[opensuse-programming] Is it a bug in the kernel or in my program?
Hi, I am the author of the perl module IO::Handle::Record. This module provides also file descriptor passing between processes. The current release on CPAN has worked up to opensuse 11.0 but breaks with 11.1. I don't want to bore you with the details of interfacing perl. So here comes a short verbal description of what happens. One test case creates a socketpair, forks and then passes a big block of data along with 2 file descriptors via sendmsg/recvmsg to the other process. The sending side is in non-blocking mode and uses select() to wait for the file descriptor to become writeable. The receiving side first reads 2 integers to get the number of bytes and the number of file descriptors passed and then reads the rest of the record. As the data block is larger than the kernel buffer the sendmsg will pass only a part and then return EAGAIN. Here is what happens at the sending side. write(2, "--> sending 2 fds at blib/lib/IO"..., 60) = 60 sendmsg(5, {msg_name(0)=NULL, msg_iov(1)=[{"\0\6\335\335\0\0\0\2\5\7\2\0\1_\220\n\txyzabc123\0\0\0\0\1\0"..., 450021}], msg_controllen=24, {cmsg_len=24, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS {6, 8}}, msg_flags=0}, 0) = 128000 write(2, "--> sending data chunk: controll"..., 92) = 92 munmap(0x7fbf29894000, 450560) = 0 munmap(0x7fbf29902000, 450560) = 0 close(8) = 0 close(6) = 0 brk(0xd15000) = 0xd15000 brk(0xd83000) = 0xd83000 sendmsg(5, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 322021}], msg_controllen=0, msg_flags=0}, 0) = -1 EAGAIN (Resource temporarily unavailabl e) write(2, "--> sending data chunk: controll"..., 87) = 87 brk(0xca7000) = 0xca7000 brk(0xd15000) = 0xd15000 munmap(0x7fbf2b957000, 720896) = 0 brk(0xdc5000) = 0xdc5000 select(8, NULL, [5], NULL, NULL) = 1 (out [5]) fstat(5, {st_mode=S_IFSOCK|0777, st_size=0, ...}) = 0 brk(0xe33000) = 0xe33000 brk(0xea0000) = 0xea0000 sendmsg(5, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 322021}], msg_controllen=0, msg_flags=0}, 0) = 112000 write(2, "--> sending data chunk: controll"..., 91) = 91 sendmsg(5, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 210021}], msg_controllen=0, msg_flags=0}, 0) = 128000 write(2, "--> sending data chunk: controll"..., 91) = 91 sendmsg(5, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 82021}], msg_controllen=0, msg_flags=0}, 0) = 82021 You see there are 5 sendmsg calls but only the first passes descriptors. The 2nd returns then EAGAIN. So far it is correct. The problem is the receiver. There are 11 recvmsg calls. The first 8 of them handle the 128000 bytes chunk that was sent by the first sendmsg, the one that sends the 2 file descriptors. Those 8 syscalls receive 8 bytes, then 31992 bytes (8+31992==32000) and then 6 times 16000 bytes. But all of those calls receive file descriptors! While only the first should. Is that a kernel bug? Or is my program wrong? getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\0\6\335\335\0\0\0\2", 8}], msg_controllen=24, {cmsg_len=24, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, {5, 8}}, msg_flags=0}, 0) = 8 write(2, "==> expecting 1024 fds -- got 8 "..., 86) = 86 fcntl(5, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(5, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 ioctl(5, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(5, 0, SEEK_CUR) = 0 fstat(5, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(5, F_SETFD, FD_CLOEXEC) = 0 fstat(5, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(8, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(8, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 ioctl(8, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(8, 0, SEEK_CUR) = 0 fstat(8, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 fcntl(8, F_SETFD, FD_CLOEXEC) = 0 fstat(8, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 mmap(NULL, 450560, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fbf2b999000 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\5\7\2\0\1_\220\n\txyzabc123\0\0\0\0\1\0\0\0\0\1\0\0\0\0"..., 450013}], msg_controllen=24, {cmsg_len=24, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, {11, 14}} , msg_flags=0}, 0) = 31992 write(2, "==> expecting 1024 fds -- got 31"..., 90) = 90 fcntl(11, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(11, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 ioctl(11, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(11, 0, SEEK_CUR) = 0 fstat(11, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(11, F_SETFD, FD_CLOEXEC) = 0 fstat(11, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(14, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(14, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 ioctl(14, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(14, 0, SEEK_CUR) = 0 fstat(14, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 fcntl(14, F_SETFD, FD_CLOEXEC) = 0 fstat(14, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 418021}], msg_controllen=24, {cmsg_len=24, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, { 15, 16}}, msg_flags=0}, 0) = 16000 write(2, "==> expecting 1024 fds -- got 16"..., 90) = 90 fcntl(15, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(15, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 ioctl(15, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(15, 0, SEEK_CUR) = 0 fstat(15, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(15, F_SETFD, FD_CLOEXEC) = 0 fstat(15, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(16, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(16, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 ioctl(16, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(16, 0, SEEK_CUR) = 0 fstat(16, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 fcntl(16, F_SETFD, FD_CLOEXEC) = 0 fstat(16, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 402021}], msg_controllen=24, {cmsg_len=24, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, { 17, 18}}, msg_flags=0}, 0) = 16000 write(2, "==> expecting 1024 fds -- got 16"..., 90) = 90 fcntl(17, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(17, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 ioctl(17, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(17, 0, SEEK_CUR) = 0 fstat(17, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(17, F_SETFD, FD_CLOEXEC) = 0 fstat(17, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(18, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(18, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 ioctl(18, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(18, 0, SEEK_CUR) = 0 fstat(18, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 fcntl(18, F_SETFD, FD_CLOEXEC) = 0 fstat(18, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 386021}], msg_controllen=24, {cmsg_len=24, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, { 19, 20}}, msg_flags=0}, 0) = 16000 write(2, "==> expecting 1024 fds -- got 16"..., 90) = 90 fcntl(19, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(19, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 ioctl(19, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(19, 0, SEEK_CUR) = 0 fstat(19, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(19, F_SETFD, FD_CLOEXEC) = 0 fstat(19, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(20, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(20, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 ioctl(20, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(20, 0, SEEK_CUR) = 0 fstat(20, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 fcntl(20, F_SETFD, FD_CLOEXEC) = 0 fstat(20, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 370021}], msg_controllen=24, {cmsg_len=24, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, { 21, 22}}, msg_flags=0}, 0) = 16000 write(2, "==> expecting 1024 fds -- got 16"..., 90) = 90 fcntl(21, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(21, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 ioctl(21, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(21, 0, SEEK_CUR) = 0 fstat(21, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(21, F_SETFD, FD_CLOEXEC) = 0 fstat(21, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(22, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(22, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 ioctl(22, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(22, 0, SEEK_CUR) = 0 fstat(22, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 fcntl(22, F_SETFD, FD_CLOEXEC) = 0 fstat(22, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 354021}], msg_controllen=24, {cmsg_len=24, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, { 23, 24}}, msg_flags=0}, 0) = 16000 write(2, "==> expecting 1024 fds -- got 16"..., 90) = 90 fcntl(23, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(23, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 ioctl(23, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(23, 0, SEEK_CUR) = 0 fstat(23, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(23, F_SETFD, FD_CLOEXEC) = 0 fstat(23, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(24, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(24, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 ioctl(24, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(24, 0, SEEK_CUR) = 0 fstat(24, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 fcntl(24, F_SETFD, FD_CLOEXEC) = 0 fstat(24, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 338021}], msg_controllen=24, {cmsg_len=24, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, { 25, 26}}, msg_flags=0}, 0) = 16000 write(2, "==> expecting 1024 fds -- got 16"..., 90) = 90 fcntl(25, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(25, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 ioctl(25, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(25, 0, SEEK_CUR) = 0 fstat(25, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(25, F_SETFD, FD_CLOEXEC) = 0 fstat(25, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(26, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(26, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 ioctl(26, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(26, 0, SEEK_CUR) = 0 fstat(26, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 fcntl(26, F_SETFD, FD_CLOEXEC) = 0 fstat(26, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 322021}], msg_controllen=0, msg_flags=0}, 0) = 112000 write(2, "==> expecting 1024 fds -- got 11"..., 93) = 93 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 210021}], msg_controllen=0, msg_flags=0}, 0) = 128000 write(2, "==> expecting 1024 fds -- got 12"..., 93) = 93 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 82021}], msg_controllen=0, msg_flags=0}, 0) = 82021 write(2, "==> expecting 1024 fds -- got 82"..., 92) = 92 Thanks, Torsten -- To unsubscribe, e-mail: opensuse-programming+unsubscribe@opensuse.org For additional commands, e-mail: opensuse-programming+help@opensuse.org
Torsten, If you don't get an answer on this very lightly used mailing list, you might want to repost to the factory list. The factory list tends to have a lot more suse developers participating. (There may be an even better list for you, but factory is the best I know.) Greg On Tue, Jan 6, 2009 at 2:13 PM, Torsten Foertsch <torsten.foertsch@gmx.net> wrote:
Hi,
I am the author of the perl module IO::Handle::Record. This module provides also file descriptor passing between processes. The current release on CPAN has worked up to opensuse 11.0 but breaks with 11.1.
I don't want to bore you with the details of interfacing perl. So here comes a short verbal description of what happens. One test case creates a socketpair, forks and then passes a big block of data along with 2 file descriptors via sendmsg/recvmsg to the other process. The sending side is in non-blocking mode and uses select() to wait for the file descriptor to become writeable.
The receiving side first reads 2 integers to get the number of bytes and the number of file descriptors passed and then reads the rest of the record.
As the data block is larger than the kernel buffer the sendmsg will pass only a part and then return EAGAIN. Here is what happens at the sending side.
write(2, "--> sending 2 fds at blib/lib/IO"..., 60) = 60 sendmsg(5, {msg_name(0)=NULL, msg_iov(1)=[{"\0\6\335\335\0\0\0\2\5\7\2\0\1_\220\n\txyzabc123\0\0\0\0\1\0"..., 450021}], msg_controllen=24, {cmsg_len=24, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS {6, 8}}, msg_flags=0}, 0) = 128000 write(2, "--> sending data chunk: controll"..., 92) = 92 munmap(0x7fbf29894000, 450560) = 0 munmap(0x7fbf29902000, 450560) = 0 close(8) = 0 close(6) = 0 brk(0xd15000) = 0xd15000 brk(0xd83000) = 0xd83000 sendmsg(5, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 322021}], msg_controllen=0, msg_flags=0}, 0) = -1 EAGAIN (Resource temporarily unavailabl e) write(2, "--> sending data chunk: controll"..., 87) = 87 brk(0xca7000) = 0xca7000 brk(0xd15000) = 0xd15000 munmap(0x7fbf2b957000, 720896) = 0 brk(0xdc5000) = 0xdc5000 select(8, NULL, [5], NULL, NULL) = 1 (out [5]) fstat(5, {st_mode=S_IFSOCK|0777, st_size=0, ...}) = 0 brk(0xe33000) = 0xe33000 brk(0xea0000) = 0xea0000 sendmsg(5, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 322021}], msg_controllen=0, msg_flags=0}, 0) = 112000 write(2, "--> sending data chunk: controll"..., 91) = 91 sendmsg(5, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 210021}], msg_controllen=0, msg_flags=0}, 0) = 128000 write(2, "--> sending data chunk: controll"..., 91) = 91 sendmsg(5, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 82021}], msg_controllen=0, msg_flags=0}, 0) = 82021
You see there are 5 sendmsg calls but only the first passes descriptors. The 2nd returns then EAGAIN.
So far it is correct. The problem is the receiver. There are 11 recvmsg calls. The first 8 of them handle the 128000 bytes chunk that was sent by the first sendmsg, the one that sends the 2 file descriptors.
Those 8 syscalls receive 8 bytes, then 31992 bytes (8+31992==32000) and then 6 times 16000 bytes.
But all of those calls receive file descriptors! While only the first should.
Is that a kernel bug? Or is my program wrong?
getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\0\6\335\335\0\0\0\2", 8}], msg_controllen=24, {cmsg_len=24, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, {5, 8}}, msg_flags=0}, 0) = 8 write(2, "==> expecting 1024 fds -- got 8 "..., 86) = 86 fcntl(5, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(5, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 ioctl(5, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(5, 0, SEEK_CUR) = 0 fstat(5, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(5, F_SETFD, FD_CLOEXEC) = 0 fstat(5, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(8, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(8, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 ioctl(8, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(8, 0, SEEK_CUR) = 0 fstat(8, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 fcntl(8, F_SETFD, FD_CLOEXEC) = 0 fstat(8, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 mmap(NULL, 450560, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fbf2b999000 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\5\7\2\0\1_\220\n\txyzabc123\0\0\0\0\1\0\0\0\0\1\0\0\0\0"..., 450013}], msg_controllen=24, {cmsg_len=24, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, {11, 14}} , msg_flags=0}, 0) = 31992 write(2, "==> expecting 1024 fds -- got 31"..., 90) = 90 fcntl(11, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(11, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 ioctl(11, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(11, 0, SEEK_CUR) = 0 fstat(11, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(11, F_SETFD, FD_CLOEXEC) = 0 fstat(11, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(14, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(14, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 ioctl(14, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(14, 0, SEEK_CUR) = 0 fstat(14, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 fcntl(14, F_SETFD, FD_CLOEXEC) = 0 fstat(14, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 418021}], msg_controllen=24, {cmsg_len=24, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, { 15, 16}}, msg_flags=0}, 0) = 16000 write(2, "==> expecting 1024 fds -- got 16"..., 90) = 90 fcntl(15, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(15, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 ioctl(15, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(15, 0, SEEK_CUR) = 0 fstat(15, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(15, F_SETFD, FD_CLOEXEC) = 0 fstat(15, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(16, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(16, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 ioctl(16, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(16, 0, SEEK_CUR) = 0 fstat(16, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 fcntl(16, F_SETFD, FD_CLOEXEC) = 0 fstat(16, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 402021}], msg_controllen=24, {cmsg_len=24, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, { 17, 18}}, msg_flags=0}, 0) = 16000 write(2, "==> expecting 1024 fds -- got 16"..., 90) = 90 fcntl(17, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(17, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 ioctl(17, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(17, 0, SEEK_CUR) = 0 fstat(17, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(17, F_SETFD, FD_CLOEXEC) = 0 fstat(17, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(18, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(18, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 ioctl(18, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(18, 0, SEEK_CUR) = 0 fstat(18, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 fcntl(18, F_SETFD, FD_CLOEXEC) = 0 fstat(18, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 386021}], msg_controllen=24, {cmsg_len=24, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, { 19, 20}}, msg_flags=0}, 0) = 16000 write(2, "==> expecting 1024 fds -- got 16"..., 90) = 90 fcntl(19, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(19, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 ioctl(19, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(19, 0, SEEK_CUR) = 0 fstat(19, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(19, F_SETFD, FD_CLOEXEC) = 0 fstat(19, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(20, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(20, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 ioctl(20, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(20, 0, SEEK_CUR) = 0 fstat(20, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 fcntl(20, F_SETFD, FD_CLOEXEC) = 0 fstat(20, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 370021}], msg_controllen=24, {cmsg_len=24, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, { 21, 22}}, msg_flags=0}, 0) = 16000 write(2, "==> expecting 1024 fds -- got 16"..., 90) = 90 fcntl(21, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(21, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 ioctl(21, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(21, 0, SEEK_CUR) = 0 fstat(21, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(21, F_SETFD, FD_CLOEXEC) = 0 fstat(21, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(22, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(22, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 ioctl(22, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(22, 0, SEEK_CUR) = 0 fstat(22, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 fcntl(22, F_SETFD, FD_CLOEXEC) = 0 fstat(22, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 354021}], msg_controllen=24, {cmsg_len=24, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, { 23, 24}}, msg_flags=0}, 0) = 16000 write(2, "==> expecting 1024 fds -- got 16"..., 90) = 90 fcntl(23, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(23, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 ioctl(23, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(23, 0, SEEK_CUR) = 0 fstat(23, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(23, F_SETFD, FD_CLOEXEC) = 0 fstat(23, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(24, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(24, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 ioctl(24, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(24, 0, SEEK_CUR) = 0 fstat(24, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 fcntl(24, F_SETFD, FD_CLOEXEC) = 0 fstat(24, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 338021}], msg_controllen=24, {cmsg_len=24, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, { 25, 26}}, msg_flags=0}, 0) = 16000 write(2, "==> expecting 1024 fds -- got 16"..., 90) = 90 fcntl(25, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(25, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 ioctl(25, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(25, 0, SEEK_CUR) = 0 fstat(25, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(25, F_SETFD, FD_CLOEXEC) = 0 fstat(25, {st_mode=S_IFREG|0644, st_size=1405, ...}) = 0 fcntl(26, F_GETFL) = 0x8000 (flags O_RDONLY|O_LARGEFILE) fstat(26, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 ioctl(26, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7fff33b53fc0) = -1 ENOTTY (Inappropriate ioctl for device) lseek(26, 0, SEEK_CUR) = 0 fstat(26, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 fcntl(26, F_SETFD, FD_CLOEXEC) = 0 fstat(26, {st_mode=S_IFREG|0644, st_size=246, ...}) = 0 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 322021}], msg_controllen=0, msg_flags=0}, 0) = 112000 write(2, "==> expecting 1024 fds -- got 11"..., 93) = 93 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 210021}], msg_controllen=0, msg_flags=0}, 0) = 128000 write(2, "==> expecting 1024 fds -- got 12"..., 93) = 93 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=8*1024}) = 0 recvmsg(6, {msg_name(0)=NULL, msg_iov(1)=[{"\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0\0\0\0\1\0"..., 82021}], msg_controllen=0, msg_flags=0}, 0) = 82021 write(2, "==> expecting 1024 fds -- got 82"..., 92) = 92
Thanks, Torsten -- To unsubscribe, e-mail: opensuse-programming+unsubscribe@opensuse.org For additional commands, e-mail: opensuse-programming+help@opensuse.org
-- Greg Freemyer Litigation Triage Solutions Specialist http://www.linkedin.com/in/gregfreemyer First 99 Days Litigation White Paper - http://www.norcrossgroup.com/forms/whitepapers/99%20Days%20whitepaper.pdf The Norcross Group The Intersection of Evidence & Technology http://www.norcrossgroup.com -- To unsubscribe, e-mail: opensuse-programming+unsubscribe@opensuse.org For additional commands, e-mail: opensuse-programming+help@opensuse.org
participants (2)
-
Greg Freemyer -
Torsten Foertsch