s3: smbd: Fix Solaris sendfile() for SMB2. Ensure we don't spin on EAGAIN.

For SMB2 the socket is set non-blocking. Ensure sendfile()
calls complete if they return EAGAIN by saving the socket state,
setting it blocking, doing the sendfile until completion and then
restoring the socket state.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13537

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Volker Lendecke <vl@samba.org>
(cherry picked from commit 16a587075c8c62c1160869358ca56a133e90247a)

diff --git a/source3/lib/sendfile.c b/source3/lib/sendfile.c
index f7db57acee1165380f95e73e21daf2812451775a..db66bf72d169aba789bedc9e5334f72e47ff39c3 100644 (file)
--- a/source3/lib/sendfile.c
+++ b/source3/lib/sendfile.c
@@ -169,6 +169,9 @@ ssize_t sys_sendfile(int tofd, int fromfd, const DATA_BLOB *header, off_t offset
        size_t total, xferred;
        struct sendfilevec vec[2];
        ssize_t hdr_len = 0;
+       int old_flags = 0;
+       ssize_t ret = -1;
+       bool socket_flags_changed = false;
 
        if (header) {
                sfvcnt = 2;
@@ -205,17 +208,37 @@ ssize_t sys_sendfile(int tofd, int fromfd, const DATA_BLOB *header, off_t offset
                xferred = 0;
 
                        nwritten = sendfilev(tofd, vec, sfvcnt, &xferred);
-               if  (nwritten == -1 && (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)) {
+               if  (nwritten == -1 && errno == EINTR) {
                        if (xferred == 0)
                                continue; /* Nothing written yet. */
                        else
                                nwritten = xferred;
                }
 
-               if (nwritten == -1)
-                       return -1;
-               if (nwritten == 0)
-                       return -1; /* I think we're at EOF here... */
+               if (nwritten == -1) {
+                       if (errno == EAGAIN || errno == EWOULDBLOCK) {
+                               /*
+                                * Sendfile must complete before we can
+                                * send any other outgoing data on the socket.
+                                * Ensure socket is in blocking mode.
+                                * For SMB2 by default the socket is in
+                                * non-blocking mode.
+                                */
+                               old_flags = fcntl(tofd, F_GETFL, 0);
+                               ret = set_blocking(tofd, true);
+                               if (ret == -1) {
+                                       goto out;
+                               }
+                               socket_flags_changed = true;
+                               continue;
+                       }
+                       ret = -1;
+                       goto out;
+               }
+               if (nwritten == 0) {
+                       ret = -1;
+                       goto out; /* I think we're at EOF here... */
+               }
 
                /*
                 * If this was a short (signal interrupted) write we may need
@@ -237,7 +260,28 @@ ssize_t sys_sendfile(int tofd, int fromfd, const DATA_BLOB *header, off_t offset
                }
                total -= nwritten;
        }
-       return count + hdr_len;
+       ret = count + hdr_len;
+
+  out:
+
+       if (socket_flags_changed) {
+               int saved_errno;
+               int err;
+
+               if (ret == -1) {
+                       saved_errno = errno;
+               }
+               /* Restore the old state of the socket. */
+               err = fcntl(tofd, F_SETFL, old_flags);
+               if (err == -1) {
+                       return -1;
+               }
+               if (ret == -1) {
+                       errno = saved_errno;
+               }
+       }
+
+       return ret;
 }
 
 #elif defined(HPUX_SENDFILE_API)