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#ifndef __sys
#error "The __sys macro is required"
#endif
static void scm_fdset_init_chunk(struct scm_fdset *fdset, int nr_fds, void *data, unsigned ch_size)
{
struct cmsghdr *cmsg;
static char dummy;
fdset->hdr.msg_controllen = CMSG_LEN(sizeof(int) * nr_fds);
cmsg = CMSG_FIRSTHDR(&fdset->hdr);
cmsg->cmsg_len = fdset->hdr.msg_controllen;
if (data) {
fdset->iov.iov_base = data;
fdset->iov.iov_len = nr_fds * ch_size;
} else {
fdset->iov.iov_base = &dummy;
fdset->iov.iov_len = 1;
}
}
static int *scm_fdset_init(struct scm_fdset *fdset, struct sockaddr_un *saddr, int saddr_len)
{
struct cmsghdr *cmsg;
BUILD_BUG_ON(sizeof(fdset->msg_buf) < (CMSG_SPACE(sizeof(int) * CR_SCM_MAX_FD)));
fdset->iov.iov_base = (void *)0xdeadbeef;
fdset->hdr.msg_iov = &fdset->iov;
fdset->hdr.msg_iovlen = 1;
fdset->hdr.msg_name = (struct sockaddr *)saddr;
fdset->hdr.msg_namelen = saddr_len;
fdset->hdr.msg_control = &fdset->msg_buf;
fdset->hdr.msg_controllen = CMSG_LEN(sizeof(int) * CR_SCM_MAX_FD);
cmsg = CMSG_FIRSTHDR(&fdset->hdr);
cmsg->cmsg_len = fdset->hdr.msg_controllen;
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
return (int *)CMSG_DATA(cmsg);
}
int send_fds(int sock, struct sockaddr_un *saddr, int len, int *fds, int nr_fds, void *data, unsigned ch_size)
{
/* In musl_libc the msghdr structure has pads which has to be zeroed */
struct scm_fdset fdset = {};
int *cmsg_data;
int i, min_fd, ret;
cmsg_data = scm_fdset_init(&fdset, saddr, len);
for (i = 0; i < nr_fds; i += min_fd) {
min_fd = min(CR_SCM_MAX_FD, nr_fds - i);
scm_fdset_init_chunk(&fdset, min_fd, data, ch_size);
memcpy(cmsg_data, &fds[i], sizeof(int) * min_fd);
ret = __sys(sendmsg)(sock, &fdset.hdr, 0);
if (ret <= 0)
return ret ?: -1;
if (data)
data += min_fd * ch_size;
}
return 0;
}
int __recv_fds(int sock, int *fds, int nr_fds, void *data, unsigned ch_size, int flags)
{
/* In musl_libc the msghdr structure has pads which has to be zeroed */
struct scm_fdset fdset = {};
struct cmsghdr *cmsg;
int *cmsg_data;
int ret;
int i, min_fd;
cmsg_data = scm_fdset_init(&fdset, NULL, 0);
for (i = 0; i < nr_fds; i += min_fd) {
min_fd = min(CR_SCM_MAX_FD, nr_fds - i);
scm_fdset_init_chunk(&fdset, min_fd, data, ch_size);
ret = __sys(recvmsg)(sock, &fdset.hdr, flags);
if (ret <= 0)
return ret ? __sys_err(ret) : -ENOMSG;
cmsg = CMSG_FIRSTHDR(&fdset.hdr);
if (!cmsg || cmsg->cmsg_type != SCM_RIGHTS)
return -EINVAL;
if (fdset.hdr.msg_flags & MSG_CTRUNC)
return -ENFILE;
min_fd = (cmsg->cmsg_len - sizeof(struct cmsghdr)) / sizeof(int);
/*
* In case if kernel screwed the recipient, most probably
* the caller stack frame will be overwritten, just scream
* and exit.
*
* FIXME Need to sanitize util.h to be able to include it
* into files which do not have glibc and a couple of
* sys_write_ helpers. Meawhile opencoded BUG_ON here.
*/
BUG_ON(min_fd > CR_SCM_MAX_FD);
if (unlikely(min_fd <= 0))
return -EBADFD;
memcpy(&fds[i], cmsg_data, sizeof(int) * min_fd);
if (data)
data += ch_size * min_fd;
}
return 0;
}
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