[PATCH] blktap2: update connection handling to fix build with gcc5

* [PATCH] blktap2: update connection handling to fix build with gcc5
@ 2015-07-19  9:33 Olaf Hering
  2015-07-20  9:09 ` Jan Beulich
  0 siblings, 1 reply; 12+ messages in thread
From: Olaf Hering @ 2015-07-19  9:33 UTC (permalink / raw)
  To: xen-devel
  Cc: Wei Liu, Olaf Hering, Ian Jackson, Ian Campbell, Stefano Stabellini

blktap2 fails to build with gcc5 because it fails to recognize that
there can be just one active connection (enforced in ctl_accept).

Rearrange the code to handle just a single connection.
Adjust two strerror calls to use errno instead -1 as input.

[  198s] block-log.c: In function 'ctl_close_sock':
[  198s] block-log.c:363:23: error: array subscript is above array bounds [-Werror=array-bounds]
[  198s]      if (s->connections[i].fd == fd) {
[  198s]                        ^
[  198s] block-log.c: In function 'ctl_request':
[  198s] block-log.c:549:23: error: array subscript is above array bounds [-Werror=array-bounds]
[  198s]      if (s->connections[i].id == id)
[  198s]                        ^
[  198s] cc1: all warnings being treated as errors
[  198s] /home/abuild/rpmbuild/BUILD/xen-4.6.31382/non-dbg/tools/blktap2/drivers/../../../tools/Rules.mk:107: recipe for target 'block-log.o' failed
[  198s] make[5]: *** [block-log.o] Error 1

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
---

This is just compile tested.


 tools/blktap2/drivers/block-log.c | 49 +++++++++++++++++----------------------
 1 file changed, 21 insertions(+), 28 deletions(-)

diff --git a/tools/blktap2/drivers/block-log.c b/tools/blktap2/drivers/block-log.c
index 5330cdc..10a6966 100644
--- a/tools/blktap2/drivers/block-log.c
+++ b/tools/blktap2/drivers/block-log.c
@@ -54,8 +54,6 @@
 #include "tapdisk-driver.h"
 #include "tapdisk-interface.h"
 
-#define MAX_CONNECTIONS 1
-
 typedef struct poll_fd {
   int          fd;
   event_id_t   id;
@@ -69,8 +67,7 @@ struct tdlog_state {
   char*        ctlpath;
   poll_fd_t    ctl;
 
-  int          connected;
-  poll_fd_t    connections[MAX_CONNECTIONS];
+  poll_fd_t    connection;
 
   char*        shmpath;
   void*        shm;
@@ -305,7 +302,7 @@ static int ctl_open(struct tdlog_state* s, const char* name)
   s->ctl.id = tapdisk_server_register_event(SCHEDULER_POLL_READ_FD,
 					    s->ctl.fd, 0, ctl_accept, s);
   if (s->ctl.id < 0) {
-    BWPRINTF("error register event handler: %s", strerror(s->ctl.id));
+    BWPRINTF("error register event handler: %s", strerror(errno));
     goto err_sock;
   }
 
@@ -323,12 +320,11 @@ static int ctl_open(struct tdlog_state* s, const char* name)
 
 static int ctl_close(struct tdlog_state* s)
 {
-  while (s->connected) {
-    s->connected--;
-    tapdisk_server_unregister_event(s->connections[s->connected].id);
-    close(s->connections[s->connected].fd);
-    s->connections[s->connected].fd = -1;
-    s->connections[s->connected].id = 0;
+  if (s->connection.fd >= 0) {
+    tapdisk_server_unregister_event(s->connection.id);
+    close(s->connection.fd);
+    s->connection.fd = -1;
+    s->connection.id = 0;
   }
 
   if (s->ctl.fd >= 0) {
@@ -359,15 +355,12 @@ static int ctl_close_sock(struct tdlog_state* s, int fd)
 {
   int i;
 
-  for (i = 0; i < s->connected; i++) {
-    if (s->connections[i].fd == fd) {
-      tapdisk_server_unregister_event(s->connections[i].id);
-      close(s->connections[i].fd);
-      s->connections[i].fd = -1;
-      s->connections[i].id = 0;
-      s->connected--;
-      return 0;
-    }
+  if (fd >= 0 && s->connection.fd == fd) {
+    tapdisk_server_unregister_event(s->connection.id);
+    close(s->connection.fd);
+    s->connection.fd = -1;
+    s->connection.id = 0;
+    return 0;
   }
 
   BWPRINTF("requested to close unknown socket %d", fd);
@@ -385,7 +378,7 @@ static void ctl_accept(event_id_t id, char mode, void *private)
     return;
   }
 
-  if (s->connected) {
+  if (s->connection.fd >= 0) {
     BWPRINTF("control session in progress, closing new connection");
     close(fd);
     return;
@@ -394,14 +387,13 @@ static void ctl_accept(event_id_t id, char mode, void *private)
   cid = tapdisk_server_register_event(SCHEDULER_POLL_READ_FD,
 				      fd, 0, ctl_request, s);
   if (cid < 0) {
-    BWPRINTF("error registering connection event handler: %s", strerror(cid));
+    BWPRINTF("error registering connection event handler: %s", strerror(errno));
     close(fd);
     return;
   }
 
-  s->connections[s->connected].fd = fd;
-  s->connections[s->connected].id = cid;
-  s->connected++;
+  s->connection.fd = fd;
+  s->connection.id = cid;
 }
 
 /* response format: 4 bytes shmsize, 0-terminated path */
@@ -545,9 +537,8 @@ static inline int ctl_find_connection(struct tdlog_state *s, event_id_t id)
 {
   int i;
 
-  for (i = 0; i < s->connected; i++)
-    if (s->connections[i].id == id)
-      return s->connections[i].fd;
+  if (s->connection.fd >= 0 && s->connection.id == id)
+      return s->connection.fd;
 
   BWPRINTF("unrecognized event callback id %d", id);
   return -1;
@@ -593,6 +584,8 @@ static int tdlog_open(td_driver_t* driver, const char* name, td_flag_t flags)
   memset(s, 0, sizeof(*s));
 
   s->size = driver->info.size;
+  s->connection.fd = -1;
+  s->ctl.fd = -1;
 
   if ((rc = writelog_create(s))) {
     tdlog_close(driver);

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