Tag Archives: Mac OS X

Free Apple support

Imagine running a trillion dollar company that bundles various open source components into your products, making billions of dollars of profit annually. When one of your users reach out and ask for help, with the product you ship to your customers, you instead refer the user to the open source project. The project which is run by volunteers which you never sponsored with a cent.

Who would do something like that?

curl’s first twenty years on the mac

September 25, 2001 is the official release date for Mac OS X 10.1. Exactly twenty years ago today.

Mac OS X 10.1

This was the first macOS release from Apple that bundled curl. It was a complete surprise to me as well when I realized this had happened. Nobody had told me about it ahead of time. I don’t even recall anymore how I figured this out, as I’m not a mac user and I’ve never had any direct contact with the peeps at Apple Inc who were and are responsible for shipping curl on that platform. Not before then and not after that either.

The general consensus at the time seemed to be that Apple replaced Wget with curl due to licensing reasons as Wget had been included in their previous OS X release. Wget is licensed under GPL and curl comes under an MIT-like license. I’m not sure if they shipped libcurl too already at that point.

Various Apple products have been using libcurl over the years on several of their operating systems.

We ship source, they build and ship binaries

Apple downloaded our source code tarball, built curl from it and shipped it. (They also made the exact code they used available.) If I remember this correctly, they built curl against OpenSSL and shipped a version of that as well in the beginning.

In later macOS releases (you know they later changed the name of their OS from being Mac OS X to macOS), they’ve switched curl to use different TLS backends over time. At one point they converted over to using Secure Transport (their own native TLS library) only to somewhat later switch again and then to libressl – which is what the current most recent macOS version uses for curl’s default TLS backend.

curl 7.7.2

The original cURL logo

The original curl version they bundled in that first release had been released by us in April earlier that same year. It was our 55th curl release but curl was only a little over three years old at the time. It was a young project and it was just in the beginning phase of what it would become.

Early, not first

Apple was certainly early with shipping curl bundled with their operating system but they were not first. curl was already then provided to several Linux distributions. Apple might’ve been one if the first to ship it by default though.

I remember that it felt awesome and as some sort of recognition and acknowledgement of what we’ve done.

Other operating systems

During the early 2000s lots of operating systems would ultimately one by one start to package and provide curl for their platforms. Linux distributions and BSD flavors of course, but soon the legacy Unixes would also follow. If it wasn’t offered by the primary vendor, third party providers would very soon offer packages,

iOS

The third party license screen in iOS (click on the image shown on the right here for the full resolution version) includes the curl license, showing that Apple use it in iPhones and iPads. I don’t know for what.

Releases

Apple has kept updating curl in their subsequent operating updates and has done a somewhat reasonable job at keeping up with our releases. In their most up-to-date macOS version 11.5.2 (release date: August 11, 2021) they ship curl 7.64.1, released from us on 2019-03-27. Our 181st release. It has twenty-two known vulnerabilities.

This can be compared to Windows 10 which keeps shipping OS updates very frequently but is seemingly stuck with curl 7.55.1, released in August 2017.

Futile attempts to help

For a while I reported security issues we found (that would be relevant) to Apple product security ahead of time before our releases went public, to give them time to react and ship fixes, the same way we send alerts to free operating systems.

I stopped doing that because 1. the Apple security people always complained on me for giving them too short time to react (something like two weeks, which is also the maximum notification time allowed by others) and 2. Apple never released any quick updates as a reaction to my notifications anyway. It took them months or years, making my efforts pointless. Basically they were just rude.

Nothing in return

Neither me personally nor the project have ever gotten anything or any compensation from Apple. Nothing. Nada. Perhaps Apple using curl early on was somewhat of a stamp of approval for some, which helped persuade others that curl is a tool to trust. Perhaps.

Apple has not sponsored the project, not paid for feature development, not helped us with hardware and never paid for support. They don’t cooperate with us to help us fix Apple-specific issues nor do they ever report problems to us (which we know they must find occasionally). Apple users who run into problems with curl on Apple’s operating systems regularly contact the curl project to get us to help fix Apple’s products. For free of course. We never even get a thank you.

I have a mac these days (purchased with my own money) that I use to debug and test mac-specific issues and problems on.

Apple is of course far from alone is this almost predatory behavior, but this post is about curl’s twenty years of serving Apple customers. Also: yes curl is open source and the license allows them to do this. We continue to ship a product that runs perfectly on macOS and other Apple operating systems. They continue to ship curl bundled with their operating systems.

Future

The curl project has no drastic course-altering changes planned ahead and we’re not going away, so I believe the tool and library have the potential to continue being used on Apple products going forward as well. Possibly for a long time ahead. I have zero knowledge or visibility into that, so it’s just guessing on my part based on what’s been done in the past twenty years.

isalnum() is not my friend

The other day we noticed some curl test case failures, that only happened on macos and not on Linux. Curious!

The failures were detected in our unit test 1307, when testing a particular internal pattern matching function (Curl_fnmatch). Both targets run almost identical code but somehow they ended up with different results! Test cases acting differently on different platforms isn’t an extremely rare situation, but in this case it is just a pattern matching function and there’s really nothing timing dependent or anything that I thought could explain different behaviors. It piqued my interest, so I dug in.

The isalnum() return value

Eventually I figured out that the libc function isalnum(), when it got the 8 input value hexadecimal c3 (decimal 195), would return true on the macos machine and false on the box running Linux with glibc!

int value = isalnum(0xc3);

Setting LANG=C before running the test on macos made its isalnum() return false. The input became c3 because the test program has an UTF-8 encoded character in it and the function works on bytes, not “characters”.

Or in the words of the opengroup.org documentation:

The isalnum() function shall test whether c is a character of class alpha or digit in the program’s current locale.

It’s all documented – of course. It was just me not really considering the impact of this.

Avoiding this

I don’t like different behaviors on different platforms given the same input. I don’t like having string functions in curl act differently depending on locale, mostly because curl and libcurl can very well be used with many different locales and I prefer having a stable fixed behavior that we can document and stand by. Also, the libcurl functionality has never been documented to vary due to locale so it would be a surprise (bug!) to users anyway.

We’ve now introduced a private version of isalnum() and the rest of the ctype family of functions for curl. Hopefully this will make the tests more stable now. And make our functions work more similar and independent of locale.

See also: strcasecmp in Turkish.

poll on mac 10.12 is broken

When Mac OS X first launched they did so without an existing poll function. They later added poll() in Mac OS X 10.3, but we quickly discovered that it was broken (it returned a non-zero value when asked to wait for nothing) so in the curl project we added a check in configure for that and subsequently avoided using poll() in all OS X versions to and including Mac OS 10.8 (Darwin 12). The code would instead switch to the alternative solution based on select() for these platforms.

With the release of Mac OS X 10.9 “Mavericks” in October 2013, Apple had fixed their poll() implementation and we’ve built libcurl to use it since with no issues at all. The configure script picks the correct underlying function to use.

Enter macOS 10.12 (yeah, its not called OS X anymore) “Sierra”, released in September 2016. Quickly we discovered that poll() once against did not act like it should and we are back to disabling the use of it in preference to the backup solution using select().

The new error looks similar to the old problem: when there’s nothing to wait for and we ask poll() to wait N milliseconds, the 10.12 version of poll() returns immediately without waiting. Causing busy-loops. The problem has been reported to Apple and its Radar number is 28372390. (There has been no news from them on how they plan to act on this.)

poll() is defined by POSIX and The Single Unix Specification it specifically says:

If none of the defined events have occurred on any selected file descriptor, poll() waits at least timeout milliseconds for an event to occur on any of the selected file descriptors.

We pushed a configure check for this in curl, to be part of the upcoming 7.51.0 release. I’ll also show you a small snippet you can use stand-alone below.

Apple is hardly alone in the broken-poll department. Remember how Windows’ WSApoll is broken?

Here’s a little code snippet that can detect the 10.12 breakage:

#include <poll.h>
#include <stdio.h>
#include <sys/time.h>

int main(void)
{
  struct timeval before, after;
  int rc;
  size_t us;

  gettimeofday(&before, NULL);
  rc = poll(NULL, 0, 500);
  gettimeofday(&after, NULL);

  us = (after.tv_sec - before.tv_sec) * 1000000 +
    (after.tv_usec - before.tv_usec);

  if(us < 400000) {
    puts("poll() is broken");
    return 1;
  }
  else {
    puts("poll() works");
  }
  return 0;
}

Follow-up, January 2017

This poll bug has been confirmed fixed in the macOS 10.12.2 update (released on December 13, 2016), but I’ve found no official mention or statement about this fact.

Changing networks on Mac with Firefox

Not too long ago I blogged about my work to better deal with changing networks while Firefox is running. That job was basically two parts.

A) generic code to handle receiving such a network-changed event and then

B) a platform specific part that was for Windows that detected such a network change and sent the event

Today I’ve landed yet another fix for part B called bug 1079385, which detects network changes for Firefox on Mac OS X.

mac miniI’ve never programmed anything before on the Mac so this was sort of my christening in this environment. I mean, I’ve written countless of POSIX compliant programs including curl and friends that certainly builds and runs on Mac OS just fine, but I never before used the Mac-specific APIs to do things.

I got a mac mini just two weeks ago to work on this. Getting it up, prepared and my first Firefox built from source took all-in-all less than three hours. Learning the details of the mac API world was much more trouble and can’t say that I’m mastering it now either but I did find myself at least figuring out how to detect when IP addresses on the interfaces change and a changed address is a pretty good signal that the network changed somehow.