From c17c44d9e0ef28f0f0521656f335f836ad8b7754 Mon Sep 17 00:00:00 2001 From: Eric Wong Date: Sun, 10 Jan 2021 12:15:02 +0000 Subject: cmd_ipc: send FDs with buffer payload For another step in in syscall reduction, we'll support transferring 3 FDs and a buffer with a single sendmsg/recvmsg syscall using Socket::MsgHdr if available. Beyond script/lei itself, this will be used for internal IPC between search backends (perhaps with SOCK_SEQPACKET). There's a chance this could make it to the public-facing daemons, too. This adds an optional dependency on the Socket::MsgHdr package, available as libsocket-msghdr-perl on Debian-based distros (but not CentOS 7.x and FreeBSD 11.x, at least). Our Inline::C version in PublicInbox::Spawn remains the last choice for script/lei due to the high startup time, and IO::FDPass remains supported for non-Debian distros. Since the socket name prefix changes from 3 to 4, we'll also take this opportunity to make the argv+env buffer transfer less error-prone by relying on argc instead of designated delimiters. --- lib/PublicInbox/Spawn.pm | 45 +++++++++++++++++++++++++++------------------ 1 file changed, 27 insertions(+), 18 deletions(-) (limited to 'lib/PublicInbox/Spawn.pm') diff --git a/lib/PublicInbox/Spawn.pm b/lib/PublicInbox/Spawn.pm index cd94ba96..7d0d9597 100644 --- a/lib/PublicInbox/Spawn.pm +++ b/lib/PublicInbox/Spawn.pm @@ -201,6 +201,8 @@ void nodatacow_dir(const char *dir) } SET_NODATACOW +# last choice for script/lei, 1st choice for lei internals +# compatible with PublicInbox::CmdIPC4 my $fdpass = <<'FDPASS'; #include #include @@ -213,16 +215,23 @@ union my_cmsg { char pad[sizeof(struct cmsghdr)+ 8 + sizeof(struct my_3fds) + 8]; }; -int send_3fds(int sockfd, int infd, int outfd, int errfd) +int send_cmd4(PerlIO *s, int in, int out, int err, SV *data, int flags) { struct msghdr msg = { 0 }; struct iovec iov; union my_cmsg cmsg = { 0 }; int *fdp; size_t i; + STRLEN dlen = 0; - iov.iov_base = &msg.msg_namelen; /* whatever */ - iov.iov_len = 1; + if (SvOK(data)) { + iov.iov_base = SvPV(data, dlen); + iov.iov_len = dlen; + } + if (!dlen) { /* must be non-zero */ + iov.iov_base = &msg.msg_namelen; /* whatever */ + iov.iov_len = 1; + } msg.msg_iov = &iov; msg.msg_iovlen = 1; msg.msg_control = &cmsg.hdr; @@ -232,38 +241,38 @@ int send_3fds(int sockfd, int infd, int outfd, int errfd) cmsg.hdr.cmsg_type = SCM_RIGHTS; cmsg.hdr.cmsg_len = CMSG_LEN(sizeof(struct my_3fds)); fdp = (int *)CMSG_DATA(&cmsg.hdr); - *fdp++ = infd; - *fdp++ = outfd; - *fdp++ = errfd; - return sendmsg(sockfd, &msg, 0) >= 0; + *fdp++ = in; + *fdp++ = out; + *fdp++ = err; + return sendmsg(PerlIO_fileno(s), &msg, flags) >= 0; } -void recv_3fds(int sockfd) +void recv_cmd4(PerlIO *s, SV *buf, STRLEN n) { union my_cmsg cmsg = { 0 }; struct msghdr msg = { 0 }; struct iovec iov; size_t i; Inline_Stack_Vars; + Inline_Stack_Reset; - iov.iov_base = &msg.msg_namelen; /* whatever */ - iov.iov_len = 1; + if (!SvOK(buf)) + sv_setpvn(buf, "", 0); + iov.iov_base = SvGROW(buf, n + 1); + iov.iov_len = n; msg.msg_iov = &iov; msg.msg_iovlen = 1; msg.msg_control = &cmsg.hdr; msg.msg_controllen = CMSG_SPACE(sizeof(struct my_3fds)); - if (recvmsg(sockfd, &msg, 0) <= 0) - return; - - errno = EDOM; - Inline_Stack_Reset; - if (cmsg.hdr.cmsg_level == SOL_SOCKET && + i = recvmsg(PerlIO_fileno(s), &msg, 0); + if (i < 0) + croak("recvmsg: %s", strerror(errno)); + SvCUR_set(buf, i); + if (i > 0 && cmsg.hdr.cmsg_level == SOL_SOCKET && cmsg.hdr.cmsg_type == SCM_RIGHTS && cmsg.hdr.cmsg_len == CMSG_LEN(sizeof(struct my_3fds))) { int *fdp = (int *)CMSG_DATA(&cmsg.hdr); - size_t i; - for (i = 0; i < 3; i++) Inline_Stack_Push(sv_2mortal(newSViv(*fdp++))); } -- cgit v1.2.3-24-ge0c7