From cd5f1904032e9fcb62ad8094addc841a6b9cb73a Mon Sep 17 00:00:00 2001
From: Amitay Isaacs <amitay@gmail.com>
Date: Wed, 11 Jul 2018 18:35:46 +1000
Subject: ctdb-protocol: Avoid fgets in ctdb_connection_list_read

C library buffering API can behave in unexpected fashion if underlying
fd for stdin, stdout or stderr is closed and re-opened.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13520

Signed-off-by: Amitay Isaacs <amitay@gmail.com>
Reviewed-by: Martin Schwenke <martin@meltin.net>
(cherry picked from commit c9b42d27e6cf9e6ae36f44970f0a388edc737a7a)
---
 ctdb/protocol/protocol_util.c | 86 ++++++++++++++++++++++++-------------------
 ctdb/wscript                  |  4 +-
 2 files changed, 51 insertions(+), 39 deletions(-)

diff --git a/ctdb/protocol/protocol_util.c b/ctdb/protocol/protocol_util.c
index c75555fa734..45c639d747f 100644
--- a/ctdb/protocol/protocol_util.c
+++ b/ctdb/protocol/protocol_util.c
@@ -22,6 +22,8 @@
 
 #include <talloc.h>
 
+#include "common/line.h"
+
 #include "protocol.h"
 #include "protocol_util.h"
 
@@ -603,56 +605,66 @@ const char *ctdb_connection_list_to_string(
 	return out;
 }
 
-int ctdb_connection_list_read(TALLOC_CTX *mem_ctx, bool client_first,
-			      struct ctdb_connection_list **conn_list)
-{
+struct ctdb_connection_list_read_state {
 	struct ctdb_connection_list *list;
-	char line[128]; /* long enough for IPv6 */
+	bool client_first;
+};
+
+static int ctdb_connection_list_read_line(char *line, void *private_data)
+{
+	struct ctdb_connection_list_read_state *state =
+		(struct ctdb_connection_list_read_state *)private_data;
+	struct ctdb_connection conn;
 	int ret;
 
-	if (conn_list == NULL) {
-		return EINVAL;
+	/* Skip empty lines */
+	if (line[0] == '\0') {
+		return 0;
 	}
 
-	list = talloc_zero(mem_ctx, struct ctdb_connection_list);
-	if (list == NULL) {
-		return ENOMEM;
+	/* Comment */
+	if (line[0] == '#') {
+		return 0;
 	}
 
-	while (fgets(line, sizeof(line), stdin) != NULL) {
-		char *t;
-		struct ctdb_connection conn;
+	ret = ctdb_connection_from_string(line, state->client_first, &conn);
+	if (ret != 0) {
+		return ret;
+	}
 
-		/* Skip empty lines */
-		if (line[0] == '\n') {
-			continue;
-		}
+	ret = ctdb_connection_list_add(state->list, &conn);
+	if (ret != 0) {
+		return ret;
+	}
 
-		/* Comment */
-		if (line[0] == '#') {
-			continue;
-		}
+	return 0;
+}
 
-		t = strtok(line, "\n");
-		if (t == NULL) {
-			goto fail;
-		}
+int ctdb_connection_list_read(TALLOC_CTX *mem_ctx, bool client_first,
+			      struct ctdb_connection_list **conn_list)
+{
+	struct ctdb_connection_list_read_state state;
+	int ret;
 
-		ret = ctdb_connection_from_string(t, client_first, &conn);
-		if (ret != 0) {
-			goto fail;
-		}
+	if (conn_list == NULL) {
+		return EINVAL;
+	}
 
-		ret = ctdb_connection_list_add(list, &conn);
-		if (ret != 0) {
-			goto fail;
-		}
+	state.list = talloc_zero(mem_ctx, struct ctdb_connection_list);
+	if (state.list == NULL) {
+		return ENOMEM;
 	}
 
-	*conn_list = list;
-	return 0;
+	state.client_first = client_first;
+
+	ret = line_read(0,
+			128,
+			mem_ctx,
+			ctdb_connection_list_read_line,
+			&state,
+			NULL);
 
-fail:
-	talloc_free(list);
-	return EINVAL;
+	*conn_list = state.list;
+
+	return ret;
 }
diff --git a/ctdb/wscript b/ctdb/wscript
index e3bcdf7e962..8727fd8aefa 100644
--- a/ctdb/wscript
+++ b/ctdb/wscript
@@ -433,7 +433,7 @@ def build(bld):
 
     bld.SAMBA_SUBSYSTEM('ctdb-protocol-util',
                         source='protocol/protocol_util.c',
-                        deps='replace talloc tdb')
+                        deps='ctdb-util replace talloc tdb')
 
     bld.SAMBA_SUBSYSTEM('ctdb-client',
                         source=bld.SUBDIR('client', 'ctdb_client.c'),
@@ -824,7 +824,7 @@ def build(bld):
         bld.SAMBA_BINARY(target,
                          source=src,
                          deps='''protocol-tests-common
-                                 samba-util talloc tdb''',
+                                 samba-util ctdb-util talloc tdb''',
                          install_path='${CTDB_TEST_LIBEXECDIR}')
 
     bld.SAMBA_SUBSYSTEM('ctdb-tests-common',
-- 
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