increase sendmsg internal buffer to support SCM_MAX_FD

[musl] / src / network / sendmsg.c

diff --git a/src/network/sendmsg.c b/src/network/sendmsg.c
index 80cc5f4..acdfdf2 100644 (file)
--- a/src/network/sendmsg.c
+++ b/src/network/sendmsg.c
@@ -8,13 +8,16 @@ ssize_t sendmsg(int fd, const struct msghdr *msg, int flags)
 {
 #if LONG_MAX > INT_MAX
        struct msghdr h;
-       struct cmsghdr chbuf[1024/sizeof(struct cmsghdr)+1], *c;
+       /* Kernels before 2.6.38 set SCM_MAX_FD to 255, allocate enough
+        * space to support an SCM_RIGHTS ancillary message with 255 fds.
+        * Kernels since 2.6.38 set SCM_MAX_FD to 253. */
+       struct cmsghdr chbuf[CMSG_SPACE(255*sizeof(int))/sizeof(struct cmsghdr)+1], *c;
        if (msg) {
                h = *msg;
                h.__pad1 = h.__pad2 = 0;
                msg = &h;
                if (h.msg_controllen) {
-                       if (h.msg_controllen > 1024) {
+                       if (h.msg_controllen > sizeof chbuf) {
                                errno = ENOMEM;
                                return -1;
                        }