Add configure option to enable or disable fd passing with sendmsg

[free-sw/xcb/libxcb] / src / xcb_conn.c

diff --git a/src/xcb_conn.c b/src/xcb_conn.c
index f2a2636..50e7fb6 100644 (file)
--- a/src/xcb_conn.c
+++ b/src/xcb_conn.c
@@ -25,6 +25,10 @@
 
 /* Connection management: the core of XCB. */
 
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
 #include <assert.h>
 #include <string.h>
 #include <stdio.h>
@@ -32,6 +36,7 @@
 #include <stdlib.h>
 #include <fcntl.h>
 #include <errno.h>
+#include <limits.h>
 
 #include "xcb.h"
 #include "xcbint.h"
@@ -44,6 +49,7 @@
 #ifdef _WIN32
 #include "xcb_windefs.h"
 #else
+#include <sys/socket.h>
 #include <netinet/in.h>
 #endif /* _WIN32 */
 
@@ -58,7 +64,10 @@ typedef struct {
     uint16_t length;
 } xcb_setup_generic_t;
 
-static const int error_connection = 1;
+static const int xcb_con_error = XCB_CONN_ERROR;
+static const int xcb_con_closed_mem_er = XCB_CONN_CLOSED_MEM_INSUFFICIENT;
+static const int xcb_con_closed_parse_er = XCB_CONN_CLOSED_PARSE_ERR;
+static const int xcb_con_closed_screen_er = XCB_CONN_CLOSED_INVALID_SCREEN;
 
 static int set_fd_flags(const int fd)
 {
@@ -201,14 +210,48 @@ static int write_vec(xcb_connection_t *c, struct iovec **vector, int *count)
          i++;
     }
 #else
-    n = writev(c->fd, *vector, *count);
-    if(n < 0 && errno == EAGAIN)
-        return 1;
+    n = *count;
+    if (n > IOV_MAX)
+       n = IOV_MAX;
+
+#if HAVE_SENDMSG
+    if (c->out.out_fd.nfd) {
+        char cmsgbuf[CMSG_SPACE(sizeof(int) * XCB_MAX_PASS_FD)];
+        struct msghdr msg = {
+            .msg_name = NULL,
+            .msg_namelen = 0,
+            .msg_iov = *vector,
+            .msg_iovlen = n,
+            .msg_control = cmsgbuf,
+            .msg_controllen = CMSG_LEN(c->out.out_fd.nfd * sizeof (int)),
+        };
+        int i;
+        struct cmsghdr *hdr = CMSG_FIRSTHDR(&msg);
+
+        hdr->cmsg_len = msg.msg_controllen;
+        hdr->cmsg_level = SOL_SOCKET;
+        hdr->cmsg_type = SCM_RIGHTS;
+        memcpy(CMSG_DATA(hdr), c->out.out_fd.fd, c->out.out_fd.nfd * sizeof (int));
+
+        n = sendmsg(c->fd, &msg, 0);
+        if(n < 0 && errno == EAGAIN)
+            return 1;
+        for (i = 0; i < c->out.out_fd.nfd; i++)
+            close(c->out.out_fd.fd[i]);
+        c->out.out_fd.nfd = 0;
+    } else
+#endif
+    {
+        n = writev(c->fd, *vector, n);
+        if(n < 0 && errno == EAGAIN)
+            return 1;
+    }
+
 #endif /* _WIN32 */    
 
     if(n <= 0)
     {
-        _xcb_conn_shutdown(c);
+        _xcb_conn_shutdown(c, XCB_CONN_ERROR);
         return 0;
     }
 
@@ -257,18 +300,20 @@ xcb_connection_t *xcb_connect_to_fd(int fd, xcb_auth_info_t *auth_info)
 {
     xcb_connection_t* c;
 
+#ifndef _WIN32
 #ifndef USE_POLL
     if(fd >= FD_SETSIZE) /* would overflow in FD_SET */
     {
         close(fd);
-        return (xcb_connection_t *) &error_connection;
+        return _xcb_conn_ret_error(XCB_CONN_ERROR);
     }
 #endif
+#endif /* !_WIN32*/
 
     c = calloc(1, sizeof(xcb_connection_t));
     if(!c) {
         close(fd);
-        return (xcb_connection_t *) &error_connection;
+        return _xcb_conn_ret_error(XCB_CONN_CLOSED_MEM_INSUFFICIENT) ;
     }
 
     c->fd = fd;
@@ -285,7 +330,7 @@ xcb_connection_t *xcb_connect_to_fd(int fd, xcb_auth_info_t *auth_info)
         ))
     {
         xcb_disconnect(c);
-        return (xcb_connection_t *) &error_connection;
+        return _xcb_conn_ret_error(XCB_CONN_ERROR);
     }
 
     return c;
@@ -310,13 +355,46 @@ void xcb_disconnect(xcb_connection_t *c)
     _xcb_xid_destroy(c);
 
     free(c);
+
+#ifdef _WIN32
+    WSACleanup();
+#endif
 }
 
 /* Private interface */
 
-void _xcb_conn_shutdown(xcb_connection_t *c)
+void _xcb_conn_shutdown(xcb_connection_t *c, int err)
 {
-    c->has_error = 1;
+    c->has_error = err;
+}
+
+/* Return connection error state.
+ * To make thread-safe, I need a seperate static
+ * variable for every possible error.
+ */
+xcb_connection_t *_xcb_conn_ret_error(int err)
+{
+
+    switch(err)
+    {
+        case XCB_CONN_CLOSED_MEM_INSUFFICIENT:
+        {
+            return (xcb_connection_t *) &xcb_con_closed_mem_er;
+        }
+        case XCB_CONN_CLOSED_PARSE_ERR:
+        {
+            return (xcb_connection_t *) &xcb_con_closed_parse_er;
+        }
+        case XCB_CONN_CLOSED_INVALID_SCREEN:
+        {
+            return (xcb_connection_t *) &xcb_con_closed_screen_er;
+        }
+        case XCB_CONN_ERROR:
+        default:
+        {
+            return (xcb_connection_t *) &xcb_con_error;
+        }
+    }
 }
 
 int _xcb_conn_wait(xcb_connection_t *c, pthread_cond_t *cond, struct iovec **vector, int *count)
@@ -377,22 +455,32 @@ int _xcb_conn_wait(xcb_connection_t *c, pthread_cond_t *cond, struct iovec **vec
     } while (ret == -1 && errno == EINTR);
     if(ret < 0)
     {
-        _xcb_conn_shutdown(c);
+        _xcb_conn_shutdown(c, XCB_CONN_ERROR);
         ret = 0;
     }
     pthread_mutex_lock(&c->iolock);
 
     if(ret)
     {
+        /* The code allows two threads to call select()/poll() at the same time.
+         * First thread just wants to read, a second thread wants to write, too.
+         * We have to make sure that we don't steal the reading thread's reply
+         * and let it get stuck in select()/poll().
+         * So a thread may read if either:
+         * - There is no other thread that wants to read (the above situation
+         *   did not occur).
+         * - It is the reading thread (above situation occurred).
+         */
+        int may_read = c->in.reading == 1 || !count;
 #if USE_POLL
-        if((fd.revents & POLLIN) == POLLIN)
+        if(may_read && (fd.revents & POLLIN) != 0)
 #else
-        if(FD_ISSET(c->fd, &rfds))
+        if(may_read && FD_ISSET(c->fd, &rfds))
 #endif
             ret = ret && _xcb_in_read(c);
 
 #if USE_POLL
-        if((fd.revents & POLLOUT) == POLLOUT)
+        if((fd.revents & POLLOUT) != 0)
 #else
         if(FD_ISSET(c->fd, &wfds))
 #endif