stevens@hsi.UUCP (Richard Stevens) (01/11/89)
I'm trying to figure out how to create a "stream pipe" with System 5,
Release 3.2 (386 version). The streamio(7) man page says the only
way to pass a file descriptor is using these, but I can't find
any reference as to how a stream pipe is created. In Steve
Bellovin's "Session TTY Manager" paper from the San Francisco
Usenix, he describes the "strange" way they're created under
Research Unix, but I can't find any mention of /dev/spx in my
System 5 manuals.
Richard Stevens
Health Systems International, New Haven, CT
stevens@hsi.com
... { uunet | yale } ! hsi ! stevensdougm@ico.ISC.COM (Doug McCallum) (01/12/89)
In article <244@hsi86.hsi.UUCP> stevens@hsi.UUCP (Richard Stevens) writes: >I'm trying to figure out how to create a "stream pipe" with System 5, >Release 3.2 (386 version). The streamio(7) man page says the only >way to pass a file descriptor is using these, but I can't find >any reference as to how a stream pipe is created. In Steve I don't believe there is any "clear" documentation on using them since the streams pipe is sort of a kludge to get RFS started. I say kludge because spx violates most STREAMS conventions and has problems if you attempt to push a module on it. You also need to be running as root to do things unless you get prearranged dev entries. (this is based on V.3.0 not 3.2) Quick summary is that you open /dev/spx twice, connect the two streams, create a device file for one of them (using the major/minor found via fstat) and close the one that you want others to connect on. Hope this is of some help, Doug McCallum Interactive Systems Corp. dougm@ico.isc.com The following is a quick-and-dirty program to show the mechanism of setting one up. --------------------------------------------------------------------- /* * spdemo * This program gets a pair of "streams pipe" file descriptors from * the clone open of "/dev/spx". It then finds the major/minor * number of the second descriptor, creates the special device file * "/tmp/sp_server", links the two "pipes" together and then waits in * a "getmsg" on the first file descriptor which will block until * something gets written on the sp_server file. A simple test is to * run the following command: * date >/tmp/sp_server * from another terminal. spdemo will print the date out. Almost * any streams operation may be performed, however. */ #include <stdio.h> #include <sys/types.h> #include <sys/stream.h> #include <stropts.h> #include <sys/stat.h> #include <sys/fcntl.h> main() { queue_t *dummy; int fd, fd2; struct stat statbuf; struct strbuf b1, b2; struct strfdinsert ins; char buff1[1024], buff2[1024]; int opts = 0; fd = open("/dev/spx", O_RDWR); if (fd<0){ perror("open"); exit(1); } fd2 = open("/dev/spx", O_RDWR); if (fd2<0){ perror("open"); exit(1); } ins.databuf.maxlen = ins.databuf.len = -1; ins.databuf.buf = NULL; ins.ctlbuf.maxlen = ins.ctlbuf.len = sizeof(queue_t *); ins.ctlbuf.buf = &dummy; ins.offset = 0; ins.fildes = fd; ins.flags = 0; if (ioctl(fd2, I_FDINSERT, &ins)<0){ perror("I_FDINSERT"); exit(2); } if(fstat(fd2, &statbuf)<0){ perror("fstat"); exit(3); } if (mknod("/tmp/sp_server", S_IFCHR|0666, statbuf.st_rdev)<0){ perror("mknod"); exit(4); } b1.maxlen = sizeof buff1; b1.len = 0; b1.buf = buff1; b2.maxlen = sizeof buff2; b2.len = 0; b2.buf = buff2; if (getmsg(fd, &b1, &b2, &opts)<0){ perror("getmsg"); } else { if (b1.len > 0){ printf("control\n"); } if (b2.len > 0){ printf("data: [%s]\n", buff2); } } unlink("/tmp/sp_server"); }
dougm@ico.ISC.COM (Doug McCallum) (01/12/89)
One thing I didn't mention is that if all you want are two STREAMS endpoints connected like normal pipes except bi-directional, you can omit the mknod step and give one end to a child process. This doesn't require being root, only the mknod does.
larry@hcr.UUCP (Larry Philps) (01/16/89)
In article <244@hsi86.hsi.UUCP> stevens@hsi.UUCP writes: >I'm trying to figure out how to create a "stream pipe" with System 5, >Release 3.2 (386 version). The streamio(7) man page says the only >way to pass a file descriptor is using these, but I can't find >any reference as to how a stream pipe is created. In Steve >Bellovin's "Session TTY Manager" paper from the San Francisco >Usenix, he describes the "strange" way they're created under >Research Unix, but I can't find any mention of /dev/spx in my >System 5 manuals. > > Richard Stevens > Health Systems International, New Haven, CT > stevens@hsi.com > ... { uunet | yale } ! hsi ! stevens Call the function "spipe" exactly as you would call "pipe" and then link your program against the -lns library. --- Larry Philps HCR Corporation 130 Bloor St. West, 10th floor Toronto, Ontario. M5S 1N5 (416) 922-1937 {utzoo,utcsri,decvax,ihnp4}!hcr!larry