2f50736782
Turns out this is necessary even if the fd is going to be passed through exec() soon, because the supervisor might receive multiple fds before spawning another process, in which case all of them are going to be passed to the new process instead of just one.
77 lines
2 KiB
C
77 lines
2 KiB
C
/* File descriptor passing based on
|
|
* https://manned.org/man.c2c6968a/cmsg.3 */
|
|
|
|
static ssize_t fufdpass_send(int socket, int fd, const char *buf, size_t buflen) {
|
|
union {
|
|
char buf[CMSG_SPACE(sizeof(int))];
|
|
struct cmsghdr align;
|
|
} cmsgbuf = {};
|
|
|
|
struct iovec iov;
|
|
iov.iov_base = (char *)buf;
|
|
iov.iov_len = buflen;
|
|
|
|
struct msghdr msg;
|
|
msg.msg_name = NULL;
|
|
msg.msg_namelen = 0;
|
|
msg.msg_iov = &iov;
|
|
msg.msg_iovlen = 1;
|
|
msg.msg_control = cmsgbuf.buf;
|
|
msg.msg_controllen = sizeof(cmsgbuf.buf);
|
|
msg.msg_flags = 0;
|
|
|
|
struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
|
|
cmsg->cmsg_level = SOL_SOCKET;
|
|
cmsg->cmsg_type = SCM_RIGHTS;
|
|
cmsg->cmsg_len = CMSG_LEN(sizeof(int));
|
|
memcpy(CMSG_DATA(cmsg), &fd, sizeof(int));
|
|
|
|
return sendmsg(socket, &msg, 0);
|
|
}
|
|
|
|
static int fufdpass_recv(pTHX_ I32 ax, int socket, size_t len) {
|
|
if (GIMME_V != G_LIST)
|
|
fu_confess("Invalid use of fdpass_recv() in scalar context");
|
|
|
|
union {
|
|
char buf[CMSG_SPACE(sizeof(int))];
|
|
struct cmsghdr align;
|
|
} cmsgbuf;
|
|
|
|
SV *buf = sv_2mortal(newSV(len));
|
|
SvPOK_only(buf);
|
|
struct iovec iov;
|
|
iov.iov_base = SvPVX(buf);
|
|
iov.iov_len = len;
|
|
|
|
struct msghdr msg;
|
|
msg.msg_name = NULL;
|
|
msg.msg_namelen = 0;
|
|
msg.msg_iov = &iov;
|
|
msg.msg_iovlen = 1;
|
|
msg.msg_control = cmsgbuf.buf;
|
|
msg.msg_controllen = sizeof(cmsgbuf.buf);
|
|
msg.msg_flags = 0;
|
|
|
|
ssize_t r = recvmsg(socket, &msg, MSG_CMSG_CLOEXEC);
|
|
if (r < 0) {
|
|
ST(0) = &PL_sv_undef;
|
|
ST(1) = &PL_sv_undef;
|
|
return 2;
|
|
}
|
|
|
|
struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
|
|
if (cmsg == NULL || cmsg->cmsg_level != SOL_SOCKET
|
|
|| cmsg->cmsg_type != SCM_RIGHTS || cmsg->cmsg_len != CMSG_LEN(sizeof(int))) {
|
|
ST(0) = &PL_sv_undef;
|
|
} else {
|
|
int fd;
|
|
memcpy(&fd, CMSG_DATA(cmsg), sizeof(int));
|
|
ST(0) = sv_2mortal(newSViv(fd));
|
|
}
|
|
|
|
SvCUR_set(buf, r);
|
|
SvPVX(buf)[r] = 0;
|
|
ST(1) = buf;
|
|
return 2;
|
|
}
|