cURL and libcurl, Linux

The hack will still be useful

Okay, in my recent blog entry about Flash 10 using native libcurl I got a bit side-tracked and mentioned something about distros confusing libcurl’s soname 3 and 4. This caused some comments in that post and some further activities behind the curtains, so let me spell out exactly what I mean:

The ABI for libcurl did change between soname 3 and 4, but the change was in a rather subtle area (FTP third party transfers, sometimes known as FXP) which is rarely used. It certainly will not hurt the Adobe Flash system.

I’m not against “the hack” (or perhaps “a hack” as there are several ways an ordinary system could provide work-arounds or fixes for this problem) per-se, I am mainly trying to fight the belief or misconception that the ABI break doesn’t exist.

Since Adobe doesn’t want to provide an updated package that links against a modern libcurl and refuses to provide multiple packages, distros of course need to address this dilemma.

I just want all to know that 3 != 4, even if the risk that it’ll cause problems is very slim.

Update: it seems Adobe will change this behavior in their next release and then try to load either 3 or 4.

cURL and libcurl, Open Source

CA cert bundle from Firefox

It could be interesting to note that extracting all the cacerts from your local Firefox installation isn’t that tricky, if you just use some of the magic that are at hand with the NSS certutil tool.

Users of OpenSSL or GnuTLS based tools or libraries (such as libcurl) might be pleased to learn this.

curl users in general of course should be aware that we no longer ship any ca-cert bundle with curl (as of curl 7.18.1), as it seems some ports haven’t yet updated or discovered this.

Update: this script is now present as lib/firefox-db2pem.sh in the curl CVS repository.

Rockbox

A talk that won’t happen

2 Comments

I had already talked to the guys about going to FSCONS 2008 and do a talk about Rockbox and reverse engineering when I realized that the very same weekend we’re going to Rome, Italy with my company and if that isn’t enough, the Google summer of code mentor summit is also taking place that weekend in late October so if Italy somehow got canceled I would probably rather go to California… I quite enjoyed FSCONS last year so I’m a bit annoyed about this situation.

Isn’t that just the irony of life? Here I have an entire autumn with nothing much planned and then all of a sudden three events all take place on the same weekend.

I’m still on for another talk in September in Stockholm though but since I haven’t seen any public details about it I’ll refrain from being specific just yet.

Blogging, cURL and libcurl, Rockbox, Technology, Web

Site deadness

When I got to work this morning I immediately noticed that one of the servers that host a lot of services for open source projects I tend to play around with (curl, Rockbox and more), had died. It responded to pings but didn’t allow my usual login via ssh. It also hosts this blog.

I called our sysadmin guy who works next to the server and he reported that the screen mentioned inode problems on an ext3 filesystem on sda1. Powercycling the machine did nothing good but the machine simply didn’t even see the hard drive…

I did change our slave DNS for rockbox.org and made it point to a backup web server in the mean time, just to make people aware of the situation.

Some 12 hours after the discovery of the situation, Linus Nielsen Feltzing had the system back up again and it’s looking more or less identical to how it was yesterday. The backup procedure proved itself to be working flawlessly. Linus inserted a new disk, partitioned similar like the previous one, restored the whole backup, fixed the boot (lilo) and wham (ignoring some minor additional fiddling) the server was again up and running.

Thanks Linus!

Development, Open Source

popen() in pthreaded program confuses gdb

1 Comment

I just thought I’d share a lesson I learned today:

I’ve been struggling for a long time at work with a gdb problem. When I set a break-point and then single-step from that point, it sometimes (often) decides to act as if I had done ‘continue‘ and not ‘next‘. It is highly annoying and makes debugging nasty problems really awkward.

Today I searched around for the topic and after some experiments I can now confirm: if I remove all uses of popen() I no longer get the problems! I found posts that indicated that forking could confuse threaded programs, and since this program at work uses threads I could immediately identify that it uses both popen() and system() and both of them use fork() internally. (And yes, I believe my removal of popen() also removed the system() calls.)

And now I can finally debug my crappy code again to become less crappy!

My work PC runs glibc 2.6.1, gcc 4.1.3 and gdb 6.6. But I doubt the specific versions matter much.

Development, IT Politics, Web

Standardized cookies never took off

David M. Kristol is one of the authors of RFC2109 and RFC2965, “HTTP State Management Mechanism”. RFC2109 is also known as the first attempt to standardize how cookies should be sent and received. Prior to that document, the only cookie spec was the very brief document released by Netscape in the old days and it certainly left many loose ends.

Mr Kristol has published a great and long document, HTTP Cookies: Standards, Privacy, and Politics, about the slow and dwindling story of how the work on the IETF with the cookie standard took place and how it proceeded.

Still today, none of those documents are used very much. The original Netscape way is still how cookies are done and even if a lot of good will and great efforts were spent on doing things right in these RFCs, I can’t honestly say that I can see anything on the horizon that will push the web world towards changing the cookies to become compliant.

Licensing, Rockbox

Rockbox is mainly GPL v2 or later

I just wanted to express this loud and clearly:

At the Rockbox devcon back in June, we discussed this issue and we did deem the Rockbox license to be “GPL v2 or later”, so during this summer we have updated the Rockbox source code headers pretty much all over to reflect this fact. (Previously we had a bit of flux where the exact “v2” or “v2 or later” status wasn’t expressed.)

Of course we have not (and should not) change the headers for files we have imported into the project, and there are still pieces in Rockbox that are plain GPLv2 (without the “or later”) like a few snippets that origin from the Linux kernel.

We also did receive permission from Bernard Leach, the main ipodlinux kernel hacker, to put his code under the “v2 or later” label as well.

The net result is of course that Rockbox is GPLv2 but with the largest parts v2 or later.

Rockbox

cURL and libcurl, Linux, Web

Flash 10 uses native libcurl

5 Comments

In Adobe’s Penguin.SWF blog, we can learn some details about the upcoming version 10 of the Adobe flash player for Linux:

They’ll rely on more libraries to be present in the system rather than provide them all by themselves in their own install. This apparently includes libcurl.

So if you get the RPM of the pre-release player, you’ll notice that it requires “libcurl.so.3” which is the old SONAME for libcurl (libcurl 7.15.5 was the last release which used the number 3) which no up-to-date distribution should provide anymore. Since october 2006 we’ve shipped libcurl.so.4.

Apparently, this made the Fedora people first implement a work-around for this that re-introduces the SONAME 3 from the same source the SONAME 4 is made from, only to a short while afterwards revert that decision…

An interesting side-note is how the Fedora people repeat over and over in those threads that libcurl with SONAME 3 and SONAME 4 use the same ABI, although that is not true (at least not by my definition of what an ABI is). The bump was not accidentally made.

Update: it seems some blame this 3 == 4 thing on Debian…

cURL and libcurl, libssh2, Open Source

Projects in need of your help

I’m involved in numerous projects, and a subset of them take a lot of my “copious” spare time. This has the unfortunate downside that a few other projects get left behind a bit. Projects that also really could use with some more attention and improvements. Two of the most obvious examples of this are c-ares and libssh2. Coincidentally, both of these projects are also used by libcurl (although of course also by others).

c-ares is a library that performs asynchronous DNS lookups. It is quite mature and functional already, as it is based on the ares project and has been proved in use for quite some time. There are currently one or two issues that have appeared recently when the Debian project tried to provide the curl package built with c-ares…

libssh2 is a client library for talking SSH2 with servers. There are actually not very many SSH libraries “out there”, and in an evaluation I did a few years ago libssh2 was the best one around. libcurl uses libssh2 for SCP and SFTP transfers, and it (libssh2) does suffer from a few API flaws, a few bugs and perhaps most noticably it is significantly slower than the openssh tools in just about all transfer tests.

I’m still highly involved in both of these projects, but lack of time prevents me from participating as much as I’d like to.

cURL and libcurl, Licensing, Linux

Two fellow curl hackers

During many years I was really and truly the primary and almost single developer of curl and libcurl. Sure we’ve always got a steady stream of quality patches by contributors but I was the single guy who cared for the whole picture and who took on greater work to advance the project.

This is no longer the case. These days there are more people around that bite the really big bullets and who show that they know a lot about the internals, the protocols and have a feel and understanding for the general ideas and concepts of the project. I think they get too little attention, so I thought I’d put the light on two of our bright hackers that really are true rocks in the community:

Daniel Fandrich first appeared on the curl-library list in April 2003. More than 1500 email posts later, he’s a knowledgeable, friendly and skilled contributor in just about all areas of curl and libcurl.

Yang Tse appeared on the curl-users list in September 2005 and has somewhat specialized in cleaning up dusty corners of the code. Redoing things The Right Way, fixing compiler warnings and fixing up configure checks so that the code runs all over as it is supposed to.

These are two of our valuable committers. Ohloh.net counts 10 committers during the last 12 months, which puts us within the top 10% of all project teams on Ohloh!

But as I mentioned above, the curl development is largely built upon patches provided by people who send in one or two patches and never appear in the project again. We have over 650 named contributors and the list keeps growing at a steady pace all the time.

You can be our next contributor or even committer. Just join us and help out!

curl, open source and networking