From 9ae83505d8025ab32a8bdf7904ff4df8f9e661bf Mon Sep 17 00:00:00 2001
From: Sebastian Harl <sh@tokkee.org>
Date: Mon, 31 Mar 2014 23:17:34 +0200
Subject: [PATCH] frontend: Added 'FETCH <name>' query command.

For now, <name> may only be a simple identifier.
---
 src/frontend/connection-private.h | 18 ++++++++++++
 src/frontend/grammar.y            | 16 ++++++++++-
 src/frontend/query.c              | 46 +++++++++++++++++++++++++++++++
 src/frontend/scanner.l            |  2 ++
 src/include/frontend/connection.h | 11 ++++++++
 src/include/frontend/proto.h      |  2 ++
 6 files changed, 94 insertions(+), 1 deletion(-)

diff --git a/src/frontend/connection-private.h b/src/frontend/connection-private.h
index 82cece9..534d3cb 100644
--- a/src/frontend/connection-private.h
+++ b/src/frontend/connection-private.h
@@ -41,6 +41,8 @@
 #include <inttypes.h>
 #include <arpa/inet.h>
 
+#include <stdlib.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -73,12 +75,28 @@ struct sdb_conn {
  * node types
  */
 
+typedef struct {
+	sdb_conn_node_t super;
+	char *name;
+} conn_fetch_t;
+#define CONN_FETCH(obj) ((conn_fetch_t *)(obj))
+
 typedef struct {
 	sdb_conn_node_t super;
 	sdb_store_matcher_t *matcher;
 } conn_node_matcher_t;
 #define CONN_MATCHER(obj) ((conn_node_matcher_t *)(obj))
 
+/*
+ * type helper functions
+ */
+static void __attribute__((unused))
+conn_fetch_destroy(sdb_object_t *obj)
+{
+	if (CONN_FETCH(obj)->name)
+		free(CONN_FETCH(obj)->name);
+} /* conn_fetch_destroy */
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif
diff --git a/src/frontend/grammar.y b/src/frontend/grammar.y
index 551d171..004a5ef 100644
--- a/src/frontend/grammar.y
+++ b/src/frontend/grammar.y
@@ -37,6 +37,7 @@
 #include "utils/llist.h"
 
 #include <stdio.h>
+#include <string.h>
 
 int
 sdb_fe_yylex(YYSTYPE *yylval, YYLTYPE *yylloc, sdb_fe_yyscan_t yyscanner);
@@ -75,10 +76,11 @@ sdb_fe_yyerror(YYLTYPE *lval, sdb_fe_yyscan_t scanner, const char *msg);
 %token SCANNER_ERROR
 
 %token <str> IDENTIFIER
-%token <node> LIST
+%token <node> FETCH LIST
 
 %type <list> statements
 %type <node> statement
+	fetch_statement
 	list_statement
 	expression
 
@@ -135,6 +137,8 @@ statements:
 	;
 
 statement:
+	fetch_statement
+	|
 	list_statement
 	|
 	/* empty */
@@ -143,6 +147,16 @@ statement:
 		}
 	;
 
+fetch_statement:
+	FETCH IDENTIFIER
+		{
+			$$ = SDB_CONN_NODE(sdb_object_create_dT(/* name = */ NULL,
+						conn_fetch_t, conn_fetch_destroy));
+			CONN_FETCH($$)->name = strdup($2);
+			$$->cmd = CONNECTION_FETCH;
+		}
+	;
+
 list_statement:
 	LIST
 		{
diff --git a/src/frontend/query.c b/src/frontend/query.c
index ffec03a..96c46d2 100644
--- a/src/frontend/query.c
+++ b/src/frontend/query.c
@@ -45,6 +45,8 @@ sdb_fe_exec(sdb_conn_t *conn, sdb_conn_node_t *node)
 		return -1;
 
 	switch (node->cmd) {
+		case CONNECTION_FETCH:
+			return sdb_fe_fetch(conn, CONN_FETCH(node)->name);
 		case CONNECTION_LIST:
 			return sdb_fe_list(conn);
 
@@ -55,6 +57,50 @@ sdb_fe_exec(sdb_conn_t *conn, sdb_conn_node_t *node)
 	return -1;
 } /* sdb_fe_exec */
 
+int
+sdb_fe_fetch(sdb_conn_t *conn, const char *name)
+{
+	sdb_strbuf_t *buf;
+	sdb_store_base_t *host;
+
+	host = sdb_store_get_host(name);
+	if (! host) {
+		sdb_log(SDB_LOG_DEBUG, "frontend: Failed to fetch host '%s': "
+				"not found", name);
+
+		sdb_strbuf_sprintf(conn->errbuf, "Host %s not found", name);
+		return -1;
+	}
+
+	buf = sdb_strbuf_create(1024);
+	if (! buf) {
+		char errbuf[1024];
+		sdb_log(SDB_LOG_ERR, "frontend: Failed to create "
+				"buffer to handle FETCH command: %s",
+				sdb_strerror(errno, errbuf, sizeof(errbuf)));
+
+		sdb_strbuf_sprintf(conn->errbuf, "Out of memory");
+		sdb_strbuf_destroy(buf);
+		sdb_object_deref(SDB_OBJ(host));
+		return -1;
+	}
+
+	if (sdb_store_host_tojson(host, buf, /* flags = */ 0)) {
+		sdb_log(SDB_LOG_ERR, "frontend: Failed to serialize "
+				"host '%s' to JSON", name);
+		sdb_strbuf_sprintf(conn->errbuf, "Out of memory");
+		sdb_strbuf_destroy(buf);
+		sdb_object_deref(SDB_OBJ(host));
+		return -1;
+	}
+
+	sdb_connection_send(conn, CONNECTION_OK,
+			(uint32_t)sdb_strbuf_len(buf), sdb_strbuf_string(buf));
+	sdb_strbuf_destroy(buf);
+	sdb_object_deref(SDB_OBJ(host));
+	return 0;
+} /* sdb_fe_fetch */
+
 int
 sdb_fe_list(sdb_conn_t *conn)
 {
diff --git a/src/frontend/scanner.l b/src/frontend/scanner.l
index 87367f6..c279a48 100644
--- a/src/frontend/scanner.l
+++ b/src/frontend/scanner.l
@@ -92,6 +92,8 @@ identifier	([A-Za-z_][A-Za-z_0-9$]*)
 		/* XXX */
 		if (! strcasecmp(yytext, "LIST"))
 			return LIST;
+		else if (! strcasecmp(yytext, "FETCH"))
+			return FETCH;
 
 		yylval->str = strdup(yytext);
 		return IDENTIFIER;
diff --git a/src/include/frontend/connection.h b/src/include/frontend/connection.h
index dc93db6..bf902dd 100644
--- a/src/include/frontend/connection.h
+++ b/src/include/frontend/connection.h
@@ -164,6 +164,17 @@ sdb_fe_session_start(sdb_conn_t *conn);
  * store access
  */
 
+/*
+ * sdb_fe_fetch:
+ * Send the named host, serialized as JSON, to the client.
+ *
+ * Returns:
+ *  - 0 on success
+ *  - a negative value else
+ */
+int
+sdb_fe_fetch(sdb_conn_t *conn, const char *name);
+
 /*
  * sdb_fe_list:
  * Send a complete listing of the store, serialized as JSON, to the client.
diff --git a/src/include/frontend/proto.h b/src/include/frontend/proto.h
index 76d1997..132e10c 100644
--- a/src/include/frontend/proto.h
+++ b/src/include/frontend/proto.h
@@ -49,6 +49,8 @@ typedef enum {
 
 	/* querying */
 	CONNECTION_QUERY,
+	/* query commands */
+	CONNECTION_FETCH,
 	CONNECTION_LIST,
 
 	/* command elements */
-- 
2.30.2