TUHS December 2015

tuhs@tuhs.org

53 participants
90 discussions

Broken TUHS mirror: li1202-53.members.linode.com

by Dave Horsfall

Could whoever runs this broken mirror please fix the damned mailer so that it handles my RFC-compliant banner? I do not appreciate retries every five seconds or so, because Dovecot cannot seem to handle a multi-line SMTP banner (a great spam defence); I have since firewalled the IP address of 45.79.103.53 out of self-defence. Thank you. -- Dave Horsfall DTM (VK2KFU) "Those who don't understand security will suffer."

8 years, 9 months

TUHS Mail Archive is now searchable

by Warren Toomey

All, I've finally set up a search system for the mailing list. It's at http://minnie.tuhs.org/cgi-bin/mailman/tuhs.cgi and it's also hyperlinked on the main list page at http://minnie.tuhs.org/cgi-bin/mailman/listinfo/tuhs I've not yet set up a cron job to keep it updated, and yes the interface is ugly but it works. Cheers, Warren

8 years, 9 months

tar on v6 not creating directories on v6

by Will Senn

All, I'm stuck trying to determine what is going on with v6tar on v6. It seems to work ok for files, but gets confused with subdirectories. I set up a test folder structure: t/dmr/vs.c t/dmr/vt.c t/ken/prf.c then I created a tarball tar cvf t.tar t then I tried to extract the tarball. It made a mess: # tar xvf t.tar Tar: blocksize = 17 y ? tar: t/ken/prf.c - cannot create y ? y ? tar: t/dmr/vs.c - cannot create y ? y ? tar: t/dmr/vt.c - cannot create That was ugly and all of it was output. What exactly did I wind up with?: # ls -l total 19 drwxrwxrwx 2 root 32 Oct 10 12:54 y -rw-rw-rw- 1 root 8704 Oct 10 12:54 t.tar Ugh. Probably don't need the y directory... # rmdir y y ? # ls y y not found Wow! It appears that I am unable to delete the y directory or list it by name. That can't be good. Any ideas of how to remove this directory are welcome. Not to be deterred by one small failure, I copied the same tarball over to v7 on the off chance that maybe v6tar isn't really for v6, but more for moving files(and directories) over to v7 as Haley and Ritchie describe, and lo and behold tar on v7 is able to extract both files and directories from the same tarball without any trouble: # tar xvf t.tar Tar: blocksize = 17 x t/ken/prf.c, 2301 bytes, 5 tape blocks x t/dmr/vs.c, 1543 bytes, 4 tape blocks x t/dmr/vt.c, 834 bytes, 2 tape blocks # ls -l total 18 drwxrwxr-x 4 root 64 Dec 31 19:27 t -rw-rw-r-- 1 root 8704 Dec 31 19:27 t.tar # ls t dmr ken # ls t/dmr vs.c vt.c # ls t/ken prf.c Interesting. After looking at the tar source, the question marks in the output appear to be coming from somewhere outside of tar (perhaps mkdir or chown?). Also, the "cannot create" message comes from the following snippet of the tar source, which looks reasonable: ... if ((ofile = creat(dblock.dbuf.name, stbuf.st_mode & 07777)) < 0) { fprintf(stderr, "tar: %s - cannot create\n", dblock.dbuf.name); ... I think this error is simply an effect related to the failure to create the necessary directories properly. The code to do that looks pretty straightforward: checkdir(name) register char *name; { register char *cp; int i; for (cp = name; *cp; cp++) { if (*cp == '/') { *cp = '\0'; if (access(name, 01) < 0) { if (fork() == 0) { execl("/bin/mkdir", "mkdir", name, 0); execl("/usr/bin/mkdir", "mkdir", name, 0); fprintf(stderr, "tar: cannot find mkdir!\n"); done(0); } while (wait(&i) >= 0); chown(name, stbuf.st_uid, stbuf.st_gid); } *cp = '/'; } } } I speculate that chown is causing the "?" to be displayed. Is it safe enough for me to add printf statements around this code to see what's going on, or is there a better approach? Thanks, Will

8 years, 10 months

Re: [TUHS] why does tar have the tape device hard coded into it and why is it mt1 instead of mt0

by norman＠oclsc.org

/dev/makefile on the V7 distribution tape (or at least the unpacked image I have that I believe to be same) says: ht: /etc/mknod mt0 b 7 64 /etc/mknod mt1 b 7 0 /etc/mknod rmt0 c 15 64 /etc/mknod rmt1 c 15 0 /etc/mknod nrmt0 c 15 192 /etc/mknod nrmt1 c 15 128 chmod go+w mt0 mt1 rmt0 rmt1 nrmt0 nrmt1 According to /usr/sys/dev/ht.c, the minor device number was used as follows: minor(dev) & 07 slave unit number minor(dev) & 070 controller unit number minor(dev) & 0100 tape density: set == 800 bpi, clear 1600 minor(dev) & 0200 no-rewind flag It takes some digging in the source code (and the PDP-11 Peripherals Handbook) to understand all this numerology. In most of the code, minor(dev) & 077 is just treated as a unit number (fair enough). The use of 0200 appears only as a magic number in htopen; that of 0100 only as a magic number in htstart, and that only implied: the test is not minor(dev) & 0100, but unit = minor(bp->b_dev) & 0177; if(unit > 077) Not so bad when the whole driver is only 376 lines of code, but it wouldn't have hurt to make it 400 lines if that meant fewer magic numbers. Anyway, what all this means is that /dev/*mt0 and /dev/*mt1 both actually meant slave 0 on TU16 controller 0, but mt0 was 800 bpi and mt1 1600 bpi. Hence, I would guess, tar's default to mt1. My first exposure to the insides of UNIX was in the High Energy Physics group at Caltech. Some of our systems had multiple tape drives and every drive supported multiple densities, so we invented for ourselves a system like that many other sites invented, with names like /dev/rmt3h to mean the third tape drive at high density. (Hence the USG naming scheme of /dev/rmt/3h and the like--not that we taught it to them, just that many places had the same idea.) Our world wasn't nearly as exciting as that of our neighbors, across the building and three floors down, in the Space Radiation Laboratory. They had a huge room full of racks of magtapes full of data from satellites, and many locally- written tools for extracting the data so researchers could work on it. The hardware was an 11/70 with eight tape drives, and at any given time at least half the the drives would be spinning. One of the drives was seven-track rather than nine-track, because some of the satellite data had been written in that format. Fair disclosure: I had a vague memory that the `drive number' in the device name had been recycled for other purposes, but couldn't remember whether it was density or something else. (I'm a little surprised none of the other old-timers here remembered that, but maybe I worked with tapes more than them.) But I had to dig into the source code for the details; I didn't remember all that. And I did have to climb up to the high shelf in my home office for a Peripherals Handbook to understand the magic numbers being stuffed into registers! Norman Wilson Toronto ON

8 years, 10 months

Re: [TUHS] why does tar have the tape device hard coded into it and why is it mt1 instead of mt0

by Doug McIlroy

> I have no memory of why Ken used mt1 not mt0. Doug may know. I don't know either. Come to think of it, I can't remember ever using tar without option -f. Direct machine-to-machine trasfer, e.g. by uucp, took a lot of business away from magtape soon after tar was introduced. Incidentally, I think tar was written by Chuck Haley or Greg Chesson, not Ken. Doug

8 years, 10 months

Re: [TUHS] TUHS] why does tar have the tape device hard coded into it and why is it mt1 instead of mt0

by Doug McIlroy

Forget that I said, "I think that tar was written by Chuck Haley or Greg Chesson". Ken confirms that he wrote it, for dectape. Doug

8 years, 10 months

Re: [TUHS] Pre-v6 images and 2.11BSD patches

by Johnny Billquist

On 2015-12-12 07:16, William Pechter<pechter(a)gmail.com> wrote: > > Warren Toomey wrote: >> >On Sat, Dec 12, 2015 at 03:54:16PM +1100, Peter Jeremy wrote: >>> >>Also, I've seen suggestions that there's a 2.11BSD patch later than >>> >>447 but I can't find anything "official" andwww.2bsd.com is either >>> >>down or inaccessible from all the systems I have access to. Does >>> >>anyone know if 448 or later were released? And given the issues with >>> >>www.2bsd.com would someone be willing to mirror it (assuming we can >>> >>got a copy of it)? >> >[ Back to a real keyboard ]. Yes I'd be very happy to mirror 2bsd.com. >> >Does anybody know what's happened to Steven Schultz? >> > >> >Cheers, Warren >> >_______________________________________________ >> >TUHS mailing list >> >TUHS(a)minnie.tuhs.org >> >http://minnie.tuhs.org/cgi-bin/mailman/listinfo/tuhs > Last patch is 447 from June 2012. Uh. No. 447 is from December 31, 2008. See /VERSION in the patch set, which holds the patch version and date for the patch. And I did an unofficial 448 in 2010, which I have tried to spread, and which I suspect is the patch referred to above... > I can get to the site just fine... pasted the patch below if it helps > anyone. > I haven't heard anything about him. Haven't worked at the same company > since the early 1990's... I used to talk with him a lot in the past, but have not been able to raise him, and haven't seen anything from him in over 5 years... No idea what he is up to nowadays... Johnny -- Johnny Billquist || "I'm on a bus || on a psychedelic trip email: bqt(a)softjar.se || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol

8 years, 10 months

Re: [TUHS] why is sum reporting different checksum's between v6 and v7

by jnc＠mercury.lcs.mit.edu

> From: Random832 > Interestingly, the SysIII sum.c program, which I assume yields the same > result for this input, appears to go through the whole input > accumulating the sum of all the bytes into a long, then adds the two > halves of the long at the end rather than after every byte. That's the same hack a lot of TCP/IP checksums routines used on machines with longer words; add the words, then fold the result in the shorter length at the end. The one I wrote for the 68K back in '84 did that. > This suggests that the two programs would give different results for > very large files that overflow a 32-bit value. No, I don't think so, depending on the exact detals of the implementation. As long as when folding the two halves together, you add any carry into the sum, you get the same result as doing it into a 16-bit sum. (If my memory of how this all works is correct - the neurons aren't what they used to be, especially late in the day... :-) > Also, if this sign extends, then its behavior on "negative" (high bit > set) bytes is likely to be very different from the SysIII one, which > uses getc. I have this bit set that in C, 'char' is defined to be signed, and furthermore that when you assign a shorter int to a longer one, the sign is extended. So if one has a char holding '0200' octal (i.e. -128), assigning it to a 16-bit int should result in the latter holding '0177600' (i.e. still -128). So in fact I think they probably act the same. Noel

8 years, 10 months

Re: [TUHS] why is sum reporting different checksum's between v6 and v7

by jnc＠mercury.lcs.mit.edu

> From: Will Senn > I noticed that the sum utility from v6 reports a different checksum > than it does using the sum utility from v7 for the same file. > ... does anyone know what's going on here? > Why is sum reporting different checksum's between v6 and v7? The two use different algorithms to accumulate the sum (I have added comments to the relevant portion of the V6 assembler one, to help understand it): V6: mov $buf,r2 / Pointer to buffer in R2 2: movb (r2)+,r4 / Get new byte into R4 (sign extends!) add r4,r5 / Add to running sum adc r5 / If overflow, add carry into low end of sum sob r0,2b / If any bytes left, go around again Read the description of MOVB in the PDP-11 Processor manual. V7: while ((c = getc(f)) != EOF) { nbytes++; if (sum&01) sum = (sum>>1) + 0x8000; else sum >>= 1; sum += c; sum &= 0xFFFF; } I'm not clear on some of that, so I'll leave its exact workings as an exercise, but I'm pretty sure it's not a equivalent algorithm (as in, something that would produce the same results); it's certainly not identical. (The right shift is basically a rotate, so it's not a straight sum, it's more like the Fletcher checksum used by XNS, if anyone remembers that.) Among the parts I don't get, for instance, sum is declared as 'unsigned', presumably 16 bits, so the last line _should_ be a NOP!? Also, with 'c' being implicitly declared as an 'int', does the assignment sign extend? I have this vague memory that it does. And does the right shift if the low bit is one really do what the code seems to indicate it does? I have this bit that ASR on the PDP-11 copies the high bit, not shifts in a 0 (check the processor manual). That is, of course, assuming that the compiler implements the '>>' with an ASR, not a ROR followed by a clear of the high bit, or something. Noel

8 years, 10 months

where is the v6tar source?

by Mark Longridge

Ok, it definitely sounds like the v6tar source is around somewhere so if someone could point me in the right direction... I've only seen the binary, and I can't remember where I got it. Mark

8 years, 10 months

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TUHS December 2015