GotW #98 Solution: Assertion levels (Difficulty: 5/10)
This special Guru of the Week series focuses on contracts. We covered basic assertions in GotW #97? but not all asserted conditions are created equal. Given some assertion facility that can be used like this: 1. Give one example each of an asserted condition whose run-time evaluation is: a) super cheap It?s hard to find … Continue reading GotW #98 Solution: Assertion levels (Difficulty: 5/10) →
Caught:dereel problem
Into the office this morning to find windows from dereel on eureka gone again. What did the console say? Most of that is firefox grumbling to itself, but what's this ECONNRESET? That doesn't make much sense, but at least I know what it was. In passing, this is yet another situation showing how silly it is to have text on a black background, especially dark blue. Things were slightly different this time, though, possibly because the starting terminal didn't go away: It lied, of course.
Late Plague Winter
The first time I posted the first crocuses on this blog was in 2003. And then a lot of times since then. It?s therapeutic; I may be a Canadian and happy about it, but damn I hate winter. Here at Canada?s bottom left corner we don?t get the brutal cold but also we don?t get much winter light, so sun on petals is a morale-booster. And do we ever need one this particular winter. The little guy above is awfully cute, sneaking into the sun. The flowers are early this year; they usually don?t show till sometime in February.
teevee hang
While cooking dinner, I had the recipe displayed on the TV. But when I looked back a little later, the display was plain white, and I couldn't get any response from teevee, the computer driving it. A quick check showed: yes, it had hung. No response over the net. The Big Red Button worked, and after rebooting there was no evidence of any issues, including not in the log files. Computers crash, of course, but this one seems surprising.
dereel issues
I'm still running firefox on dereel until I can finally update eureka. But in the past couple of days I've come into the office to find all windows from dereel on eureka:0 closed, including firefox. Why? dereel was still running, and I was able to restart the xterms and firefox without difficulty. And there were no messages in the system logs. Nothing for it: start firefox from a vty. That way, when it dies, I'll see something. In fact, I'll see plenty without it crashing.
GPS pain, yet again
Finding my way to Melbourne is pretty straightforward, though I always run into issues from leaving the freeway (where?) to getting the the Victoria Market. But now I have my route in my phone, and I have a backup in my old, worn-out GPS navigator. Both failed completely. Today was bright sunshine, and the position of the navigator (difficult to change) reflected the sunshine on my left wrist. I couldn't see anything. And the phone had forgotten all about my route! OK, back to Notifications. But those were yesterday's Notifications. Who cares about them? So the phone had deleted them. OK, enter manually.
Microsoft? Linux? FreeBSD?
Discussing with Jamie Fraser on IRC today: <groggyhimself> Did anybody hear the rumour that there won't be a Microsoft 11? <groggyhimself> That they'll migrate to Linux instead? <jf> that sounds like horseshit to me <groggyhimself> Very possible. <jf> i've heard that they're going to keep doing rolling updates for windows 10 <groggyhimself> I saw it in passing and wondered if there could be an element of truth in it. <jf> but i honestly am not even sure where they go from here, with the exception of office there's not much besides inertia tethering a lot of folks to microsoft products <jf> (for the home anyway, for business it's a different kettle of fish) <groggyhimself> And marketing?
Understanding Android, once more
So what went wrong with sending my route to my mobile phone? It's looking more and more like there's something wrong with the phone, or that there's some strange configuration issue. Discussed it on IRC, which was illuminating. I was expecting either a message or a direct invocation of Google Maps. But no, fool, it's a Notification. And while there are icons for phone, messages and contacts, you need a Completely Different Interface for Notifications: steal (or as the US Americans say, swipe) the phone from the top and you'll see your Notifications. And sure enough, there it was, waiting to be collected.
Network failure!
Came into the office this morning to find that we had been off the net for nearly and hour between 6:48 and 7:45. That used to be nothing worth mentioning here: it happened all the time. It wasn't a scheduled National Broadband Network outage, and it was the longest in nearly a year. OK, outages can happen, and this one didn't worry me overly. But that in itself is an indication of how things are improving. Hopefully it will stay that way. In this case, Andy Snow tells me that the outage affected the whole state (of Victoria). What, NBN? No, Aussie Broadband.
GotW #98: Assertion levels (Difficulty: 5/10)
This special Guru of the Week series focuses on contracts. We covered basic assertions in GotW #97? but not all asserted conditions are created equal. JG Questions Given some assertion syntax: 1. Give one example each of an asserted condition whose run-time evaluation is: a) super cheap b) arbitrarily expensive Guru Questions 2. What does … Continue reading GotW #98: Assertion levels (Difficulty: 5/10) →
When You Know
I?m a person who knows a lot about how computers and software work, is generally curious, and reads fast. I?ve been wrong about lots of things over the years. But there have a been a few times when a combination of technology-literacy and just paying attention to the world have made me 100% sure that I was seeing something coming that many others weren?t. Here are a few of those stories. The reason I?m telling them is that I?m in another of those moments, seeing something obvious that not enough other people have, and I want to offer credentials before I share it.
Next Android challenge
We're off to Melbourne for the first time in well over 2 years on Thursday, so time to program a map into my GPS navigator. First, though, an overview with Google Maps. That was straightforward enough, and it offered to send it to my Nokia 3 phone (or, as it chooses to call it, my HMD Global TA-1020). OK, that makes sense. Do it! And how about that, the phone buzzed, and that was that. No popup. Do I have to ?open? ?Maps?? Tried that. No route. Looking around at various options, I discovered that it had noted all my waypoints, and would happily take me to any of them.
Making friends^W acquaintance with git
So I have to finally use Git to update my software. I really wish they hadn't done it, but I'm going to have to come to terms with it. OK, where's the docco? I had saved some mail messages on the subject for later perusal. Now's the time. 529 messages! There must be a simpler way. Peter Jeremy has been there before me (and grumbled mightily). Ask on IRC. No Peter, but Andy Snow came up with this summary, which refers to Warner Losh's git primer, the one that he had sent to me some months ago. OK, follow that: cd /usr/src REPO=https://github.com/freebsd/freebsd.git git clone $REPO -b stable/12 Nothing happened.
Next system upgrade attempt
As part of my migration attempts for eureso, brought dereel up to date: new kernel, new userland, update ports. It almost worked: [43/194] Installing librsvg2-rust-2.50.2... pkg: librsvg2-rust-2.50.2 conflicts with librsvg2-2.40.21 (installs files into the same place). Problematic file: /usr/local/bin/rsvg-convert There's too much of that kind of thing. OK, it looks like librsvg2-rust-2.50.2 should win, so let's remove the other: === root@dereel (/dev/pts/0) /home/grog 2 -> Log pkg delete librsvg2-2.40.21 ===== Tue 19 Jan 2021 12:37:08 AEDT on dereel: pkg delete librsvg2-2.40.21 Installed packages to be REMOVED: ImageMagick7: 7.0.10.24 audacity: 2.4.2_2 chromium: 84.0.4147.135 darktable: 3.2.1_3 emacs: 27.1_1,3 firefox: 84.0.1,2 gimp: 2.10.20_1,2 gtk3: ...
The revenge of Microsoft
Yvonne in to my office with a problem: distress, the Microsoft ?Windows? 10 box, wouldn't talk to her, something to do with all slots being full. Sure enough, it was repeatable. Bloody Microsoft! Does this have something to do with the unsolicited upgrade last week? Probably. In to my office to check. Worked fine for me. Simulate Yvonne's environment and try again. Long delay while it logged her in and did whatever else Microsoft does when it starts up. But it worked. Back to her office. Worked. So what went wrong? She had to log in, but the first couple of times around we didn't get that far.
More eureso pain
Some time in the early hours of this morning my port upgrade completed. Well, it stopped running: [8/1417] Upgrading gstreamer1-plugins from 1.8.0 to 1.16.2_2... pkg: gstreamer1-plugins-1.16.2_2 conflicts with gstreamer1-plugins-bad-1.8.0_1 (installs files into the same place). Problematic file: /usr/local/include/gstreamer-1.0/gst/audio/gstaudioaggregator.h I had expected that. Somehow I had 26 gstreamer-related ports installed, including gstreamer-0.10.36_4 Development framework for creating media applications gstreamer-ffmpeg-0.10.13_4 GStreamer plug-in for manipulating MPEG video streams gstreamer1-1.8.0 Media applications framework OK, take note of the fact and remove them all.
firefox will help!
I'm still suffering from slow performance from web browsers. firefox thinks so too, and offered to help. OK, I know what the real problem is, but it would be interesting to see what it wants to do. But I never expected this: Throw out all customizations! All my settings! All the things I've worked to carefully get the thing to be halfway usable and less painful! These people need their heads read.
eureso upgrade, day 3
Into the office this morning. The build, now with /usr/obj NFS mounted, almost worked. But then, towards the end of the kernel build, I saw something I've never seen before: ===> Ports module x11/nvidia-driver (all) cd ${PORTSDIR:-/usr/ports}/x11/nvidia-driver; env -u CC -u CXX -u CPP -u MAKESYSPATH -u MK_AUTO_OBJ -u MAKEOBJDIR MAKEFLAGS="-I /Photos/Tools -D NOCLEAN -I /Photos/Tools -D NOCLEAN -D NO_MODULES_OBJ .MAKE.LEVEL.ENV=MAKELEVEL KERNEL=kernel TARGET=amd64 TARGET_ARCH=amd64" SYSDIR=/home/src/FreeBSD/svn/stable/12/sys PATH=/home/src/eureso/home/src/FreeBSD/svn/stable/12/amd64.amd64/tmp/legacy/usr/sbin:/home/src/eureso/home/src/FreeBSD/svn/stable/12/amd64.amd64/tmp/legacy/usr/bin:/home/src/eureso/home/src/FreeBSD/svn/stable/12/amd64.amd64/tmp/legacy/bin:/home/src/eureso/home/src/FreeBSD/svn/stable/12/amd64.amd64/tmp/usr/sbin:/home/src/eureso/home/src/FreeBSD/svn/stable/12/amd64.amd64/tmp/usr/bin:/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/bin:/usr/local/sbin SRC_BASE=/home/src/FreeBSD/svn/stable/12 OSVERSION=1202504 WRKDIRPREFIX=/home/src/eureso/home/src/FreeBSD/svn/stable/12/amd64.amd64/sys/GENERIC make -B clean build pkg-static: Warning: Major OS version upgrade detected. Running "pkg-static install -f pkg" recommended ===> Cleaning for nvidia-driver-440.100_1 ===> nvidia-driver-440.100_1 pkg(8) must be version 1.15.9 or greater, but you have 1.10.5.
eureso upgrade
Continued with eureso today. The disk image that I copied from the stable12 VM booted happily, though I ran into a couple of minor issues. First, my intention is to have as good as the same configuration files for both eureso and eureka. /etc/rc.conf contains: FORREAL=0 if [ $FORREAL -eq 0 ]; then hostname="eureso.lemis.com" hostip=192.109.197.143 defaultrouter="192.109.197.137" else hostname="eureka.lemis.com" hostip=192.109.197.137 fi All I need to do, I thought, was change FORREAL from 0 to 1 or back. But life isn't that simple. At the very least I need a different /etc/fstab.
Anatomy of a power failure
In the early afternoon my office UPS beeped once. I've heard that before: it often happens when there's a grid power failure. Why? I wish I knew; maybe a slow cutover to battery power? Out to confirm: yes, the power was out. It started at 13:46:29, and continued long enough for me to investigate. Check the Powercor outage map, the one that displays a map of all of Victoria, 95% of populated South Australia and half of New South Wales, and always insists on going back to that view. Zoom in. Yes, a large pink-shaded area round Ballarat, going about as far as Buninyong.
Android messages: caught in the act
Over the past few weeks, these irritating ?here now and gone forever? messages on my phone have become fewer. But today one appeared just as I happened to be looking at the phone. It was from VicEmergency, about which I have complained in the past. Something about Covid, but I didn't have time to read the rest. Somehow that's typical of the app. It's supposed to inform me about emergencies, notably bushfires, not ongoing incidents. But could it be that it was too polite to send to my Messages tab, and wanted to display it itself? Fired up the app, which is as useless as it has ever been, and indeed I saw a warning about COVID-19?from two days ago!
eureso again
My system upgrade ground to a halt, not for the first time, a month ago. I ran into an unexpected feature (yes, really) of VirtualBox that gave me what looked like inconsistent disk images. I'm sure that I can work around it, and the feature itself (different views of the same disk on different VMs) can be very useful, but here it's just another way to shoot myself in the foot. So, how about a real computer? Looking around, I was surprised to discover that I have no fewer than 8 ThinkCentre boxes. Five are in use, one appears to be dead, but that still leaves two.
distress crash
Into the office this morning to process some photos, and found that distress, my Microsoft ?Windows? 10 box, had apparently crashed and rebooted during the night: === grog@eureka (/dev/pts/37) ~/Photos/20210113 449 -> date; ruptime Thu 14 Jan 2021 09:45:23 AEDT dischord down 3+21:13 distress up 13:59, 0 users, load 0.00, 0.00, 0.00 How did that happen? How do I find out? First, of course, I establish contact with the machine: Setting up your device?
Phantom files
While backing up my photos today, came across this strange information: ... 2-grog/.nfs.d7ef1349.29924.4 2-grog/.nfs.d7ef3635.29924.4 2-grog/.nfs.d7ef5a7a.29924.4 ... What are they? /Photos/2-grog/ is a staging directory that I use to make life with Microsoft bearable: put the files I need to process there and run a Microsoft-space program always against the same directory so that I don't have to climb trees directory for directory. The software (in this case DxO PhotoLab) is set to write its results back to the same directory. But what does that have to do with NFS? I'm using SMB with Samba.
Rotated photos
While looking at old photos today, came across this thoroughly forgettable image: It would be bad enough the right way round: It was taken with the old Samsung GT-I9100T mobile phone, and intended to show that even that camera could take better photos than this, which we had received a day earlier: But why was it rotated?
GotW #97 Solution: Assertions (Difficulty: 4/10)
Assertions have been a foundational tool for writing understandable computer code since we could write computer code? far older than C?s assert() macro, they go back to at least John von Neumann and Herman Goldstine (1947) and Alan Turing (1949). [1,2] How well do we understand them? exactly? 1. What is an assertion, and what … Continue reading GotW #97 Solution: Assertions (Difficulty: 4/10) →
Putting Microsoft to sleep
Interesting question on Quora today: Did Windows remove the sleep mode. That's quite relevant to me, since I haven't been able to get distress, my Microsoft ?Windows? 10 box, to sleep. But the answer (now thoughtfully downvoted) referred to hibernating, not sleeping. A bit of searching found the answer anyway. The problem was that I was looking in the wrong place. SHUTDOWN/H will hibernate, but there's no corresponding option for ?sleep?. Instead you need to open the menu at the bottom of the screen, select ? (IO), find ?Sleep? in the new menu, and click on it. Clearly much friendlier than using old-fashioned commands.
More old diary insights
Only yesterday I noted the advantages of old diary entries. And then today I found one addressing the issue of inputting special characters into X clients. How do you enter a ? or a °? Ten years ago I found one way: put them into a custom ~/.XCompose file. But recently it stopped working. Why? My way of entering ° is Multi_key d e. But that stopped working on firefox, and I discovered that I could create it with Multi_key o o. Why? I was running firefox on dereel, because eureka is still so down-rev that many sites won't talk to its old, worn-out firefox.
Processing photos with distress again
So now I can use distress again for my photo processing. All OK? Hardly. First, while processing the weekly house photos, 66 out of 72 DxO PhotoLab conversions failed: I've had problems in the past where a couple failed, but over 90%? Looking at the destination directory showed: === grog@eureka (/dev/pts/37) ~/Photos/20210102 190 -> l orig/*f ... -rwxr--r-- 2 grog wheel 121,228,768 2 Jan 12:41 orig/41026156_DxO.tiff -rwxr--r-- 2 grog wheel 121,228,680 2 Jan 12:41 orig/41026157_DxO.tiff -rwxr--r-- 2 grog wheel 29,483,408 2 Jan 13:05 orig/41026158_DxO.tiff ...
Samba documentation again
While writing up yesterday's pain with Samba, noted this emblem at the top of the page That's the title page of the O'Reilly book, Using Samba, 2nd Edition, February 2003?18 years ago! No wonder it's out of date. Is that an excuse? It's an explanation, of course. But anything that old should come with obvious disclaimers. And it was the only thing I found on the Samba site that dealt with that configuration detail.
Reviving the 1973 Unix text to voice translator
The early Research Edition Unix versions featured a program that would turn a stream of ASCII text into utterances that could be played by a voice synthesizer. The source code of this program was lost for years. Here's the story of how I brought it back to life.
Microsoft problems: bloody Samba!
So what's going on with my SMB connection between distress (Microsoft 10) and my FreeBSD computers? Yesterday I established that it was related to the system not listening on port microsoft-ds (445). And that was almost certainly because I didn't tell inetd to listen on that port. OK, clearly a configuration issue, probably because I've been dragging the same configuration with me for over 20 years, and in those days microsoft-ds probably wasn't used. In principle it seems that this would do the trick (last line, bold face): # Enable the following two entries to enable samba startup from inetd # (from the Samba documentation).
GotW #97: Contracts, part 1 ? Assertions and postconditions
As WG21 continues work on contracts, I thought I?d join other WG21ers like Andrzej Krzemie?ski who are writing ?explainer? blog posts about various considerations related to contracts, and to draw attention to the existing work and papers like P0542. Assertions have been a foundational tool for writing understandable computer code since we could write computer … Continue reading GotW #97: Contracts, part 1 ? Assertions and postconditions →
Long Links
Happy new year! Welcome to the first Long Links of 2021; this is a monthly curation of long-form pieces that I, due to being semiretired, have time to read. Probably, most people reading this have less time, but perhaps one or two will add value even for a busy person. The last month of the year is an invitation to best-of pieces. Music is probably my chief recreation so I?m a sucker for for this kind of piece. In The New Yorker, Amanda Petrusich?s The Best Music of 2020 showed me a couple of musical paths I hadn?t been aware of.
More Microsoft pain
While editing our annual newsletter, I looked back to previous years. Our photography has really improved, and I felt inspired to go back and reprocess some of the worse ones. Prepared for processing on distress, the Microsoft ?Windows? 10 box. Boy, was it slow! It had been up for nearly a month, and was clearly running out of steam. OK, Microsoft solution: reboot. When it came back, it couldn't access the file systems on lagoon, including the photo disk! I had exactly this problem with eureka a month ago, but not with lagoon. Dammit, what is wrong with this horrible ?operating system??