Add DECLARE STATEMENT support to ECPG.

DECLARE STATEMENT is a statement that lets users declare an identifier
pointing at a connection.  This identifier will be used in other embedded
dynamic SQL statement such as PREPARE, EXECUTE, DECLARE CURSOR and so on.
When connecting to a non-default connection, the AT clause can be used in
a DECLARE STATEMENT once and is no longer needed in every dynamic SQL
statement.  This makes ECPG applications easier and more efficient.  Moreover,
writing code without designating connection explicitly improves portability.

Authors: Ideriha-san ("Ideriha, Takeshi" <ideriha.takeshi@jp.fujitsu.com>)
         Kuroda-san ("Kuroda, Hayato" <kuroda.hayato@jp.fujitsu.com>)

Discussion: https://postgr.es/m4E72940DA2BF16479384A86D54D0988A565669DF@G01JPEXMBKW04

1 files changed, 237 insertions, 5 deletions

diff --git a/src/interfaces/ecpg/ecpglib/prepare.c b/src/interfaces/ecpg/ecpglib/prepare.c
index 2dd56b02df5..85c61d23f2c 100644
--- a/src/interfaces/ecpg/ecpglib/prepare.c
+++ b/src/interfaces/ecpg/ecpglib/prepare.c
@@ -36,10 +36,11 @@ typedef struct
 
 static int	nextStmtID = 1;
 static stmtCacheEntry *stmtCacheEntries = NULL;
+static struct declared_statement *g_declared_list; 
 
 static bool deallocate_one(int lineno, enum COMPAT_MODE c, struct connection *con,
 			   struct prepared_statement *prev, struct prepared_statement *this);
-
+static struct declared_statement *ecpg_find_declared_statement(const char *); 
 static bool
 isvarchar(unsigned char c)
 {
@@ -128,6 +129,7 @@ prepare_common(int lineno, struct connection *con, const char *name, const char
 		ecpg_free(this);
 		return false;
 	}
+	memset(stmt, 0, sizeof(struct statement));
 
 	/* create statement */
 	stmt->lineno = lineno;
@@ -175,12 +177,22 @@ ECPGprepare(int lineno, const char *connection_name, const bool questionmarks,
 	struct connection *con;
 	struct prepared_statement *this,
 			   *prev;
+	const char *real_connection_name = NULL; 
 
 	(void) questionmarks;		/* quiet the compiler */
 
-	con = ecpg_get_connection(connection_name);
+	real_connection_name = ecpg_get_con_name_by_declared_name(name);
+	if (real_connection_name == NULL)
+	{
+		/* 
+		 * If can't get the connection name by declared name then using connection name
+		 * coming from the parameter connection_name
+		 */
+		real_connection_name = connection_name;
+	}
 
-	if (!ecpg_init(con, connection_name, lineno))
+	con = ecpg_get_connection(real_connection_name);
+	if (!ecpg_init(con, real_connection_name, lineno))
 		return false;
 
 	/* check if we already have prepared this statement */
@@ -273,9 +285,19 @@ ECPGdeallocate(int lineno, int c, const char *connection_name, const char *name)
 	struct connection *con;
 	struct prepared_statement *this,
 			   *prev;
+	const char *real_connection_name = NULL;
 
-	con = ecpg_get_connection(connection_name);
+	real_connection_name = ecpg_get_con_name_by_declared_name(name);
+	if (real_connection_name == NULL)
+	{
+		/*
+		 * If can't get the connection name by declared name then using connection name
+		 * coming from the parameter connection_name
+		 */
+		real_connection_name = connection_name;
+	}
 
+	con = ecpg_get_connection(real_connection_name);
 	if (!ecpg_init(con, connection_name, lineno))
 		return false;
 
@@ -324,8 +346,21 @@ ecpg_prepared(const char *name, struct connection *con)
 char *
 ECPGprepared_statement(const char *connection_name, const char *name, int lineno)
 {
+	const char *real_connection_name = NULL;
+
 	(void) lineno;				/* keep the compiler quiet */
-	return ecpg_prepared(name, ecpg_get_connection(connection_name));
+
+	real_connection_name = ecpg_get_con_name_by_declared_name(name);
+	if (real_connection_name == NULL)
+	{
+		/*
+		 * If can't get the connection name by declared name then using connection name
+		 * coming from the parameter connection_name
+		 */
+		real_connection_name = connection_name;
+	}
+
+	return ecpg_prepared(name, ecpg_get_connection(real_connection_name));
 }
 
 /*
@@ -556,3 +591,200 @@ ecpg_auto_prepare(int lineno, const char *connection_name, const int compat, cha
 
 	return true;
 }
+
+/*
+ * handle the EXEC SQL DECLARE STATEMENT
+ * Input: connection_name -- connection name
+ *		  name -- declared name
+ */
+bool
+ECPGdeclare(int lineno, const char *connection_name, const char *name)
+{
+	struct connection *con = NULL;
+	struct declared_statement *p = NULL;
+
+	if (name == NULL)
+	{
+		/* Should never go to here because ECPG pre-compiler will check it */
+		return false;
+	}
+
+	if (connection_name == NULL)
+	{
+		/*
+		 * Going to here means not using AT clause in the DECLARE STATEMENT
+		 * ECPG pre-processor allows this case.
+		 * However, we don't allocate a node to store the declared name
+		 * because the DECLARE STATEMENT without using AT clause will be ignored.
+		 * The following statement such as PREPARE, EXECUTE are executed
+		 * as usual on the current connection.
+		 */
+		return true;
+	}
+
+	con = ecpg_get_connection(connection_name);
+	if (!ecpg_init(con, connection_name, lineno))
+		return false;
+
+	if (ecpg_find_declared_statement(name))
+	{
+		/* Should not go to here because the pre-compiler has check the duplicate name */
+		return false;
+	}
+
+	/* allocate a declared_statement as a new node */
+	p = (struct declared_statement *) ecpg_alloc(sizeof(struct declared_statement), lineno);
+	if (!p)
+		return false;
+
+	memset(p, 0, sizeof(struct declared_statement));
+
+	ecpg_log("ECPGdeclare on line %d: declared name %s on connection: \"%s\"\n", lineno, name, connection_name);
+
+	p->name = ecpg_strdup(name, lineno);
+	p->connection_name = ecpg_strdup(connection_name, lineno);
+
+	/* Add the new node into the g_declared_list */
+	if (g_declared_list != NULL)
+	{
+		p->next = g_declared_list;
+		g_declared_list = p;
+	}
+	else
+		g_declared_list = p;
+
+	return true;
+}
+
+/*
+ * Find a declared node by declared name
+ * Input: name -- declared name
+ * Return: Found -- The pointer points to the declared node
+ *		   Not found -- NULL
+ */
+static struct declared_statement *
+ecpg_find_declared_statement(const char *name)
+{
+	struct declared_statement *p;
+
+	if (name == NULL)
+		return NULL;
+
+	p = g_declared_list;
+	while (p)
+	{
+		if (strcmp(p->name, name) == 0)
+			return p;
+		p = p->next;
+	}
+
+	return NULL;
+}
+
+/*
+ * Build the relationship between the declared name and cursor name
+ * Input: declared_name -- the name declared in the DECLARE STATEMENT
+ *		  cursor_name -- cursor name declared in the DECLARE/OPEN CURSOR statement
+ */
+void
+ecpg_update_declare_statement(const char *declared_name, const char *cursor_name, const int lineno)
+{
+	struct declared_statement *p = NULL;
+
+	if (!declared_name || !cursor_name)
+		return;
+
+	/* Find the declared node by declared name */
+	p = ecpg_find_declared_statement(declared_name);
+	if (p)
+		p->cursor_name = ecpg_strdup(cursor_name,lineno);
+}
+
+/*
+ * Find and return the connection name referred by the declared name
+ * Input: declared_name -- the name declared in the DECLARE STATEMENT
+ * Return: Found -- The connection name
+ *		   Not found -- NULL
+ */
+char *
+ecpg_get_con_name_by_declared_name(const char *declared_name)
+{
+	struct declared_statement *p;
+
+	p = ecpg_find_declared_statement(declared_name);
+	if (p)
+		return p->connection_name;
+
+	return NULL;
+}
+
+/*
+ * Find the connection name by referring the declared statements
+ * cursors by using the provided cursor name
+ * Input: cursor_name -- the cursor name
+ * Return: Found -- The connection name
+ *		   Not found -- NULL
+ */
+const char *
+ecpg_get_con_name_by_cursor_name(const char *cursor_name)
+{
+	struct declared_statement *p;
+
+	if (cursor_name == NULL)
+		return NULL;
+
+	p = g_declared_list;
+	while (p)
+	{
+		/* Search the cursor name in the declared list */
+		if (p->cursor_name && (strcmp(p->cursor_name, cursor_name) == 0))
+			return p->connection_name;
+
+		p = p->next;
+	}
+
+	return NULL;
+}
+
+/*
+ * Release the declare node from the g_declared_list which refers the connection_name
+ * Input: connection_name -- connection name
+ */
+void
+ecpg_release_declared_statement(const char *connection_name)
+{
+	struct declared_statement *cur = NULL;
+	struct declared_statement *prev = NULL;
+
+	if (connection_name == NULL)
+		return;
+
+	cur = g_declared_list;
+	while (cur)
+	{
+		if (strcmp(cur->connection_name, connection_name) == 0)
+		{
+			/* If find then release the declared node from the list */
+			if (prev)
+				prev->next = cur->next;
+			else
+				g_declared_list = cur->next;
+
+			ecpg_log("ecpg_release_declared_statement: declared name %s is released\n", cur->name);
+
+			ecpg_free(cur->name);
+			ecpg_free(cur->connection_name);
+			ecpg_free(cur->cursor_name);
+			ecpg_free(cur);
+
+			/* One connection can be used by multiple declared name, so no break here */
+		}
+		else
+			prev = cur;
+
+		if (prev)
+			cur = prev->next;
+		else
+			cur = g_declared_list;
+	}
+}