res_config_odbc: Avoid deadlock when max_connections = 1

Rather than calling ast_odbc_find_table() in the prepare callback, call
it beforehand and pass it in to the callback to avoid the need for a
second connection.

ASTERISK-28166 #close

Change-Id: I6f8a0b9990d636fd6bc1a92ed70f7050d2436202

diff --git a/res/res_config_odbc.c b/res/res_config_odbc.c
index 62d8dc3d1f1a732f2fd2eaf815aa37ce1fbdb8e4..09eff210bc3994102f9edc6d9b4c60f9fa2b1f4f 100644 (file)
--- a/res/res_config_odbc.c
+++ b/res/res_config_odbc.c
@@ -574,6 +574,7 @@ struct update2_prepare_struct {
        const char *table;
        const struct ast_variable *lookup_fields;
        const struct ast_variable *update_fields;
+       struct odbc_cache_tables *tableptr;
 };
 
 static SQLHSTMT update2_prepare(struct odbc_obj *obj, void *data)
@@ -583,29 +584,21 @@ static SQLHSTMT update2_prepare(struct odbc_obj *obj, void *data)
        const struct ast_variable *field;
        struct ast_str *sql = ast_str_thread_get(&sql_buf, SQL_BUF_SIZE);
        SQLHSTMT stmt;
-       struct odbc_cache_tables *tableptr;
 
        if (!sql) {
                return NULL;
        }
 
-       tableptr = ast_odbc_find_table(ups->database, ups->table);
-       if (!tableptr) {
-               ast_log(LOG_ERROR, "Could not retrieve metadata for table '%s@%s'.  Update will fail!\n", ups->table, ups->database);
-               return NULL;
-       }
-
        res = SQLAllocHandle(SQL_HANDLE_STMT, obj->con, &stmt);
        if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
                ast_log(LOG_WARNING, "SQL Alloc Handle failed!\n");
-               ast_odbc_release_table(tableptr);
                return NULL;
        }
 
        ast_str_set(&sql, 0, "UPDATE %s SET ", ups->table);
 
        for (field = ups->update_fields; field; field = field->next) {
-               if (ast_odbc_find_column(tableptr, field->name)) {
+               if (ast_odbc_find_column(ups->tableptr, field->name)) {
                        ast_str_append(&sql, 0, "%s%s=? ", first ? "" : ", ", field->name);
                        SQLBindParameter(stmt, x++, SQL_PARAM_INPUT, SQL_C_CHAR, SQL_CHAR, strlen(field->name), 0, (void *)field->value, 0, NULL);
                        first = 0;
@@ -618,9 +611,8 @@ static SQLHSTMT update2_prepare(struct odbc_obj *obj, void *data)
        first = 1;
 
        for (field = ups->lookup_fields; field; field = field->next) {
-               if (!ast_odbc_find_column(tableptr, field->name)) {
+               if (!ast_odbc_find_column(ups->tableptr, field->name)) {
                        ast_log(LOG_ERROR, "One or more of the criteria columns '%s' on '%s@%s' for this update does not exist!\n", field->name, ups->table, ups->database);
-                       ast_odbc_release_table(tableptr);
                        SQLFreeHandle(SQL_HANDLE_STMT, stmt);
                        return NULL;
                }
@@ -629,9 +621,6 @@ static SQLHSTMT update2_prepare(struct odbc_obj *obj, void *data)
                first = 0;
        }
 
-       /* Done with the table metadata */
-       ast_odbc_release_table(tableptr);
-
        res = ast_odbc_prepare(obj, stmt, ast_str_buffer(sql));
        if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
                if (res == SQL_ERROR) {
@@ -663,20 +652,36 @@ static int update2_odbc(const char *database, const char *table, const struct as
 {
        struct odbc_obj *obj;
        SQLHSTMT stmt;
-       struct update2_prepare_struct ups = { .database = database, .table = table, .lookup_fields = lookup_fields, .update_fields = update_fields, };
+       struct update2_prepare_struct ups = {
+               .database = database,
+               .table = table,
+               .lookup_fields = lookup_fields,
+               .update_fields = update_fields,
+       };
        struct ast_str *sql;
        int res;
        SQLLEN rowcount = 0;
 
+       ups.tableptr = ast_odbc_find_table(database, table);
+       if (!ups.tableptr) {
+               ast_log(LOG_ERROR, "Could not retrieve metadata for table '%s@%s'. Update will fail!\n", table, database);
+               return -1;
+       }
+
        if (!(obj = ast_odbc_request_obj(database, 0))) {
+               ast_odbc_release_table(ups.tableptr);
                return -1;
        }
 
        if (!(stmt = ast_odbc_prepare_and_execute(obj, update2_prepare, &ups))) {
                ast_odbc_release_obj(obj);
+               ast_odbc_release_table(ups.tableptr);
                return -1;
        }
 
+       /* We don't need the table anymore */
+       ast_odbc_release_table(ups.tableptr);
+
        res = SQLRowCount(stmt, &rowcount);
        SQLFreeHandle(SQL_HANDLE_STMT, stmt);
        ast_odbc_release_obj(obj);
@@ -690,7 +695,7 @@ static int update2_odbc(const char *database, const char *table, const struct as
        }
 
        if (rowcount >= 0) {
-               return (int)rowcount;
+               return (int) rowcount;
        }
 
        return -1;