3 files changed, 62 insertions, 29 deletions

diff --git a/src/backend/utils/fmgr/dfmgr.c b/src/backend/utils/fmgr/dfmgr.c
index 4409e3e6fa8..dd4c83d1bba 100644
--- a/src/backend/utils/fmgr/dfmgr.c
+++ b/src/backend/utils/fmgr/dfmgr.c
@@ -71,8 +71,6 @@ pg_noreturn static void incompatible_module_error(const char *libname,
 												  const Pg_magic_struct *module_magic_data);
 static char *expand_dynamic_library_name(const char *name);
 static void check_restricted_library_name(const char *name);
-static char *substitute_libpath_macro(const char *name);
-static char *find_in_dynamic_libpath(const char *basename);
 
 /* Magic structure that module needs to match to be accepted */
 static const Pg_magic_struct magic_data = PG_MODULE_MAGIC_DATA;
@@ -398,7 +396,7 @@ incompatible_module_error(const char *libname,
 /*
  * If name contains a slash, check if the file exists, if so return
  * the name.  Else (no slash) try to expand using search path (see
- * find_in_dynamic_libpath below); if that works, return the fully
+ * find_in_path below); if that works, return the fully
  * expanded file name.  If the previous failed, append DLSUFFIX and
  * try again.  If all fails, just return the original name.
  *
@@ -413,17 +411,25 @@ expand_dynamic_library_name(const char *name)
 
 	Assert(name);
 
+	/*
+	 * If the value starts with "$libdir/", strip that.  This is because many
+	 * extensions have hardcoded '$libdir/foo' as their library name, which
+	 * prevents using the path.
+	 */
+	if (strncmp(name, "$libdir/", 8) == 0)
+		name += 8;
+
 	have_slash = (first_dir_separator(name) != NULL);
 
 	if (!have_slash)
 	{
-		full = find_in_dynamic_libpath(name);
+		full = find_in_path(name, Dynamic_library_path, "dynamic_library_path", "$libdir", pkglib_path);
 		if (full)
 			return full;
 	}
 	else
 	{
-		full = substitute_libpath_macro(name);
+		full = substitute_path_macro(name, "$libdir", pkglib_path);
 		if (pg_file_exists(full))
 			return full;
 		pfree(full);
@@ -433,14 +439,14 @@ expand_dynamic_library_name(const char *name)
 
 	if (!have_slash)
 	{
-		full = find_in_dynamic_libpath(new);
+		full = find_in_path(new, Dynamic_library_path, "dynamic_library_path", "$libdir", pkglib_path);
 		pfree(new);
 		if (full)
 			return full;
 	}
 	else
 	{
-		full = substitute_libpath_macro(new);
+		full = substitute_path_macro(new, "$libdir", pkglib_path);
 		pfree(new);
 		if (pg_file_exists(full))
 			return full;
@@ -474,48 +480,61 @@ check_restricted_library_name(const char *name)
  * Substitute for any macros appearing in the given string.
  * Result is always freshly palloc'd.
  */
-static char *
-substitute_libpath_macro(const char *name)
+char *
+substitute_path_macro(const char *str, const char *macro, const char *value)
 {
 	const char *sep_ptr;
 
-	Assert(name != NULL);
+	Assert(str != NULL);
+	Assert(macro[0] == '$');
 
-	/* Currently, we only recognize $libdir at the start of the string */
-	if (name[0] != '$')
-		return pstrdup(name);
+	/* Currently, we only recognize $macro at the start of the string */
+	if (str[0] != '$')
+		return pstrdup(str);
 
-	if ((sep_ptr = first_dir_separator(name)) == NULL)
-		sep_ptr = name + strlen(name);
+	if ((sep_ptr = first_dir_separator(str)) == NULL)
+		sep_ptr = str + strlen(str);
 
-	if (strlen("$libdir") != sep_ptr - name ||
-		strncmp(name, "$libdir", strlen("$libdir")) != 0)
+	if (strlen(macro) != sep_ptr - str ||
+		strncmp(str, macro, strlen(macro)) != 0)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_NAME),
-				 errmsg("invalid macro name in dynamic library path: %s",
-						name)));
+				 errmsg("invalid macro name in path: %s",
+						str)));
 
-	return psprintf("%s%s", pkglib_path, sep_ptr);
+	return psprintf("%s%s", value, sep_ptr);
 }
 
 
 /*
  * Search for a file called 'basename' in the colon-separated search
- * path Dynamic_library_path.  If the file is found, the full file name
+ * path given.  If the file is found, the full file name
  * is returned in freshly palloc'd memory.  If the file is not found,
  * return NULL.
+ *
+ * path_param is the name of the parameter that path came from, for error
+ * messages.
+ *
+ * macro and macro_val allow substituting a macro; see
+ * substitute_path_macro().
  */
-static char *
-find_in_dynamic_libpath(const char *basename)
+char *
+find_in_path(const char *basename, const char *path, const char *path_param,
+			 const char *macro, const char *macro_val)
 {
 	const char *p;
 	size_t		baselen;
 
 	Assert(basename != NULL);
 	Assert(first_dir_separator(basename) == NULL);
-	Assert(Dynamic_library_path != NULL);
+	Assert(path != NULL);
+	Assert(path_param != NULL);
+
+	p = path;
 
-	p = Dynamic_library_path;
+	/*
+	 * If the path variable is empty, don't do a path search.
+	 */
 	if (strlen(p) == 0)
 		return NULL;
 
@@ -532,7 +551,7 @@ find_in_dynamic_libpath(const char *basename)
 		if (piece == p)
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_NAME),
-					 errmsg("zero-length component in parameter \"dynamic_library_path\"")));
+					 errmsg("zero-length component in parameter \"%s\"", path_param)));
 
 		if (piece == NULL)
 			len = strlen(p);
@@ -542,7 +561,7 @@ find_in_dynamic_libpath(const char *basename)
 		piece = palloc(len + 1);
 		strlcpy(piece, p, len + 1);
 
-		mangled = substitute_libpath_macro(piece);
+		mangled = substitute_path_macro(piece, macro, macro_val);
 		pfree(piece);
 
 		canonicalize_path(mangled);
@@ -551,13 +570,13 @@ find_in_dynamic_libpath(const char *basename)
 		if (!is_absolute_path(mangled))
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_NAME),
-					 errmsg("component in parameter \"dynamic_library_path\" is not an absolute path")));
+					 errmsg("component in parameter \"%s\" is not an absolute path", path_param)));
 
 		full = palloc(strlen(mangled) + 1 + baselen + 1);
 		sprintf(full, "%s/%s", mangled, basename);
 		pfree(mangled);
 
-		elog(DEBUG3, "find_in_dynamic_libpath: trying \"%s\"", full);
+		elog(DEBUG3, "%s: trying \"%s\"", __func__, full);
 
 		if (pg_file_exists(full))
 			return full;
diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c
index ead80257192..cc8f2b1230a 100644
--- a/src/backend/utils/misc/guc_tables.c
+++ b/src/backend/utils/misc/guc_tables.c
@@ -39,6 +39,7 @@
 #include "catalog/namespace.h"
 #include "catalog/storage.h"
 #include "commands/async.h"
+#include "commands/extension.h"
 #include "commands/event_trigger.h"
 #include "commands/tablespace.h"
 #include "commands/trigger.h"
@@ -4365,6 +4366,18 @@ struct config_string ConfigureNamesString[] =
 	},
 
 	{
+		{"extension_control_path", PGC_SUSET, CLIENT_CONN_OTHER,
+			gettext_noop("Sets the path for extension control files."),
+			gettext_noop("The remaining extension script and secondary control files are then loaded "
+						 "from the same directory where the primary control file was found."),
+			GUC_SUPERUSER_ONLY
+		},
+		&Extension_control_path,
+		"$system",
+		NULL, NULL, NULL
+	},
+
+	{
 		{"krb_server_keyfile", PGC_SIGHUP, CONN_AUTH_AUTH,
 			gettext_noop("Sets the location of the Kerberos server key file."),
 			NULL,
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 6abd1baeac8..ad54585cf1d 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -804,6 +804,7 @@ autovacuum_worker_slots = 16	# autovacuum worker slots to allocate
 # - Other Defaults -
 
 #dynamic_library_path = '$libdir'
+#extension_control_path = '$system'
 #gin_fuzzy_search_limit = 0