expat 2.2.2 fails to build on Snow Leopard -- missing arc4random_buf

[gnw3]

lib/xmlparse.c:56:3: error: #error You do not have support for any sources of high quality entropy enabled. For end user security, that is probably not what you want. Your options include:
 * Linux + glibc >=2.25 (getrandom): HAVE_GETRANDOM,
 * Linux + glibc <2.25 (syscall SYS_getrandom): HAVE_SYSCALL_GETRANDOM, 
 * BSD / macOS (arc4random_buf): HAVE_ARC4RANDOM_BUF,
 * libbsd (arc4random_buf): HAVE_ARC4RANDOM_BUF + HAVE_LIBBSD,
 * Windows (RtlGenRandom): _WIN32. 
If insist on not using any of these, bypass this error by defining XML_POOR_ENTROPY; you have been warned. For CMake, one way to pass the define is: cmake -DCMAKE_C_FLAGS="-pipe -O2 -DHAVE_SYSCALL_GETRANDOM" . If you have reasons to patch this detection code away or need changes to the build system, please open a bug. Thank you!

A workaround is to append -DXML_POOR_ENTROPY to CPPFLAGS in the generated Makefile.

[udbraumann]

The same error occurs on 10.5.8 PPC. Does it mean that the respective Xcode is too old to have an acceptable arc4random, or is it missing at all?

[ryandesign (Ryan Carsten Schmidt)]

It's the operating system (not Xcode) that's missing arc4random_buf.

I'll see what we can do about this.

[udbraumann]

Thanks. expat 2.2.1_1 however could be built on 10.5.8, so the requirements must have changed very recently.

[ballapete (Peter "Pete" Dyballa)]

And, needless to mention, the same also happens on PPC Tiger, Mac OS X 10.4.11.

[ballapete (Peter "Pete" Dyballa)]

main.log from PPC Tiger

[ballapete (Peter "Pete" Dyballa)]

The supplied patch file fixes the build of expat 2.2.2.

[ballapete (Peter "Pete" Dyballa)]

Work around missing system functions

[kencu (Ken)]

Perhaps this is something that could/should be added to snowleopardfixes as well, to get the proper functionality.

arc4random.c is available on apple open source.

[ballapete (Peter "Pete" Dyballa)]

Replying to kencu:

arc4random.c is available on apple open source.

The needed funktion is arc4random_buf().

[kencu (Ken)]

Yep; that, and about 10 related, are all in that one C file.

[ryandesign (Ryan Carsten Schmidt)]

Replying to ballapete:

The supplied patch file fixes the build of expat 2.2.2.

I don't want to add -DXML_POOR_ENTROPY unconditionally, only when building for 10.6 or earlier.

See also the ​upstream bug report and ​pull request that might solve this better in a future version of expat.

[ryandesign (Ryan Carsten Schmidt)]

In b2b6b1e03b126df77195029670197b7ce1396f32/macports-ports:

expat: Work around build failure on 10.6 and earlier

Acknowledge lack of arc4random_buf.

Closes: #54474

[ryandesign (Ryan Carsten Schmidt)]

Has duplicate #54503.

[ballapete (Peter "Pete" Dyballa)]

It built on Mac OS X 10.6.8, Snow Leopard.

[ballapete (Peter "Pete" Dyballa)]

It also built on PPC Tiger, Mac OS X 10.4.11.