char	   *pgdata_D;
-						char	   *env_var;
 
 						pgdata_D = pg_strdup(optarg);
 						canonicalize_path(pgdata_D);
-						env_var = psprintf("PGDATA=%s", pgdata_D);
+						setenv("PGDATA", pgdata_D, 1);
-						putenv(env_var);
 
 						/*
 						 * We could pass PGDATA just in an environment
@@ -2353,6 +2350,7 @@ main(int argc, char **argv)
 						 * 'ps' display
 						 */
 						pgdata_opt = psprintf("-D \"%s\" ", pgdata_D);
+						free(pgdata_D);
 						break;
 					}
 				case 'e':

src/bin/pg_upgrade/controldata.c

@@ -97,20 +97,20 @@ get_control_data(ClusterInfo *cluster, bool live_check)
 	if (getenv("LC_MESSAGES"))
 		lc_messages = pg_strdup(getenv("LC_MESSAGES"));
 
-	pg_putenv("LC_COLLATE", NULL);
+	unsetenv("LC_COLLATE");
-	pg_putenv("LC_CTYPE", NULL);
+	unsetenv("LC_CTYPE");
-	pg_putenv("LC_MONETARY", NULL);
+	unsetenv("LC_MONETARY");
-	pg_putenv("LC_NUMERIC", NULL);
+	unsetenv("LC_NUMERIC");
-	pg_putenv("LC_TIME", NULL);
+	unsetenv("LC_TIME");
 #ifndef WIN32
-	pg_putenv("LANG", NULL);
+	unsetenv("LANG");
 #else
 	/* On Windows the default locale may not be English, so force it */
-	pg_putenv("LANG", "en");
+	setenv("LANG", "en", 1);
 #endif
-	pg_putenv("LANGUAGE", NULL);
+	unsetenv("LANGUAGE");
-	pg_putenv("LC_ALL", NULL);
+	unsetenv("LC_ALL");
-	pg_putenv("LC_MESSAGES", "C");
+	setenv("LC_MESSAGES", "C", 1);
 
 	/*
 	 * Check for clean shutdown
@@ -490,17 +490,31 @@ get_control_data(ClusterInfo *cluster, bool live_check)
 	pclose(output);
 
 	/*
-	 * Restore environment variables
+	 * Restore environment variables.  Note all but LANG and LC_MESSAGES were
+	 * unset above.
 	 */
-	pg_putenv("LC_COLLATE", lc_collate);
+	if (lc_collate)
-	pg_putenv("LC_CTYPE", lc_ctype);
+		setenv("LC_COLLATE", lc_collate, 1);
-	pg_putenv("LC_MONETARY", lc_monetary);
+	if (lc_ctype)
-	pg_putenv("LC_NUMERIC", lc_numeric);
+		setenv("LC_CTYPE", lc_ctype, 1);
-	pg_putenv("LC_TIME", lc_time);
+	if (lc_monetary)
-	pg_putenv("LANG", lang);
+		setenv("LC_MONETARY", lc_monetary, 1);
-	pg_putenv("LANGUAGE", language);
+	if (lc_numeric)
-	pg_putenv("LC_ALL", lc_all);
+		setenv("LC_NUMERIC", lc_numeric, 1);
-	pg_putenv("LC_MESSAGES", lc_messages);
+	if (lc_time)
+		setenv("LC_TIME", lc_time, 1);
+	if (lang)
+		setenv("LANG", lang, 1);
+	else
+		unsetenv("LANG");
+	if (language)
+		setenv("LANGUAGE", language, 1);
+	if (lc_all)
+		setenv("LC_ALL", lc_all, 1);
+	if (lc_messages)
+		setenv("LC_MESSAGES", lc_messages, 1);
+	else
+		unsetenv("LC_MESSAGES");
 
 	pg_free(lc_collate);
 	pg_free(lc_ctype);

src/bin/pg_upgrade/option.c

@@ -193,7 +193,7 @@ parseCommandLine(int argc, char *argv[])
 				 * Push the user name into the environment so pre-9.1
 				 * pg_ctl/libpq uses it.
 				 */
-				pg_putenv("PGUSER", os_info.user);
+				setenv("PGUSER", os_info.user, 1);
 				break;
 
 			case 'v':
@@ -245,11 +245,11 @@ parseCommandLine(int argc, char *argv[])
 		char	   *pgoptions = psprintf("%s %s", FIX_DEFAULT_READ_ONLY,
 										 getenv("PGOPTIONS"));
 
-		pg_putenv("PGOPTIONS", pgoptions);
+		setenv("PGOPTIONS", pgoptions, 1);
 		pfree(pgoptions);
 	}
 	else
-		pg_putenv("PGOPTIONS", FIX_DEFAULT_READ_ONLY);
+		setenv("PGOPTIONS", FIX_DEFAULT_READ_ONLY, 1);
 
 	/* Get values from env if not already set */
 	check_required_directory(&old_cluster.bindir, "PGBINOLD", false,

src/bin/pg_upgrade/pg_upgrade.h

@@ -436,7 +436,6 @@ void		end_progress_output(void);
 void		prep_status(const char *fmt,...) pg_attribute_printf(1, 2);
 void		check_ok(void);
 unsigned int str2uint(const char *str);
-void		pg_putenv(const char *var, const char *val);
 
 
 /* version.c */

src/bin/pg_upgrade/util.c

@@ -241,39 +241,3 @@ str2uint(const char *str)
 {
 	return strtoul(str, NULL, 10);
 }
-
-
-/*
- *	pg_putenv()
- *
- *	This is like putenv(), but takes two arguments.
- *	It also does unsetenv() if val is NULL.
- */
-void
-pg_putenv(const char *var, const char *val)
-{
-	if (val)
-	{
-#ifndef WIN32
-		char	   *envstr;
-
-		envstr = psprintf("%s=%s", var, val);
-		putenv(envstr);
-
-		/*
-		 * Do not free envstr because it becomes part of the environment on
-		 * some operating systems.  See port/unsetenv.c::unsetenv.
-		 */
-#else
-		SetEnvironmentVariableA(var, val);
-#endif
-	}
-	else
-	{
-#ifndef WIN32
-		unsetenv(var);
-#else
-		SetEnvironmentVariableA(var, "");
-#endif
-	}
-}

src/bin/psql/command.c

@@ -2296,17 +2296,8 @@ exec_command_setenv(PsqlScanState scan_state, bool active_branch,
 		else
 		{
 			/* Set variable to the value of the next argument */
-			char	   *newval;
+			setenv(envvar, envval, 1);
-
-			newval = psprintf("%s=%s", envvar, envval);
-			putenv(newval);
 			success = true;
-
-			/*
-			 * Do not free newval here, it will screw up the environment if
-			 * you do. See putenv man page for details. That means we leak a
-			 * bit of memory here, but not enough to worry about.
-			 */
 		}
 		free(envvar);
 		free(envval);

src/common/exec.c

@@ -435,9 +435,6 @@ set_pglocale_pgservice(const char *argv0, const char *app)
 {
 	char		path[MAXPGPATH];
 	char		my_exec_path[MAXPGPATH];
-	char		env_path[MAXPGPATH + sizeof("PGSYSCONFDIR=")];	/* longer than
-																 * PGLOCALEDIR */
-	char	   *dup_path;
 
 	/* don't set LC_ALL in the backend */
 	if (strcmp(app, PG_TEXTDOMAIN("postgres")) != 0)
@@ -462,28 +459,15 @@ set_pglocale_pgservice(const char *argv0, const char *app)
 	get_locale_path(my_exec_path, path);
 	bindtextdomain(app, path);
 	textdomain(app);
-
+	/* set for libpq to use, but don't override existing setting */
-	if (getenv("PGLOCALEDIR") == NULL)
+	setenv("PGLOCALEDIR", path, 0);
-	{
-		/* set for libpq to use */
-		snprintf(env_path, sizeof(env_path), "PGLOCALEDIR=%s", path);
-		canonicalize_path(env_path + 12);
-		dup_path = strdup(env_path);
-		if (dup_path)
-			putenv(dup_path);
-	}
 #endif
 
 	if (getenv("PGSYSCONFDIR") == NULL)
 	{
 		get_etc_path(my_exec_path, path);
-
 		/* set for libpq to use */
-		snprintf(env_path, sizeof(env_path), "PGSYSCONFDIR=%s", path);
+		setenv("PGSYSCONFDIR", path, 0);
-		canonicalize_path(env_path + 13);
-		dup_path = strdup(env_path);
-		if (dup_path)
-			putenv(dup_path);
 	}
 }
 

src/common/restricted_token.c

@@ -171,7 +171,7 @@ get_restricted_token(void)
 
 		cmdline = pg_strdup(GetCommandLine());
 
-		putenv("PG_RESTRICT_EXEC=1");
+		setenv("PG_RESTRICT_EXEC", "1", 1);
 
 		if ((restrictedToken = CreateRestrictedProcess(cmdline, &pi)) == 0)
 		{

src/include/pg_config.h.in

@@ -473,6 +473,9 @@
 /* Define to 1 if you have the <security/pam_appl.h> header file. */
 #undef HAVE_SECURITY_PAM_APPL_H
 
+/* Define to 1 if you have the `setenv' function. */
+#undef HAVE_SETENV
+
 /* Define to 1 if you have the `setproctitle' function. */
 #undef HAVE_SETPROCTITLE
 

src/include/port.h

@@ -447,8 +447,12 @@ extern size_t strnlen(const char *str, size_t maxlen);
 extern long random(void);
 #endif
 
+#ifndef HAVE_SETENV
+extern int	setenv(const char *name, const char *value, int overwrite);
+#endif
+
 #ifndef HAVE_UNSETENV
-extern void unsetenv(const char *name);
+extern int	unsetenv(const char *name);
 #endif
 
 #ifndef HAVE_SRANDOM

src/include/port/win32_port.h

@@ -490,7 +490,12 @@ extern void _dosmaperr(unsigned long);
 
 /* in port/win32env.c */
 extern int	pgwin32_putenv(const char *);
-extern void pgwin32_unsetenv(const char *);
+extern int	pgwin32_setenv(const char *name, const char *value, int overwrite);
+extern int	pgwin32_unsetenv(const char *name);
+
+#define putenv(x) pgwin32_putenv(x)
+#define setenv(x,y,z) pgwin32_setenv(x,y,z)
+#define unsetenv(x) pgwin32_unsetenv(x)
 
 /* in port/win32security.c */
 extern int	pgwin32_is_service(void);
@@ -499,9 +504,6 @@ extern int	pgwin32_is_admin(void);
 /* Windows security token manipulation (in src/common/exec.c) */
 extern BOOL AddUserToTokenDacl(HANDLE hToken);
 
-#define putenv(x) pgwin32_putenv(x)
-#define unsetenv(x) pgwin32_unsetenv(x)
-
 /* Things that exist in MinGW headers, but need to be added to MSVC */
 #ifdef _MSC_VER
 

src/interfaces/ecpg/test/pg_regress_ecpg.c

@@ -147,8 +147,9 @@ ecpg_start_test(const char *testname,
 			 outfile_stdout,
 			 outfile_stderr);
 
-	appnameenv = psprintf("PGAPPNAME=ecpg/%s", testname_dash.data);
+	appnameenv = psprintf("ecpg/%s", testname_dash.data);
-	putenv(appnameenv);
+	setenv("PGAPPNAME", appnameenv, 1);
+	free(appnameenv);
 
 	pid = spawn_process(cmd);
 
@@ -160,7 +161,6 @@ ecpg_start_test(const char *testname,
 	}
 
 	unsetenv("PGAPPNAME");
-	free(appnameenv);
 
 	free(testname_dash.data);
 

src/port/setenv.c

@@ -0,0 +1,48 @@
+/*-------------------------------------------------------------------------
+ *
+ * setenv.c
+ *	  setenv() emulation for machines without it
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/port/setenv.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "c.h"
+
+
+int
+setenv(const char *name, const char *value, int overwrite)
+{
+	char	   *envstr;
+
+	/* Error conditions, per POSIX */
+	if (name == NULL || name[0] == '\0' || strchr(name, '=') != NULL ||
+		value == NULL)
+	{
+		errno = EINVAL;
+		return -1;
+	}
+
+	/* No work if variable exists and we're not to replace it */
+	if (overwrite == 0 && getenv(name) != NULL)
+		return 0;
+
+	/*
+	 * Add or replace the value using putenv().  This will leak memory if the
+	 * same variable is repeatedly redefined, but there's little we can do
+	 * about that when sitting atop putenv().
+	 */
+	envstr = (char *) malloc(strlen(name) + strlen(value) + 2);
+	if (!envstr)				/* not much we can do if no memory */
+		return -1;
+
+	sprintf(envstr, "%s=%s", name, value);
+
+	return putenv(envstr);
+}

src/port/unsetenv.c

@@ -16,13 +16,20 @@
 #include "c.h"
 
 
-void
+int
 unsetenv(const char *name)
 {
 	char	   *envstr;
 
+	/* Error conditions, per POSIX */
+	if (name == NULL || name[0] == '\0' || strchr(name, '=') != NULL)
+	{
+		errno = EINVAL;
+		return -1;
+	}
+
 	if (getenv(name) == NULL)
-		return;					/* no work */
+		return 0;				/* no work */
 
 	/*
 	 * The technique embodied here works if libc follows the Single Unix Spec
@@ -40,11 +47,12 @@ unsetenv(const char *name)
 
 	envstr = (char *) malloc(strlen(name) + 2);
 	if (!envstr)				/* not much we can do if no memory */
-		return;
+		return -1;
 
 	/* Override the existing setting by forcibly defining the var */
 	sprintf(envstr, "%s=", name);
-	putenv(envstr);
+	if (putenv(envstr))
+		return -1;
 
 	/* Now we can clobber the variable definition this way: */
 	strcpy(envstr, "=");
@@ -53,5 +61,5 @@ unsetenv(const char *name)
 	 * This last putenv cleans up if we have multiple zero-length names as a
 	 * result of unsetting multiple things.
 	 */
-	putenv(envstr);
+	return putenv(envstr);
 }

src/port/win32env.c

@@ -1,8 +1,10 @@
 /*-------------------------------------------------------------------------
  *
  * win32env.c
- *	  putenv() and unsetenv() for win32, which update both process environment
+ *	  putenv(), setenv(), and unsetenv() for win32.
- *	  and caches in (potentially multiple) C run-time library (CRT) versions.
+ *
+ * These functions update both the 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
@@ -16,6 +18,11 @@
 
 #include "c.h"
 
+
+/*
+ * Note that unlike POSIX putenv(), this doesn't use the passed-in string
+ * as permanent storage.
+ */
 int
 pgwin32_putenv(const char *envval)
 {
@@ -64,7 +71,7 @@ pgwin32_putenv(const char *envval)
 	}
 	*cp = '\0';
 	cp++;
-	if (strlen(cp))
+	if (*cp)
 	{
 		/*
 		 * Only call SetEnvironmentVariable() when we are adding a variable,
@@ -110,16 +117,47 @@ pgwin32_putenv(const char *envval)
 	return _putenv(envval);
 }
 
-void
+int
+pgwin32_setenv(const char *name, const char *value, int overwrite)
+{
+	int			res;
+	char	   *envstr;
+
+	/* Error conditions, per POSIX */
+	if (name == NULL || name[0] == '\0' || strchr(name, '=') != NULL ||
+		value == NULL)
+	{
+		errno = EINVAL;
+		return -1;
+	}
+
+	/* No work if variable exists and we're not to replace it */
+	if (overwrite == 0 && getenv(name) != NULL)
+		return 0;
+
+	envstr = (char *) malloc(strlen(name) + strlen(value) + 2);
+	if (!envstr)				/* not much we can do if no memory */
+		return -1;
+
+	sprintf(envstr, "%s=%s", name, value);
+
+	res = pgwin32_putenv(envstr);
+	free(envstr);
+	return res;
+}
+
+int
 pgwin32_unsetenv(const char *name)
 {
+	int			res;
 	char	   *envbuf;
 
 	envbuf = (char *) malloc(strlen(name) + 2);
 	if (!envbuf)
-		return;
+		return -1;
 
 	sprintf(envbuf, "%s=", name);
-	pgwin32_putenv(envbuf);
+	res = pgwin32_putenv(envbuf);
 	free(envbuf);
+	return res;
 }

src/test/isolation/isolation_main.c

@@ -98,8 +98,9 @@ isolation_start_test(const char *testname,
 		exit(2);
 	}
 
-	appnameenv = psprintf("PGAPPNAME=isolation/%s", testname);
+	appnameenv = psprintf("isolation/%s", testname);
-	putenv(appnameenv);
+	setenv("PGAPPNAME", appnameenv, 1);
+	free(appnameenv);
 
 	pid = spawn_process(psql_cmd);
 
@@ -111,7 +112,6 @@ isolation_start_test(const char *testname,
 	}
 
 	unsetenv("PGAPPNAME");
-	free(appnameenv);
 
 	return pid;
 }

src/test/regress/pg_regress.c

@@ -724,18 +724,6 @@ get_expectfile(const char *testname, const char *file)
 	return NULL;
 }
 
-/*
- * Handy subroutine for setting an environment variable "var" to "val"
- */
-static void
-doputenv(const char *var, const char *val)
-{
-	char	   *s;
-
-	s = psprintf("%s=%s", var, val);
-	putenv(s);
-}
-
 /*
  * Prepare environment variables for running regression tests
  */
@@ -746,7 +734,7 @@ initialize_environment(void)
 	 * Set default application_name.  (The test_function may choose to
 	 * override this, but if it doesn't, we have something useful in place.)
 	 */
-	putenv("PGAPPNAME=pg_regress");
+	setenv("PGAPPNAME", "pg_regress", 1);
 
 	if (nolocale)
 	{
@@ -769,7 +757,7 @@ initialize_environment(void)
 		 * variables unset; see PostmasterMain().
 		 */
 #if defined(WIN32) || defined(__CYGWIN__) || defined(__darwin__)
-		putenv("LANG=C");
+		setenv("LANG", "C", 1);
 #endif
 	}
 
@@ -781,21 +769,21 @@ initialize_environment(void)
 	 */
 	unsetenv("LANGUAGE");
 	unsetenv("LC_ALL");
-	putenv("LC_MESSAGES=C");
+	setenv("LC_MESSAGES", "C", 1);
 
 	/*
 	 * Set encoding as requested
 	 */
 	if (encoding)
-		doputenv("PGCLIENTENCODING", encoding);
+		setenv("PGCLIENTENCODING", encoding, 1);
 	else
 		unsetenv("PGCLIENTENCODING");
 
 	/*
 	 * Set timezone and datestyle for datetime-related tests
 	 */
-	putenv("PGTZ=PST8PDT");
+	setenv("PGTZ", "PST8PDT", 1);
-	putenv("PGDATESTYLE=Postgres, MDY");
+	setenv("PGDATESTYLE", "Postgres, MDY", 1);
 
 	/*
 	 * Likewise set intervalstyle to ensure consistent results.  This is a bit
@@ -809,9 +797,10 @@ initialize_environment(void)
 
 		if (!old_pgoptions)
 			old_pgoptions = "";
-		new_pgoptions = psprintf("PGOPTIONS=%s %s",
+		new_pgoptions = psprintf("%s %s",
 								 old_pgoptions, my_pgoptions);
-		putenv(new_pgoptions);
+		setenv("PGOPTIONS", new_pgoptions, 1);
+		free(new_pgoptions);
 	}
 
 	if (temp_instance)
@@ -832,17 +821,17 @@ initialize_environment(void)
 		unsetenv("PGDATA");
 #ifdef HAVE_UNIX_SOCKETS
 		if (hostname != NULL)
-			doputenv("PGHOST", hostname);
+			setenv("PGHOST", hostname, 1);
 		else
 		{
 			sockdir = getenv("PG_REGRESS_SOCK_DIR");
 			if (!sockdir)
 				sockdir = make_temp_sockdir();
-			doputenv("PGHOST", sockdir);
+			setenv("PGHOST", sockdir, 1);
 		}
 #else
 		Assert(hostname != NULL);
-		doputenv("PGHOST", hostname);
+		setenv("PGHOST", hostname, 1);
 #endif
 		unsetenv("PGHOSTADDR");
 		if (port != -1)
@@ -850,7 +839,7 @@ initialize_environment(void)
 			char		s[16];
 
 			sprintf(s, "%d", port);
-			doputenv("PGPORT", s);
+			setenv("PGPORT", s, 1);
 		}
 	}
 	else
@@ -864,7 +853,7 @@ initialize_environment(void)
 		 */
 		if (hostname != NULL)
 		{
-			doputenv("PGHOST", hostname);
+			setenv("PGHOST", hostname, 1);
 			unsetenv("PGHOSTADDR");
 		}
 		if (port != -1)
@@ -872,10 +861,10 @@ initialize_environment(void)
 			char		s[16];
 
 			sprintf(s, "%d", port);
-			doputenv("PGPORT", s);
+			setenv("PGPORT", s, 1);
 		}
 		if (user != NULL)
-			doputenv("PGUSER", user);
+			setenv("PGUSER", user, 1);
 
 		/*
 		 * However, we *don't* honor PGDATABASE, since we certainly don't wish
@@ -2431,7 +2420,7 @@ regression_main(int argc, char *argv[], init_function ifunc, test_function tfunc
 				fprintf(stderr, _("port %d apparently in use, trying %d\n"), port, port + 1);
 				port++;
 				sprintf(s, "%d", port);
-				doputenv("PGPORT", s);
+				setenv("PGPORT", s, 1);
 			}
 			else
 				break;

src/test/regress/pg_regress_main.c

@@ -91,8 +91,9 @@ psql_start_test(const char *testname,
 		exit(2);
 	}
 
-	appnameenv = psprintf("PGAPPNAME=pg_regress/%s", testname);
+	appnameenv = psprintf("pg_regress/%s", testname);
-	putenv(appnameenv);
+	setenv("PGAPPNAME", appnameenv, 1);
+	free(appnameenv);
 
 	pid = spawn_process(psql_cmd);
 
@@ -104,7 +105,6 @@ psql_start_test(const char *testname,
 	}
 
 	unsetenv("PGAPPNAME");
-	free(appnameenv);
 
 	return pid;
 }

src/test/regress/regress.c

@@ -624,22 +624,18 @@ make_tuple_indirect(PG_FUNCTION_ARGS)
 	PG_RETURN_POINTER(newtup->t_data);
 }
 
-PG_FUNCTION_INFO_V1(regress_putenv);
+PG_FUNCTION_INFO_V1(regress_setenv);
 
 Datum
-regress_putenv(PG_FUNCTION_ARGS)
+regress_setenv(PG_FUNCTION_ARGS)
 {
-	MemoryContext oldcontext;
+	char	   *envvar = text_to_cstring(PG_GETARG_TEXT_PP(0));
-	char	   *envbuf;
+	char	   *envval = text_to_cstring(PG_GETARG_TEXT_PP(1));
 
 	if (!superuser())
 		elog(ERROR, "must be superuser to change environment variables");
 
-	oldcontext = MemoryContextSwitchTo(TopMemoryContext);
+	if (setenv(envvar, envval, 1) != 0)
-	envbuf = text_to_cstring((text *) PG_GETARG_POINTER(0));
-	MemoryContextSwitchTo(oldcontext);
-
-	if (putenv(envbuf) != 0)
 		elog(ERROR, "could not set environment variable: %m");
 
 	PG_RETURN_VOID();

src/tools/msvc/Solution.pm

@@ -348,6 +348,7 @@ sub GenerateFiles
 		HAVE_RL_FILENAME_QUOTING_FUNCTION        => undef,
 		HAVE_RL_RESET_SCREEN_SIZE                => undef,
 		HAVE_SECURITY_PAM_APPL_H                 => undef,
+		HAVE_SETENV                              => undef,
 		HAVE_SETPROCTITLE                        => undef,
 		HAVE_SETPROCTITLE_FAST                   => undef,
 		HAVE_SETSID                              => undef,