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/* ISC license. */
#include <skalibs/sysdeps.h>
#include <skalibs/nonposix.h>
#include <errno.h>
#include <string.h>
#include <sys/uio.h>
#include <sys/socket.h>
#include <skalibs/allreadwrite.h>
#include <skalibs/djbunix.h>
#include <skalibs/ancil.h>
#include <skalibs/posixishard.h>
union aligner_u
{
struct cmsghdr cmsghdr ;
int i ;
} ;
int ancil_recv_fd (int sock, char expected_ch)
{
static int const awesomeflags =
#ifdef SKALIBS_HASMSGDONTWAIT
MSG_DONTWAIT
#else
0
#endif
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#ifdef SKALIBS_HASCMSGCLOEXEC
MSG_CMSG_CLOEXEC
#else
0
#endif
;
int fd ;
struct cmsghdr *c ;
ssize_t r ;
char ch ;
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 msghdr =
{
.msg_name = 0,
.msg_namelen = 0,
.msg_iov = &v,
.msg_iovlen = 1,
.msg_flags = 0,
.msg_control = ancilbuf,
.msg_controllen = CMSG_SPACE(sizeof(int))
} ;
do r = recvmsg(sock, &msghdr, awesomeflags) ;
while (r < 0 && errno == EINTR) ;
if (r < 0) return r ;
if (!r) return (errno = EPIPE, -1) ;
c = CMSG_FIRSTHDR(&msghdr) ;
if (ch != expected_ch
|| !c
|| c->cmsg_level != SOL_SOCKET
|| c->cmsg_type != SCM_RIGHTS
|| (size_t)(c->cmsg_len - (CMSG_DATA(c) - (unsigned char *)c)) != sizeof(int)) return (errno = EPROTO, -1) ;
memcpy(&fd, CMSG_DATA(c), sizeof(int)) ;
#ifndef SKALIBS_HASCMSGCLOEXEC
if (coe(fd) < 0)
{
fd_close(fd) ;
return -1 ;
}
#endif
return fd ;
}
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