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authorLaurent Bercot <ska-skaware@skarnet.org>2020-10-26 14:21:53 +0000
committerLaurent Bercot <ska-skaware@skarnet.org>2020-10-26 14:21:53 +0000
commit7530e8cdd506ecec1f4ad3bbd55f94de5a6d63ac (patch)
tree20917d9312d38cf57e04f17cec119d89873b57b3 /src/libunixonacid/ancil_send_fd.c
parentad90bc1107ef9a76f4ca530cc41e86d4f352e3d9 (diff)
downloadskalibs-7530e8cdd506ecec1f4ad3bbd55f94de5a6d63ac.tar.xz
Separate and expose ancil_recv_fd/ancil_send_fd
The goal is to make late channel creation easy, as opposed to textclient which always creates a new channel at start time. This commit also moves posixishard.h inclusions as late as possible.
Diffstat (limited to 'src/libunixonacid/ancil_send_fd.c')
-rw-r--r--src/libunixonacid/ancil_send_fd.c45
1 files changed, 45 insertions, 0 deletions
diff --git a/src/libunixonacid/ancil_send_fd.c b/src/libunixonacid/ancil_send_fd.c
new file mode 100644
index 0000000..98366c7
--- /dev/null
+++ b/src/libunixonacid/ancil_send_fd.c
@@ -0,0 +1,45 @@
+/* ISC license. */
+
+#include <skalibs/nonposix.h>
+
+#include <errno.h>
+#include <string.h>
+#include <sys/uio.h>
+#include <sys/socket.h>
+
+#include <skalibs/djbunix.h>
+#include <skalibs/ancil.h>
+#include <skalibs/posixishard.h>
+
+union aligner_u
+{
+ struct cmsghdr cmsghdr ;
+ int i ;
+} ;
+
+int ancil_send_fd (int sock, int fd, char ch)
+{
+ ssize_t r ;
+ struct iovec v = { .iov_base = &ch, .iov_len = 1 } ;
+ union aligner_u ancilbuf[1 + (CMSG_SPACE(sizeof(int)) - 1) / sizeof(union aligner_u)] ;
+ struct msghdr hdr =
+ {
+ .msg_name = 0,
+ .msg_namelen = 0,
+ .msg_iov = &v,
+ .msg_iovlen = 1,
+ .msg_control = ancilbuf,
+ .msg_controllen = CMSG_SPACE(sizeof(int))
+ } ;
+ struct cmsghdr *c = CMSG_FIRSTHDR(&hdr) ;
+ memset(hdr.msg_control, 0, hdr.msg_controllen) ;
+ c->cmsg_level = SOL_SOCKET ;
+ c->cmsg_type = SCM_RIGHTS ;
+ c->cmsg_len = CMSG_LEN(sizeof(int)) ;
+ *(int *)CMSG_DATA(c) = fd ;
+ do r = sendmsg(sock, &hdr, MSG_NOSIGNAL) ;
+ while (r < 0 && errno == EINTR) ;
+ if (r <= 0) return 0 ;
+ fd_close(fd) ;
+ return 1 ;
+}