From 9048b73184b6852b71faf4481b75ab5850a9cd1b Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 22 Sep 2009 23:43:43 +0000
Subject: Implement the DO statement to support execution of PL code without
 having to create a function for it.

Procedural languages now have an additional entry point, namely a function
to execute an inline code block.  This seemed a better design than trying
to hide the transient-ness of the code from the PL.  As of this patch, only
plpgsql has an inline handler, but probably people will soon write handlers
for the other standard PLs.

In passing, remove the long-dead LANCOMPILER option of CREATE LANGUAGE.

Petr Jelinek
---
 src/backend/commands/functioncmds.c | 109 +++++++++++++++++++++++++++++++++++-
 1 file changed, 108 insertions(+), 1 deletion(-)

(limited to 'src/backend/commands/functioncmds.c')

diff --git a/src/backend/commands/functioncmds.c b/src/backend/commands/functioncmds.c
index 2151fd94f09..cf206b3f090 100644
--- a/src/backend/commands/functioncmds.c
+++ b/src/backend/commands/functioncmds.c
@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/functioncmds.c,v 1.110 2009/06/11 14:48:55 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/functioncmds.c,v 1.111 2009/09/22 23:43:37 tgl Exp $
  *
  * DESCRIPTION
  *	  These routines take the parse tree and pick out the
@@ -1915,3 +1915,110 @@ AlterFunctionNamespace(List *name, List *argtypes, bool isagg,
 
 	heap_close(procRel, RowExclusiveLock);
 }
+
+
+/*
+ * ExecuteDoStmt
+ *		Execute inline procedural-language code
+ */
+void
+ExecuteDoStmt(DoStmt *stmt)
+{
+	InlineCodeBlock *codeblock = makeNode(InlineCodeBlock);
+	ListCell   *arg;
+	DefElem    *as_item = NULL;
+	DefElem    *language_item = NULL;
+	char	   *language;
+	char	   *languageName;
+	Oid			laninline;
+	HeapTuple	languageTuple;
+	Form_pg_language languageStruct;
+
+	/* Process options we got from gram.y */
+	foreach(arg, stmt->args)
+	{
+		DefElem    *defel = (DefElem *) lfirst(arg);
+
+		if (strcmp(defel->defname, "as") == 0)
+		{
+			if (as_item)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			as_item = defel;
+		}
+		else if (strcmp(defel->defname, "language") == 0)
+		{
+			if (language_item)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			language_item = defel;
+		}
+		else
+			elog(ERROR, "option \"%s\" not recognized",
+				 defel->defname);
+	}
+
+	if (as_item)
+		codeblock->source_text = strVal(as_item->arg);
+	else
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("no inline code specified")));
+
+	/* if LANGUAGE option wasn't specified, use the default language */
+	if (language_item)
+		language = strVal(language_item->arg);
+	else
+		language = default_do_language;
+
+	/* Convert language name to canonical case */
+	languageName = case_translate_language_name(language);
+
+	/* Look up the language and validate permissions */
+	languageTuple = SearchSysCache(LANGNAME,
+								   PointerGetDatum(languageName),
+								   0, 0, 0);
+	if (!HeapTupleIsValid(languageTuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("language \"%s\" does not exist", languageName),
+				 (PLTemplateExists(languageName) ?
+				  errhint("Use CREATE LANGUAGE to load the language into the database.") : 0)));
+
+	codeblock->langOid = HeapTupleGetOid(languageTuple);
+	languageStruct = (Form_pg_language) GETSTRUCT(languageTuple);
+
+	if (languageStruct->lanpltrusted)
+	{
+		/* if trusted language, need USAGE privilege */
+		AclResult	aclresult;
+
+		aclresult = pg_language_aclcheck(codeblock->langOid, GetUserId(),
+										 ACL_USAGE);
+		if (aclresult != ACLCHECK_OK)
+			aclcheck_error(aclresult, ACL_KIND_LANGUAGE,
+						   NameStr(languageStruct->lanname));
+	}
+	else
+	{
+		/* if untrusted language, must be superuser */
+		if (!superuser())
+			aclcheck_error(ACLCHECK_NO_PRIV, ACL_KIND_LANGUAGE,
+						   NameStr(languageStruct->lanname));
+	}
+
+	/* get the handler function's OID */
+	laninline = languageStruct->laninline;
+	if (!OidIsValid(laninline))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("language \"%s\" does not support inline code execution",
+						NameStr(languageStruct->lanname))));
+
+	ReleaseSysCache(languageTuple);
+
+	/* execute the inline handler */
+	OidFunctionCall1(laninline, PointerGetDatum(codeblock));
+}
-- 
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